Identifying genes controlled by the catabolite repressor protein, CRP, and the anti-activator protein, CytR, and their roles in the quorum sensing and natural competence pathways in Vibrio cholerae Open Access

Nellessen, Maria Lynn (2012)

Permanent URL: https://etd.library.emory.edu/concern/etds/z029p513z?locale=en
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Abstract

The bacterium, Vibrio cholerae is a natural inhabitant of brackish waters, but can also cause the diarrheal disease, cholera, when ingested by a human host. In the environment, V. cholerae often attaches to chitinous surfaces such as those found on crabs and copepods. In the presence of chitin, a V. cholerae cell-cell communications system called quorum sensing (QS) induces expression of genes permitting this pathogen to take up extracellular DNA. The purpose of this study is to define the genetic components and regulatory connections that link QS and chitin signaling to natural transformation, using molecular genetics and biochemical techniques. Natural transformation is one mechanism of horizontal gene transfer (HGT) that allows individual cells to incorporate foreign DNA fragments into their genome. Such a process may increase the evolutionary fitness of the bacterium because the incorporated DNA may encode beneficial genes such as those coding for antibiotic resistance. Recently, it has been shown that V. cholerae natural competence utilizes a molecular mechanism involving two regulators, CRP and CytR. The goal of the studies described below was to define the role that these two genes, other genetic components, and the environment play in the evolution of this waterborne pathogen.

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TABLE OF CONTENTS


Index of Figures………………………………………………………………….…1

Introduction…………………………………………………………………………..3

Materials and Methods……………………………………………………....20

Results…………………………………………………………………………….....29

Discussion………………………………………………….……………………....37

References……………………………………………………………………..…..46

Supplemental Figures………………………………………………………….54



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