Dissertations / Theses on the topic 'Integrative conjugative element'
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SANTORO, FRANCESCO. "Functional characterization of the pneumococcal Integrative Conjugative Element Tn5253." Doctoral thesis, Università di Siena, 2017. http://hdl.handle.net/11365/1005925.
Full textHarden, Mark Michael Jr. "Interactions between an integrative and conjugative element and its bacterial host." Thesis, Massachusetts Institute of Technology, 2021. https://hdl.handle.net/1721.1/130662.
Full textCataloged from the official PDF of thesis.
Includes bibliographical references.
Conjugative elements are mobile genetic elements that can transfer from a donor bacterium to a recipient via an element-encoded type IV secretion system. Integrative and conjugative elements (ICEs) are an abundant class of conjugative element. ICEs are typically integrated into the bacterial host chromosome, but under certain conditions, or stochastically, they can excise from the chromosome and transfer to a recipient. ICEs likely interact with their bacterial host at every stage of their life cycle, but few of these interactions have been characterized. In this work I sought to 1) identify bacterial host factors necessary for efficient transfer of the integrative and conjugative element ICEBs1 to a recipient, and 2) determine whether the ICEBs1-encoded cell wall-modifying enzyme CwlT acts on the cell wall of the donor bacterium, the recipient bacterium, or both.
I used CRISPR interference to induce a knockdown of individual essential Bacillus subtilis genes, and then screened for gene knockdowns that caused an acute defect in transfer of ICEBs1. I found that wall teichoic acids were necessary in both ICEBs1 donors and recipients for efficient conjugative transfer. I found that depletion of wall teichoic acids caused cells involved in ICEBs1 conjugation to sustain lethal envelope damage caused by active conjugation machinery. Conjugative elements must bypass the cell wall of both the donor and recipient cells in a mating pair. Conjugative elements encode cell wall hydrolases that are required for efficient transfer, which are presumed to partly degrade the cell wall of the donor bacterium during conjugation. In order to investigate the role of the ICEBs1-encoded cell wall hydrolase CwlT in conjugation, I generated cell wall-less (L-form) strains of B. subtilis which could donate or receive ICEBs1.
In the absence of either the donor or recipient cell wall, CwlT was dispensable for efficient transfer. This finding indicates that CwlT acts on both the donor and recipient cell wall in a mating pair.
by Mark Michael Harden, Jr.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Biology
Avello, Monika M. M. (Monika Maria Masumi). "Characterization of an exclusion mechanism in an integrative and conjugative element in Bacillus subtilis." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119980.
Full textCataloged from PDF version of thesis.
Includes bibliographical references.
Horizontal gene transfer is the acquisition of new genetic material that can confer novel phenotypes to bacteria and contribute to their evolution. Conjugation is an important mechanism of horizontal gene transfer that involves the direct transfer of DNA between two cells and is mediated by mobile genetic elements encoding type IV secretion systems. Conjugative elements prevent redundant transfer by a mechanism known as exclusion that inhibits their cognate secretion systems. Exclusion is prevalent among conjugative elements, suggesting it is advantageous and potentially essential. Yet very few exclusion mechanisms are characterized, and the advantages they provide are not well understood. My work characterizes the exclusion mechanism of an integrative and conjugative element found in a Gram-positive bacterium. In combination with several other studies, my results point to a potentially conserved mechanism and novel benefits of this phenomenon, furthering our understanding of how mobile genetic elements regulate their transfer, impact their bacterial hosts, and mediate horizontal gene transfer.
by Monika M. M. Avello.
Ph. D.
fox, Valeria. "Mobile genetic elements carrying stress response systems, antibiotic resistance determinants, and catabolic pathways." Doctoral thesis, Università di Siena, 2021. http://hdl.handle.net/11365/1159250.
Full textCarraro, Nicolas. "Analyse comparative de la dynamique de deux éléments intégratifs conjugatifs de streptococcus thermophilus." Thesis, Nancy 1, 2011. http://www.theses.fr/2011NAN10080/document.
Full textIntegrative and Conjugative Elements (ICEs) are genomic islands, which excise from the chromosome, self-transfer by conjugation and integrate. They harbor a modular organization: genes and sequences involved in the same biological process are grouped in the same region. This work concerns the modality of transfer and maintenance of ICESt1 and ICESt3, two ICEs of Streptococcus thermophilus that share closely related core region. ICESt1 excises much less frequently than ICESt3. Nevertheless, excision of the two elements is activated by the same stimuli (DNA damage, stationary phase and/or cell density) and depends of the host strain. Bioinformatical and transcriptional analyses highlight several differences in their organization. However, each of these two ICEs would encode two different regulators, cI and ImmR, suggesting that a complex and original pathway govern to ICESt1' and ICESt3' regulation. This regulation would be shared with numerous ICEs that we identified in the genome of various commensal or pathogenic streptococci. According to the original definition, ICE's maintenance would be exclusively due to their integration in the host chromosome, and ICEs would not be able of extracellular replication. However, in addition to the induction of ICESt3' excision and transfer, DNA damage cause replication of its extrachromosomal form. This unexpected property is encoded by the core region and would be implicated in the maintenance of the element. Comparision with data recently published on other ICEs suggest that intracellular replication could be involved in the maintenance of numerous ICEs, besides their integration
Eidam, Christopher [Verfasser]. "Molecular analysis of multiresistant Mannheimia haemolytica isolates with particular reference to novel macrolide resistance genes and variants of the integrative and conjugative element ICEPmu1 / Christopher Eidam." Hannover : Bibliothek der Tierärztlichen Hochschule Hannover, 2014. http://d-nb.info/106486256X/34.
Full textSilva, Miriam Lopes da. "Detecção e caracterização de elementos conjugativos integrativos em bactérias isoladas de amostras ambientais." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/6/6135/tde-14052014-155858/.
Full textRecognition of antimicrobial resistance as an emerging phenomenon in public health has been a problem worldwide. The abuse in the use of antibiotics in human and veterinary medicine, and agriculture, has caused an increase in the diversity of resistant microorganisms, reflecting in treatment failure. The mechanisms of antibiotic resistance in microorganisms are primarily mediated by genes acquired from exogenous DNA. The dynamics of the horizontal transfer is performed by mobile genetic elements which carry resistance genes. The wide distribution of these structures, such as the SXT element originally isolated from V. cholerae, has contributed to the spread of specific clonal complexes in certain geographical areas. This pioneering study in Brazil researched the presence of SXT elements in the group of bacterial species in environmental gamma-proteobacteria species, determined their structural and functional characteristics, including genes for resistance to antibiotics and the antibiotic susceptibility among bacterial isolates that harbor them. The result was the classification of 43 SXT elements found in Brazil, by comparison with those found in the literature. Among the SXT elements found, four are sheltered by Morganella morganii, unprecedented in the literature. Knowledge of bacterial evolution is an important to establish effective strategies to control and treat infections without increasing the selective pressure on microorganisms, as well as a precise instrument and very important tool to support epidemiological studies.
Wright, Laurel D. "Autonomous replication of integrative and conjugative elements." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/106738.
Full textCataloged from PDF version of thesis.
Includes bibliographical references.
Mobile genetic elements facilitate movement of genes, including those conferring antibiotic resistance and other traits, between bacteria. Integrative and conjugative elements (ICEs), also known as conjugative transposons, are a large family of mobile genetic elements that can transfer between neighboring cells. ICEs are found integrated in the chromosome of their host bacterium, where they are transmitted to daughter cells by chromosomal replication and cell division. Under certain conditions, ICE DNA will excise and form a circular plasmid-like intermediate. It was previously thought that ICEs were incapable of autonomous replication. However, my research, along with the work of others, shows that ICEs can replicate autonomously, and that many ICEs utilize a rolling circle replication mechanism. Plasmids and phages that use rolling circle replication encode a single strand origin (sso) that enhances priming of DNA synthesis. We identified a functional single strand origin, sso1, in the integrative and conjugative element ICEBs1 of Bacillus subtilis. Genetic analyses indicated that ICEBs1 uses sso1 and at least one other region for second strand DNA synthesis. Sso activity was important for autonomous, rolling circle replication of ICEBs1 in host cells, and for stable acquisition of the element in new host cells. I also showed that the broad-host range ICE Tn916 replicates autonomously by a rolling circle mechanism. Replication of Tn916 was dependent on the relaxase encoded by Tn916 orf20. The origin of transfer of Tn916, oriT(916), also functioned as an origin of replication. I found that the relaxase (Orf20) and the two putative helicase processivity factors (Orf22 and Orf23) encoded by Tn916 likely interact in a complex to facilitate replication. Lastly, I identified a functional single strand origin of replication (sso) in Tn916 that I predict primes second strand synthesis during rolling circle replication. The importance of autonomous replication by rolling circle in the ICE lifecycle and horizontal gene transfer processes is discussed.
by Laurel D. Wright.
Ph. D.
Haskett, Timothy L. "Discovery and characterisation of tripartite Integrative & Conjugative Elements." Thesis, Haskett, Timothy L. (2018) Discovery and characterisation of tripartite Integrative & Conjugative Elements. PhD thesis, Murdoch University, 2018. https://researchrepository.murdoch.edu.au/id/eprint/41086/.
Full textStagg, Georgina. "Creation and characterisation of genetically-marked Mesorhizobium integrative and conjugative elements." Thesis, Stagg, Georgina (2018) Creation and characterisation of genetically-marked Mesorhizobium integrative and conjugative elements. Honours thesis, Murdoch University, 2018. https://researchrepository.murdoch.edu.au/id/eprint/42888/.
Full textBöltner, Dietmar. "Genomic analysis of the conjugative integrating element R391 from Providencia rettgeri." Thesis, University of Essex, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268707.
Full textFarzand, Robeena. "Occurrence and roles of two integrative and conjugative elements in Klebsiella pneumoniae." Thesis, University of Leicester, 2017. http://hdl.handle.net/2381/40665.
Full textColuzzi, Charles. "L'exploration des génomes par l'outil ICEFinder révèle la forte prévalence et l'extrême diversité des ICE et des IME de streptocoques." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0352/document.
Full textMobile genetic elements largely contribute to the evolution and diversity of bacterial genomes through horizontal gene transfer. Among them, the integrative and conjugative elements (ICEs) encode their own excision, conjugative transfer and integration. On the other hand, integrative mobilizable elements (IMEs) are autonomous for excision and integration but encode only some of the proteins needed for their conjugative transfer. IMEs therefore need a “helper” conjugative element to transfer. Despite their impact on gene flow and genome dynamics, the prevalence of ICEs remains largely underscored and very few IMEs were identified at the beginning of this study. Furthermore, although several in silico methods exist to detect genomic islands, none are dedicated to ICEs or IMEs, thus complicating exhaustive examination of these mobile elements. The Streptococcus genus belongs to the firmicutes’ phylum. Almost all streptococci are commensal bacteria or pathogenes to men and animals. Two species of Streptococcus are also used in the dairy industry as lactic ferments in order to produce fermented milk and different types of cheese. Studying the gene flux of the Steptococci genus and the impact it can have on the lifestyle of these organisms is essential, as it has a lot of interest for human health and activities. In this work, we searched for ICEs and IMEs in 124 strains of streptococci belonging to 27 species using a reference database of ICE and IME signature proteins (from their conjugation, mobilization and integration/excision modules). This exhaustive analysis led to the identification and delimitation of 131 ICEs or slightly decayed ICEs and 144 IMEs. All these elements were delimited, which allowed us to identify their integration specificities in the genomes. In total, 17 ICE integration specificities were identified. Among them, 8 had never been described before (ftsK, guaA, lysS, mutT, rpmG, rpsI, traG and ybaB/EbfC). 18 specificities were also identified for IMEs, among which only 5 were known for the firmicutes. ICEs encode high or low-specificity tyrosine integrases (13 different specificities), single serine intégrases (1 specificity), triplet of serine integrases (3 different specificities), or DDE transposases while IMEs encode either tyrosine integrases (10 different specificities) or single serine integrases (8 different specificities). ICE were grouped in 7 distinct families according to the proteins encoded by their conjugation module whereas the mobilization modules of IMEs were highly diverse, preventing them from grouping into families according to their mobilization modules. The phylogenetic analysis of the signature proteins encoded by all ICEs and IMEs showed integration module exchanges between ICEs and IMEs and several mobilization module exchanges between IMEs. The overall results reveal a strong prevalence and extreme diversity of these elements among Streptococci genomes. Better understanding and knowledge of ICEs and IMEs prompted us to build a semi-automated command-line tool to identify streptococcal ICEs and IMEs as well as to determine their insertion site
Nouvel, Laurent-Xavier. "Etude de la diversité génétique de Mycoplasma agalactiae : plasticité des génomes, mobilome et dynamique de surface." Thesis, Toulouse, INPT, 2009. http://www.theses.fr/2009INPT013A/document.
Full textMycoplasma agalactiae is responsible of contagious agalactia, a disease of small ruminants that is still difficult to control and is listed by the OIE. In order to evaluate the genetic diversity of this pathogen, 101 isolates were compared using three techniques (VNTR, RFLP, vpma repertoire). Results revealed a high genetic homogeneity with the PG2 type strain as representative. Some isolates however diverged such as the 5632 which was sequenced and analysed here. Whole comparative genomic and proteomic analyses of the 5632 and PG2 strains indicate that their genomic plasticity resides in important genes flux and in the presence of several mobile genetic elements (10% of the genome). These analyses also revealed that specific loci encoding repertoire of surface proteins are highly dynamic. For these minimal bacteria that lack a cell-wall, these events have most likely played a major role in their survival and adaptation to complex hosts
SPAGNOLETTI, MATTEO. "Comparative genomics of V. cholerae 7th pandemic strains. Analysis of integrative conjugative elements, genomic islands and prophages." Doctoral thesis, 2012. http://hdl.handle.net/11573/917386.
Full text"Using comparative genomics to identify virulence traits and vaccine candidates in Mannheimia haemolytica." Thesis, 2015. http://hdl.handle.net/10388/ETD-2015-06-2118.
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