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Author: Emily Lauryn Clark
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Integrative and conjugative elements (ICEs) are widespread mobile genetic elements that facilitate the spread of many important genes, including those involved in antibiotic resistance, metabolism, pathogenesis, or symbiosis. These elements are also powerful tools for genetic analyses and engineering. ICEs are typically found integrated in a host chromosome. Either stochastically, or upon some signal, they can excise, undergo DNA processing events, be transferred through encoded conjugation machinery into a neighboring cell, and stably integrate into the new chromosome. Interactions between an ICE and its hosts throughout the life cycle can influence the efficiency of acquisition by new hosts. In this work, I investigated and compared the interactions that two ICEs, Tn916 and ICEBs1, have with their host cells. First, I explored how the different functional modules of these elements impact how efficiently they are transferred into different host species. I generated hybrid conjugative elements that merge functions of both elements to increase transfer efficiencies, presenting exciting potential to be used for genetic engineering. Next, I investigated a previously unknown ability of Tn916 to cause a growth arrest and kill its host cell. I took genetic approaches to determine that two Tn916-encoded genes interact with a defective phage-like element in the B. subtilis chromosome to elicit some of these effects. Finally, I evaluated the integration site selection of Tn916 in the B. subtilis chromosome, identifying several hundred unique AT-rich insertion sites, one of which is a "hot spot" for integration. I found that a host nucleoid-associated protein does not influence integration site selection. I conclude this body of work with a discussion of how the efficient spread of an element is shaped by its interactions with host cells and other horizontally acquired elements
Author: Emily Lauryn Clark
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Integrative and conjugative elements (ICEs) are widespread mobile genetic elements that facilitate the spread of many important genes, including those involved in antibiotic resistance, metabolism, pathogenesis, or symbiosis. These elements are also powerful tools for genetic analyses and engineering. ICEs are typically found integrated in a host chromosome. Either stochastically, or upon some signal, they can excise, undergo DNA processing events, be transferred through encoded conjugation machinery into a neighboring cell, and stably integrate into the new chromosome. Interactions between an ICE and its hosts throughout the life cycle can influence the efficiency of acquisition by new hosts. In this work, I investigated and compared the interactions that two ICEs, Tn916 and ICEBs1, have with their host cells. First, I explored how the different functional modules of these elements impact how efficiently they are transferred into different host species. I generated hybrid conjugative elements that merge functions of both elements to increase transfer efficiencies, presenting exciting potential to be used for genetic engineering. Next, I investigated a previously unknown ability of Tn916 to cause a growth arrest and kill its host cell. I took genetic approaches to determine that two Tn916-encoded genes interact with a defective phage-like element in the B. subtilis chromosome to elicit some of these effects. Finally, I evaluated the integration site selection of Tn916 in the B. subtilis chromosome, identifying several hundred unique AT-rich insertion sites, one of which is a "hot spot" for integration. I found that a host nucleoid-associated protein does not influence integration site selection. I conclude this body of work with a discussion of how the efficient spread of an element is shaped by its interactions with host cells and other horizontally acquired elements
Author: Adam P. Roberts
Publisher: CRC Press
ISBN: 1000724700
Category : Science
Languages : en
Pages : 456
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Book Description
As our understanding of mobile genetic elements continues to grow we are gaining a deeper appreciation of their importance in shaping the bacterial genome and in the properties they confer to their bacterial hosts. These include, but are by no means limited to, resistance to antibiotics, and heavy metals, toxin production and increased virulence, production of antibiotics and the ability to utilize a diverse range of metabolic substrates. We are also gaining an understanding of diversity of these elements and their interactions with each other; a property which continually complicates any attempt to classify them. We are learning more about the molecular mechanisms by which they translocate to new genomic sites both within genomes and between different bacteria. This book provides a timely, state of the art update on the properties of an important selection of different bacterial integrative mobile genetic elements and the myriad of different ways in which they move and influence the biology of the host bacterium. The chapters are all written by authors who have undertaken pioneering work in their respective fields, making this book vital reading for all who are interested in the biology of bacteria and the mobile elements they carry.
Author: Mark Michael Harden (Jr.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 137
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Book Description
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.
Author: Michael Chandler
Publisher: John Wiley & Sons
ISBN: 1555819214
Category : Science
Languages : en
Pages : 1321
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Book Description
An exploration of the raw power of genetic material to refashion itself to any purpose... Virtually all organisms contain multiple mobile DNAs that can move from place to place, and in some organisms, mobile DNA elements make up a significant portion of the genome. Mobile DNA III provides a comprehensive review of recent research, including findings suggesting the important role that mobile elements play in genome evolution and stability. Editor-in-Chief Nancy L. Craig assembled a team of multidisciplinary experts to develop this cutting-edge resource that covers the specific molecular mechanisms involved in recombination, including a detailed structural analysis of the enzymes responsible presents a detailed account of the many different recombination systems that can rearrange genomes examines the tremendous impact of mobile DNA in virtually all organisms Mobile DNA III is valuable as an in-depth supplemental reading for upper level life sciences students and as a reference for investigators exploring new biological systems. Biomedical researchers will find documentation of recent advances in understanding immune-antigen conflict between host and pathogen. It introduces biotechnicians to amazing tools for in vivo control of designer DNAs. It allows specialists to pick and choose advanced reviews of specific elements and to be drawn in by unexpected parallels and contrasts among the elements in diverse organisms. Mobile DNA III provides the most lucid reviews of these complex topics available anywhere.
Author: Joshua Mark Jones
Publisher:
ISBN:
Category :
Languages : en
Pages : 111
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Book Description
Mobile genetic elements drive bacterial evolution by mediating horizontal gene transfer and by carrying cargo genes that confer important traits to host cells. Traits provided by mobile genetic elements include antibiotic resistance, novel metabolic capabilities, virulence factors, and the ability to form symbioses. Mobile genetic elements, especially Integrative Conjugative Elements (ICEs), are abundant in bacteria. Many do not contain cargo genes with known functions, but some likely carry novel types of cargo genes that provide traits beyond the scope of those currently attributed to mobile elements. In this thesis I describe the characterization of a fitness benefit provided by the mobile genetic element ICEBs1 to its bacterial host, Bacillus subtilis. Activation of ICEBs1 conferred a frequency-dependent selective advantage to host cells during biofilm formation and sporulation. The advantage was due to inhibition of biofilm-associated gene expression and delayed sporulation, which enabled ICEBs1 host cells to exploit their neighbors and grow more prior to sporulation. I identified a single gene within ICEBs1, ydcO, as both necessary and sufficient for the repression of development. Manipulation of host development programs allows ICEBs1 to increase host fitness. These findings highlight that cargo genes can alter existing aspects of physiology rather than providing entirely new traits, broadening our understanding of how mobile genetic elements influence their hosts.
Author: Mislav Acman
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Many bacteria can exchange genetic material through horizontal gene transfer (HGT) mediated by plasmids and plasmid-borne transposable elements. One grave consequence of this exchange is the rapid spread of antibiotic resistance determinants among bacterial communities across the world. In this thesis, I make use of large datasets of publicly available bacterial genomes and various analytical approaches to improve our understanding of the nature and the impact of HGT at a global scale. In the first part, I study the population structure and dynamics of over 10,000 bacterial plasmids. By reconstructing and analysing a network of plasmids based on their shared k-mer content, I was able to sort them into biologically meaningful clusters. This network-based analysis allowed me to make further inferences into global network of HGT and opened up prospect for a natural and exhaustive classification framework of bacterial plasmids. The second part focuses on global spreading of blaNDM - an important antibiotic resistance gene. To this end, I compiled a dataset of over 6000 bacterial genomes harbouring this element and developed a novel computational approach to track structural variants surrounding blaNDM across bacterial genomes. This facilitated identification of prevalent genomic contexts of blaNDM and reconstruction of key mobile genetic elements and events which led to its global dissemination. Taken together, my results highlight transposable elements as the main drivers of HGT at broad phylogenetic and geographical scales with plasmid exchange being much more spatially restricted due to the adaptation to specific bacterial hosts and evolutionary pressures.
Author: National Academy of Sciences
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 388
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Book Description
The Arthur M. Sackler Colloquia of the National Academy of Sciences address scientific topics of broad and current interest, cutting across the boundaries of traditional disciplines. Each year, four or five such colloquia are scheduled, typically two days in length and international in scope. Colloquia are organized by a member of the Academy, often with the assistance of an organizing committee, and feature presentations by leading scientists in the field and discussions with a hundred or more researchers with an interest in the topic. Colloquia presentations are recorded and posted on the National Academy of Sciences Sackler colloquia website and published on CD-ROM. These Colloquia are made possible by a generous gift from Mrs. Jill Sackler, in memory of her husband, Arthur M. Sackler.
Author: Hiromi Nishida
Publisher: Springer
ISBN: 9811334110
Category : Science
Languages : en
Pages : 278
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Book Description
This book comprehensively discusses our current understanding of the role and biological mechanisms of horizontal transfer of genetic elements in the environment, which has been important in the evolution of prokaryotes (archaea and bacteria). Horizontal transfer of genetic elements generates variations of prokaryotes and their genomes. Comparative studies of genomes revealed that it frequently occurred during archaeal and bacterial evolution. The book introduces a variety of studies related to horizontal gene transfer, gene silencing, plasmids, phages, transposons, and the emergence of microbes that degrade man-made xenobiotics and have antimicrobial resistance. Written by leading researchers in DNA traffic, the book is a valuable guide to horizontal transfer for both young scientists and experts in the field.
Author:
Publisher:
ISBN: 9780815332183
Category : Cells
Languages : en
Pages : 0
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Book Description
Author: Hervé Tettelin
Publisher: Springer Nature
ISBN: 3030382818
Category : Science
Languages : en
Pages : 311
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Book Description
This open access book offers the first comprehensive account of the pan-genome concept and its manifold implications. The realization that the genetic repertoire of a biological species always encompasses more than the genome of each individual is one of the earliest examples of big data in biology that opened biology to the unbounded. The study of genetic variation observed within a species challenges existing views and has profound consequences for our understanding of the fundamental mechanisms underpinning bacterial biology and evolution. The underlying rationale extends well beyond the initial prokaryotic focus to all kingdoms of life and evolves into similar concepts for metagenomes, phenomes and epigenomes. The book’s respective chapters address a range of topics, from the serendipitous emergence of the pan-genome concept and its impacts on the fields of microbiology, vaccinology and antimicrobial resistance, to the study of microbial communities, bioinformatic applications and mathematical models that tie in with complex systems and economic theory. Given its scope, the book will appeal to a broad readership interested in population dynamics, evolutionary biology and genomics.
