Bibliographies thématiques / Filaments de type IV

Littérature scientifique sur le sujet « Filaments de type IV »

Auteur : Grafiati
Publié le 25 mai 2024

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Articles de revues sur le sujet "Filaments de type IV"

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Ching, GY, et RK Liem. « Assembly of type IV neuronal intermediate filaments in nonneuronal cells in the absence of preexisting cytoplasmic intermediate filaments ». Journal of Cell Biology 122, no 6 (15 septembre 1993) : 1323–35. http://dx.doi.org/10.1083/jcb.122.6.1323.

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We report here on the in vivo assembly of alpha-internexin, a type IV neuronal intermediate filament protein, in transfected cultured cells, comparing its assembly properties with those of the neurofilament triplet proteins (NF-L, NF-M, and NF-H). Like the neurofilament triplet proteins, alpha-internexin coassembles with vimentin into filaments. To study the assembly characteristics of these proteins in the absence of a preexisting filament network, transient transfection experiments were performed with a non-neuronal cell line lacking cytoplasmic intermediate filaments. The results showed that only alpha-internexin was able to self-assemble into extensive filamentous networks. In contrast, the neurofilament triplet proteins were incapable of homopolymeric assembly into filamentous arrays in vivo. NF-L coassembled with either NF-M or NF-H into filamentous structures in the transfected cells, but NF-M could not form filaments with NF-H. alpha-internexin could coassemble with each of the neurofilament triplet proteins in the transfected cells to form filaments. When all but 2 and 10 amino acid residues were removed from the tail domains of NF-L and NF-M, respectively, the resulting NF-L and NF-M deletion mutants retained the ability to coassemble with alpha-internexin into filamentous networks. These mutants were also capable of forming filaments with other wild-type neurofilament triplet protein subunits. These results suggest that the tail domains of NF-L and NF-M are dispensable for normal coassembly of each of these proteins with other type IV intermediate filament proteins to form filaments.
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Goosens, Vivianne J., Andreas Busch, Michaella Georgiadou, Marta Castagnini, Katrina T. Forest, Gabriel Waksman et Vladimir Pelicic. « Reconstitution of a minimal machinery capable of assembling periplasmic type IV pili ». Proceedings of the National Academy of Sciences 114, no 25 (6 juin 2017) : E4978—E4986. http://dx.doi.org/10.1073/pnas.1618539114.

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Type IV pili (Tfp), which are key virulence factors in many bacterial pathogens, define a large group of multipurpose filamentous nanomachines widespread in Bacteria and Archaea. Tfp biogenesis is a complex multistep process, which relies on macromolecular assemblies composed of 15 conserved proteins in model gram-negative species. To improve our limited understanding of the molecular mechanisms of filament assembly, we have used a synthetic biology approach to reconstitute, in a nonnative heterologous host, a minimal machinery capable of building Tfp. Here we show that eight synthetic genes are sufficient to promote filament assembly and that the corresponding proteins form a macromolecular complex at the cytoplasmic membrane, which we have purified and characterized biochemically. Our results contribute to a better mechanistic understanding of the assembly of remarkable dynamic filaments nearly ubiquitous in prokaryotes.
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Couturier, Marc Roger, et Markus Stein. « Helicobacter pylori produces unique filaments upon host contact in vitro ». Canadian Journal of Microbiology 54, no 7 (juillet 2008) : 537–48. http://dx.doi.org/10.1139/w08-042.

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Helicobacter pylori exists in 2 distinct morphological states, helicoid and coccoid. Both have been observed in in vitro culture and in gastric biopsies. We visualized H. pylori during AGS cell infections using immunofluorescence microscopy. Anti-H. pylori mouse serum as well as human serum from H. pylori-positive patients recognized long, thin bacterial filaments, which formed on helicoids and more frequently on coccoids. These filaments reached lengths of 59 μm and often connected bacteria. Periodate oxidation abolished antibody recognition, suggesting that carbohydrates compose a major antigenic component of the filaments. Similar to results obtained using immunofluorescence microscopy, scanning electron microscopy imaging revealed thin filamentous structures, which were absent on uninfected cells. Both coccoid conversion and filament development increased over the time course of infection with peak filament formation at 4 h. The number of visible filaments then decreased as bacteria clustered on the apical surface of AGS cells. Since the observed filaments were clearly distinct from previously described surface structures, including flagella and the cag type IV secretion system, our results demonstrate that these filaments represent a unique, previously unrecognized, organelle.
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Kraljic, Katarina, Christopher Duckworth, Rita Tojeiro, Shadab Alam, Dmitry Bizyaev, Anne-Marie Weijmans, Nicholas Fraser Boardman et Richard R. Lane. « SDSS-IV MaNGA : 3D spin alignment of spiral and S0 galaxies ». Monthly Notices of the Royal Astronomical Society 504, no 3 (21 avril 2021) : 4626–33. http://dx.doi.org/10.1093/mnras/stab1109.

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ABSTRACT We investigate the 3D spin alignment of galaxies with respect to the large-scale filaments using the MaNGA survey. The cosmic web is reconstructed from the Sloan Digital Sky Survey using disperse and the 3D spins of MaNGA galaxies are estimated using the thin disc approximation with integral field spectroscopy kinematics. Late-type spiral galaxies are found to have their spins parallel to the closest filament’s axis. The alignment signal is found to be dominated by low-mass spirals. Spins of S0-type galaxies tend to be oriented preferentially in perpendicular direction with respect to the filament’s axis. This orthogonal orientation is found to be dominated by S0s that show a notable misalignment between their kinematic components of stellar and ionized gas velocity fields and/or by low-mass S0s with lower rotation support compared to their high-mass counterparts. Qualitatively similar results are obtained when splitting galaxies based on the degree of ordered stellar rotation, such that galaxies with high spin magnitude have their spin aligned, and those with low spin magnitude in perpendicular direction to the filaments. In the context of conditional tidal torque theory, these findings suggest that galaxies’ spins retain memory of their larger scale environment. In agreement with measurements from hydrodynamical cosmological simulations, the measured signal at low redshift is weak, yet statistically significant. The dependence of the spin-filament orientation of galaxies on their stellar mass, morphology, and kinematics highlights the importance of sample selection to detect the signal.
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Braun, Tatjana, Matthijn R. Vos, Nir Kalisman, Nicholas E. Sherman, Reinhard Rachel, Reinhard Wirth, Gunnar F. Schröder et Edward H. Egelman. « Archaeal flagellin combines a bacterial type IV pilin domain with an Ig-like domain ». Proceedings of the National Academy of Sciences 113, no 37 (30 août 2016) : 10352–57. http://dx.doi.org/10.1073/pnas.1607756113.

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The bacterial flagellar apparatus, which involves ∼40 different proteins, has been a model system for understanding motility and chemotaxis. The bacterial flagellar filament, largely composed of a single protein, flagellin, has been a model for understanding protein assembly. This system has no homology to the eukaryotic flagellum, in which the filament alone, composed of a microtubule-based axoneme, contains more than 400 different proteins. The archaeal flagellar system is simpler still, in some cases having ∼13 different proteins with a single flagellar filament protein. The archaeal flagellar system has no homology to the bacterial one and must have arisen by convergent evolution. However, it has been understood that the N-terminal domain of the archaeal flagellin is a homolog of the N-terminal domain of bacterial type IV pilin, showing once again how proteins can be repurposed in evolution for different functions. Using cryo-EM, we have been able to generate a nearly complete atomic model for a flagellar-like filament of the archaeon Ignicoccus hospitalis from a reconstruction at ∼4-Å resolution. We can now show that the archaeal flagellar filament contains a β-sandwich, previously seen in the FlaF protein that forms the anchor for the archaeal flagellar filament. In contrast to the bacterial flagellar filament, where the outer globular domains make no contact with each other and are not necessary for either assembly or motility, the archaeal flagellin outer domains make extensive contacts with each other that largely determine the interesting mechanical properties of these filaments, allowing these filaments to flex.
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Sheppard, Devon, Jamie-Lee Berry, Rémi Denise, Eduardo P. C. Rocha, Steve Matthews et Vladimir Pelicic. « The major subunit of widespread competence pili exhibits a novel and conserved type IV pilin fold ». Journal of Biological Chemistry 295, no 19 (9 avril 2020) : 6594–604. http://dx.doi.org/10.1074/jbc.ra120.013316.

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Type IV filaments (T4F), which are helical assemblies of type IV pilins, constitute a superfamily of filamentous nanomachines virtually ubiquitous in prokaryotes that mediate a wide variety of functions. The competence (Com) pilus is a widespread T4F, mediating DNA uptake (the first step in natural transformation) in bacteria with one membrane (monoderms), an important mechanism of horizontal gene transfer. Here, we report the results of genomic, phylogenetic, and structural analyses of ComGC, the major pilin subunit of Com pili. By performing a global comparative analysis, we show that Com pili genes are virtually ubiquitous in Bacilli, a major monoderm class of Firmicutes. This also revealed that ComGC displays extensive sequence conservation, defining a monophyletic group among type IV pilins. We further report ComGC solution structures from two naturally competent human pathogens, Streptococcus sanguinis (ComGCSS) and Streptococcus pneumoniae (ComGCSP), revealing that this pilin displays extensive structural conservation. Strikingly, ComGCSS and ComGCSP exhibit a novel type IV pilin fold that is purely helical. Results from homology modeling analyses suggest that the unusual structure of ComGC is compatible with helical filament assembly. Because ComGC displays such a widespread distribution, these results have implications for hundreds of monoderm species.
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Daehnel, Katrin, Robin Harris, Lucinda Maddera et Philip Silverman. « Fluorescence assays for F-pili and their application ». Microbiology 151, no 11 (1 novembre 2005) : 3541–48. http://dx.doi.org/10.1099/mic.0.28159-0.

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Conjugative pili are extracellular filaments elaborated by Gram-negative bacteria expressing certain type IV secretion systems. They are required at the earliest stages of conjugal DNA transfer to establish specific and secure cell–cell contacts. Conjugative pili also serve as adsorption organelles for both RNA and DNA bacteriophages. Beyond these facts, the structure, formation and function of these filaments are poorly understood. This paper describes a rapid, quantitative assay for F-pili encoded by the F plasmid type IV secretion system. The assay is based on the specific lateral adsorption of icosahedral RNA bacteriophage R17 by F-pili. Bacteriophage particles conjugated with a fluorescent dye, Alexa 488, and bound to F-pili defined filaments visible by immunofluorescence microscopy. F-pili attached to F+ cells and free F-pili were both visible by this method. For quantification, cell-bound bacteriophage were separated from free bacteriophage particles by sedimentation and released by suspending cell pellets in 0·1 % SDS. Fluorescence in cell-free supernatant fractions was measured by fluorometry. The authors present a characterization of this assay and its application to F-pilus formation by cells carrying mutations in the gene for the F-pilus subunit F-pilin. Each mutation introduced a cysteine, which F-pilin normally lacks, at a different position in its primary structure. Cysteine residues in the N-terminal domain I abolished filament formation as measured by fluorescent R17 binding. This was confirmed by measurements of DNA donor activity and filamentous DNA bacteriophage infection. With one exception (G53C), cysteines elsewhere in the F-pilin primary structure did not abolish filament formation, although some mutations differentially affected F-pilus functions.
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Ching, G. Y., et R. K. Liem. « Analysis of the roles of the head domains of type IV rat neuronal intermediate filament proteins in filament assembly using domain-swapped chimeric proteins ». Journal of Cell Science 112, no 13 (1 juillet 1999) : 2233–40. http://dx.doi.org/10.1242/jcs.112.13.2233.

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Type IV neuronal intermediate filament proteins consist of alpha-internexin, which can self-assemble into filaments and the neurofilament triplet proteins, which are obligate heteropolymers, at least in rodents. These IF proteins therefore provide good systems for elucidating the mechanism of intermediate filament assembly. To analyze the roles of the head domains of these proteins in contributing to their differential assembly properties, we generated chimeric proteins by swapping the head domains between rat alpha-internexin and either rat NF-L or NF-M and examined their assembly properties in transfected cells that lack their own cytoplasmic intermediate filament network. Lalphaalpha and Malphaalpha, the chimeric proteins generated by replacing the head domain of alpha-internexin with those of NF-L and NF-M, respectively, were unable to self-assemble into filaments. In contrast, alphaLL, a chimeric NF-L protein generated by replacing the head domain of NF-L with that of alpha-internexin, was able to self-assemble into filaments, whereas MLL, a chimeric NF-L protein containing the NF-M head domain, was unable to do so. These results demonstrate that the alpha-internexin head domain is essential for alpha-internexin's ability to self-assemble. While coassembly of Lalphaalpha with NF-M and coassembly of Malphaalpha with NF-L resulted in formation of filaments, coassembly of Lalphaalpha with NF-L and coassembly of Malphaalpha with NF-M yielded punctate patterns. These coassembly results show that heteropolymeric filament formation requires that one partner has the NF-L head domain and the other partner has the NF-M head domain. Thus, the head domains of rat NF-L and NF-M play important roles in determining the obligate heteropolymeric nature of filament formation. The data obtained from these self-assembly and coassembly studies provide some new insights into the mechanism of intermediate filament assembly.
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Lamparter, Tilman, Jennifer Babian, Katrin Fröhlich, Marion Mielke, Nora Weber, Nadja Wunsch, Finn Zais et al. « The involvement of type IV pili and the phytochrome CphA in gliding motility, lateral motility and photophobotaxis of the cyanobacterium Phormidium lacuna ». PLOS ONE 17, no 1 (27 janvier 2022) : e0249509. http://dx.doi.org/10.1371/journal.pone.0249509.

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Phormidium lacuna is a naturally competent, filamentous cyanobacterium that belongs to the order Oscillatoriales. The filaments are motile on agar and other surfaces and display rapid lateral movements in liquid culture. Furthermore, they exhibit a photophobotactic response, a phototactic response towards light that is projected vertically onto the area covered by the culture. However, the molecular mechanisms underlying these phenomena are unclear. We performed the first molecular studies on the motility of an Oscillatoriales member. We generated mutants in which a kanamycin resistance cassette (KanR) was integrated in the phytochrome gene cphA and in various genes of the type IV pilin apparatus. pilM, pilN, pilQ and pilT mutants were defective in gliding motility, lateral movements and photophobotaxis, indicating that type IV pili are involved in all three kinds of motility. pilB mutants were only partially blocked in terms of their responses. pilB is the proposed ATPase for expelling of the filament in type IV pili. The genome reveals proteins sharing weak pilB homology in the ATPase region, these might explain the incomplete phenotype. The cphA mutant revealed a significantly reduced photophobotactic response towards red light. Therefore, our results imply that CphA acts as one of several photophobotaxis photoreceptors or that it could modulate the photophobotaxis response.
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Steinert, Peter M., Lyuben N. Marekov et David A. D. Parry. « Molecular Parameters of Type IV α-Internexin and Type IV-Type III α-Internexin-Vimentin Copolymer Intermediate Filaments ». Journal of Biological Chemistry 274, no 3 (15 janvier 1999) : 1657–66. http://dx.doi.org/10.1074/jbc.274.3.1657.

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Thèses sur le sujet "Filaments de type IV"

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Jacobsen, Theis. « Structure and assembly of bacterial type IV filaments unravelled by an integrative approach ». Electronic Thesis or Diss., Sorbonne université, 2022. http://www.theses.fr/2022SORUS146.

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La superfamille des filaments de type IV (TFF) est un groupe de machines moléculaires localisées dans la membrane des bactéries et des archées. Ces machines associent des polymères protéiques de manière non-covalente appelés des pili, qui s’étendent depuis la cellule pour réaliser plusieurs fonctions qui ont évolué spécifiquement pour s’adapter à des organismes hôtes différents. La superfamille TFF comprend le système de sécrétion de type II (T2SS) et les pili de type IVa (T4aP). Le T2SS induit la sécrétion de substrats chez les bactéries Gram-négatives. Ces substrats sont en général des enzymes qui dégradent les complexes carbohydrates, le peptidoglycane, les lipides, ce qui à terme entraîne la libération de nutriments. Les T4aP sont de longues fibres flexibles qui sont ancrées dans la membrane et permettent de nombreuses fonctions. Le mécanisme par lequel le T2SS et les T4aP remplissent ces différentes fonctions n’est toujours pas entièrement compris. Pour comprendre le mécanisme de sécrétion du T2SS, nous avons étudié par RMN la structure de la pseudopiline OutG, le composant majeur du pseudopilus chez Dickeya dadantii. Dans une seconde partie, nous avions pour objectif d’aborder la structure et l’assemblage des pilines mineures, des protéines qui composent le T4P d’Escherichia coli entérohémorragique. Nous avons optimisé la surexpression, la purification et le marquage de les pilines mineures pour leur étude par RMN. De plus, la modélisation des pilines et le cross-linking ont été réalisés sur les échantillons de pseudopili T4P et T2SS purifiés en tant que méthodologie pour déterminer la structure et les interactions des pilines et pseudopilines au sein du pilus natif
The type IV filament (TFF) superfamily is a group of molecular machineries located in the membrane of bacteria and archaea. These machineries assemble non-covalent protein polymers called pili extending away from the cell to perform multiple functions which have evolved specifically to adapt to different host organisms. The TFF superfamily includes the type II secretion system (T2SS) and the type IVa pili (T4aP). The T2SS promotes the secretion of substrates in Gram-negative bacteria. These substrates are in general enzymes degrading complex carbohydrates, peptidoglycan, and lipids, resulting in the release of nutrients. The T4aP are long flexible fibres anchored in the membrane and enable various functions such as twitching motility, DNA uptake and biofilm formation. The mechanism by which the T2SS and T4aP pilus fulfil their different functions is still not completely understood. To understand the mechanism of secretion by T2SS, we studied the structure of the pseudopilin OutG, the major component of the pseudopilus in Dickeya dadantii by Nuclear Magnetic Resonance (NMR). In a second part, we aimed to address the structure and the assembly of minor pilins, protein components of Enterohemorrhagic Escherichia coli T4aP. We optimised the overexpression, purification and labelling of the minor pilins for their structural study by NMR. Furthermore, molecular modelling of the minor pilins and crosslinking mass spectrometry were performed on whole T4aP and T2SS pseudopili purified samples as a methodology to determine the structure and the interactions of pilins and pseudopilins within the native pilus
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Leh, David. « Optimisation du dimensionnement d'un réservoir composite type IV pour stockage très haute pression d'hydrogène ». Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00942731.

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Ce travail a pour but de proposer une nouvelle approche du dimensionnement optimisé des réservoirs de stockage d'hydrogène de type IV visant à mieux répondre aux enjeux industriels. Les objectifs scientifiques et techniques consistent à disposer de modèles qualifiés pour la simulation du comportement de ces réservoirs, associés à des méthodologies de dimensionnement et d'optimisation fiables. La démarche s'appuie sur trois axes principaux :- proposer une démarche de conception prédictive en intégrant (i) un premier aspect lié à la ruine de la structure qui est la conséquence de mécanismes complexes et multiples d'endommagement s'initiant, s'accumulant et se développant dans un milieu anisotrope et (ii) des modèles de simulation de la structuration composite spécifique au procédé d'enroulement filamentaire, technologie employée largement dans la fabrication des réservoirs de stockage à haute pression. Leurs implémentations constituent une première avancée face à l'existant ;- choisir et évaluer les paramètres structuraux par une démarche d'optimisation où nous sommes amenés à utiliser (i) des méthodes de métamodélisation permettant de répondre aux contraintes de coûts, (ii) des méthodes spécifiques de tri et (iii) des méthodes à spectres larges qui recherchent des solutions sur une large population telles que des méthodes génétiques ;- qualifier la démarche dans sa globalité par une comparaison entre calculs et essais. Ainsi, la finalité de ce travail est de développer et valider des modèles et méthodes pour permettre de mieux concevoir, tester et fabriquer à moindre coût un réservoir avec une structure calculée optimisée.
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Roumagnac, Agnès. « Hyperlipoprotéinémie type IV ». Paris 5, 1988. http://www.theses.fr/1988PA05P031.

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Elliott, Jayne Louise. « Properties and interactions of type III intermediate filaments with CRYAB ». Thesis, Durham University, 2013. http://etheses.dur.ac.uk/7017/.

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Glial fibrillary acidic protein is a type three intermediate filament found within astrocytes in the central nervous system and mutations have been found as the cause of Alexander disease, resulting in protein aggregates of Rosenthal fibers with αBcrystallin. Here two glial fibrillary acidic protein mutants of R79C and R239H, located in the LNDR and rod 2A domain respectively, were assembled in vitro and their morphology, assembly competence and interactions with αB-crystallin were assessed. Both mutants were unable to form usual filament lengths but instead were similar to unit length filaments with R239H forming aggregates due to such high protein interactions and the R79C mutant having much lower assembly competent protein interactions. R239H had a much greater affinity for αB-crystallin, likely a reflection that it has one of the most severe phenotypes. An absence of divalent cations equally affected GFAP assembly resulting in compromised compaction and increased filament-filament interactions. The R120G αB-crystallin mutant results in cardiomyopathy and cataract due to aberrant interactions with desmin intermediate filaments, due to an increased oligomer size and therefore these interactions were studied and compared to wild-type interactions. Temperature and pH also alter the oligomer size of αB-crystallin and were therefore investigated with αB-crystallin-type III intermediate filament interactions. It was found that ischemic conditions and increased temperatures promote their association, demonstrated by increased co-pelleting under high speed sedimentations. There was a preference for binding to desmin filaments thus showing how desmin-wild-type αB-crystallin interactions are important for homeostasis in muscle. Passive microrheology was used to complement this and investigate how αB-crystallin may be modulating desmin filaments under equilibrium. From these experiments wild-type αB-crystallin reduced the frequency-dependent passive viscosity η(f) and the G’, whereas the cardiomyopathy- and cataract- causing R120G mutant increased the η(f).
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Brunmark, Charlott. « Type IV collagen and renal disease ». Lund : Dept. of Nephrology, University of Lund, 1994. http://books.google.com/books?id=owdrAAAAMAAJ.

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Louw, Cassandra Alexandrovna. « Characterisation of Trypanosomal Type III and Type IV Hsp40 proteins ». Thesis, Rhodes University, 2009. http://hdl.handle.net/10962/d1003985.

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The heat shock protein-70 (Hsp70) family of molecular chaperones are ubiquitous highly conserved proteins that are critical for the viability of cellular homeostasis. The ATPase activity of Hsp70 proteins is critical to their function as the affinity of a given Hsp70 for non-native substrate is modulated by ATP binding and hydrolysis. When bound to ATP, Hsp70s possess a low affinity for a given substrate protein, while the hydrolysis of ATP to ADP causes a conformational change that results in a high affinity for substrate proteins. The basal ATPase activity of Hsp70s is too low to facilitate their function in vivo, and co-chaperones are essential to modulate the efficient protein folding by Hsp70. Heat shock protein-40 (Hsp40) heat shock proteins are essential for the in vivo function of Hsp70s by stimulating the ATPase activity of these proteins and facilitating transfer of substrates. The Type III class of Hsp40 proteins have not been well characterised due to their poor levels of conservation at the primary sequence level. This is due to the fact that Type III Hsp40s only contain a J-domain and a poorly conserved C-terminal region. The newly identified Type IV class of Hsp40s, contain an abrogated HPD tripeptide motif in the J-domain and have also not been extensively studied. Trypanosoma brucei (T. brucei) is a unicellular flagellated protozoan parasite. It is the causative agent of Human African Trypansomiasis (HAT) which results in thousands of deaths and devastating agricultural losses in many parts of Africa. T. brucei undergoes a complex lifecycle that is characterised by the transition from an insect vector to a mammalian host in markedly different conditions of temperature, pH, nutrient availability and respiratory requirements. It has been proposed that molecular chaperones may enhance the survival of these parasites due to their cytoprotective effect in combating cellular stress. Due to the fact that T. brucei infection is invariably fatal if left untreated, and that no novel treatment regimens have been developed recently, the identification of potential novel drug targets among proteins essential to the parasite’s survival in the host organism is an attractive aspect of T. brucei research. Because Type III Hsp40s are poorly conserved with respect to Hsp40s found in the human host, the identification of any of these proteins found to be essential to T. brucei survival in humans could potentially make attractive novel drug targets. An in depth in silico investigation into the Type III Hsp40 complement as well as partner Hsp70 proteins in T.brucei was performed. T. brucei possesses 65 Hsp40 proteins, of which 47 were classed as Type III and 6 of which were identified as being putative Type IV Hsp40s. A small but significant number (5) of Type III TbHsp40s contained tetratricopeptide (TPR) domains in addition to the J-domain. The J-domains of the Type III TbHsp40 complement were found to be conserved with respect to those of canonical Hsp40 proteins, although the mutation of certain residues that play a key role in Hsp40-Hsp70 interaction was noted. Potential partnerships of these proteins in the parasite was also investigated. The coding regions of three previously uncharacterised TbHsp40s were successfully amplified from T. brucei TREU927 genomic DNA and cloned into an expression vector. Tbj1, a Tcj1 ortholog, was selected for further study and successfully expressed and biochemically characterised. Tbj1 expressed in E. coli was found to be insoluble, but large amounts were recovered with the aid of a denaturing purification followed by refolding elution strategies, and the bulk of the protein recovered was in compact monomeric form as determined by size-exclusion chromatography fast protein liquid chromatography (SEC-FPLC). The addition of Tbj1 to a thermally aggregated substrate resulted in increased levels of aggregation, although Tbj1 was able to assist two Hsp70 proteins in the suppression of aggregation. Tbj1 proved unable to stimulate the ATPase activity of these same Hsp70s, and could not rescue temperature sensitive cells when replacing E.coli DnaJ and CbpA. It was concluded that Tbj1 does not possess independent chaperone activity, but could display Hsp40 co-chaperone properties under certain circumstances. This could allude to a specialised function in the T. brucei parasite. The lack of human orthologues to Tbj1 could result in the attractiveness of this protein as a novel drug target.
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Liou, Angela Yen-Chun. « Characterization of members of type IV and type IIC of human P-type ATPase ». Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62488.

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P-type ATPases comprise a superfamily of proteins that play vital roles in the human body and can cause severe diseases if their functions are impaired. P₄-ATPases or type 4 of P-type ATPases are implicated in the ATP-dependent flipping of phospholipids across cell membranes. This generates and maintains transverse phospholipid asymmetry, a property important for biological processes including vesicle trafficking. ATP9A is a P₄-ATPase that remains poorly characterized despite its high expression in brain and testis. Interestingly, loss of Neo1p, the yeast ortholog of ATP9A, is lethal. The first part of this study investigates the functional properties and cellular localization of ATP9A. Human ATP9A was expressed in HEK293T cells and characterized using biochemical and cell-based approaches. ATP9A exhibited little if any phospholipid-dependent ATPase activity, but underwent hydroxylamine-sensitive phosphorylation, a characteristic feature of the P-type ATPase reaction cycle. A monoclonal antibody to ATP9A was generated for analysis of ATP9A in cells and brain tissues by western blotting and immunofluorescence microscopy. In transfected HEK293T cells ATP9A localized to perinuclear and peripheral punctate structures possibly related to the endocytic pathway. Our findings suggest that ATP9A undergoes autophosphorylation, but fails to dephosphorylate, possibly due to lack of an accessory protein or a specific substrate. Further studies on endogenous ATP9A should provide further insight into its physiological function and possible role in human disease. On the other hand, Na⁺/K⁺-ATPase (NKA) belongs to type 2C of P-type ATPases and establishes Na⁺ and K⁺ gradients across cell membranes. NKA has been shown to interact with retinoschisin (RS1), an adhesion protein essential for normal retinal structure and function. Mutations in the gene encoding RS1 cause a macular degeneration disorder called X-linked retinoschisis (XLRS). RS1 is thought to be anchored to the membranes of photoreceptor and bipolar cells through interaction with the α3 and β2 isoforms of NKA. The second part aims to characterize the RS1-NKA complex by generating monoclonal antibodies specific for the components. Indeed, immunoaffinity purification of NKAβ2 from bovine retinal membranes co-immunoprecipitated the α3 subunit and RS1. Tandem affinity purification of the native protein complexes should enhance understanding of the molecular and cellular mechanisms underlying XLRS.
Medicine, Faculty of
Biochemistry and Molecular Biology, Department of
Graduate
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Karuppiah, Vijaykumar. « Structural studies of type IV pilus biogenesis proteins ». Thesis, University of Manchester, 2010. http://www.manchester.ac.uk/escholar/uk-ac-man-scw:101892.

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Berry, Jamie. « Structural characterization of type IV pilus biogenesis proteins ». Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/structural-characterization-of-type-iv-pilus-biogenesis-proteins(1e0d7119-58d5-4e5d-839d-daef8deb76ab).html.

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Type IV pili, or fimbriae, are long, thin proteinaceous appendages found on the surface of many well-known pathogens. They mediate a variety of important virulence functions for the organism, such as twitching motility, biofilm formation, uptake of genetic material and host cell recognition and adhesion. Pili are formed by the rapid polymerization and de-polymerization of the pilin subunit, and this is orchestrated by a complex macromolecular machine which spans the bacterial cell envelope, requiring a variety of gene products. The type IV pilus biogenesis system is closely related to the bacterial type II secretion system, one of six designated multi-protein cell envelope complexes which are dedicated to the specific secretion of exotoxins and virulence factors. Many of these secretion systems also produce fimbrial structures to facilitate the extrusion of their substrates or to communicate with the host. As they form crucial virulence factors, the secretion systems and the type IV pilus biogenesis system have become attractive potential antimicrobial targets and obtaining structural and functional information for the components of these systems is an important first step towards achieving this.Type IV pili appear on the surface of bacteria through an outer membrane pore, PilQ, which is a member of the secretin family. Secretins are also found in the type II and III secretion systems, but the way in which they are regulated remains unclear. PilQ forms a dodecameric chamber in the outer membrane with a large vestibule which reaches into the periplasm, composed of its N-terminal domains. In this project, N-terminal domains from PilQ were produced in recombinant form and their structures determined by NMR. One of these domains revealed an eight-stranded beta-sandwich structure which appears to be unique to type IV pilus secretins and has not been structurally characterized before. Another revealed an alpha/beta type fold which is common to secretins of other systems. In the second part of this project, the interaction formed between the N-terminal alpha/beta domains of PilQ and an essential inner membrane-anchored lipoprotein, PilP, was probed by NMR chemical shift perturbation. Based on changes to the 15N-HSQC spectra the binding site was mapped onto each protein to produce a computational model for the complex formed between the two. Using a recent cryo-EM structure for the Neisseria PilQ dodecamer determined by colleagues, it was possible to model the PilQ N-terminal domains in complex with PilP into the electron density map. This produced a model for the trans-periplasmic assembly formed by PilQ and PilP in the type IV pilus biogenesis system, and led to the conclusion that the PilQ dodecamer needs to disassemble considerably at the base to accommodate a pilus fibre. The novel beta-domains might therefore function to gate or open the secretin, and PilP may play a role in stabilizing the secretin during this and serve to connect the outer and inner membrane system components.
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Schröder, Gunnar. « TraG-like transporter proteins of type IV secretion systems ». [S.l. : s.n.], 2003. http://www.diss.fu-berlin.de/2003/179/index.html.

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Livres sur le sujet "Filaments de type IV"

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United States. Forest Service. Pacific Northwest Region., dir. Call-when-needed type III and IV light helicopters. [Portland, Or.?] : USDA Forest Service, Pacific Northwest Region (R-6), 1998.

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United States. Forest Service. Pacific Northwest Region., dir. Call-when-needed type III and IV light helicopters. [Portland, Or.?] : USDA Forest Service, Pacific Northwest Region (R-6), 1998.

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United States. Forest Service. Pacific Northwest Region, dir. Call-when-needed type III and IV light helicopters. [Portland, Or.?] : USDA Forest Service, Pacific Northwest Region (R-6), 1998.

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United States. Forest Service. Pacific Northwest Region, dir. Call-when-needed type III and IV light helicopters. [Portland, Or.?] : USDA Forest Service, Pacific Northwest Region (R-6), 1998.

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United States. Forest Service. Pacific Northwest Region, dir. Call-when-needed type III and IV light helicopters. [Portland, Or.?] : USDA Forest Service, Pacific Northwest Region (R-6), 1998.

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Backert, Steffen, et Elisabeth Grohmann, dir. Type IV Secretion in Gram-Negative and Gram-Positive Bacteria. Cham : Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-75241-9.

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Reponen, Paula. The primary structure and developement expression of mouse type IV collagenases. Oulu : Oulun yliopisto, 1994.

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B, Sanjeevi C., Hanafusa Toshiaki et New York Academy of Sciences, dir. Immunology of diabetes IV : Progress in our understanding. Boston : Blackwell Pub. on behalf of the New York Academy of Sciences, 2006.

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Butterworth, Helen Claire. The novel chains of type IV collagen : Cloning and exploration of function. Manchester : University of Manchester, 1994.

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Center, Langley Research, dir. Laminar and turbulent flow computations of type IV shock-shock interference aerothermal loads using unstructured grids. Hampton, Va : National Aeronautics and Space Administration, Langley Research Center, 1994.

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Chapitres de livres sur le sujet "Filaments de type IV"

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Mitchel Opremcak, E. « Type IV Hypersensitivity ». Dans Uveitis, 228–61. New York, NY : Springer New York, 1995. http://dx.doi.org/10.1007/978-1-4612-4174-4_18.

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Halpern, M. J., F. Mesquita, E. M. Campos et W. J. McConathy. « Latent Type IV ». Dans Advances in Experimental Medicine and Biology, 213–18. Boston, MA : Springer US, 1987. http://dx.doi.org/10.1007/978-1-4684-1268-0_31.

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Timson, David J., Richard J. Reece, James B. Thoden, Hazel M. Holden, Andrea L. Utz, Beverly M. K. Biller, Eugen-Matthias Strehle et al. « Glycogenosis Type IV ». Dans Encyclopedia of Molecular Mechanisms of Disease, 735. Berlin, Heidelberg : Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-29676-8_8636.

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Halpern, M. J. « Type IV Hyperlipemia ». Dans Lipid Metabolism and Its Pathology, 153–60. Boston, MA : Springer US, 1985. http://dx.doi.org/10.1007/978-1-4613-2445-4_19.

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Habenstein, Birgit, Nadia El Mammeri, James Tolchard, Gaëlle Lamon, Arpita Tawani, Mélanie Berbon et Antoine Loquet. « Structures of Type III Secretion System Needle Filaments ». Dans Bacterial Type III Protein Secretion Systems, 109–31. Cham : Springer International Publishing, 2019. http://dx.doi.org/10.1007/82_2019_192.

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Mintz, Bruce L. « Ehlers-Danlos Type IV (Vascular Type) ». Dans Atlas of Clinical Vascular Medicine, 60–61. Oxford, UK : Blackwell Publishing Ltd., 2013. http://dx.doi.org/10.1002/9781118618189.ch30.

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Hill, Robert A. « Type IV Tibial Dysplasia ». Dans Limb Lengthening and Reconstruction Surgery Case Atlas, 1–9. Cham : Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-02767-8_50-1.

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Gonçalves, João, Helena Soares, Norman L. Eberhardt, Sarah C. R. Lummis, David R. Soto-Pantoja, David D. Roberts, Umadas Maitra et al. « Type IV cAMP Phosphodiesterase ». Dans Encyclopedia of Signaling Molecules, 1943. New York, NY : Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4419-0461-4_101424.

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Gooch, Jan W. « Delayed (Type IV) Hypersensitivity ». Dans Encyclopedic Dictionary of Polymers, 886. New York, NY : Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_13531.

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Schröder, Gunnar, Savvas N. Savvides, Gabriel Waksman et Erich Lanka. « Type IV Secretion Machinery ». Dans Structural Biology of Bacterial Pathogenesis, 179–221. Washington, DC, USA : ASM Press, 2014. http://dx.doi.org/10.1128/9781555818395.ch10.

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Actes de conférences sur le sujet "Filaments de type IV"

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Farhood, Naseer H., Saravanan Karuppanan, H. H. Ya et Mohamad Ariff Baharom. « Burst pressure investigation of filament wound type IV composite pressure vessel ». Dans ADVANCED MATERIALS FOR SUSTAINABILITY AND GROWTH : Proceedings of the 3rd Advanced Materials Conference 2016 (3rd AMC 2016). Author(s), 2017. http://dx.doi.org/10.1063/1.5010482.

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BIANCHI, I. « Process and structural simulation for the development of a pressure vessel through filament winding technology ». Dans Material Forming. Materials Research Forum LLC, 2023. http://dx.doi.org/10.21741/9781644902479-38.

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Abstract. Recently, Università Politecnica delle Marche and COMEC Innovative srl are involved in the research project “Smart Tow Winding” funded by MIUR (Ministry of Education, University and Research), concerning the development of an innovative process for the realization of a pressure vessel through Filament Winding (FW) technology. In this context, a design procedure for type IV composite pressure vessel is proposed. To design the component, the dedicated simulation software CADWIND was used to virtually generate the pressure vessel through the definition of the desired geometry, the type of prepreg, the number of layers and the bandwidth. The generated file was imported in the FEM simulation software Siemens NX with the aim of evaluating the structural resistance under an internal pressure of 70 MPa. Different external configurations of mandrels and stratification were tested in order to optimize the geometry of the vessel and the resistance to weight ratio. A high performance and low weight vessel configuration was finally identified.
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Geints, Yuri E., Andrey Ionin, Daria Mokrousova, Georgy Rizaev, Leonid Seleznev, Elena Sunchugasheva et Alexander Zemlyanov. « Filaments and post-filaments formation during high-power Ti:sapphire laser pulses propagation in air and optical glasses ». Dans Technologies for Optical Countermeasures XVII ; and High-Power Lasers : Technology and Systems, Platforms, Effects IV, sous la direction de David H. Titterton, Robert J. Grasso, Mark A. Richardson, Willy L. Bohn et Harro Ackermann. SPIE, 2020. http://dx.doi.org/10.1117/12.2566799.

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Jang, Dogeun. « High efficient terahertz generation from two-color femtosecond laser filaments ». Dans Relativistic Plasma Waves and Particle Beams as Coherent and Incoherent Radiation Sources IV, sous la direction de Dino A. Jaroszynski et MinSup Hur. SPIE, 2021. http://dx.doi.org/10.1117/12.2591951.

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Bechtel, S. E., J. G. Cao et M. G. Forest. « Viscoelastic Free Surface Jets and Filaments ». Dans ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-0470.

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Abstract In this paper we examine the necessary versus self-consistent consequences of a slender aspect ratio on viscoelastic free surface jet flows. As in Schultz & Davis (1982), the equations of the 3-D free surface jet problem are nondimensionalized with presumed disparate length scales in the transverse and axial directions, and a perturbation theory for the slender jet is obtained by positing an expansion in the slenderness parameter (i.e. the ratio ε of these scales). A different perturbation problem ensues for each regime of free jet behavior. We exhibit three regimes, one in which the slenderness scaling of the 3-D free surface jet problem forces a separation-of-variables (s-o-v) structure of the solution (that is, the radial coordinate explicitly factors out at each order in ε), another in which the s-o-v structure is not forced but is a solution, and a third in which the s-o-v structure is not a solution. These three regimes are prototypes for general filament behavior: of the many possible regimes, many are of the first type (the separation of variables structure is unique), many more are of the second type (the separation of variables solution exists but cannot be shown to be unique), and the rest are of the third type (if a slender solution exists it does not have a s-o-v structure).
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Buehler, Markus J., et Je´re´mie Bertaud. « Hierarchical Structure Controls Nanomechanical Properties of Vimentin Intermediate Filaments ». Dans ASME 2010 First Global Congress on NanoEngineering for Medicine and Biology. ASMEDC, 2010. http://dx.doi.org/10.1115/nemb2010-13103.

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Intermediate filaments (often abbreviated as IFs), in addition to microtubules and microfilaments, are one of the three major components of the cytoskeleton in eukaryotic cells (Figure 1). It has been suggested that intermediate filaments are crucial in defining key mechanical functions of cells such as cell migration, cell division and mechanotransduction, and have also been referred to as the “safety belts of cells” reflecting their role in preventing exceedingly large cell stretch [1, 2]. Vimentin is a specific type of this protein filament found in fibroblasts, leukocytes, and blood vessel endothelial cells, representing the most widely distributed type of intermediate filaments. Several diseases have been linked to the structure and density of intermediate filaments. Here we report a systematic study of the effects of intermediate filaments on cell mechanics, specifically focused on changes in the density of filaments. We compare the results with experimental studies in vimentin deficient cells, showing good qualitative agreement.
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Acici, Koray, Duygu Dede Sener et Hasan Ogul. « Sensitive prediction of bacterial type IV effectors ». Dans 2014 18th National Biomedical Engineering Meeting (BIYOMUT). IEEE, 2014. http://dx.doi.org/10.1109/biyomut.2014.7026341.

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Jella, Saatvik, Ramesh Burela Gupta, Ankit Gupta et Shravan Kumar Bhadoria. « Computational study of type IV hydrogen tanks ». Dans 14TH INTERNATIONAL CONFERENCE ON MATERIALS PROCESSING AND CHARACTERIZATION 2023. AIP Publishing, 2024. http://dx.doi.org/10.1063/5.0192690.

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Pijanowska, Dorota, Katarzyna Wygladacz, Jerzy Jazwinski, Jan M. Lysko, Jan Koszur, Zbigniew Brzozka et Elzbieta Malinowska. « Technological aspects of potentiometric BSC-type microsensor fabrication ». Dans Optoelectronic and Electronic Sensors IV, sous la direction de Jerzy Fraczek. SPIE, 2001. http://dx.doi.org/10.1117/12.435944.

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Huttunen, Heikki, Fatemeh Shokrollahi Yancheshmeh et Ke Chen. « Car type recognition with Deep Neural Networks ». Dans 2016 IEEE Intelligent Vehicles Symposium (IV). IEEE, 2016. http://dx.doi.org/10.1109/ivs.2016.7535529.

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Rapports d'organisations sur le sujet "Filaments de type IV"

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Elbaum, Michael, et Peter J. Christie. Type IV Secretion System of Agrobacterium tumefaciens : Components and Structures. United States Department of Agriculture, mars 2013. http://dx.doi.org/10.32747/2013.7699848.bard.

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Objectives: The overall goal of the project was to build an ultrastructural model of the Agrobacterium tumefaciens type IV secretion system (T4SS) based on electron microscopy, genetics, and immunolocalization of its components. There were four original aims: Aim 1: Define the contributions of contact-dependent and -independent plant signals to formation of novel morphological changes at the A. tumefaciens polar membrane. Aim 2: Genetic basis for morphological changes at the A. tumefaciens polar membrane. Aim 3: Immuno-localization of VirB proteins Aim 4: Structural definition of the substrate translocation route. There were no major revisions to the aims, and the work focused on the above questions. Background: Agrobacterium presents a unique example of inter-kingdom gene transfer. The process involves cell to cell transfer of both protein and DNA substrates via a contact-dependent mechanism akin to bacterial conjugation. Transfer is mediated by a T4SS. Intensive study of the Agrobacterium T4SS has made it an archetypal model for the genetics and biochemistry. The channel is assembled from eleven protein components encoded on the B operon in the virulence region of the tumor-inducing plasmid, plus an additional coupling protein, VirD4. During the course of our project two structural studies were published presenting X-ray crystallography and three-dimensional reconstruction from electron microscopy of a core complex of the channel assembled in vitro from homologous proteins of E. coli, representing VirB7, VirB9, and VirB10. Another study was published claiming that the secretion channels in Agrobacterium appear on helical arrays around the membrane perimeter and along the entire length of the bacterium. Helical arrangements in bacterial membranes have since fallen from favor however, and that finding was partially retracted in a second publication. Overall, the localization of the T4SS within the bacterial membranes remains enigmatic in the literature, and we believe that our results from this project make a significant advance. Summary of achievements : We found that polar inflations and other membrane disturbances relate to the activation conditions rather than to virulence protein expression. Activation requires low pH and nutrient-poor medium. These stress conditions are also reflected in DNA condensation to varying degrees. Nonetheless, they must be considered in modeling the T4SS as they represent the relevant conditions for its expression and activity. We identified the T4SS core component VirB7 at native expression levels using state of the art super-resolution light microscopy. This marker of the secretion system was found almost exclusively at the cell poles, and typically one pole. Immuno-electron microscopy identified the protein at the inner membrane, rather than at bridges across the inner and outer membranes. This suggests a rare or transient assembly of the secretion-competent channel, or alternatively a two-step secretion involving an intermediate step in the periplasmic space. We followed the expression of the major secreted effector, VirE2. This is a single-stranded DNA binding protein that forms a capsid around the transferred oligonucleotide, adapting the bacterial conjugation to the eukaryotic host. We found that over-expressed VirE2 forms filamentous complexes in the bacterial cytoplasm that could be observed both by conventional fluorescence microscopy and by correlative electron cryo-tomography. Using a non-retentive mutant we observed secretion of VirE2 from bacterial poles. We labeled the secreted substrates in vivo in order detect their secretion and appearance in the plant cells. However the low transfer efficiency and significant background signal have so far hampered this approach.
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Wiersman, B. J. F-Area Type IV Tank Liner Life Estimation. Office of Scientific and Technical Information (OSTI), octobre 2005. http://dx.doi.org/10.2172/881430.

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Wilmarth, W. R. Desilication Study of DWPF Recycle Stored in Type IV Tanks. Office of Scientific and Technical Information (OSTI), janvier 2003. http://dx.doi.org/10.2172/806927.

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McMonagle, Morgan P. Type IV Thoracoabdominal Aneurysm (TAA) with External Axillo-Unifemoral Bypass. Touch Surgery Publications, novembre 2019. http://dx.doi.org/10.18556/touchsurgery/2016.s0172.

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McMonagle, Morgan P. Type IV Thoracoabdominal Aneurysm (TAA) with External Axillo-Unifemoral Bypass. Touch Surgery Simulations, novembre 2019. http://dx.doi.org/10.18556/touchsurgery/2019.s0172.

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Wiersma, B. AN ASSESSMENT OF THE SERVICE HISTORY AND CORROSION SUSCEPTIBILITY OF TYPE IV WASTE TANKS. Office of Scientific and Technical Information (OSTI), septembre 2008. http://dx.doi.org/10.2172/939191.

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Pemberton, R., et S. Giannis. Unravelling the hydrogen regulatory framework : approval process for type IV onboard vehicle hydrogen fuel containers. National Physical Laboratory, juillet 2021. http://dx.doi.org/10.47120/npl.eng70.

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Zapp, P. E. Applicability of the sludge processing technical standard to type IV waste tanks with high fluoride concentration. Office of Scientific and Technical Information (OSTI), mars 1992. http://dx.doi.org/10.2172/10137101.

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Zapp, P. E. Applicability of the sludge processing technical standard to type IV waste tanks with high fluoride concentration. Office of Scientific and Technical Information (OSTI), mars 1992. http://dx.doi.org/10.2172/6893162.

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Tang, Wan-Yee. Investigation of a Putative Estrogen-Imprinting Gene, Phosphodiesterase Type IV Variant (PDE4D4), in Determining Prostate Cancer Risk. Fort Belvoir, VA : Defense Technical Information Center, avril 2007. http://dx.doi.org/10.21236/ada469241.

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