Dissertations / Theses on the topic 'Recombinase protein'
To see the other types of publications on this topic, follow the link: Recombinase protein.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Recombinase protein.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Liu, Siyu. "Dynamics of Rad51 during homologous recombination in living yeast." Electronic Thesis or Diss., Université Paris sciences et lettres, 2022. http://www.theses.fr/2022UPSLS050.
Full textAbstract:
L'ADN est le principal vecteur d'information génétique et son intégrité est vitale pour la survie des cellules. Pourtant, l'ADN est sous la pression des dommages causés par des facteurs exogènes et endogènes. Les cassures double brin (CDB) sont parmi les dommages les plus toxiques puisqu’une CDB non réparée peut être léthale. Les cellules ont développé plusieurs voies pour réparer les CDB, dont la jonction d'extrémités non homologues (NHEJ) et la recombinaison homologue (RH). RH est une voie de réparation fidèle qui utilise une séquence homologue intacte comme modèle pour réparer les dommages. Cela implique d'identifier la séquence homologue parmi les mégabases du génome et dans le volume nucléaire des cellules eucaryotes. Au niveau moléculaire, la recherche d’homologie de l'ADN et l'invasion de l’ADN double brin homologue sont réalisées par un filament nucléoprotéique (NPF), formé par la recombinase, RecA chez les bactéries et Rad51 chez les eucaryotes, associée à l'ADN simple brin flanquant la CDB. Ce mécanisme a été largement étudié in vitro et in vivo par des approches génétiques et moléculaires au niveau des populations cellulaires, mais sa dynamique n'a pas pu être étudiée dans les cellules vivantes faute de version fluorescente fonctionnelle de Rad51. Ainsi, comment l'ADN brisé peut-il trouver une séquence homologue dans le volume du noyau et parmi les mégabases d'ADN reste mystérieux.Sur la base d’études structurales, en collaboration avec Raphael Guerois (I2BC, CEA, France), nous avons développé et caractérisé la première version fonctionnelle étiquetée d'une recombinase chez la levure S. cerevisiae.Suite à l'induction de DSB unique, nous observons pour la première fois dans des cellules vivantes, Rad51 formant des filaments pouvant atteindre un ou deux microns de longueur et traverser le volume du noyau pour contacter une séquence homologue. Comme prédit par des études génétiques et des données obtenues in vitro, leur formation nécessite le chargeur de recombinase Rad52 et la formation d'un long fragment d'ADNsb. De plus, les filaments Rad51 adoptent une variété de formes qui sont modulées par des facteurs auxiliaires de Rad51, apportant un nouvel éclairage sur la fonction de ces facteurs dans les cellules vivantes.Contrairement à ce qui a été rapporté pour les filaments RecA chez les bactéries, les filaments Rad51 montrent un comportement étonnamment dynamique : avec de fréquents événements de compaction suivis d’une ré-extension offrant des opportunités pour le filament d'être projeté dans une zone nucléaire différente, et ainsi d'explorer de nouvelles régions génomiques. La modélisation biophysique du processus de recherche d'homologie par notre collaborateur Leonid Mirny (MIT, USA) révèle que ces cycles de compaction/extension constituent une stratégie très robuste pour qu'une identité unique trouve sa cible dans l'espace nucléaireDNA is the major carrier of genetic information in prokaryotic and eukaryotic cells and its integrity is vital for the survival of cells. However, DNA is under pressure of damages caused by both exogenous and endogenous factors. Double strand break (DSB) is one of the most toxic DNA damages and even one unrepaired DSB is lethal to cells. Cells have evolved several pathways to repair DSBs, including non-homologous end joining (NHEJ), and homologous recombination (HR). HR is an error free repair pathway that uses an intact homologous sequence as a template to repair the damage. This involves identifying the homologous sequence among the mega bases of the genome and in the nuclear volume of eukaryotic cells. At the molecular level, DNA sampling and strand invasion of the homologous dsDNA is achieved by a nucleoprotein filament (NPF), formed by the recombinase, RecA in bacteria and Rad51 in eukaryotes, coating ssDNA. This mechanism has been extensively studied in vitro and in vivo through genetic and molecular approaches at the level of cell populations, but its dynamics could not be studied in living cells due to lack of functional fluorescent version of Rad51. Thus, how broken DNA can find a homologous sequence in the volume of the nucleus and among the megabases of DNA remains mysterious.Thanks to structural insights from our collaborator Raphael Guerois (I2BC, CEA, France), we developed and characterized the first functional, internally tagged version of a recombinase in the yeast S. cerevisiae. Following the induction of unique DSB, we observe for the first time in living cells, Rad51 forming micrometer long filaments spanning across the whole nucleus and contacting the donor sequence. As predicted from genetic and in vitro data, their formation requires the recombinase loader Rad52 and the formation of long stretch of ssDNA. Furthermore, emerging filaments adopt a variety of shapes, not reported in vitro and modulated by Rad51 ancillary factors, shedding new light on the function of these factors in living cells.In contrast to what has been reported for RecA filaments in bacteria, Rad51 filaments show a surprisingly dynamic behavior: with frequent compaction events followed by re-extension providing opportunities for the NPF to be projected into a different nuclear area, and thus explore new genomic regions. Biophysical modeling of the homology search process by our collaborator Leonid Mirny (MIT, USA) reveals that these cycles of compaction/extension constitute a very robust strategy for a unique identity to find its target in the nuclear space
2
Zhekov, Ivailo. "Dissection of a functional interaction between the XerD recombinase and the DNA translocase FtsK." Thesis, University of Oxford, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.572642.
Full textAbstract:
Successful bacterial circular chromosome segregation requires that any dimeric chromosomes, which arise by crossing over during homologous recombination, are converted to monomers. Resolution of dimers to monomers requires the action of the XerCD site-specific recombinase at dif in the chromosome replication terminus region. This reaction requires the DNA translocase, FtsK(C), which activates dimer resolution by catalysing an ATP hydrolysis-dependent switch in the catalytic state of the nucleoprotein recombination complex. We show that a 62-amino-acid fragment of FtsK(C) interacts directly with the XerD C-terminus in order to stimulate the cleavage by XerD of BSN, a dif-DNA suicide substrate containing a nick in the 'bottom' strand. The resulting recombinase-DNA covalent complex can undergo strand exchange with intact duplex dif in the absence of ATP. FtsK(C)-mediated stimulation of BSN cleavage by XerD requires synaptic complex formation. Mutational impairment of the XerD-FtsK(C) interaction leads to reduction in the in vitro stimulation of BSN cleavage by XerD and a concomitant deficiency in the resolution of chromosomal dimers at dif in vivo, although other XerD functions are not affected.
3
Corbett, Sybilla Louise. "Nanoscale patterning of complex DNA structures with the bacterial protein Recombinase A." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/15373/.
Full textAbstract:
The use of DNA as a structural material has been intensively developed since its inception in the early 1980s. The potential of DNA structures in the field of materials science is hampered by current approaches to augmentation. It is not currently possible to alter the targeting of heterogenous additional elements to structures once they have been made. The post hoc patterning of DNA architectures is therefore of great importance. The bacterial protein Recombinase A (RecA) may be able to provide this function. This thesis will discuss the patterning of DNA structures with RecA. RecA has been shown to pattern linear dsDNA strands with high levels of efficiency. To test the potential of RecA to pattern more complex DNA, novel strategies for creating DNA topologies have been explored. This work has produced DNA strands containing regions of base pair mismatching and with terminal three-way junctions. A method has also been developed for the creation of a 200 base product with unpaired branched junctions, using four synthetic oligomers in a scaffolded cycling ligation reaction with a heat stable ligase. A method to create longer DNA strands with three-way junctions at the termini has also been developed. RecA patterning of a structure with internal mismatches was carried out. Mismatches proximal to the patterning area led to an increase in patterning efficiency with an increase in mismatch length. When the mismatch was separated from the patterning region a more complex relationship was observed, with intermediate-length mismatches resulting in a decrease in pattering efficiency. The introduction of a nick in the phosphate backbone proximal to the patterning region also increased patterning efficiency. Two further DNA structures were produced on which patterning did not prove possible. The ligase chain reaction was shown to produce DNA strands that could be incorporated into a structure with central base pairing and terminal single stranded DNA regions. Attempts to create three-way junctions from these structures were not successful. A second structure was created through treatment of double stranded DNA from the polymerase chain reaction. Single strands of DNA were produced that could be annealed to produce terminal three-way junctions. Atomic force microscopy demonstrated the correct annealing of this structure. However, it did not prove possible to pattern these structures with RecA. Recombinant RecA production through bacterial induction produced soluble protein at a high yield. There was some evidence of DNA contamination and the purified protein showed low activity.
4
Yu, David Sung-wen. "Role of the BRCA2 breast cancer susceptibility protein in control of RAD51 recombinase." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620033.
Full text
5
Bates, D. L. "Control of the RAD51 recombinase by the BRC repeat motifs in the breast cancer susceptibility protein BRCA2." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596469.
Full textAbstract:
The interaction between the breast cancer susceptibility protein BRCA2 and the RAD51 DNA recombinase is essential for DNA repair via homologous recombination. Its disruption in human cells causes genomic instability and cancer predisposition. Studies to define the biochemical and biological features of the BRCA2:RAD51 interaction are described. Human BRCA2 features eight BRC repeat motifs encoded within exon 11 through which it can bind RAD51. The BRC repeat motifs are believed to mimic and disrupt RAD51 oligomerisation at its self-association interface. I defined the minimal structural determinants required for RAD51 binding by ‘humanising’ a primitive RAD51 from an Archaeon species lacking BRCA2. Surface Plasmon Resonance (SPR) technology supported by cell biology was employed to study the characteristics of RAD51 binding to each of the BRC repeat motifs, both independently and collectively within the context of the BRCA2 protein. A single point mutation within an individual BRC repeat motif impaired RAD51 binding. Further, RAD51 was unable to interact effectively with a BRC repeat motif in which the proposed interaction interface had been disrupted by mutagenesis. Kinetic data for the interaction of an individual BRC repeat motif with RAD51 were obtained. An SPR competition assay was developed, revealing that the binding affinity of each BRC repeat motif for RAD51 differs significantly, and that their organisation within the scaffold of BRCA2 contributes to efficient interaction. Thus, I propose that both the differential binding affinities of the individual BRC repeat motifs for RAD51, and their observed cooperativity, contribute to the control of RAD51 by BRCA2. The implications of this proposal for DNA repair via homologous recombination, and for the role of BRCA2 mutations in human carcinogenesis, are discussed.
6
Amero, Carlos D. "Protein Function Study by NMR Spectroscopy." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1205431343.
Full text
7
Ghorbal, Mehdi. "Caractérisation biochimique, fonctionnelle et structurale de l'integrase Pf-Int de plasmodium." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00685428.
Full textAbstract:
Plasmodium falciparum est un parasite protozoaire responsable de la forme la plus sévère de la malaria. Depuis quelques années, les cas de résistance aux antipaludiques sont devenus de plus en plus fréquents et de plus en plus répandus. En plus de sa résistance aux drogues actuellement disponibles, ce parasite reste jusqu' à aujourd'hui réfractaire aux vaccinations. L'identification de nouvelles approches basées sur l'inhibition spécifique de certaines de ses cibles moléculaires vitales est devenue une nécessité. La recombinase à site spécifique de P. falciparum (Pf-Int) est un enzyme qui a été récemment identifié dans le laboratoire à partir de PlasmoDB. Cette recombinase à site spécifique joue potentiellement un rôle clé dans le système de recombinaison nécessaire à la viabilité du parasite. Cette protéine de 490 acides aminés, soit ~57 kDa, contient une région C-terminale qui porte les résidus conservés du site catalytique des recombinases à tyrosine R-H-K-R-(H/W)-Y. La prédiction montre une région N-terminale qui ressemble à celle de l'intégrase du phage lambda avec un mélange de structures secondaires α et β.Lors de ces travaux, nous avons d'abord montré par RT-PCR que le gène (MAL13P1.42) qui code pour PF-Int est transcrit pendant le cycle intra-érythrocytaire avec un maximum pendant la phase schizont. Nous avons ensuite essayé de montrer l'implication de Pf-Int dans le cycle parasitaire. Ceci a été réalisé grâce à un parasite (KO: knock-out) dont le gène Pf-Int a été invalidé. Ces analyses montrent que Pf-Int n'a aucun impact apparent sur le cycle de développement intra-érythrocytaire du parasite, en particulier sur la durée du cycle et le taux de croissance. Au niveau moléculaire, nous avons également procédé à la production d'anticorps anti-Pf-Int en utilisant le fragment C-162 (Résidus 162-490). La comparaison des profils de marquage, par cet anticorps, des extraits protéiques du KO et du parasite sauvage par la technique de Western blot n'a pas permis d'identifier la protéine endogène dans le parasite sauvage. Dans le but de déterminer la localisation sub-cellulaire de Pf-Int, nous avons réalisé des essais de sur-expression de différentes protéines de fusion dans le parasite. Nous avons essayé de déterminer l'impact de trois codons d'initiation différents ainsi que l'impact de la présence de la région N-terminale (1-190aa) de Pf-Int sur sa localisation subcellulaire en utilisant une chimère entre la partie N-terminale et la protéine GFP. Lors de ces travaux, nous avons réussi à sur-exprimer différentes régions de Pf-Int sous forme recombinante dans E. coli. Nous l'avons d'abord caractérisé par des études biophysiques. Ainsi nous avons pu déterminer, par dichroïsme circulaire (CD), le contenu en structures secondaires de Pf-Int, qui est proche de celui des autres membres de la même famille. Nous avons également démontré sa stabilité par CD couplé à la dénaturation thermique. Le spectre RMN-1D a aussi pu être enregistré. La troisième partie de nos travaux a concerné l'identification des cibles ADN de Pf-Int. Deux stratégies de recherche de cibles par affinité ont été utilisées au laboratoire en utilisant une première bibliothèque de séquences synthétisées chimiquement et une deuxième bibliothèque formée de fragments d'ADN génomique de P. falciparum. Ces deux approches ont permis l'identification de deux séries de cibles ADN. Grace aux cibles ADN identifiées, nous avons pu démontrer l'interaction de différents fragments de Pf-Int avec ces cibles par des expériences de retard sur gel natif (EMSA). Nous avons aussi pu démontrer que les protéines recombinantes sont actives in vitro. En effet, ces dernières sont capables de former des complexes covalents en présence de l'ADN cible. La conservation de la protéine, ainsi que son expression différentielle nous laisse à penser que son rôle est certes loin d'être élucidé, mais que Pf-Int reste une cible potentielle pour P. falciparum.
8
Koscky, Paier Carlos Roberto 1983. "Padronização da expressão heterologa e de modelo de ensaio de atividade para a proteina quinase humana S6K." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/314787.
Full textAbstract:
Orientador: Nilson Ivo Tonin ZanchinDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-14T12:40:52Z (GMT). No. of bitstreams: 1 KosckyPaier_CarlosRoberto_M.pdf: 3760581 bytes, checksum: 99331529324819b59a4360d60efd9b9a (MD5) Previous issue date: 2009
Resumo: A quinase de 70 kDa da proteína ribossomal S6, isoforma 1 (S6K1), é uma fosfoproteína implicada na regulação de genes relacionados ao controle da tradução em mamíferos e possui uma forma nuclear (a1) e uma citoplasmática (a2). A fosforilação do seu principal alvo, a proteína RPS6, tem sido comumente associada ao recrutamento seletivo dos 5'-TOP (5' tract of oligopyrimidine) mRNAs pela maquinaria de tradução, embora haja estudos contrariando esta hipótese. Devido às funções de seus demais alvos, S6K1 tem sido implicada na sobrevivência celular e em diversos outros processos, como crescimento, câncer e resistência à insulina. S6K1 é ativada por um mecanismo que envolve fosforilação seqüencial através da ativação das vias mTORC1 (complexo 1 do alvo da rapamicina em mamíferos) e PI3K (fosfoinositol-3 quinase). Como uma quinase da família AGC, S6K1 deve ser fosforilada por mTORC1 no resíduo Thr389 do domínio hidrofóbico e, em seguida, por PDPK1 (proteína quinase 1 dependente de fosfoinositol) no resíduo Thr229 da alça T do domínio catalítico. Estes eventos ocorrem somente após a fosforilação em diversos sítios do domínio auto-inibitório carboxiterminal, por mTORC1. O objetivo deste trabalho foi desenvolver um ensaio modelo para análise da função da S6K1 in vitro e utilizá-lo como ferramenta na elucidação do papel de proteínas adaptadoras da via de mTOR em interações com a S6K1. Para isso foi necessário produzir as proteínas recombinantes para ensaios de interação e para realização de um ensaio de atividade para a S6K1. Foram testados vários sistemas de expressão para Escherichia coli para produção das construções GST-S6K1a1-His6, GST-S6K1a2-His6 e GST-S6K1a2T389E?CT (forma a2 de S6K1 com a substituição T389E e o carboxiterminal truncado), GST-PDPK1 e GST-CDPDPK1 (domínio catalítico de PDPK1 fusionado a GST). A expressão das formas truncadas de S6K1 e PDPK1 foi mais eficiente em E. coli. Embora o rendimento tenha ficado muito aquém do esperado, foi suficiente para os ensaios de interação in vitro. Também foi feita a expressão em E. coli da região C-terminal da proteína RPS6, que é o substrato da S6K1, em fusão com a proteína D do fago ?. Posteriormente, foram montados sistemas de expressão das construções His6-S6K1a2T389E?CT e His6-CDPDPK1 em células de inseto, a partir de vetor de baculovírus. Constatou-se que essas construções são expressas na forma de fosfoproteínas em células de inseto. Ensaios de GST pull-down com GST-S6K1a2-His6 e GST-S6K1a2T389E?CT contra as duas isoformas da subunidade catalítica da PP2AC, His6-PP2ACa(maior) e His6-PP2ACa(menor), revelaram que His6-PP2ACa(maior) não interage com GST-S6K1a2-His6, embora interaja fortemente com GST-S6K1a2T389E?CT. Já a construção His6-PP2ACa(menor) interage fracamente com as construções GST-S6K1a2-His6 e GST-S6K1a2T389E?CT. Tomados em conjunto, os resultados sugerem que a presença do C-terminal não fosforilado de S6K1a2 impede a interação com PP2ACa(maior). PP2ACa(menor) comporta-se de forma completamente diferente da isoforma maior, pois a interação entre PP2ACa(menor) e S6K1a2 parece ser independente do carboxiterminal da quinase, visto que as quantidades de S6K1a2T389E?CT e de S6K1a2 inteira que interagem com PP2ACa(menor) são semelhantes. Esses resultados necessitam ainda serem confirmados in vivo. Outros experimentos de GST pull-down confirmaram que as construções de S6K1 não interagem com a4, embora interajam com TIPRL1. Se confirmado in vivo, esse resultado compõe um novo quadro na regulação coordenada entre mTOR1 e PP2A, do qual TIPRL1 parece participar. As construções genéticas e os sistemas de expressão gerados neste trabalho possibilitaram a obtenção dos reagentes necessários para analisar o mecanismo de regulação da quinase S6K1, mediado por proteínas regulatórias. Permitem também desenvolver uma série de experimentos, como busca de inibidores específicos para a S6K1, que dependem da reconstituição de ensaios de atividade in vitro com a S6K1 ativada. Contudo, o ensaio de atividade realizado não apresentou resultados satisfatórios e precisa ser desenvolvido.
Abstract: The 70kDa ribosomal S6 protein kinase 1 (S6K1) is a phosphoprotein involved in the regulation of genes related to translational control in mammals. S6K1 shows distinct nuclear (a1) and cytoplasmic (a2) forms. Phosphorylation of the S6K1 best characterized target, the protein of the small ribosomal subunit (RPS6), has been generally associated to the selective recruitment of the 5'-TOP mRNAs (5' tract of oligopyrimidine) by the translational machinery, although there is still some controversy on this issue. Due to the function of its targets, S6K1 has been implicated in several cellular processes including cell growth, cancer and insulin resistance. S6K1 is activated by a mechanism of sequential phosphorylation following activation of the mTORC1 (mammalian target of rapamycin complex 1) and PI3K (phosphoinositide-3-kinase) pathways. As a kinase of the AGC family, S6K1 activation requires mTORC1 phosphorylation of residue Thr389 of the hydrophobic domain followed by PDPK1 (phosphoinositide dependent protein kinase 1) phosphorylation of residue Thr229 at the T loop of the catalytic domain. These take place only after phosphorylation by mTORC1 of several residues of the autoinhibitory C-terminal domain. The objective of this work was to develop an assay to analyze the function of S6K1 in vitro and use it as a tool in the discovering of the functions of regulators proteins of the mTOR cascade in interactions with S6K1. For these purposes, expression systems were constructed to produce the various recombinant proteins to be used in the interaction and activity assays. Several genetic constructions were tested in Escherichia coli for the production of GST-S6K1a1-His6, GST-S6K1a2-His6 and GST-S6K1a2T389E?CT (a2 form of S6K1 with the T389E substitution and truncated carboxiterminus), GST-PDPK1 and GST-CDPDPK1 (GST fusion protein of the catalytic domain of PDPK1). The truncated forms were expressed more efficiently in E. coli. Although the yield in E. coli was lower than expected, it was sufficient to perform interaction assays. The C-terminal domain of RPS6, a substrate for S6K1, was successfully expressed in E. coli as a fusion protein with the phage ? protein D. Subsequently, expression systems for production of His6-S6K1a2T389E?CT and His6-CDPDPK1 in insect cells were constructed using baculovirus vectors. It was found that these constructs are expressed in the form of phosphoproteins in insect cells. GST pull-down assays using GST-S6K1a2-His6 e GST-S6K1a2T389E?CT to test interaction with the PP2AC isoforms His6-PP2ACa(major) and His6-PP2ACa(minor) revealed that His6-PP2ACa(major) does not interact with GST-S6K1a2-His6, although it interacts strongly with GST-S6K1a2T389E?CT. On the other hand, His6-PP2ACa(minor) interacts weakly with both GST- S6K1a2-His6 and GST-S6K1a2T389E?CT. This finding suggests that the unphosphorylated C-terminal of S6K1a2 inhibits interaction with PP2ACa(major). His6-PP2ACa(minor) behaves differently form His6-PP2ACa(major). Its interaction with S6K1a2 seems to be independent of the C-terminal since the amounts of S6K1a2T389E?CT and S6K1a2 that interact with His6-PP2ACa(minor) are similar. Future work in vivo is required to confirm these results. GST pull-down assays confirmed that a4 does not interact with the constructions of S6K1, while TIPRL1 interacts with them. If confirmed in vivo, these results provides a new perspective for the coordinated regulation between mTOR1 and PP2A, which apparently involves also TIPRL1. The genetic constructions and expression systems established in this work allow the production of the reagents required to study the mechanism of S6K1 regulation mediated by adaptor proteins. They will also allow the development of experiments such as screening for specific S6K1 inhibitors, which depend on reconstitution of S6K1 activity assays using activated S6K1. Nevertheless, the activity assay performed did not yield satisfactory outcomes and must be improved.
Mestrado
Bioquimica
Mestre em Biologia Funcional e Molecular
9
Lu, Yang. "Functional studies of new protein-protein interactions potentially involved in homologous recombination in hyperthermophilic archaea : study of interactions between PCNA and Mre11-Rad50 complex & Primase and RadA." Thesis, Brest, 2018. http://www.theses.fr/2018BRES0077/document.
Full textAbstract:
Les archées hyperthermophiles ont une température optimale de croissance supérieure à 80°C.Les cellules exposées à un stress thermique subissent une augmentation de la sensibilité aux agents induisant des cassures double brin de l’ADN. Les études sur les eucaryotes et bactéries ont démontré que la recombinaison homologue joue un rôle essentiel non seulement dans la réparation de l’ADN, mais aussi dans le redémarrage des arrêts de la fourche de réplication. Les enzymes associées aux étapes initiales de la recombinaison homologue chez les archées sont homologues à celles des eucaryotes, et différentes des analogues bactériens. De plus, plusieurs études ont démontré que les protéines impliquées dans la recombinaison homologue sont essentielles chez les archées hyperthermophiles, soulignant l’importance biologique de cette voie de réparation chez ces organismes particuliers. Le rôle de la recombinaison homologue pour la stabilité génomique a été bien étudié chez les eucaryotes et les bactéries, cependant, peu de ses propriétés fonctionnelles ont été étudiées chez les archées hyperthermophiles. Pour mieux comprendre le mécanisme de recombinaison homologue impliquée au niveau de la maintenance génomique chez les archées, un réseau d’interactions protéine-protéines a été révélé précédemment au laboratoire à partir des protéines de Pyrococcus abyssi. Ces travaux ont démontré de nouvelles interactions où interviennent les protéines de la réplication et les protéines de la recombinaison de l’ADN. L’objet de cette étude de thèse est de présenter deux interactions : PCNA/Mre11-rad50 (MR) complexe et Primase/RadA. Pour la première fois chez P. furiosus, une interaction physique et fonctionnelle a été démontrée entre le PCNA et le complexe MR (l’initiateur de HR). Un motif, situé en position Cterminale de Mre11, permet l’interaction avec PCNA.PCNA stimule l’activité endonucléase du complexe MR à distance proche de l’extrémité 5’ d’une cassure double brin. Cette propriété est en accord avec l’intervention ultérieure des enzymes assurant la suite du mécanisme de réparation par recombinaison homologue. Par ailleurs, les protéines RadA, Primase et P41 ont été produites et purifiées. Leurs fonctions enzymatiques ont été confirmées. Cependant, nous n’avons pas pu caractériser la fonction de l’association de RadA/PrimaseHyperthermophilic archaea (HA) are found in high-temperature environments and grow optimally above 80°C. Usually, cells exposed to heat stress display an increased sensitivity to agents inducing double-stranded DNA breaks (DSBs). Studies in Eukaryotes and Bacteria have revealed that homologous recombination (HR) plays a crucial role not only in DNA DSBs repair, but also in the collapsed/stalled DNA replication fork restart.Recombinase and various HR-associated enzymes in archaea specifically resemble the eukaryotic homologues, rather than bacterial homologues.Furthermore, several studies have demonstrated the necessity of HR proteins in HA, suggesting that, HR is an important mechanism in HA. HR influencing genome stability has been well studied in Eukaryotes andBacteria, however, few of its functional properties have been studied in HA.To better understand how HR mechanism is involved in the archaeal genome maintenance process, a previous work proposed a protein-protein interaction network based on Pyrococcus abyssi proteins. Through the network, new interactions involving proteins from DNA replication and DNA recombination were highlighted. The targets of the study presented here for two protein interaction are: PCNA/Mre11-rad50 complex (MR complex) and Primase/RadA. For the first time in P. furiosus, we showed both physical and functional interactions between PCNA (Maestro in DNA replication) and MR complex (initiator of HR). We have identified a PCNA-interaction motif (PIP) located in the C-terminal of Mre11, and shown that PCNA stimulated MR complex endonuclease cleavage proximal to the s’ strand of DNA DSBs at physiological ionic strength. For the second interaction, we have purified the proteins PabRadA/PfuRadA, PabPrimase and PabP41, and confirmed its enzymatic functions. However, we were not able to characterize the function of Primase/RadA association
10
Corgozinho, Carolina Nunes Costa. "Desenvolvimento de vacina baseada em sistema de liberação sustentada contendo proteína recombinante." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/60/60137/tde-31072009-083709/.
Full textAbstract:
No Brasil, e em outros paises de clima tropical, os carrapatos se tornaram um enorme problema economico de^$de que a industria do gado se desenvolveu. O carrapato Boophilus microplus, um dos artropodes mais importantes na veterinaria, causa efeitos direto, como suc,cao de sangue, e indireto, como a transmissao de uma grande variedade de patogenos que normalmente resulta em infec,c~es letais. As vacinas genicas contendo o antigeno Bm86, uma proteina ligada a membrana do intestino do carrapato B. microplus, representam uma alternativa atrativa aos acaricidas para controlar as infesta~oes por carrapatos em contrapartida aos inconvenientes produtos quimicos. Devido sua administra,cao ser feita em 4 doses no primeiro ano, seguida de refor,cos a cada seis meses, estas formula,coes vacinais nao s3c adequadas para paises com cria,cao extensiva de gado, como no Brasil. Visando uma libera~ao sustentada do antigeno Bm86, neste trabalho desenvolveuse uma vacina de dose unica baseada em microesferas polimericas. Para obter o padrao de liberac,ao desejavel, diferentes formula,coes e parametros de processo foram variados, como a composi,cao do polimero, a taxa entre os monomeros ^Uacido latico:acido glicolico\" e o tamanho das microparticulas. As formula,coes foram preparadas pelo metodo de emulsao multipla e evapora,cao do solvente. A formula~ao que melhor se enquadrou nos objetivos da vacina de dose unica foi preparada com PLGA 75:25, solu,cao 3% de PVA como estabilizante, agita,cao de 11000 rpm para forma,cao da emulsao primaria e de 800 rpm para forma,cao da emulsao multipla e evapora,cao do solvente. As particulas assim obtidas apresentaram um tamanho medio de 25 ,um, uma taxa de encapsula,cao maior que 90% e aproximadamente 50% da proteina foi liberada in vitro em 60 dias. Analises por SDS-PAGE e Westem Bloning revelaram que a proteina se manteve integra apos encapsula,cao. Os resultados da avalia,cao da imunogenicidade em bovinos mostraram que a formula,cao baseada em microesferas polimericas biodegradaveis e habil a conseguir, com uma unica dose, uma resposta imune similar aquela conseguida com tres doses das formula,coes convencionais da vacina de Bm86.In Brazil, and in others tropical countries, the ticks have become a huge economic problem since the industry of livestock has developed. Ticks and tick-borne diseases affect animal and human health and are the cause of significant economic losses. The cattle tick Boophilus microplus is one of the most important arthropods in veterinary. This tick species causes both direct effects, such as blood sucking, and indirect effects, such as transmission of a wide variety of pathogens, which usually result in lethal infections. The gene vaccines based on Bm86 antigen, a midgut membrane-bound protein of the cattle tick B. microplus, represent a good alternative to control tick infestations, compared to chemicals. However, due to these vaccine formulations need 4 doses over the first year with booster at each 6 months to be effective, they are not suitable for countries with extensive cattle raising, like Brazil. Aiming a sustained release of Bm86 antigen, in this work we developed a single shot vaccine based on Bm86 loaded polymeric microspheres. In order to obtain desired release patterns, different formulations and processing parameters were varied, for example, the composition of the polymer, the monomer ratio lactic acid:glycolic acid and the size of the microparticles. The formulations were prepared by solvent evaporation method based on double emulsion. The formulation that presented better result as single shot vaccine was prepared with PLGA 75:25, solution 3% of PVA as stabilizer, agitation of 11000 rpm to form the primary emulsion and 800 rpm to obtain the double emulsion and solvent evaporation. The particles thus obtained presented an average size of 25 m, encapsulation ratio greater than 90% and approximately 50% of the protein was released in vitro in 60 days. Analysis by SDSPAGE and Western Blot showed that the integrity of the protein remained after encapsulation. The immunogenic studies showed that the formulation based onbiodegradable polymeric microspheres is able to elicit, with a single dose, an immune response and protection similar to that attained with 3 doses of conventional Bm86 vaccine formulations.
11
Tse, Muk-hei. "Investigations on recombinant Arabidopsis acyl-coenzyme A binding protein 1." View the Table of Contents & Abstract, 2005. http://sunzi.lib.hku.hk/hkuto/record/B36427664.
Full text
12
Ndabambi, Nonkululeko. "Recombinant expression of the pRb- and p53-interacting domains from the human RBBP6 protein for in vitro binding studies." Thesis, University of the Western Cape, 2004. http://etd.uwc.ac.za/index.php?module=etd&.
Full textAbstract:
The aim of this thesis was to produce DNA expression constructs and use them to investigate the feasibility of recombinantly expression proteins for future interaction studies between human RBBP6 and p53 and pRb proteins.
13
Sage, Jay M. "Support of Mitochondrial DNA Replication by Human Rad51: A Dissertation." eScholarship@UMMS, 2011. https://escholarship.umassmed.edu/gsbs_diss/574.
Full textAbstract:
The function of homologous DNA recombination in human mitochondria has been a topic of ongoing debate for many years, with implications for fields ranging from DNA repair and mitochondrial disease to population genetics. While genetic and biochemical evidence supports the presence of a mitochondrial recombination activity, the purpose for this activity and the proteins involved have remained elusive. The work presented in this thesis was designed to evaluate the mitochondrial localization of the major recombinase protein in human cells, Rad51, as well as determine what function it plays in the maintenance of mitochondrial DNA (mtDNA) copy number that is critical for production of chemical energy through aerobic respiration. The combination of subcellular fractionation with immunoblotting and immunoprecipitation approaches used in this study clearly demonstrates that Rad51 is a bona fide mitochondrial protein that localizes to the matrix compartment following oxidative stress, where it physically interacts with mtDNA. Rad51 was found to be critical for mtDNA copy number maintenance under stress conditions. This requirement for Rad51 was found to be completely dependent on ongoing mtDNA replication, as treatment with the DNA polymerase gamma (Pol ϒ) inhibitor, ddC, suppresses both recruitment of Rad51 to the mitochondria following the addition of stress, as well as the mtDNA degradation observed when Rad51 has been depleted from the cell.
The data presented here support a model in which oxidative stress induces a three-part response: (1) The recruitment of repair factors including Rad51 to the mitochondrial matrix, (2) the activation of mtDNA degradation systems to eliminate extensively or persistently damaged mtDNA, and (3) the increase in mtDNA replication in order to maintain copy number. The stress-induced decrease in mtDNA copy number observed when Rad51 is depleted is likely the result of failure to stabilize or repair replication forks that encounter blocking lesions resulting in further damaged to the mtDNA and its eventual degradation.
14
Tse, Muk-hei, and 謝牧熙. "Investigations on recombinant Arabidopsis acyl-coenzyme A binding protein 1." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B36427664.
Full text
15
Barua, Bipasha. "Design and study of Trp-cage miniproteins /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/8533.
Full text
16
Comenale, Gabriela. "Expressão e purificação da proteína recombinante L2 do Papilomavírus bovino tipo-2 em sistema bacteriano." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/10/10132/tde-11102013-104819/.
Full textAbstract:
A papilomatose bovina é uma doença infectocontagiosa de ocorrência mundial, que assola o rebanho brasileiro, sem qualquer atitude efetiva de controle, e que tem como enfermidades associadas a tumores de bexiga hematúria enzoótica e tumores de trato digestório superior caraguatá, responsáveis por sensíveis perdas para a pecuária. Várias tentativas vacinais têm sido empreendidas com finalidades profiláticas ou terapêuticas, porém sem resultados eficazes. Esta situação se deve a aspectos relacionados à estrutura viral que dificultam uma manipulação eficiente para produção de produtos vacinais. Para que tais dados possam ser obtidos, faz-se necessário uma melhor compreensão da ação das proteínas recombinantes. A clonagem em vetores bacterianos para a expressão e purificação dessas proteínas serve a diferentes propósitos. Entre eles, a produção de insumos imunológicos, como testes diagnósticos ou mesmo vacinas. O presente projeto visou à expressão e purificação da proteína de capsídeo recombinante L2 de BPV-2. A proteína foi expressa em bactéria e tentou-se a purificação por coluna de afinidade; entretanto, problemas na purificação não possibilitaram a conclusão deste objetivo. Todas as abordagens e protocolos utilizados nesse trabalho são discutidos para contribuição ao conhecimento do processo.The bovine papillomatosis is an infectious disease of worldwide occurrence, plaguing the Brazilian herd, without any effective attitude control, and whose illnesses associated with bladder tumors \"enzootic hematuria\" and upper digestive tract tumors \"caraguatá\" sensitive responsible for losses to livestock. Several attempts have been undertaken vaccine with prophylactic or therapeutic purposes, but without effective results. This is due to issues related to viral structure that hinder efficient manipulation for production of vaccine products. In order to obtain such information, it is necessary better understanding of the action of recombinant proteins. The bacterial cloning vectors for the expression and purification of such proteins serve different purposes. Among them, the production of immune inputs, such as diagnostic tests or vaccines. This project aimed the expression and purification of recombinant L2 capsid protein of BPV-2. The protein was expressed in bacteria and purification was carried out by affinity column. However, difficulties in the purification process, impaired the full completion of this objective. All the attempted approaches and protocols were discussed and potential solutions proposed.
17
Teixeira, Lais Helena. "Geração e análise da imunogenicidade de proteínas recombinantes baseadas nas diferentes formas do antígeno circumsporozoíta de Plasmodium vivax visando o desenvolvimento de uma vacina universal contra malária." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/42/42133/tde-11072014-110149/.
Full textAbstract:
O P. vivax é a segunda espécie mais prevalente causadora de malária no mundo. Medidas de controle ineficientes exigem o desenvolvimento de novas estratégias de prevenção, como vacinas, novas drogas e novos inseticidas. O objetivo geral do trabalho foi gerar uma formulação vacinal universal com proteínas e adenovírus recombinantes capazes de induzir anticorpos contra as diferentes formas alélicas da proteína circumsporozoíta (CSP) do P. vivax. As proteínas foram produzidas em E. coli e purificadas por cromatografia de afinidade e troca iônica. A obtenção destas proteínas nos permitiu testar qual seria a melhor formulação vacinal para a indução de anticorpos contra as três formas alélicas da proteína CSP de P. vivax (PvCSP). Anticorpos específicos reconheceram esporozoítas do P. vivax por imunofluorescência. Por fim testamos o uso de dois adenovírus recombinantes, um símio e um humano, deficientes em replicação, expressando as três regiões imunodominantes da proteína PvCSP em fusão. Estes foram capazes de induzir resposta imune específica contra as proteínas PvCSP sendo testados em esquema de prime-boost heterólogo, onde camundongos foram primados com os adenovírus e nas doses-reforço receberam a mistura com as três proteínas recombinantes.The Plasmodium vivax is the second most prevalent species of malaria in the world. Inefficient measures of control used today demand the development of new strategies for prevention, as vaccines, new drugs and new insecticides. The central objective of this thesis was to generate a universal vaccine formulation with proteins and recombinant adenoviral vectors representing the different allelic forms of the circumsporozoite protein (CSP) of the P. vivax. The recombinant proteins were expressed in E. coli and purified. These proteins allowed us to test which would be the best vaccine formulation for the induction of antibodies against the three allelic forms of CSP. The specific antibodies also recognized P. vivax sporozoites by immunofluorescence. Finally we test the use of two recombinant adenoviral vectors, a simian and a human, both replication deficient, expressing a protein containing the repeat regions of the CSP in fusion. These adenoviral vectors induced specific immune response against CSP and were successfully used in an immunization regimen of heterologous prime and boost where in the first dose the mice received recombinant adenoviral vector and in the subsequent doses, the mixture with three recombinant proteins.
18
Liu, Fangbing. "Monoclonal and recombinant antibodies to potyviral proteins and their application Monoklonale und recombinante Antikörper gegen potyvirale Proteine und ihre Anwendung /." [S.l.] : Universität Stuttgart , Fakultät Geo- und Biowissenschaften, 1999. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB8473253.
Full text
19
O'Hara, John F. "An investigation of post-translational processing in the transgenic mammary gland." Thesis, University of Kent, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365215.
Full text
20
Tarsounas, Madalina Cecilia. "Synaptonemal complex proteins, post-translational modifications, protein-protein interactions and interaction with the rad51/dmc1 recombinases." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0007/NQ39313.pdf.
Full text
21
Danh, Tu Thien. "ANALYSIS OF CHROMATIN ACCESSIBILITY OF THE HUMAN C-MYC REPLICATION ORIGIN." Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1449845546.
Full text
22
Protopopova, Marina. "Modulation of activity of the tumour suppressor p53 by small molecules and damaged DNA /." Stockholm, 2004. http://diss.kib.ki.se/2004/91-7349-926-9/.
Full text
23
Pesarrodona, Roches Mireia. "Supramolecular organisation and biological properties of tumor targeted, self-assembling protein nanoparticles." Doctoral thesis, Universitat Autònoma de Barcelona, 2017. http://hdl.handle.net/10803/402365.
Full textAbstract:
Degut a la seva flexibilitat funcional i arquitectònica, l’ús de proteïnes recombinants formades per múltiples dominis representen una eina interesant pel desenvolupament de nanopartícules capaces de transportar fàrmacs de manera específica. Recentment, en el nostre grup, hem aplicat un nou sistema d’enginyeria pel desenvolupament de nanoparticles formades mitjançant l’oligomerització de proteïnes modulars. L’eficàcia selectiva i l’absència de toxicitat d’unes nanopartícules dirigides al càncer colorectal demostra la capacitat d’aquest enfoc biotecnològic. Un enfoc basat en l’ús de pèptids catiònics en els extrems terminal d’una proteïna modular que li confereix la capacitat d’interaccionar amb sí mateixa formant nanopartícules proteiques. Per tal d’explorar la flexibilitat d’aquest enfoc, hem desenvolupat dues nanopartícules proteiques, anomenades A5G27-GFP-H6 i FNI/II/V-GFP-H6, que reconeixen i internalitzen, de manera específica, cèl·lules que expressen el receptor CD44. Aquestes proteïnes modulars formen estructures anulars de 14 nm, estables en plasma capaces d’internalitzar a través d’endocitosis sense presentar toxicitat cel·lular. Aquestes nanopartícules específiques són una plataforma prometedora com a nanomedicines pel transport de fàrmacs o sondes pel diagnòstic i tractament d’afliccions relacionades amb CD44.
Durant la producció recombinant microbiana, moltes proteïnes heteròlogues tendeixen a acumular-se en cossos d’inclusió. Tenint en compte la última descripció d’aquestes entitats, constitueixen una font de proteïna pràcticament pura. Tot i que s’han desenvolupat tècniques per l’obtenció de proteïna activa mitjançant l’ús de detergents solubilitzadors no desnaturalitzants de manera satisfactòria, és desconegut com aquests procediments afecten el procés d’oligomerització de nanopartícules proteiques. En aquesta tesi, hem analitzat quin impacte té, a nivell estructural i funcional, l’origen de la font proteica. Depenent de si les nanopartícules deriven de la fracció soluble o de la resolubilització dels cossos d’inclusió, s’obtenen diferents organitzacions supramoleculars amb comportaments funcionals diferenciats. Aquests resultats demostren la rellevància que té l’origen cel·lular del material quan parlem d’estructures proteiques complexes.
Tot i que recentment s’ha demostrat que la bactèria hoste té una influencia directe en la estructura i el rendiment de les nanopartícules proteiques, es desconeix com els hi afecta l’ús de bactèries amb un perfil genètic diferent com soques deficients en xaperones o lliures de lipopolisacàrids. En aquesta tesi, s’ha investigat l’estructura de nanopartícules dirigides a CD44 o CXCR4 produïdes en diferents soques d’E.coli i com les característiques fisicoquímiques afecten la biointeracció d’aquestes nanopartícules. Els resultats demostres la robustesa dels patrons d’oligomerització d’aquestes nanopartícules dirigides a tumor i la influencia que té el perfil genètic microbià en la proporció de les diferents poblacions oligomèriques en el producte cru. Aquesta variabilitat, intrínseca de la bioproducció, tot i ser imprevisible o incontrolable, constitueix un ventall de nanomaterial. De manera exclusiva es pot seleccionar aquella població de nanopartícules amb les característiques funcionals i fisicoquímiques òptimes considerant l’aplicació per la qual s’han dissenyat.Recombinant multidomain protein building-blocks have demonstrated to be an appealing biotechnological approach for the development of cell-targeted, nanoscale drug carriers on account of protein functional and architectonic versatility. The colorectal tumor targeting efficacy as well as non-toxicity of T22-empowered nanoparticles validates the potential of the de novo engineering approach developed in our research group. An approach based on end-terminal cationic peptides as pleiotropic tags in self-assembling protein building blocks. In an attempt to explore the flexibility of this approach, we have developed two protein-only nanoparticles that specifically bind CD44-receptor, namely A5G27-GFP-H6 and FNI/II/V-GFP-H6. These designed building-blocks promote the formation of ring-shaped structures which are approximately 14 nm in size, stable in plasma that can internalise cells through endocytosis in absence of cell toxicity. These targeted protein nanoparticles, together with the stability and biodistribution of other tested multifunctional self-assembling protein nanoparticles, are promising platforms for the transport of drugs or imaging agents as nanomedicines for breast cancer or other CD44-linked afflictions. Referring to microbial cell factories, many of the recombinant proteins are likely accumulated in IBs upon induction stress; however, considering non-classical structure description of these protein build-ups they represent an abundant and pure protein source. Although active protein has been obtained from IBs through mild solubilisation procedures, it is still unknown how the recovery of active protein from IBs affects the self-assembling process into protein nanoparticles. Thus, we have analyse the impact on nanoparticle structure and functionality considering the protein material source (nanoparticles from the soluble cell fraction or resolubilised from IBs) of the developed CD44-targeted protein vehicles. We have identified altered supramolecular organisation and consequently distinct in vitro and in vivo performance of cell-targeted protein nanoparticles depending on material’s origin. It is a particularly important aspect regarding recombinant production of smart and complex protein structures Albeit it has been recently known that the bacterial host directly influence the architecture and the performance of the produced protein nanoparticles, how the genetic background of E. coli strains deficient of chaperons or LPS-free affect these protein assemblies has not been addressed. In this thesis we have investigated the fine structure of CXCR4 and CD44 targeted nanoparticles produced in different E. coli strains and how their physicochemical characteristics affect the nanoparticles’ biointeractions. Results illustrate the robustness of self-assembling patterns among tumor-targeted GFP nanoparticles and also the influence of genetic background of the producing cells on shifting the distribution of oligomeric population in the pooled material. The intrinsic variability derived from the bioproduction, although being unpredictable or uncontrollable, offers a scope of nanoparticulated material from where optimal population can be selected considering their ultimate application
24
Delucchi, Anthony Benjamin. "Bacterial expression of radio-labeled recombinant proteins for studying AHR signalling." Scholarly Commons, 2001. https://scholarlycommons.pacific.edu/uop_etds/550.
Full textAbstract:
The ligand activated transcription factor Aryl Hydrocarbon Receptor (AHR) forms a DNA binding heterodimer with the Aryl Hydrocarbon Nuclear Translocator (ARNT) in response to planar aromatic hydrocarbons. In addition to AHR and ARNT there are at least three other proteins involved in AHR signaling. These proteins are the co-chaperone p23, Ara-9 and two molecules of Heat Shock Protein-90 (HSP-90). This study documents the production of Ara-9 and C∆418 (an ARNT deletion construct) in a modified thioredoxin fusion system. These proteins were expressed in a system that allowed for removal from the fusion partner via a thrombin recognition site as well as the incorporation of an in vitro phosphorylation site. The proteins were then expressed and column purified from E. coli. Once the proteins were expressed and purified they were cleaved from the thioredoxin fusion partner and radioloabeled. Following optimization of the proteolytic digest and radio-labeling each protein was subject to two methods of functional analysis. C∆418 function was assessed by electrophoretic mobility shift assay (EMSA) and proved to effectively form a DNA binding heterodimer with ARNT. In addition the functionality of C∆418 was assessed by co-precipitation showing that the ThioHis-produced C∆418 was indeed able to dimerize with C∆553 (an AHR deletion construct). The ThioHisproduced Ara-9 was also assessed for functionality by EMSA and showed that it was able to restore AHR/ ARNT/DRE complex formation as effectively as Ara-9 produced in a baculovirus system. In addition the function of ThioHis-Ara-9 was also assessed through Far-Western blotting for its ability to associate with renatured HSP-90. These studies involving C∆418 and Ara-9 show that these proteins can be efficiently produced in a functional manner utilizing an inexpensive bacterial system In addition this study documents the production of a plasmid (pCMV-Ara-9) for transfection into the HepG2 cell line to monitor the effects of increased cellular Ara-9 on AHR.
25
Kobir, Ahasanul. "Physiological roles of Eukaryotic Hanks type Ser/Thr kinase in transition to stationary phase in Bacillus subtilis." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00911812.
Full textAbstract:
Bacillus subtilis is the model organism for low GC Gram-positive bacteria and is of great biotechnological interest. Protein phosphorylation is an important regulatory mechanism in bacteria and it has not been extensively studied yet. Recent site-specific phosphoproteomic studies identified a large number of novel serine/threonine phosphorylation sites in B. subtilis, including a) two transition phase global gene regulators DegS and AbrB and b) RecA, that plays a major role in double-strand break repair and DNA recombination. .B. subtilis disposes of several putative Ser/Thr kinases like PrkA, YbdM, YabT and a characterizd kinase PrkC, but very few physiological substrates for these have been defined so far. In vitro phosphorylation assays were used to identify which of these kinases were able to phosphorylate DegS, RecA and AbrB. DegS phosphorylation on serine 76 by the kinase YbdM influenced its activity towards DegU both in vitro and in vivo, and expression of DegS S76D( on replacing serine to aspartate) in B. subtilis perturbed cellular processes regulated by the DegS/DegU two component system. This suggests a link between DegS phosphorylation at serine 76 and the level of DegU phosphorylation, establishing this post-translational modification as an additional trigger for this two-component system. At the onset of sporulation, B. subtilis expresses an unusual serine/threonine kinase YabT, which exhibits a septal localization and is activated by non-sequence-specific DNA binding. Activated YabT phosphorylates RecA at the residue serine 2, which in turn promotes the formation of RecA foci at the onset of spore development. On the other hand, non-phosphorylatable RecA or inactivated YabT lead to reduced spore formation in the presence of DNA lesions . This suggests a functional similarity between B. subtilis developmental stage dependent RecA phosphorylation and its eukaryal homologous Rad51 phosphorylation, which leads to its recruitment to the lesion sites. We therefore proposed that RecA phosphorylation serves as an additional signal mechanism that promotes focus formation during spore development. AbrB is phosphorylated by YabT, YbdM and PrkC in vitro and AbrB phosphorylation leads to reduced affinity for its target DNA and abolished binding cooperativity in vitro and in vivo. Expression of the phosphomimetic AbrB-S86D or of the non-phosphorylatable AbrB-S86A mutant protein in B. subtilis disturbed some stationary phase phenomena such as exoprotease production, competence and the onset of sporulation, probably by deregulation of AbrB-target genes and operons. We therefore, proposed that AbrB phosphorylation as an additional regulatory mechanism needed to switch off this ambiactive gene regulator during the transition phase.
26
Tan, Yu Pei. "The development of Lactococcus lactis as an antimicrobial agent." Thesis, Queensland University of Technology, 2010. https://eprints.qut.edu.au/39143/1/Yu_Pei_Tan_Thesis.pdf.
Full textAbstract:
Non-pathogenic lactic acid bacteria are economically important Gram-positive bacteria used extensively in the food industry. Due to their “generally regarded as safe” status, certain species from the genera Lactobacillus and Lactococcus are also considered desirable as candidates for the production and secretion of recombinant proteins, particular those with therapeutic applications.
The hypothesis examined by this thesis is that Lactococcus lactis can be modified to be an effective antimicrobial agent. Therefore, the aims of this thesis were to investigate the optimisation of the expression, secretion and/or activities of potential heterologous antimicrobial proteins by the model lactic acid bacterium, Lactococcus lactis subsp. cremoris MG1363.
L. lactis strains were engineered to express and secrete the recombinant CyuC surface protein from Lactobacillus reuteri BR11, and a fusion protein consisting of CyuC and lysostaphin using the Sep promoter and secretion signal. CyuC has been characterised as a cystine-binding protein, but has also been demonstrated to have fibronectin binding activity. Lysostaphin is a bacteriolytic enzyme with specific activity against the Gram-positive pathogen, Staphylococcus aureus. These modified L. lactis strains were then investigated to see if they had the ability to inhibit the adhesion of S. aureus to host extracellular matrix (ECM) proteins. It was observed that the cell extracts of the L. lactis strain with the vector only (pGhost9:ISS1) was able to inhibit the adhesion of S. aureus to fibronectin, whilst the cell extracts of the L. lactis strain expressing lysostaphin was able to inhibit adhesion to keratin.
Finally, this thesis has identified specific lactococcal genes that affect the secretion of lysostaphin through the use of random transposon mutagenesis. Ten mutants with higher lysostaphin activity contained insertions in four different genes encoding: (i) an uncharacterised putative transmembrane protein (llmg_0609), (ii) an enzyme catalysing the first step in peptidoglycan biosynthesis (murA2), (iii) a homolog of the oxidative defence regulator (trmA), and (iv) an uncharacterised putative enzyme involved in ubiquinone biosynthesis (llmg_2148). The higher lysostaphin activity observed in these mutants was found to be due to higher amounts of lysostaphin being secreted.
The findings of this thesis contribute to the development of this organism as an antimicrobial agent and also to our understanding of L. lactis genetics.
27
Gainche, Isabelle. "Les animaux transgéniques : intérêt et perspectives d'avenir dans la production de protéines d'intérêt thérapeutique." Paris 5, 1993. http://www.theses.fr/1993PA05P069.
Full text
28
Thomas, Jeffrey G. "Molecular chaperones and the folding of recombinant proteins in Escherichia coli /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/9881.
Full text
29
Kepple, Kevin V. "Analysis of the binding mechanisms and cellular targets of peptide inhibitors that block site-specific recombination in vitro /." Diss., Connect to a 24 p. preview or request complete full text in PDF formate. Access restricted to UC campuses, 2006. http://wwwlib.umi.com/cr/ucsd/fullcit?p3208620.
Full text
30
Rossi, Merja. "Investigating cell type specific metabolism using GFP as a reporter protein." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:0c418362-63e7-496d-9ff6-584a0c54c127.
Full textAbstract:
Metabolic flux analysis (MFA) is a powerful technique for quantifying the intracellular fluxes in central carbon metabolism. It relies on detection of stable isotope labelling from metabolites such as amino acids derived from protein. Current standard techniques are, however, unable to distinguish between different cell types in heterogeneous tissue. The aim of the thesis was to address this problem by developing and validating a strategy using green fluorescent protein (GFP) with cell type specific expression as a reporter protein for investigating the fluxes in specific cell types in the Arabidopsis thaliana root. The fundamental difficulty in applying a reporter protein strategy in a multicellular organism arises from the limited amount of recombinant protein expressed by the cells. The main novel contributions of the work in this thesis are threefold. First, a robust protocol for purification of GFP from the roots of Arabidopsis seedlings and for detection of reliable mass isotopomer distributions from the amino acids derived from GFP are described. Secondly, the reporter protein strategy is validated in this biological system with a focus on showing the data obtained by the use of the reporter protein is equal to that normally obtained from the total protein fraction. To expand on this, stable isotope labelling in isolated root hair cells is explored. These cells are easily isolated and show potential as a model system for cell type specific metabolism. Finally, the experimental data provide evidence for the feasibility of measuring data from specific cell types with appropriate mass spectrometric techniques. Analysis of cell type specific gene expression in this system suggests differences in the primary metabolism of different cell types cannot be ruled out without further investigation. Based on small scale in silico modelling described in this thesis, new solutions capable of providing data on sub-populations of cells are required, if central metabolism of the cell types differs significantly.
31
Oliveira, Raquel Sombra BasÃlio de. "ExpressÃo heterÃloga, caracterizaÃÃo cristalogrÃfica e anÃlise funcional de uma osmotina antifÃngica de Calotropis procera." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=13438.
Full textAbstract:
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoEm etapa anterior a este trabalho, uma proteÃna purificada a partir do lÃtex da planta Calotropis procera foi purificada e sua caracterizaÃÃo bioquÃmica revelou ser esta uma proteÃna similar a osmotinas e que a mesma, denominada de CpOsm, exibia forte atividade contra fungos fitopatogÃnicos. Neste trabalho foram investigados sistemas de expressÃo heterÃlogos, procarionte e eucarionte, com o objetivo de estabelecer sistemas de expressÃo que pudessem produzir CpOsm recombinante e avaliar se sua expressÃo produzia a proteÃna ativa, com aÃÃo antifÃngica. A partir do sequenciamento do cDNA da CpOsm e ensaios de cristalizaÃÃo desenvolvidos com a proteÃna purificada do lÃtex foi possÃvel estudar suas caracterÃsticas moleculares. Para a expressÃo em E. coli foi utilizado o vetor pET303CT-His e P. pastoris o vetor pPICZαA. A proteÃna recombinante (rCpOsm) expressa no sistema procarionte nÃo foi secretada para o meio externo, acumulando-se no espaÃo intracelular, formando corpos de inclusÃo, nos quais a proteÃna estava insolÃvel. Embora a insolubilidade represente um passo limitante, este sistema de expressÃo pode ser muito interessante para a produÃÃo quantitativa de rCpOsm para outros fins como produÃÃo de anticorpos ou estudos de folding/refolding proteico, considerado suas caracterÃsticas moleculares peculiares, observadas nos estudos cristalogrÃficos, tais como o conjunto de pontes dissulfeto intracadeia. rCpOsm foi tambÃm expressa em cÃlulas de P. pastoris, entretanto o sistema de expressÃo deverÃ, necessariamente, sofrer melhorias para maximizar o rendimento. rCpOsm de P. pastoris foi inicialmente detectada por sequenciamento de novo por espectrometria de massas a partir da digestÃo trÃptica. A identificaÃÃo de peptÃdeos internos confirmou sua presenÃa no meio extracelular. A limitaÃÃo deu-se pela baixa taxa de expressÃo, o que, por conseguinte, nÃo permitiu uma caracterizaÃÃo mais ampla da rCpOsm deste sistema. rCpOsm expressa em P. postoris estava em sua forma ativa. Em uma anÃlise comparativa, rCpOsm e CpOsm, de modo e intensidade similares, foram capazes de alterar drasticamente a morfologia de esporos de F. solani e reduzir seu volume, comparados a esporos nÃo tratados, revelado atravÃs de microscopia de forÃa atÃmica. CpOsm foi cristalizada pelo mÃtodo de gota pendente e os cristais obtidos difrataram a uma resoluÃÃo de 1,61 à com caracterÃsticas morfolÃgicas do espaÃo cristalogrÃfico P6122. Os dados coletados sugerem que a proteÃna mantÃm uma estrutura em monÃmero, correspondendo a sequÃncia de aminoÃcidos do cDNA, com 203 resÃduos. A estrutura pode ser vista como trÃs regiÃes distintas, presentes em outras osmotinas jà descritas, formando um domÃnio central onde hà um conjunto de folhas beta, sendo este o mais longo, e dois outros menores, formados de estrutura predominantemente desordenadas com pequenos segmentos em alfa-hÃlice (domÃnio II) e longas alÃas (domÃnio III). Oito pontes dissulfeto estabilizam a estrutura e envolvem todos os resÃduos de cisteÃna da estrutura primÃria. NÃo hà evidencias cristalogrÃficas para formaÃÃo de oligÃmeros. Este estudo conclui que a expressÃo heterÃloga em sistema eucarionte produz rCpOsm ativa e isto representa uma etapa a mais cumprida para a sua possÃvel expressÃo em plantas com o objetivo de proteÃÃo contra fitopatÃgenos.
In a previous step to this work, a latex protein belonging to Calotropis procera was described. The protein, named CpOsm, exhibited biochemical characteristics closely related to pathogenesis related proteins joined into PR-5 group. The new protein with osmotin characteristics displayed activity against phytopatogenic fungi. Here, attempts to obtain a suitable heterologous system to express functional recombinant CpOsm were performed in Prokaryote and Eukaryote expression systems. Further, cDNA sequencing and crystallographic assays were performed using CpOsm and the molecular and structural properties of the functional protein. The vector pET303CT-His and PICZαA were used to express CpOsm in E. coli and P. pastoris, respectively. The ecombinant protein (rCpOsm) produced in the Prokaryote system was retained into E. oli cells and deposited as inclusion bodies. rCpOsm was insoluble. Although insoluble roteins into inclusion bodies represent an adverse phase for obtaining the active CpOsm, this system of expression can be interesting to other goals as quantitative roduction of rCpOsm for producing antibodies or to study protein folding/refolding, ince CpOsm possesses peculiar structural characteristics such as occurrence of an xtended network or intra chain disulfide bonds stabilizing the overall structure. rCpOsm as also successfully expressed in P. pastoris. However, this protocol must to undergo improvement in order to maximize yield. rCpOsm was initially detected in the P. pastoris expression system by MS/MS de novo sequencing after tryptic digestion. Identification of internal peptides present in the extracellular media confirmed the production and excretion of rCpOsm in P. pastoris cells. The very low yield of recombinant protein avoided enough amount of purified rCpOsm to perform a broad characterization. On a comparative basis, native CpOsm, purified of the latex, and rCpOsm, purified from P. pastoris cultures, at similar mode and intensity were capable of drastically alter the morphological architecture of spores of F.solani and reduced their olume as compared to non-treated spores, as revealed by atomic force microscopy measurements. CpOsm was crystallized by the pendant drop method and the crystals grown diffracted at 1.61 Ã. They fit on the P6122 space. The data collecting, supported by the cDNA deduced amino acid sequence suggested that CpOsm occurs as an monomeric structure composed of a unique chain of 203 amino acid residues and no evidences for quaternary association was seen. The overall structure can separated in three structural domains, which have been reported in other osmotins. The central region preserves the set of beta-sheets and is the largest. The others exhibit short segments on alpha-helix interconnected by randomized sequences (domain II). In domain III predominates randomized sequences and long loops. Eight disulfide bonds stabilize the structure and involve all cysteine residues of the primary sequence. The heterologous expression of CpOsm on Eukaryote system produces rCpOsm active and this support the hypothesis that rCpOsm is a suitable candidate for heterologous expression in plants in order to obtain improved crops against selected phytopatogens.
32
Pereira, Priscila Romero Mazzini. "Caracterização imunogênica e funcional de duas lipoproteínas preditas de Leptospira interrogans expressas em Escherichia coli." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/87/87131/tde-23052017-141254/.
Full textAbstract:
A leptospirose é a zoonose mais disseminada no mundo e uma das principais causas de perda econômica no agronegócio. O estudo de novos antígenos de superfície de Leptospira interrogans, é intrigante e pode fornecer conhecimento na interação inicial patógeno-hospedeiro. Os genes LIC13059 e LIC10879, escolhidos por bioinformática, com predição de localização na superfície celular, foram clonados e as proteínas recombinantes expressas em E. coli, para avaliar a interação com componentes do hospedeiro. Após purificação, as proteínas encontravam-se estruturadas e foram reconhecidas por soro de indivíduos infectados. As proteínas recombinantes interagem com plasminogênio, fibrinogênio e laminina. rLIC13059, nomeada Lsa25.6, quando ligada ao fibrinogênio é capaz de inibir a formação de coágulo de fibrina e rLIC10879, nomeada Lsa16, interage com e-caderina, sugerido envolvimento na cascata de coagulação e ligação com o hospedeiro, respectivamente. O plasminogênio ligado às proteínas é convertido em plasmina, o que poderia ajudar a penetração bacteriana no hospedeiro.Leptospirosis is the most widespread zoonosis and also a major cause of economic loss in animal production worldwide. The study of new surface antigens of Leptospira interrogans is intriguing and may shed light into the initial pathogen-host interactions. We set out to study two novel coding sequences LIC13059 and LIC10879 predicted to be located at the cell surface. The genes were cloned and the recombinant proteins were expressed in E. coli. The purified recombinant proteins presented secondary structures, and interacted with plasminogen, fibrinogen and laminin human components. rLIC13059, named Lsa25.6, when bound to fibrinogen was capable of inhibiting the formation of fibrin clot, while rLIC10879, named Lsa16, interacted with e-cadherin, a mammalian cell receptor, suggesting participation in coagulation pathway and host-cell binding, respectively. The plasminogen captured by both recombinant proteins could be converted into plasmin, a mechanism that could help bacterial penetration in the host.
33
Hajjar, Christine. "Etude fonctionnelle du coeur catalytique membranaire d'enzymes de la famille NOX : Identification de la première NADPH oxydase procaryote." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENV032.
Full textAbstract:
La famille des NADPH oxydases est constituée de complexes multi protéiques, dont un des composants est la sous unité catalytique NOX. Il s'agit de protéine transmembranaire qui assure le transport des électrons à travers la membrane, à partir d'un donneur d'électrons, le NADPH, à un accepteur final, l'oxygène moléculaire. Il en résulte la production de superoxydes, précurseur d'espèces réactives de l'oxygène. Les NOX sont impliquées dans divers processus physiologiques et pathologiques qui les ont placés au rang des cibles thérapeutiques à forte valeur ajoutée.Les NOX sont reportées comme des protéines membranaires propres aux eucaryotes supérieures. Ainsi toutes les données fonctionnelles disponibles pour cette famille d'enzyme, ont été le fruit des études structure-fonction et de données putatives indirectes. D'où l'idée et l'intérêt d'identifier chez les procaryotes des candidats homologues aux Nox eucaryotes et susceptibles d'être de bons modèles pour des études structurales. En se servant d'outils bio-informatiques, nous avons définis des signatures de séquences propres aux NOX et avons identifié chez les procaryotes des centaines de séquences homologues. SpNox de chez Streptococcus Pneumoniae, a été sélectionnée et surexprimée chez E. Coli. SpNox a été purifiée et a fait l'objet d'une caractérisation fonctionnelle et biochimique approfondie. Au vue des résultats obtenus, SpNox se rapproche de part ses propriétés structurales et mechanistiques des NOX eucaryotes. Ainsi elle se présente comme le premier modèle procaryote de protéine NOX. Les premiers cristaux de cette famille de protéines ont été obtenus et son rôle in vivo reste à exploiter.En parallèle à l'approche procaryote, nous avons mené une étude structure-fonction sur la protéine NOX2 des neutrophiles PLB-985. Deux arginines conservées chez toutes les NOX eucaryotes ont été sélectionnées et leur rôle a été étudié par mutagenèse dirigée. Apres évaluation des propriétés enzymatiques des mutants NOX2, nous avons pu identifier l'arginine 513 comme étant impliquée dans la spécificité de NOX2 vis a vis du NADPH. Ces résultats nous ont permis de proposer une nouvelle orientation du NADPH dans son site d'ancrage à la protéine NOX2The NADPH oxidase complex was the first identified example of a system that generates reactive oxygen species in a dedicated manner. NOX are proteins involved in the transmembrane transfer of electrons to the molecular oxygen, resulting in the production of superoxides. In addition to ROS related damages, deregulation of Nox-dependant ROS production induces pathological consequences. Accordingly, the Nox family became a potential drug target, making the understanding of their function at molecular basis crucial.In the literature, it has always been reported that Nox proteins exist only in eukaryotes. Since eukaryotic membrane proteins have proven to be difficult to study, all the data available on Nox enzymes are obtained from putative assignments or structure-function studies.In our project, to overcome the difficulty of working on eukaryotic membrane proteins, we used an original approach based on bioinformatics tools. Through using specific filters and a novel program, we were able to identify hundreds of prokaryotic candidates. Among them, we selected SpNox, as a prokaryotic model from Streptococcus Pneumoniae. We have developed its expression in E. Coli as well as a multistep purification scheme. We also conducted an extensive enzymatic and mechanistic characterization of the purified enzyme. Our data support a strong structural and functional homology with known NOX enzymes. Finally, crystallization trials are performed leading to first crystals ever obtained for this family of protein. The understanding of Nox's physiological function in bacteria remains to investigate.In parallel to the prokaryotic approach, a structure-function study was conducted on the human model NOX2 in the PLB-985 neutrophils. Conserved arginines among eukaryotic Nox sequences were selected. Site directed mutagenesis followed by activity tests, lead us to identify a crucial role for arginine 513. It is implicated in the specificity towards NADPH as an electron donor for NOX2. With these data, we were able to suggest a new orientation of the NADPH, notably the phosphate moiety, in the binding site
34
Garrigós, Martínez Javier. "Multidisciplinary approach for recombinant protein production bioprocess design with classic and novel expression systems in Pichia pastoris." Doctoral thesis, Universitat Autònoma de Barcelona, 2021. http://hdl.handle.net/10803/671119.
Full textAbstract:
La present tesi doctoral es centra en la caracterització de sistemes d’expressió utilitzats per a la producció de proteïnes recombinants (RPP) en el llevat metilotròfic Pichia pastoris. Al llarg de tot aquest treball s’integren els resultats de diferents camps -enginyeria de bioprocessos i regulació génica- per tal d’ampliar la informació sobre els sistemes d’expressió analitzats i, així, reduir la incertesa a l’dissenyar un bioprocés RPP.
En el primer capítol de la tesi, s’estudia el sistema clàssic d’expressió basat en el PAOX1. En un primer pas, es van cultivar en quimiòstat dos clons productors de la Lipasa 1 de Candida rugosa (Cr1l) amb diferent dosi gènica. D’aquesta manera, es va determinar la interrelació de tres factors importants en els bioprocessos RPP com ara la velocitat específica de creixement (μ), els nivells d’expressió relativa de el gen heteròleg (RTL) i la velocitat específica de generació de producte (qp) . A més, també es va monitoritzar l’expressió d’un factor de transcripció important per a la via d’utilització de metanol (MIT1). Un cop establertes les condicions òptimes d’operació en continu, es van dur a terme cultius en fed-batch per validar i comparar el comportament dels clons productors observat, tant des del punt de vista del seu estat fisiològic com de la cinètica de producció de Crl1 .
Els inconvenients de l’ús de el potent sistema d’expressió basat en PAOX1-principalment derivat de l’ús de l’metanol com a font de carboni, font d’electrons i inductor de RPP- han portat a la comunitat de Pichia a investigar i desenvolupar sistemes d’expressió alternatius que no depenguin de l’addició de metanol. A causa d’això, en el segon capítol de la tesi, es van caracteritzar dos nous sistemes d’expressió, basats en el PPDF i PUPP, per determinar si poden competir amb l’àmpliament utilitzat PGAP en la producció de la Lipasa B de Candida antarctica (Calb) . El comportament dels tres sistemes d’expressió es va comparar, en primer lloc, en quimiòstat. Això va permetre obtenir informació sobre la influència de la μ i l’expressió de Calb en la cinètica de producció de la proteïna. A més, els clons productors de la proteïna recombinant sota els nous sistemes d’expressió es van cultivar a fed-batch, en les condicions òptimes observades prèviament, per tal de provar la potencial escalabilitat del bioprocés.
En l’últim capítol de la tesi es va optimitzar, utilitzant cèl·lules senceres de P. pastoris (whole cells), la producció del citrocromo P450 2C9 humà (CYP2C9). La coexpressió d’aquest enzim d’interès industrial al costat del domini donador d’electrons (cytochrome P450 reductase, CPR) es va realitzar mitjançant un nou sistema de promotors bidireccionals. Després d’una fase de screening en la qual es van provar fins a 8 promotors per a la producció de CYP2C9 / CPR, es va seleccionar la combinació que va proporcionar la major activitat oxidasa, i es van realitzar una sèrie de cultius per optimitzar el bioprocés. D’aquesta manera, es va determinar la influència de paràmetres importants de l’bioprocés -μ, pH i estratègia d’addició de metanol en la producció de biocatalizador. Finalment, l’eficiència de l’biocatalizador obtingut es va testar en la reacció de hidroxilació de l’ibuprofèn.La presente tesis doctoral se centra en la caracterización de sistemas de expresión utilizados para la producción de proteínas recombinantes (RPP) en la levadura metilotrófica Pichia pastoris. A lo largo de todo este trabajo se integran los resultados de diferentes campos —ingeniería de bioprocesos y regulación génica— con el fin de ampliar la información sobre los sistemas de expresión analizados y, así, reducir la incertidumbre al diseñar un bioproceso RPP. En el primer capítulo de la tesis, se estudia el sistema clásico de expresión basado en el PAOX1. En un primer paso, se cultivaron en quimiostato dos clones productores de la Lipasa 1 de Candida rugosa (Cr1l) con diferente dosis génica. De esta manera, se determinó la interrelación de tres factores importantes en los bioprocesos de RPP tales como la velocidad específica de crecimiento (µ), los niveles de expresión relativa del gen heterólogo (RTL) y la velocidad específica de generación de producto (qp). Además, también se monitorizó la expresión de un factor de transcripción importante para la vía de utilización del metanol (MIT1). Una vez establecidas las condiciones óptimas de operación en continuo, se llevaron a cabo cultivos en fed-batch para validar y comparar el comportamiento de los clones productores observado, tanto desde el punto de vista de su estado fisiológico como de la cinética de producción de Crl1. Los inconvenientes del uso del potente sistema de expresión basado en PAOX1—principalmente derivado del uso del metanol como fuente de carbono, fuente de electrones e inductor de RPP— han llevado a la comunidad de Pichia a investigar y desarrollar sistemas de expresión alternativos que no dependan de la adición de metanol. Debido a ello, en el segundo capítulo de la tesis, se caracterizaron dos nuevos sistemas de expresión, basados en el PPDF y PUPP, para determinar si pueden competir con el ampliamente utilizado PGAP en la producción de la Lipasa B de Candida antarctica (CalB). El comportamiento de los tres sistemas de expresión se comparó, en primer lugar, en quimiostato. Esto permitió obtener información sobre la influencia de la µ y la expresión de CALB en la cinética de producción de la proteína. Además, los clones productores de la proteína recombinante bajo los nuevos sistemas de expresión se cultivaron en fed-batch, en las condiciones óptimas observadas previamente, con el fin de probar la potencial escalabilidad del bioproceso. En el último capítulo de la tesis se optimizó, utilizando células enteras de P. pastoris (whole cells), la producción del citrocromo P450 2C9 humano (CYP2C9). La coexpresión de esta enzima de interés industrial junto al dominio donador de electrones (cytochrome P450 reductase, CPR) se realizó mediante un novedoso sistema de promotores bidireccionales. Después de una fase de screening en la que se probaron hasta 8 promotores para la producción de CYP2C9/CPR, se seleccionó la combinación que proporcionó la mayor actividad oxidasa, y se realizaron una serie de cultivos para optimizar el bioproceso. De este modo, se determinó la influencia de parámetros importantes del bioproceso —µ, pH y estrategia de adición de metanol— en la producción de biocatalizador. Finalmente, la eficiencia del biocatalizador obtenido se testó en la reacción de hidroxilación del ibuprofeno.
The present thesis is focused on the characterization of alternative expression systems used for recombinant protein production (RPP) in the methylotrophic yeast Pichia pastoris. Over this whole work, the integration of results from different fields —bioprocess engineering and gene regulation— is attempted in order to fill the gaps that frequently come up when designing a RPP bioprocess. In the first chapter of the thesis, the classical PAOX1-based expression system is thoroughly studied. Specifically, through a set of chemostat cultivations of two clones expressing the Candida rugosa lipase 1 (Cr1l) with different gene dosage, it was determined the interrelation of three important factors in RPP processes such as specific growth rate (µ), heterologous gene relative transcript levels (RTL) and specific product generation rate (qp). Moreover, the expression of a crucial transcription factor of the methanol utilization pathway (MIT1) was also determined in chemostat cultivations. Once the optimal operation conditions were identified in steady state conditions, fed-batch cultivations were conducted to validate the clones’ behaviour observed previously in terms of both physiological state and Crl1 production kinetics. The inherent drawbacks of using the powerful PAOX1-based expression system —mainly derived from the use of methanol as carbon source, electron source and RPP inducer— has forced the Pichia community to investigate and develop alternative methanol-free expression systems. Due to that, in the second chapter of the thesis, two novel expression systems, based on the PPDF and PUPP, were similarly characterized in order to determine whether they can compete in terms of protein production with the widely used PGAP, usually considered the methanol-free reference, for the production of the Lipase B from Candida antarctica (CalB). All the three expression systems performance was firstly compared in chemostat cultivations, which enabled to shed light on the influence of µ and CALB expression on the CalB production kinetics. Additionally, the clones harboring the novel expression system were cultivated in fed-batch mode at the optimal conditions observed in chemostat in order to test their potential bioprocess scalability. Finally, in the last chapter of the thesis, the production of active whole cell biocatalyst based on the human cytochrome P450 2C9 (CYP2C9) in P. pastoris was afforded. The coexpression of the protein along with its redox partner (cytochrome P450 reductase, CPR) was achieved by means of a bidirectional promoter system. After a screening phase in which up to 8 promoters were tested for CYP2C9/CPR production, the combination that provided the best balance was selected for subsequent bioprocess optimization experiments. In this way, the influence of important bioprocess parameters — pH, µ and methanol addition— on active CYP2C9/CPR whole cell biocatalyst production was determined. Finally, the efficiency of P. pastoris whole cell biocatalyst based on CYP2C9/CPR was tested in a proof of concept reaction of interest, in which ibuprofen is hydroxylated into its oxidized derivatives.
Universitat Autònoma de Barcelona. Programa de Doctorat en Biotecnologia
35
Levchenko, Tetyana. "The role of angiomotin in angiogenesis /." Stockholm, 2003. http://diss.kib.ki.se/2004/91-7349-761-4/.
Full text
36
Rossini, Amanda Diaz. "Caracterização de uma proteína de Leptospira interrogans e avaliação do seu envolvimento na relação patógeno-hospedeiro." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/87/87131/tde-15062018-101521/.
Full textAbstract:
As bactérias patogênicas do gênero Leptospira são o agente causador da leptospirose, uma doença de importância global. As leptospiras patogênicas causam infecção em um amplo espectro de animais e no homem. As leptospiras podem invadir o corpo humano através de abrasões na pele e mucosa. A invasividade bacteriana depende de várias etapas, tais como: aderência, invasão e disseminação através dos tecidos do hospedeiro. Recentemente, nosso grupo identificou proteínas de membrana externa que atuam como adesinas de leptospira e/ou receptores de componentes do plasma hospedeiro, o que poderia contribuir para a patogenicidade bacteriana. Assim, o presente projeto tem como objetivo avaliar as propriedades funcionais do gene LIC10920, identificado na sequência genômica de Leptospira interrogans sorovar Copenhageni, como uma proteína hipotética, predita de membrana externa. A sequência LIC10920 foi amplificada por PCR e clonada no vetor de expressão pAE. O plasmídeo pAE contendo o inserto foi introduzido em estirpes de E. coli para a expressão da proteína. A proteína recombinante rLIC10920 foi purificada por cromatografia de afinidade a níquel e sua integridade estrutural foi avaliada pela técnica de dicroísmo circular. Camundongos foram imunizados com a LIC10920 para a avaliação da sua imunogenicidade. A presença de IgG humano contra LIC10920, foi avaliada por ELISA, em amostras de soro de pacientes com leptospirose. Assim, como a sua ligação com componentes da matriz extracelular e plasma do hospedeiro. Animais imunizados apresentaram alto título de anticorpos contra LIC10920. Além disso, a proteína foi reconhecida por anticorpos presente em amostras de soro humano infectado. A proteína foi capaz de interagir com plasminogênio e laminina de maneira dose-dependente e saturável. Em ambas as interações, a participação das regiões imunogênicas se mostrou importante. rLIC10920 foi capaz de capturar o plasminogênio direto do soro humano também de maneira dose-dependente. Por fim, foi observado que o plasminogênio ligado a rLIC10920 pode ser convertido em plasmina. A proteína em estudo é expressa durante a infecção e podemos atribuir a função de adesina, com papel na patogênese da bactéria.Pathogenic bacteria of genus Leptospira are the causative agent of leptospirosis, a disease of global importance. Pathogenic leptospires cause infection in a broad spectrum of animals and humans. Pathogenic leptospires can efficiently invade the human body through skin and mucosa and promptly spread into blood vessels, reaching target organs. Bacterial invasiveness depends on several steps, such as adherence, invasion and throughout host tissues. Recently, our group has identified outer membrane proteins that act as leptospiral adhesins and/or receptors of host plasma components, which could contribute for bacterial pathogenesis. This project aims to evaluate the functional properties of the gene LIC10920, identified in the genome sequence of Leptospira interrogans serovar Copenhageni, as a predicted outer membrane protein of unknown function. The LIC10920 sequence was amplified by PCR, cloned into the expression vector pAE. Plasmids containing cloned DNA were introduced in E. coli strains for protein expression. The recombinant protein was purified by the metal affinity chromatography and its structural integrity was assessed by circular dichroism spectroscopy. Mice were subcutaneously immunized with LIC10920 for immunogenicity evaluation. The presence of IgG against LIC10920 in confirmed leptospirosis human serum samples was evaluated by ELISA. Binding of protein with extracellular matrix or plasma components was also assessed. Sera from immunized animals show that the rLIC10920 protein is capable to stimulate antibody immune response in mice. In addition, the protein is recognized by antibodies in leptospirosis human serum samples. The recombinant protein was capable of binding plasminogen and laminin. Dose-dependent and saturable binding was observed when increasing concentrations of the rLIC10920 were allowed adhere to a fixed concentration of plasminogen or of laminin, fulfilling the receptor-ligand interactions. In both cases, the participation of the immunogenic regions occurs, but in the case of laminin, the dependence is greater with structured epitopes. It has been shown that plasminogen linked to rLIC10920 can be converted to plasmin in the presence of activator. The recombinant protein was able to capture the plasminogen directly from normal human serum in a dose-dependent manner, suggesting the involvement of native protein in host-pathogen interactions. The protein under study is expressed during the infection and due to its capacity of interaction with host components, we may anticipate its role in leptospiral pathogenesis.
37
Forget, Anthony L. "Homologous Recombinational DNA Repair: from Prokaryotes to Eukaryotes: a Dissertation." eScholarship@UMMS, 2004. https://escholarship.umassmed.edu/gsbs_diss/68.
Full textAbstract:
The error free repair of DNA double strand breaks through the homologous recombinational repair pathway is essential for organisms of all types to sustain life. A detailed structural and mechanistic understanding of this pathway has been the target of intense study since the identification of bacterial recA, the gene whose product is responsible for the catalysis of DNA strand exchange, in 1965. The work presented here began with defining residues that are important for the assembly and stability of the RecA filament, and progressed to the identification of residues critical for the transfer of ATP-mediated allosteric information between subunits in the protein's helical filament structure. My work then evolved to investigate similar mechanistic details concerning the role of ATP in the human RecA homolog, Rad51.
Results from non-conservative mutagenesis studies of the N-terminal region of one subunit and the corresponding interacting surface on the neighboring subunit within the RecA protein, led to the identification of residues critical for the formation of the inactive RecA filament but not the active nucleoprotein filament. Through the use of specifically engineered cysteine substitutions we observed an ATP-induced change in the efficiency of cross subunit disulfide bond formation and concluded that the position of residues in this region as defined by the current crystal structure may not accurately reflect the active form of the protein.
These ATP induced changes in positioning led to the further investigation of the allosteric mechanism resulting in the identification of residue Phe217 as the key mediator for ATP-induced information transfer from one subunit to the next.
In transitioning to investigate homologous mechanisms in the human pathway I designed a system whereby we can now analyze mutant human proteins in human cells. This was accomplished through the use of RNA interference, fluorescent transgenes, confocal microscopy and measurements of DNA repair. In the process of establishing the system, I made the first reported observation of the cellular localization of one of the Rad51 paralogs, Xrcc3, before and after DNA damage. In addition we found that a damage induced reorganization of the protein does not require the presence of Rad51 and the localization to DNA breaks occurs within 10 minutes.
In efforts to characterize the role of ATP in human Rad51 mediated homologous repair of double strand breaks we analyzed two mutations in Rad51 specifically affecting ATP hydrolysis, K133A and K133R. Data presented here suggests that, in the case of human cells, ATP hydrolysis and therefore binding, by Rad51 is essential for successful repair of induced damage.
38
Díaz, Ocaña Raquel. "Recombinant self-assembling nanoparticles for cancer therapy based on toxin and venom compounds." Doctoral thesis, Universitat Autònoma de Barcelona, 2020. http://hdl.handle.net/10803/670483.
Full textAbstract:
La plataforma desenvolupada d’enginyeria de proteïnes auto-acoblables permet dissenyar nanopartícules únicament proteiques (NPs) capaces d’atacar i actuar selectivament sobre les cèl.lules canceroses mitjançant la interacció amb receptors que es sobreexpressen. Les estructures esfèriques estables de les NPs desenvolupades i la seva mida adequada, en combinació amb els pèptids d’orientació , milloren la seva especificitat. A més, la incorporació de segments de toxina i verí ha millorat els efectes terapèutics d’aquestes estructures que són totalment biocompatibles i que no tenen cap portador extern o material agregat, complint d’aquesta manera amb el nou concepte per a medicaments de precisió, que involucra un fàrmac recombinant lliure de vehicle, auto-acoblat, auto-dirigit i eficient.
Una versió modificada de la cadena catalítica ricina A, amb la capacitat de disminuir els efectes secundaris no desitjats de la síndrome de vessament vascular però conservant la seva citotoxicitat natural, es va adaptar a la plataforma de proteïnes. El disseny es va desenvolupar amb el pèptid T22, que s’uneix a CXCR4, en l’extrem N-terminal, i una cua d’histidines a la terminal-C, en combinació amb un fragment del lloc escindible de furina per alliberar la proteïna intracel.lularment, i una seqüència KDEL per evitar la secreció del reticle endoplàsmic. Les NPs de cadena de ricina A solubles purificades dirigides a CXCR4 amb un diàmetre mitjà de 11 nm, van assolir un increment de 100 vegades en la seva citotoxicitat amb un IC50 de 13 ± 0,5 x 10 -9 M en cèl.lules HeLa. També es van produir per mètodes recombinants i es van purificar cossos d’inclusió insolubles de 400-600 nm, amb resultats citotòxics parcials. El mecanisme d’entrada dependent del receptor d’T22-MRTA-H6 es va verificar i avaluar en un model de ratolí amb leucèmia mieloide aguda (AML) mitjançant la injecció sistèmica a la vena de la cua on es va verificar un bloqueig important de les cèl.lules leucèmiques sense toxicitat sistèmica o histològica lateral en els òrgans sans.
De manera similar, la clorotoxina (CTX) també es va incorporar a la plataforma de proteïnes per tal d’aprofitar la seva d’orientació i efecte terapèutic en glioblastoma (GBM), ambdues funcions en un sol pèptid. Es van dissenyar dues versions que s’uneixen a la proteïna anexina-2 i la metaloproteinasa de matriu MMP-2; CTX-GFP-H6 i CTX-KRKRK-GFP-H6. Les NPs solubles d’un diàmetre mitjà de 12 nm es van incubar en cèl·lules HeLa, sobreexpressant annexina-2, i en cèl.lules U87MG, sobreexpressant MMP2. Les dues versions eren completament fluorescents, però CTX-GFP-H6 va presentar efectes citotòxics lleus, mentre que CTX-KRKRK-GFP-H6 va mostrar ser més citotòxic en les cèl.lules U87MG que en les cèl.lules HeLa. L’afinitat selectiva de CTX es va confirmar mitjançant l’avaluació de la seva selectivitat utilitzant anticossos monoclonals i un sèrum policlonal contra la proteïna de la superfície cel.lular, actuant com un receptor de la CTX.La plataforma desarrollada de ingeniería de proteínas autoensamblables permite diseñar nanopartículas únicamente proteicas (NPs) capaces de atacar y actuar selectivamente sobre las células cancerosas mediante la interacción con receptores que se sobreexpresan. Las estructuras esféricas estables de las NPs desarrolladas y su tamaño adecuado, en combinación con los péptidos de direccionamiento involucrados, mejoran su especificidad. Además, la novedosa incorporación de segmentos de toxina y veneno ha mejorado los efectos terapéuticos de estas estructuras que son totalmente biocompatibles y que no tienen ningún portador externo o material agregado, cumpliendo de esta manera con el concepto emergente para medicamentos de precisión que involucra un fármaco recombinante libre de vehículo, autoensamblado, auto-dirigido y eficiente. Una versión modificada de la cadena catalítica de ricina A, con la capacidad de disminuir los efectos secundarios no deseados del síndrome de derrame vascular, pero conservando su citotoxicidad natural, se adaptó a la plataforma de proteínas. El diseño se desarrolló con el péptido T22, que se une a CXCR4, en el extremo N-terminal, y una cola de histidinas en el extremo C-terminal, en combinación con un fragmento del sitio escindible de furina para liberar la proteína intracelularmente, y una secuencia KDEL para evitar secreción del retículo endoplásmico. Las NPs de cadena de ricina A solubles purificadas dirigidas a CXCR4, con un diámetro promedio de 11 nm, alcanzaron un incremento de 100 veces en su citotoxicidad con un IC50 de 13 ± 0,5 x 10 -9 M en células HeLa. Pero también se produjeron por métodos recombinantes y se purificaron cuerpos de inclusión insolubles de 400-600 nm, con resultados citotóxicos parciales. El mecanismo de entrada dependiente del receptor de T22-mRTA-H6 se verificó y evaluó en un modelo de ratón con leucemia mieloide aguda (AML) mediante la inyección sistémica en la vena de la cola, donde se verificó un bloqueo importante de las células leucémicas sin toxicidad sistémica o histológica lateral en los órganos sanos. De manera similar, la clorotoxina (CTX) también se incorporó a la plataforma de proteínas con el fin de aprovechar su direccionamiento y efecto terapéutico en glioblastoma (GBM), ambas funciones en un solo péptido. Se diseñaron dos versiones que se unen a la proteína anexina-2 y la metaloproteinasa de matriz MMP-2; CTX-GFP-H6 y CTX-KRKRK-GFP-H6. Lss NPs solubles, de un diámetro promedio de 12 nm, se incubaron en células HeLa sobreexpresando anexina-2, y en células U87MG, sobreexpresando MMP2. Ambas versiones eran completamente fluorescentes, pero CTX-GFP-H6 presentó efectos citotóxicos leves, mientras que CTX-KRKRK-GFP-H6 mostró ser más citotóxico en las células U87MG que en las células HeLa. La afinidad selectiva de CTX se confirmó mediante la evaluación de su direccionamiento utilizando anticuerpos monoclonales y un suero policlonal contra la proteína de la superficie celular, actuando como un receptor de la CTX.
The developed self-assembling platform allows the engineering of protein-only nanoparticles (NPs) capable to target and act selectively over cancer cells by means of the interaction with overexpressed receptors. The stability of the spherical NP structures and their adequate size, in combination with the involved targeting peptides, enhance their specificity. Also, the novel incorporation of toxin and venom segments have improved the therapeutic effects of these fully biocompatible materials, without the need of any external carrier or added material, thus fulfilling the newfangled concept for precision medicines that involve self-assembled, self-targeted and efficient vehicle-free recombinant drugs. A modified version of the catalytic ricin A chain, with the ability to diminish the undesired vascular leak syndrome side effects but retaining its natural cytotoxicity, was adapted to the protein platform. The design was developed with the peptide T22 in the N-terminal, which binds CXCR4, and a his-tag in the C-terminal. This was combined with a furin cleavable site fragment in order to release the protein intracellularly, and a KDEL sequence to avoid endoplasmic reticulum secretion. Purified soluble CXCR4-targeted ricin A chain NPs with an average diameter of 11 nm, reached a 100-fold cytotoxic improvement with an IC50 of 13 ± 0.5 x 10 -9 M in HeLa cells. Also, insoluble 400-600 nm inclusion bodies were produced by recombinant methods and purified, with partial cytotoxic results. The receptor-dependent mechanism of T22-mRTA-H6 was verified and evaluated in an acute myeloid leukemia (AML) mouse model by systemic administration through a vein tail injection where an important blockage of the leukemic cells was verified without side systemic or histological toxicity in healthy organs. In a similar way, chlorotoxin (CTX) was also incorporated to the protein platform in order to take advantage of its targeting and therapeutic effect in glioblastoma (GBM), both functions in one peptide. Two versions that target protein Annexin-2 and the matrix metalloproteinase MMP-2 were engineered, namely CTX-GFP-H6 and CTX-KRKRK-GFP-H6. The soluble NPs of an average dimeter of 12 nm were incubated with HeLa cells, overexpressing annexin-2, and in U87MG cells, overexpressing MMP2. Both versions were fully fluorescent but CTX-GFP-H6 presented mild cytotoxic effects, whereas CTX-KRKRK-GFP-H6 showed to be more cytotoxic in U87MG cells than in HeLa cells. The selective affinity of CTX was confirmed by means of evaluating its targeting using a monoclonal antibody and a polyclonal serum against the cell surface protein, acting as a CTX receptor.
39
Katz, David Samuel. "Solid state NMR investigations of protein based biomaterials: spider silk, recombinant spider silk proteins, and electrospun spider silk proteins." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/29568.
Full textAbstract:
¹³C Nuclear Magnetic Resonance was employed to investigate the structure of spider dragline
silk, powdered recombinant major ampulate spidroin 1 (MaSp1) and 2 (MaSp2) that were
produced in the milk of genetically engineered goats, and electrospun MaSp1. Cross polarization
spectra were used to assign secondary structures to the protein residues, and longitudinal
relaxation measurements were used to investigate the molecular thermal motion.
The crystalline regions of spider silk were found to exhibit nanosecond scale thermal motion,
subject to very rigid motional limits. The recombinant MaSp1 and MaSp2 were found
to have very similar structures that exhibited abundant β sheet crystalline regions. Electrospun
MaSp1 however appears to be highly disordered and is perhaps best characterized
as denatured. These results are in contrast to previous findings of spider silk proteins in
non-fiber states, where no appreciable crystalline component was observed, and appears to
be inconsistent with previous Fourier transform infrared spectroscopy of similarly prepared
samples. Reconsideration of the FTIR data however raises concerns about the interpretation
of those data, possibly explaining the disagreement. This work suggests that the lack of
regular structure found in the electrospun MaSp1 is the cause of the very poor mechanical
properties previously measured for this material.
40
GAZZANEO, Luiz Rodrigo Saldanha. "Expressão heteróloga da defensina dehys de euphorbia hyssopifolia 32 em E. coli." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/19523.
Full textAbstract:
Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-07-12T14:29:17Z
No. of bitstreams: 2
license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5)
Tese_Gazzaneo (Biblioteca Central).pdf: 2832068 bytes, checksum: bb29fc38317d9f60a0d6129655b9b7a1 (MD5)Made available in DSpace on 2017-07-12T14:29:17Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Tese_Gazzaneo (Biblioteca Central).pdf: 2832068 bytes, checksum: bb29fc38317d9f60a0d6129655b9b7a1 (MD5) Previous issue date: 2016-03-14
Defensinas são peptídeos antimicrobianos (AMPs) que apresentam atividade contra diversos microrganismos patogênicos, em especial fungos. Embora não totalmente elucidados, há diversos mecanismos de ação propostos para as defensinas, que incluem permeabilização seletiva ou ruptura da membrana plasmática de microorganismos, ação direta em alvos intracelulares, ativação de cascatas de sinalização e aumento da produção de espécies reativas de oxigênio. Desde a sua descoberta e, tendo em vista sua ampla atividade biológica, o uso de defensinas no melhoramento de plantas cultivadas, bem como na produção de novos medicamentos tem sido proposto. Estudos de atividade biológica e possível aplicação biotecnológica das defensinas demandam uma grande quantidade dessas proteínas. Entretanto, o processo de extração da mesma é laborioso, dispendioso e, de acordo com a população ou disponibilidades da espécie vegetal escolhida, não sustentável ecologicamente. Portanto, a utilização de sistemas heterólogos de expressão é uma importante ferramenta para obtenção de defensinas recombinantes em escala industrial. Nesse estudo, um gene de defensina “DeHys”, isolado da Euphorbia hyssopifolia, foi inserido no plasmídeo pET102/D-TOPO e células da linhagem BL21(DE3) de Escherichia coli foram transformada com essa construção. Foi produzida a defensina recombinante Dehys com tamanho aproximado de 24 kDa. Sua identidade foi confirmada por western blot e pela análise do padrão de digestão com proteases.
Defensins are antimicrobial peptides (AMPs) , which present activity against a variety of pathogenic microorganism, especially funghi. Although not completely elucidated, there are a variety of proposed mechanisms of action for defensins, which includes selective microorganisms plasmatic membrane permeabilization or rupture, straight action agains intracellular targets, activation of signaling cascades and the burst of reactive oxygen species. Since it’s discovery and due to it’s wide biological activities, it’s use in crop enhancing, as well as its use in the development of new drugs have been proposed. Defensin’s biological activity and biotecnological application studies demand a reasonable amount of purified protein. However, the extraction processes is laborious, expensive, time consuming and depending on the population or the chosen plant species supply, not ecologically sustainable. So, the use of heterologous expression sytems is an importante tool to obtain purified proteins in industrial scale. In this study, a defensing gene (Dehys) isolated from Euphorbia hyssopifolia was inserted in a p pET102/D-TOPO vector and trasnformed into BL21(DE3) Escherichia coli strains. A recombinat Dehys defensin of approximately 24 kDa was obtained. It’s identity was double-checked using by Western blot and protease digestion pattern analyses.
41
Freitas, Marcela Cristina Corrêa de. "Clonagem e expressão do fator VII de coagulação sanguínea em linhagens celulares humanas." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/17/17138/tde-05012016-091813/.
Full textAbstract:
O Fator VII recombinante (FVIIr) tem sido a principal escolha terapêutica dos pacientes hemofílicos que desenvolvem inibidores contra os fatores VIII e IX utilizados como tratamento. Atualmente, o produto utilizado é produzido em células de camundongo (BHK-21), o qual oferece desvantagens considerando a complexidade das modificações pós-traducionais desta proteína e a inserção de glicosilações de origem murina altamente imunogênicas aos seres humanos. Dessa maneira a produção de proteínas para uso terapêutico em linhagens celulares humanas surge como uma alternativa promissora. Dentro desse contexto, o objetivo principal deste trabalho foi clonar e expressar o FVII de coagulação sanguínea em 3 linhagens celulares humanas (HepG2, Sk-Hep, HKB-11), compará-las com a linhagem murina BKH-21, e selecionar a melhor produtora da proteína recombinante. As células foram modificadas com o vetor lentiviral p1054-CIGWS, contendo os genes do FVII e do marcador GFP. Após a modificação das células foi observada uma eficiência de transdução de 80% nas células BHK-21-FVIIr, 73% nas células HepG2-FVIIr, 32% nas células HKB-11-FVIIr e 95% Sk-Hep-FVIIr. Análises da expressão gênica por PCR em Tempo Real mostraram que as três linhagens humanas modificadas apresentaram expressão do RNAm relativo ao FVIIr, sendo que a linhagem celular HepG2 foi a que teve maior expressão de FVIIr, seguida da Sk-Hep-1 e HKB-11. Quando submetidas ao tratamento com vitamina K por um período de 10 dias em cultura, a expressão do gene FVIIr foi semelhante para as três linhagens (HepG2: 164563 URE, HKB-11: 119122 URE e Sk-Hep: 124919 URE). O FVII é uma proteína que para sua ativação, possui como principal modificação pós traducional a -carboxilação vitamina K dependente, que ocorre por meio do ciclo da vitamina K com a participação de 3 enzimas, -carboxilase, VKORC1 e calumenina (inibidor). A expressão gênica dessas enzimas foi avaliada antes e após o tratamento com a vitamina K. Foi possível observar que houve um aumento nos níveis de RNAm nas células humanas tratadas com vitamina K, sugerindo que esta é capaz de ativar as enzimas do ciclo da -carboxilação. A cinética de crescimento celular em garrafas estáticas mostrou que a as células murinas BHK-21 modificadas possuem uma velocidade específica de crescimento 25% mais elevada que das células humanas. Contudo a cinética de produção das linhagens recombinantes mostrou que as células humanas produzem cerca de 3 vezes mais FVIIr do as células BHK-21. Devida a baixa produção de FVIIr na linhagem celular murina, e ao fato de que a linhagem humana HepG2 apresenta um perfil de crescimento extremamente lento, as linhagens recombinantes Sk-Hep-1-FVIIr e HKB-11-FVIIr foram selecionadas para ensaios de cultivo em suspensão utilizando microcarregadores em frascos spinners. Ao longo de 10 dias de cultivo as células HKB-11-FVIIr mostraram uma produção acumulada de 152 g de FVIIr, o que corresponde a 304 UI. As células Sk-Hep-1-FVIIr produziram cerca de 202,6 g de FVIIr, o que corresponde a 405,2 UI. Em suma, nossos dados comprovam que as linhagens celulares humanas são eficazes para a produção de fator VII recombinante, uma vez que, utilizando nosso modelo de produção, estas mostraram-se melhores do que a de células murinas (BHK-21) utilizadas pela indústria. Assim, estas linhagens celulares humanas podem ser usadas como uma nova plataforma para a produção de FVII, bem como para outras proteínas recombinantes, de maneira mais segura e com menor risco de desenvolvimento de anticorpos inibidoresRecombinant factor VII (FVIIr) has been the main therapeutic choice for hemophilic patients who develop inhibitors antibidies to conventional treatments (FVIII and FIX). Currently, the comercial product is produced in murine cells (BHK-21) which gives disadvantages considering the complexity of post-translational modifications of these proteins. The insertion of murine residues can be highly immunogenic in humans. Thus the production of proteins for therapeutic use in human cell lines appears as a promising alternative. In this context, the aim of this study was to clone and express the blood coagulation FVII in 3 human cell lines (HepG2, Sk-Hep-1, HKB-11) and select the best cell line for production of recombinant protein. The cells were modified with the lentiviral vector p1054-CIGWS containing the FVII gene and GFP gene marker. After cells modification we observed efficiency of transduction, in which 80% of BHK-21-FVIIr cells showed GFP expression, 73% of HepG2-FVIIr cells, 32% of HKB-11-FVIIr cells and 95% SK- Hep-FVIIr. Gene expression analysis by real-time PCR showed that the three modified human cell lines exhibited RNAm expression relative to FVIIr. When cells were treated with 5 ug/mL vitamin K in culture, the gene expression of FVIIr was similar in the three cell lines (HepG2: 164 563 URE, HKB-11: 119122 and SK-Hep URE: 124919 URE). For FVII activation, the main post translational modification is -carboxylation vitamin-K-dependent which envolves three enzymes, -carboxylase, VKORC1 and calumenina (inhibitor) . Gene expression of these enzymes was evaluated before and after treatment with vitamin K. It was observed that there was an increase in mRNA levels in human cells treated with vitamin K, suggesting that the treatment is capable of activating the enzymes of the vitamin K cycle. Cell growth kinetics showed that modified murine cells BHK-21 have a higher specific growth rate, around 25% more than human cells. However the kinetics of production of recombinant cell lines showed that human cells expressing rFVII 3-fold more rFVII than BHK-21 cells. Due the low rFVII production of murine cells, and the extremely slow growth profile of human cell line HepG2, the recombinant cell lines Sk-Hep-1-rFVII and HKB-11-rFVII have been selected for cultivation tests in suspension using microcarriers in spinners flasks. Over 10 days of cultivation the HKB-11 cells showed a cumulative production of rFVII 152 ug, corresponding to 304 IU and SK-Hep-1 cells showed a rFVII production of 202.6 ug, corresponding to 405.2 IU. In summary, our data demonstrate that human cell lines are effective for producing recombinant factor VII. Using our production model, human cells were better than murine cells (BHK-21) used by the industry. Thus, these human cell lines can be used as a new platform for the FVII production, as well as for other recombinant proteins, with less risk of developing inhibitor antibodies
42
Sousa, Luciana Pereira de. "Desenvolvimento e análise de anticorpos policlonais anti-ldh de plasmodium vivax para o diagnóstico de malária." Universidade Federal do Amazonas, 2012. http://tede.ufam.edu.br/handle/tede/2630.
Full textAbstract:
Made available in DSpace on 2015-04-11T13:55:02Z (GMT). No. of bitstreams: 1
Luciana Pereira de Sousa.pdf: 2276123 bytes, checksum: a079176d073fb54e951e38fb4291c529 (MD5)
Previous issue date: 2012-11-12Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Malaria is one of the most serious public health problems in the world, accounting for high morbidity and mortality. The diagnosis remains the most widely used microscopy, however this approach requires adequate infrastructure and highly skilled professionals for the exams, making it unfeasible in areas of difficult access. Tests for the rapid and simple diagnosis of malaria are commercially available, but none of national origin, complicating the deployment by the Unified Health System (SUS). Faced with this problem, this study has as main objective the production of Plasmodium vivax Lactate Dehydrogenase (pLDH), aiming at the development of polyclonal antibodies anti-LDH able to detect the native antigen in blood samples from patients infected with the intention of offering future perspectives for the development of a rapid diagnostic test for malaria. For this, pvLDH protein was produced by recombinant DNA technology in host cells chemically competent. Therefore, it was purified to inoculation into rabbits and mice Balb /c. The response of the inoculated animals as well as the performance of polyclonal antibodies anti-LDH in the recognition of native antigen were assessed by ELISA immunoassays and sandwich system, respectively. The animals showed good antibody titers anti-pLDH after the third inoculation of the recombinant protein pLDH, and the rabbit antibody response than the response of mice with absorbance values at dilution 1/100, 2,600 and 2,100, respectively. Polyclonal antibodies anti-pLDH were able to recognize the native protein pLDH 131 samples to 154 samples positive malaria and incapable of recognizing human isoforms of LDH when evaluated against malaria negative samples, since the 23 negative samples evaluated, all also remained negative during the tests. The proposal idealized in this study proved extremely viable and promising. The results of this study meet expectations and provided future prospects as regards the use of recombinant pvLDH for the development of polyclonal and monoclonal antibodies functional in murine model for use in rapid diagnostic test (RDT) for malaria in attempt to offer alternatives to diagnosis in Brazil, or for use in immunoassay targeting the monitoring of the disease course.
A malária é um dos mais sérios problemas de saúde pública do mundo, sendo responsável por elevada morbidade e mortalidade. O diagnóstico mais utilizado continua sendo a microscopia, contudo esta metodologia exige infraestrutura adequada e profissionais altamente qualificados para a realização dos exames, tornando-se inviável em áreas de difícil acesso. Testes para o diagnóstico rápido e simples de malária estão disponíveis no mercado, porém nenhum de origem nacional, dificultando a implantação pelo Sistema Único de Saúde (SUS). Diante desta problemática, o presente estudo tem como principal objetivo a produção de Lactato Desidrogenase de Plasmodium vivax (pvLDH), visando o desenvolvimento de anticorpo os policlonais anti-LDH capazes de detectar o antígeno nativo em amostras sanguíneas de pacientes infectados com a pretensão de oferecer perspectivas para a elaboração de um teste diagnóstico rápido para a Malária. Para isto, a proteína pvLDH foi produzida pela tecnologia do DNA recombinante em células hospedeiras quimicamente competentes. Logo, a proteína foi purificada para a imunização de coelho e camundongos Balb/c. A resposta dos animais as inoculações assim como o desempenho dos anticorpos policlonais anti-LDH no reconhecimento do antígeno nativo foram avaliados por ensaios imunoenzimáticos ELISA indireto e em sistema sanduíche, respectivamente. Os animais demonstraram boa resposta de anticorpos anti-pvLDH após a terceira imunização de proteína recombinante, sendo a resposta de anticorpos do coelho superior a resposta dos camundongos, com valores de absorbância de até 2.600 e 2.100, respectivamente. Os anticorpos policlonais anti-pvLDH foram capazes de reconhecer a proteína LDH nativa em 131 amostras de 154 amostras positivas para malária e incapazes de reconhecer isoformas de LDH humana quando avaliados em relação a amostras negativas para malária, uma vez que das 24 amostras negativas avaliadas, todas se mantiveram também negativas nos ensaios. A proposta idealizada neste trabalho se mostrou extremamente viável e promissora. Os resultados obtidos neste estudo corresponderam às expectativas e forneceram perspectivas futuras no que diz respeito à utilização da pvLDH recombinante para a produção de anticorpos policlonais e monoclonais funcionais, em modelo murino, para a utilização em teste diagnóstico rápido (TDR) para a malária, na tentativa de oferecer alternativas ao diagnóstico no Brasil, ou para a utilização em imunoensaio visando o monitoramento do curso da doença.
43
Landim, PatrÃcia Gadelha de Castro. "ProduÃÃo em Pichia pastoris de uma quitinase de feijÃo-de-corda com atividade antifÃngica." Universidade Federal do CearÃ, 2011. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=8584.
Full textAbstract:
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoAs quitinases sÃo enzimas capazes de hidrolisar as ligaÃÃes β-(1,4)-glicosÃdicas presentes em biopolÃmeros de N-acetil-β-D-glucosamina, principalmente quitina, um polissacarÃdeo estrutural presente na parede celular de diversos fungos. No presente trabalho, uma quitinase de classe I de feijÃo-de-corda (Vigna unguiculata) foi expressa em sistemas heterÃlogos e a proteÃna recombinante (rVuChi) foi caracterizada bioquimicamente bem como em relaÃÃo ao seu efeito sobre o crescimento micelial e germinaÃÃo de esporos/conÃdios de fungos filamentosos. A seqÃÃncia de DNA codificando a proteÃna foi amplificada por PCR e clonada nos vetores de expressÃo pET32a(+) e pPICZαA, para expressÃo heterÃloga em Escherichia coli e Pichia pastoris, respectivamente. A expressÃo de rVuChi em cÃlulas de E. coli ArticExpress DE3 se deu em corpos de inclusÃo. Em seis estirpes de P. pastoris a proteÃna recombinante foi secretada, de forma solÃvel, para o meio de cultura. Na fraÃÃo extracelular da estirpe KM71H foi observada a maior atividade quitinolÃtica, apÃs 72 horas de induÃÃo. A detecÃÃo de rVuChi foi feita por SDS-PAGE e com o kit Invision His-Tag stain, onde foram identificadas duas bandas protÃicas de massas moleculares aparentes de 30 e 33 kDa. Ambas as bandas apresentaram a mesma sequÃncia N-terminal e a ausÃncia de N-glicosilaÃÃo foi verificada. A quitinase recombinante estava presente principalmente na fraÃÃo F0/40 precipitada com sulfato de amÃnio e foi purificada a homogeneidade tanto por cromatografia de afinidade em matriz de quitina (com rendimento de 18,31 mg por litro de meio de cultura), quanto por cromatografia de interaÃÃes hidrofÃbicas em coluna de Phenyl Sepharose CL-4B (rendimento de 13,2 mg/L), seguidas de ultrafiltraÃÃo em membrana com limite de exclusÃo de 50 kDa. A rVuChi apresentou atividades endo e exo-quitinolÃtica frente a quitina coloidal e hidrolisou glicol-quitina em gel de SDS-PAGE, embora nÃo tenha apresentado atividade contra substratos sintÃticos contendo p-nitrofenol. A quitinase purificada apresentou massa molecular de 32 e 33,1 kDa por cromatografia de exclusÃo molecular em colunas de Superose 12 HR e Superdex 200, respectivamente. Em gel bidimensional, rVuChi apresentou um conjunto de seis âspotsâ com pI entre 4,44 e 5,15. A quitinase mostrou-se ainda termoestÃvel em temperaturas atà 50 ÂC e sua atividade enzimÃtica mÃxima ocorreu em pH 5. Em geral, a presenÃa de Ãons metÃlicos causou uma reduÃÃo de sua atividade enzimÃtica. O agente quelante EDTA (0,5%) estimulou a atividade enzimÃtica enquanto que o detergente SDS (0,5%) a inibiu totalmente. A quitinase recombinante apresentou 37% de hÃlice alfa e 26% de folha beta, como determinado por espectroscopia de dicroÃsmo circular. A desnaturaÃÃo de 50% das molÃculas de rVuChi ocorreu a 54,41 ÂC. Os espectros de fluorescÃncia revelaram que a proteÃna produzida em P. pastoris estava em sua conformaÃÃo totalmente enovelada. A quitinase recombinante de feijÃo-de-corda foi capaz de inibir totalmente a germinaÃÃo de esporos de Penicillium herquei atà 48 horas, na dose de 100 μg e causou inibiÃÃo de 68%, nas doses de 50, 25 e 12,5 μg. Na dose de 150 μg, houve uma inibiÃÃo de 55% na germinaÃÃo dos conÃdios de Rhizoctonia solani e um leve efeito sobre a germinaÃÃo dos esporos de Colletotrichum lindemuthianum e C. musae. Nenhum efeito da rVuChi foi observado sobre a germinaÃÃo de esporos dos fungos C. gloeosporioides, Fusarium solani e F. oxysporum. AlÃm disso, a proteÃna recombinante retardou o crescimento micelial de P. herquei em aproximadamente 50% (100 μg), porÃm nÃo apresentou efeito sobre o crescimento micelial dos demais fungos. Desta forma, a quitinase classe I de V. unguiculata à uma proteÃna com atividade antifÃngica.
Chitinases are enzymes that hydrolyze the β-(1,4) glycosidic bonds present in biopolymers of N-acety-β-D-glucosamine, mainly chitin, a structural polysaccharide which is found in cell walls of several fungi. In plants, chitinases play a role as defense proteins against the attack of pests and pathogens. In this work, a class I chitinase from cowpea (Vigna unguiculata) was expressed in heterologous systems. The recombinant protein (rVuChi) was purified, and characterized biochemically and in relation to its effects on mycelial growth and germination of spores/conidia of filamentous fungi. The DNA coding sequence of the cowpea chitinase was amplified by PCR and the products cloned in the expression vectors pET32a(+) and pPICZαA, for heterologous expression in Escherichia coli and Pichia pastoris, respectively. In E. coli cells, the recombinant fusion protein occurred mainly as inclusion bodies. On the other hand, in six strains of P. pastoris, the recombinant cowpea chitinase was secreted in a soluble form into the culture medium. The highest chitinase activity was detected in the extracellular fraction of KM71H strain, 72 hours after induction. The recombinant VuChi was detected by SDS-PAGE and Invision His-Tag stain kit, which identified two protein bands with apparent molecular masses of 30 and 33 kDa. These two protein bands showed the same N-terminal sequence, and an absence of N-glycosylation. Most recombinant chitinase secreted into the culture medium was recovered in the fraction F0/40, precipitated with ammonium sulfate. The expressed protein was purified to homogeneity by affinity chromatography on chitin matrix (yield of 18.31 mg per liter of culture medium), or by hydrophobic interactions chromatography on a column of Phenyl Sepharose CL-4B (yield = 13.2 mg/L), followed by ultrafiltration in a membrane with exclusion limit of 50 kDa. The purified rVuChi was able to hydrolyze colloidal chitin (in solution) as well as glycol chitin (in SDS-PAGE), although it did not show enzymatic activity against synthetic substrates containing p-nitrophenol. The purified chitinase showed molecular masses of 32 and 33.1 kDa by size exclusion chromatography on columns of Superose 12 HR and Superdex 200, respectively. When submitted to 2D electrophoresis, rVuChi presented a set of six spots with pI values between 4.44 and 5.15. The chitinase was thermostable at temperatures up to 50 Â C and the enzyme activity was highest at pH 5. In general, the presence of metal ions caused a reduction of its enzymatic activity. The chelating agent EDTA (0.5%) stimulated the enzyme activity, whereas in the presence of the detergent SDS (0.5%) the rVuChi activity was completely inhibited. The recombinant chitinase showed 37% of alpha helix and 26% of beta sheet, as determined by circular dichroism spectroscopy. Denaturing of 50% of the rVuChi molecules occurs at 54.41 Â C. The fluorescence spectra showed that the protein produced in P. pastoris was in its fully folded conformation. The recombinant cowpea chitinase was able to completely inhibit the germination of spores of Penicillium herquei, after 48 hours, at a dose of 100 mg, and caused 68% inhibition at doses of 50, 25 and 12.5 mg. At a dose of 150 mg, there was 55% inhibition on conidial germination of Rhizoctonia solani and a slight effect on spore germination of Colletotrichum lindemuthianum and C. musae. There was no effect of rVuChi on spore germination of C. gloeosporioides, Fusarium solani and F. oxysporum. In addition, the recombinant protein delayed the mycelial growth of P. herquei in approximately 50% (at the dose of 100 mg) but had no effect on mycelial growth of the other fungi. Therefore, the cowpea class I chitinase is a protein with anti-fungal activity.
44
Vaz, Michelle Rossana Ferreira. "Estudo do Cultivo de dois clones de Escherichia coli recombinantes (eIF, LACK) para a Express?o de Ant?genos da Leishmania chagasi." Universidade Federal do Rio Grande do Norte, 2008. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15741.
Full textAbstract:
Made available in DSpace on 2014-12-17T15:01:13Z (GMT). No. of bitstreams: 1
MichelleRFV.pdf: 525804 bytes, checksum: d94754591de23bce5b0b460d3e10d382 (MD5)
Previous issue date: 2008-02-25Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico
With advent of the technology of the recombinant DNA, the recombinant protein expression becomes an important tool in the studies of the structure, function and identification of new proteins, mainly with therapeutical purposes. The Escherichia coli has been procarioto predominant in the studies of genetic engineering due to wealth of information regarding its metabolism. Despite the expressivo advance of the studies of molecular biology and the immunology of the infections, it does not exist, currently, no prophylactic drug capable to prevent calazar. Of this form, it exists a great necessity of specific antigen identification for the vaccine development and kits for disgnostic against the visceral Leishmaniose. In this context, this work objectified to study the recombinant antigen expression of the Leishmania chagasi during the culture of Escherichia coli in shaker. A first set of assays was carried through with the objective of if knowing the kinetic behavior of the growth of two clones recombinant proteins (eIF, LACK) in two different compositions of culture medium (2xTY, TB) supplemented by antibiotics, without IPTG addition. In the second stage of the assays, the procedure of induction for IPTG was carried through, in order to verify the influence of the composition of the ways tested in the expression them recombinant proteins. On the basis of the gotten results, can be observed that the high complexity of culture medium favored the kinetic one of growth of clones recombinant (eIF, LACK), however, to if to deal with the assays submitted to the procedure of induction for IPTG, the raised complexity of culture medium did not favor the expression of recombinant proteins. On the other hand, they had been gotten resulted positive for all clones recombinant (eIF, LACK) tested, confirmed through the eletrofor?tico profile
Com advento da tecnologia do DNA recombinante, a express?o de prote?nas recombinantes torna-se uma ferramenta importante nos estudos da estrutura, fun??o e identifica??o de novas prote?nas, principalmente com finalidades terap?uticas. A Escherichia coli tem sido o procarioto predominante nos estudos da engenharia gen?tica devido ? riqueza de informa??es a respeito do seu metabolismo. Apesar do avan?o expressivo dos estudos da biologia molecular e da imunologia das infec??es, n?o existe, atualmente, nenhuma droga profil?tica capaz de prevenir o calazar. Desta forma, existe uma grande necessidade de identifica??o de ant?genos espec?ficos para o desenvolvimento de vacinas e kits para diagn?sticos contra a Leishmaniose visceral. Neste contexto, este trabalho objetivou estudar a express?o de ant?genos recombinantes da Leishmania chagasi durante o cultivo de Escherichia coli em incubador rotativo (shaker). Um primeiro conjunto de ensaios foi realizado com o objetivo de se conhecer o comportamento cin?tico do crescimento dois clones recombinantes (eIF, LACK) em duas diferentes composi??es de meios (2xTY, TB) suplementados por antibi?ticos, sem adi??o de IPTG. Na segunda etapa dos ensaios, foi realizado o procedimento de indu??o por IPTG, a fim de verificar a influ?ncia da composi??o dos meios testados na express?o das prote?nas recombinantes. Com base nos resultados obtidos, pode-se observar que a elevada complexidade do meio de cultivo favoreceu a cin?tica de crescimento dos clones recombinantes (eIF,LACK), no entanto, ao se tratar dos ensaios submetidos ao procedimento de indu??o por IPTG, a elevada complexidade do meio de cultivo n?o favoreceu a express?o das prote?nas recombinantes. Por outro lado, foram obtidos resultados positivos para todos os clones recombinante (eIF, LACK) testados, confirmada atrav?s do perfil eletrofor?tico
45
Miladi, Baligh. "Développement d’outils moléculaires de production et de purification de protéines recombinantes par suivi en temps réel." Thesis, Cergy-Pontoise, 2011. http://www.theses.fr/2011CERG0533/document.
Full textAbstract:
Les besoins en protéines recombinantes dans les diverses activités des bio-industries a considérablement augmenté ces dernières années. Cependant, les procédés de leur production sont encore limités par le manque de marqueurs permettant de suivre l'expression et la purification des protéines d'intérêt, la formation des corps d'inclusion et les faibles degrés de pureté.Afin de pallier à ces difficultés, nous avons développé et mis en œuvre un nouveau procédé de production et de purification de protéines recombinantes chez Escherichia coli. Ce procédé est basé sur l'utilisation d'une cassette d'expression appelée Multitags et sur le clivage par une TEV protéase immobilisée sur une matrice de streptavidine. Le Multitags comporte, à partir de son extrémité N-terminale, un double tag d'affinité (10xHis et SBP), le domaine de fixation de l'hème du cytochrome b5 et le site de clivage de la TEV protéase. En utilisant deux modèles différents de protéine d'intérêt (MyRIP et la Pfu DNA polymérase), nous avons montré l'efficacité du cytochrome b5 dans le suivi visuel et quantitatif par mesure d'absorbance des différentes étapes de production et de purification. Nous avons obtenu plus de 90% de chacune des deux protéines de fusion dans la phase soluble. L'application d'une chromatographie double via les deux tags d'affinité 10xHis et SBP a permis d'atteindre un degré de pureté du Multitags-MyRIP et du Multitag-Pfu de 99%. Nous avons construit des colonnes protéolytiques en produisant la TEV protéase sauvage et sa version mutée (S219V) en fusion avec le Streptag II et en immobilisant ces enzymes par affinité sur colonne de streptavidine-agarose. La caractérisation des colonnes protéolytiques et leur application aux protéines recombinantes d'intérêt modèles ont montré l'avantage de cette méthode d'immobilisation en termes d'activité protéase retenue, de stabilité des enzymes, de leur réutilisation et de simplification du schéma de purification et de récupération des protéines d'intérêt à haut degré de pureté. En conclusion, ces travaux de thèse ont permis de développer et de valider des outils innovants pour l'expression et la purification de protéines recombinantesIn recent years, the need for recombinant proteins has substantially increased in various bio-industry activities. However, actual recombinant processes are still limited by the lack of markers allowing real-time expression and purification monitoring of target proteins, by inclusion bodies formation and by low quality of purity of the products. To overcome these difficulties, we have developed a new process for production and purification of recombinant proteins in Escherichia coli. The method combines the use of a multifunctional expression cassette, termed Multitags and an immobilized modified TEV protease on a streptavidin matrix. The Multitags contains, its N-terminus, two affinity purification tags (10xHis and SBP) and as a marker tag, the heme-binding domain of cytochrome b5 followed by the TEV cleavage site. Using two model proteins (MyRIP and Pfu DNA polymerase), we have demonstrated the visual and the quantitative monitoring capability of the cytochrome b5 during the expression and purification steps. When expressed in E. coli KRX more than 90% of both fusion proteins were produced in a soluble form. In addition, high purity (99%) of Multitags-MyRIP and Multitags-Pfu was achieved after two consecutive affinity purification steps using the dual affinity tag. We also produced the wild-type and the S219V mutant TEV proteases fused to the Streptag II affinity sequence and realized their affinity immobilization on a streptavidin-agarose matrix. The characterization of the proteolytic columns and their application to the recombinant model proteins demonstrated the advantage of this immobilization method in terms of retaining activities, enzyme stabilities, possibility of reuse and simplification of the cleavage downstream steps.In conclusion, this study allowed the development and the validation of innovative tools for expression and purification of recombinant proteins
46
Roca, Pinilla Ramon. "Development of a new generation of antimicrobial proteins based on a versatile nanoparticulated format and multidomain structure." Doctoral thesis, Universitat Autònoma de Barcelona, 2020. http://hdl.handle.net/10803/670790.
Full textAbstract:
Durant la major part de la historia humana, els patògens han estat una de les principals causes de morts i malalties. Gràcies al descobriment dels antibiòtics hem aconseguit tractar aquestes malalties amb facilitat, però el seu mal ús ha accelerat l’aparició de resistències als antimicrobians (AMRs). Atès que les AMRs han provocat que la majoria de fàrmacs antimicrobians siguin ineficaços, el desenvolupament de tractaments alternatius és mes necessari que mai. Els pèptids de la defensa del hoste (HDPs) han estat proposats com a models per la generació de nous antimicrobians per lluitar contra les infeccions AMR. Tot i així, la majoria d’HDPs és produeixen mitjançant la síntesi química, un procés que és car, insostenible i difícil d’escalar. Alternativament, la producció recombinant d’HDPs és molt atractiva però complicada, ja que són pèptids altament susceptibles de ser degradats i són tòxics per l’hoste recombinant. Malgrat això, els cossos d’inclusió (IBs), que són agregats de proteïna formats durant els processos de producció recombinant, es poden utilitzar com a format alternatiu al de la proteïna soluble per permetre la producció d’HDPs dins l’hoste sense efectes tòxics. D’altra banda, la construcció de proteïnes quimèriques podria ser una estratègia per expressar pèptids petits amb èxit. En aquest context, aquesta tesi explora diverses estratègies per la producció recombinant d’HDPs. Per una banda, hem explorat l’ús de les cremalleres de leucina com a dominis potencials per fomentar la producció recombinant d’HDPs en la fracció insoluble i per augmentar la qualitat de la proteïna recombinant dels IBs. A més a més, hem desenvolupat diverses proteïnes antimicrobianes multidomini basades en la fusió de diferents pèptids HDP i proteïnes de la immunitat innata. Com que també hem utilitzat cremalleres de leucina en aquests constructes, es poden expressar de manera efectiva – sense toxicitat per la cèl·lula productora. A més, en cas de necessitat, podem recuperar antimicrobians solubles a partir dels IBs gràcies a un protocol de solubilització suau i no desnaturalitzant. En conjunt, hem demostrat que aquests constructes tenen un ampli espectre d’acció antimicrobiana contra bacteris multi resistents (MDR), tant en el format soluble com en el format d´IB. És més, els constructes també són capaços d’estimular l’alliberament de IL-8 dins d’un potencial rang de propietats immunomoduladores. Aquests resultats ens han convidat a utilitzar les nostres proteïnes en la biofuncionalització de monocapes autoacoblants per evitar la formació de biofilms, i hem observat que aquestes proteïnes poden ancorar-se a aquests materials i evitar el creixement de biofilms. En resum, aquests resultats reforcen les proteïnes antimicrobianes multidomini com a potencials alternatives antimicrobianes amb propietat immunomoduladores.Durante la mayor parte de la historia humana, los patógenos han sido una de las principales causas de muertes y enfermedades. Gracias al descubrimiento de los antibióticos hemos conseguido tratar estas enfermedades con facilidad, pero su mal uso ha acelerado la aparición de resistencias a los antimicrobianos (AMRs). Dado que las AMRs han provocado que la mayoría de fármacos antimicrobianos sean ineficaces, el desarrollo de tratamientos alternativos es más necesario que nunca. Los péptidos de la defensa del huésped (HDPs) han sido propuestos como modelos para la generación de nuevos antimicrobianos para luchar contra las infecciones AMR. Sin embargo, la mayoría de HDPs se producen mediante la síntesis química, un proceso que es caro, insostenible y difícil de escalar. Alternativamente, la producción recombinante de HDPs es muy atractiva pero complicada, ya que son péptidos altamente susceptibles de ser degradados y son tóxicos para el huésped recombinante. Sin embargo, los cuerpos de inclusión (IBs), que son agregados de proteína formados durante los procesos de producción recombinante, se pueden utilizar como formato alternativo al de la proteína soluble para permitir la producción de HDPs dentro del huésped sin efectos tóxicos. Por otra parte, la construcción de proteínas quiméricas podría ser una estrategia para expresar péptidos pequeños con éxito. En este contexto, esta tesis explora diversas estrategias para la producción recombinante de HDPs. Por un lado, hemos explorado el uso de las cremalleras de leucina como dominios potenciales para fomentar la producción recombinante de HDPs en la fracción insoluble y para aumentar la calidad de la proteína recombinante en los IBs. Además, hemos desarrollado varias proteínas antimicrobianas multidominio basadas en la fusión de diferentes péptidos HDP y proteínas de la inmunidad innata. Como también hemos utilizado cremalleras de leucina en estos constructos, se pueden expresar de manera efectiva - sin toxicidad para la célula productora. Además, en caso de necesidad, podemos recuperar antimicrobianos solubles a partir de los IBs gracias a un protocolo de solubilización suave y no desnaturalizando. En conjunto, hemos demostrado que estos constructos tienen un amplio espectro de acción antimicrobiana contra bacterias multi resistentes (MDR), tanto en el formato soluble como en el formato de IBs. Es más, los constructos también son capaces de estimular la liberación de IL-8 dentro de un potencial rango de propiedades inmunomoduladoras. Estos resultados nos han invitado a utilizar nuestras proteínas en la biofuncionalizacón de monocapas autoensamblantes para evitar la formación de biofilms, y hemos observado que estas proteínas pueden anclarse a estos materiales y evitar el crecimiento de biofilms. En resumen, estos resultados refuerzan las proteínas antimicrobianas multidominio como potenciales alternativas antimicrobianas con propiedades inmunomoduladoras.
For most of human history, pathogens have been a leading cause of death and illness. Although we have attained the ability to treat them easily, thanks to the discovery of antibiotics, the widespread overuse and misuse of antimicrobial drugs have accelerated the appearance of antimicrobial resistances (AMRs). Because AMRs have rendered most antimicrobial drugs ineffective, the development of alternative approaches is more necessary than ever before. Host defense peptides (HDPs) have been proposed as blueprints for the generation of new antimicrobials to fight AMR infections. Despite this, most HDPs are produced by chemical synthesis, which is expensive, unsustainable, and difficult to scale-up. Alternatively, their recombinant production is very appealing but still challenging. HDPs are highly susceptible to degradation and are generally toxic to the recombinant host. However, inclusion bodies (IBs), which are protein aggregates that usually happen during recombinant production, can be used to allow HDP formation inside the host without being harmful. Also, the construction of chimeric proteins could be a strategy for successful recombinant expression of small peptides. In this context, this dissertation explores several new strategies for the recombinant production of HDPs. We tried leucine zippers as potential domains to drive the recombinant production of HDPs to the insoluble fraction and improve IBs protein quality. After that, we developed several antimicrobial multidomain proteins based on the fusion of different peptides and proteins from innate immunity. Because we also used leucine zippers with these constructs, they could be produced effectively – without toxicity to the microbial cell factory. Moreover, when needed, we were able to recover soluble antimicrobials from IBs using a mild, non-denaturing protocol. Overall, we demonstrated that these constructs have a broad-spectrum antimicrobial action against multi-drug resistant (MDR) bacteria, in both the soluble and IB format, and that they could trigger the release of IL-8 within a range of potential immunomodulatory properties. These outcomes invited us to use our constructs in the biofunctionalization of self-assembled monolayers to avoid biofilm formation. We observed that the chimeric proteins could be anchored to these materials and avoid biofilm growth. In sum, these results reinforce multidomain antimicrobial proteins as potential antimicrobial alternatives with immunomodulatory properties and open up the possibility for many applications of this new generation of antimicrobial protein nanoparticles as well as their soluble analogs.
47
Rutt, George Clifford. "Purification of recombinant proteins." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/42614.
Full text
48
Maldonado, Rodrigo. "Erythropoietin provides a molecular model for protein burden during intracellular processing and secretion of recombinant proteins." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/erythropoietin-provides-a-molecular-model-for-protein-burden-during-intracellular-processing-and-secretion-of-recombinant-proteins(79ca36c2-75f2-4426-8ab9-d74994fa8ed9).html.
Full textAbstract:
Several elements of the unfolded protein response (UPR) signaling pathway have been engineered in Chinese hamster ovary (CHO) cells with variable effect on recombinant protein (RP) production. To gain insight into the relationship between cell productivity and UPR activation, two recombinant CHO cell lines secreting different amounts (5-fold difference) of erythropoietin (EPO) were characterised in terms of growth, RP production, intracellular EPO content and UPR activation. Differential productivity was correlated with the intracellular amounts of EPO, without affecting cell growth or expression of UPR markers. We found that intracellular EPO presents a different glycosylation status than secreted EPO, representing a possible bottleneck for EPO secretion. To gain insight into the UPR activation during batch culture, the high producing CHO-EPO cell line was used to evaluate UPR target gene expression during batch culture and tunicamycin (Tm)-induced ER stress. Increased abundance of mRNAs related to UPR activation was observed during late days of batch culture of CHO-EPO cells, suggesting UPR activation during batch culture is a consequence of environment changes during batch culture rather than RP expression. Induction of ER stress by the addition of Tm produced changes in the abundance of the UPR-related mRNAs in a pattern similar to that seen during batch culture. mRNA targets associated with the UPR that had not been previously described in the context of RP production in CHO cells were identified (such as ODZ4, HERPUD1 and SQSTM1). Finally, cells expressing EPO under the control of an inducible promoter were used to study the effect of recombinant protein expression on cell phenotype, focusing on the UPR and cell metabolism. Induction of EPO expression was not able to activate the UPR or affect cell growth. Instead, changes in the abundance of metabolites associated with the control of shuttle systems that transport electrons across the mitochondrial membrane were observed in induced cells. These shuttle systems are involved in the transport and conversion of glycerol, citrate, isocitrate and malate, which collectively regulate the redox balance of the cell. In summary, I did not find any evidence of UPR activation on response to RP expression, possible because EPO is not a good inducer of stress compared to other proteins, or I did not reached the amounts of production needed to stress the cell. Despite this, I found metabolic changes associated with the induction of RP expression. Further work will focus on characterisation if this metabolic response is something general to RP induction or if it is a protein-specific characteristic.
49
Barbosa, Maysa Santos. "Clonagem, purificação e caracterização de proteínas antigênicas recombinantes obtidas de Mycoplasma agalactiae." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/42/42132/tde-20022017-144035/.
Full textAbstract:
A agalaxia contagiosa é uma doença de notificação obrigatória que causa severas perdas econômicas para produção de ovinos e caprinos mundialmente. Apesar de seu impacto na produção animal, pouco se sabe sobre os fatores de virulência e patogenicidade do M. agalactiae (principal agente etiológico). Desta maneira, o presente estudo possuiu como objetivo a identificação, purificação e caracterização de proteínas antigênicas de M. agalactiae. Para tanto, quatro proteínas de superfície com potencial antigênico (WP_011949419.1, WP_011949418.1 (P40), WP_011949336.1, WP_011949770.1) foram selecionadas. Essas proteínas foram expressas em Escherichia coli e purificadas em coluna de níquel. As proteínas purificadas foram avaliadas quanto a antigenicidade em Western blotting utilizando soros de caprinos naturalmente infectados com M. agalactiae. Todas as proteínas expressas foram imunorreativas aos soros de caprinos naturalmente infectados, demonstrando que as proteínas utilizadas nesse estudo são possivelmente antigênicas e possuem epítopos acessíveis.The Contagious agalactia is a notifiable disease that causes severe economic losses to sheep and goats worldwide. Despite its impact on animal production, little is known about the virulence factors and pathogenicity of M. agalactiae (main etiological agent). Thus, the present study identified, purified and characterized antigenic proteins of M. agalactiae. Therefore, four surface proteins with antigenic potential (WP_011949419.1, WP_011949418.1 (P40), WP_011949336.1, WP_011949770.1) were selected. These proteins were expressed in Escherichia coli and purified on nickel column. The purified proteins were assayed for antigenicity by Western blotting using goat sera naturally infected with M. agalactiae. All expressed proteins were immunoreactive with sera from naturally infected goats, demonstrating that the proteins used in this study are possibly antigenics and it have acessible epitopes.
50
Silva, João Renato Souza Negrão e. "Construção de vetores para superexpressão da proteína L1 do HPV16 em Pichia pastoris." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/46/46131/tde-26112010-104443/.
Full textAbstract:
O papilomavirus humano (HPV) é o agente etiológico da infecção sexualmente transmissível mais comum na população mundial. A prevalência da infecção por HPV é estimada em 660 milhões de pessoas e mais de 50% das mulheres serão acometidas pela infecção ao menos uma vez na vida. O HPV é responsável por virtualmente todos os casos de câncer de colo de útero (99%), além de causar muitos outros tipos de câncer de mucosa. O câncer cervical afeta aproximadamente 1.4 milhões de mulheres e 500 mil novos casos surgem anualmente, resultando em 250 mil mortes por ano. Os maiores índices de incidência são observados na América Latina e na África. Duas vacinas contra o HPV são comercializadas desde 2006 por empresas estrangeiras. Entretanto, o custo mínimo da vacinação é superior a 600 reais. Este preço torna sua incorporação pelo sistema de saúde um processo economicamente inviável. Dessa forma, devem ser buscadas alternativas para a produção de uma vacina eficaz, de qualidade e de baixo custo no Brasil. A proteína L1, principal proteína do capsídeo do HPV, tem a propriedade de se auto agregar em partículas semelhantes às virais (VLPs), que são o principal componente das vacinas atuais e possuem muita semelhança com os vírions nativos, introduzindo inclusive, uma imunização predominantemente tipo-específica. Este projeto se propôs a construir e avaliar vetores de expressão visando à produção em larga escala da proteína L1 do HPV 16, o tipo de HPV de maior risco e incidência na população mundial. Foram construídos cinco plasmídeos para Pichia pastoris, uma das principais plataformas industriais de expressão. Eles se diferenciam pelos marcadores de seleção e pelas sequências de manutenção do vetor, mas têm exatamente o mesmo objetivo: gerar sistemas que possuam múltiplas cópias do gene da L1 e que não necessitem da utilização de antibióticos. Essa estratégia foi escolhida porque a produtividade de muitas das proteínas heterólogas tem grande dependência da dosagem gênica e porque o uso de antibióticos encarece muito o custo da produção. Na primeira etapa do projeto foi avaliado um sistema de expressão epissomal auxotrófico, mas ele não se manteve estável ao longo de 60 gerações. Na segunda parte, dois vetores de integração ao sítio do DNA ribossomal foram testados. O sistema mais estável e produtivo foi caracterizado quanto ao número de cópias integradas ao genoma da P. pastoris e ao nível de expressão. O sistema é capaz de produzir clones com mais de 30 cópias do gene da L1 e dois clones expressaram cerca de 20 a 30 miligramas/litro de L1. Adicionalmente outros dois vetores integrativos que utilizam sequências teloméricas para integração foram construídos. Ainda são necessários estudos conjuntos de fermentação em larga escala e purificação da proteína para verificar a viabilidade do sistemaThe human papillomavirus (HPV) is the etiologic agent of the sexually transmitted infection most common worldwide. The prevalence of HPV infection is estimated at 660 million people and over 50% of women will be affected by the infection at least once in their lifetime. HPV is responsible for virtually all cervical cancers cases (99%), and causes many other types of mucosal cancer. Cervical cancer affects approximately 1.4 million women, and 500.000 new cases occur annually, resulting in 250.000 deaths per year. The highest incidence rates are seen in Latin America and Africa. Two HPV vaccines are marketed since 2006 by foreign companies. However, the minimum cost of vaccination is higher than 360 dollar. This price makes its incorporation by the Brazilian Health System economically unfeasible. Thus, alternatives must be found to produce an effective vaccine, with low cost and high-quality in Brazil. The L1 protein, the major capsid protein of HPV, has the ability to self aggregate into virus-like particles (VLPs) which are the main component of current vaccines. The VLPs are very similar to the native virions and can introduce an immunization predominantly type-specific. This project aimed to construct and evaluate expression vectors to produce, at large scale, the L1 protein of HPV 16, which is the HPV type at greater risk and incidence in the world. Five plasmids were constructed for Pichia pastoris, one of the major industrial expression platforms. They differ in the selection markers and the vector maintenance sequences, but they have exactly the same goal: to create systems with multiple copies of the L1 gene and that don\'t require the use of antibiotics. This strategy was chosen because the productivity of many heterologous proteins have heavy dependence on gene dosage and because the use of antibiotics is extremely expensive for its production. In the first stage of the project, it was rated an episomal auxotrophic expression system, but it was unstable after a period of 60 generations. In the second part, two vectors for integration in the ribosomal DNA locus were tested. The most stable and productive system was featured on the number of copies integrated into the P. pastoris genome and on the expression level. It was proved that the system is able to produce clones with more than 30 copies of the L1 gene and two clones expressed approximately 20-30 milligrams/liter of L1. Additionally, two other integrative vectors for integration in telomeric sequences were constructed for future testing. More studies on large-scale fermentation and protein purification will be necessary to determine the feasibility of the system.