Characterization of the Activation of the FlgSR two-component system in Campylobacter jejuni

Show full item record

Title: Characterization of the Activation of the FlgSR two-component system in Campylobacter jejuni
Author: Joslin, Stephanie Nicole
Abstract: Epidemiological studies indicate that Campylobacter jejuni is the leading cause of bacterial gastroenteritis worldwide . This organism has the ability to live as a commensal or a pathogen , depending on the host with which it is associated . While colonization of the gastrointestinal tract of many avian and mammalian species results in a harmless commensal relationship , human infection can cause diarrheal disease . In both scenarios flagellar motility is crucial for promoting optimal host interactions , as non -motile C . jejuni colonize the gastrointestinal tracts of commensal hosts at levels significantly lower than motile isolates and are incapable of causing disease in humans . The means by which C . jejuni regulates flagellar gene transcription and assembly differ from the well -studied pathways in species of Salmonella , E . coli , and Vibrio . Previous studies found that C . jejuni requires the flagellar export apparatus , sigma54 , and a two -component regulatory system comprised of the FlgS sensor kinase and the FlgR response regulator to activate transcription of the middle and late sigma54 -dependent flagellar genes . The FlgR response regulator is an NtrC -like protein that can be divided into three domains : an N -terminal domain that is phosphorylated by FlgS , a central sigma54 interaction domain , and a C -terminal domain of unknown function . Characterization of FlgR was accomplished by generating constructs that lack the N - or C -terminal domains of the protein and the site of phosphorylation . Through genetic and biochemical analyses , we found that both the N - and C -terminal domains have suppressive functions that prevent FlgR activation of sigma54 -dependent flagellar gene transcription in the absence of FlgS . Our data also indicate that unlike other NtrC -family proteins , the C -terminus of FlgR does not bind DNA and is dispensable for FlgR activity . The FlgS sensor kinase activates FlgR through phosphorylation , but little was known about its activation prior to these studies . We have identified the site of FlgS autophosphorylation and demonstrated that formation of the flagellar export apparatus and the presence of at least one other flagellum -associated protein is required for autoactivation of this protein . This study provides insight into the unusual regulation of the FlgSR two -component system and its role in activating sigma54 -dependent flagellar gene transcription .
URI: http : / /hdl .handle .net /2152 .5 /406
Date: 2009-06-17


Characterization of the Activation of the FlgSR two-component system in Campylobacter jejuni. Graduate School of Biomedical Sciences. Available electronically from http : / /hdl .handle .net /2152 .5 /406 .

Files in this item

Files Size Format View
joslinstephanie.pdf 3.500Mb application/pdf View/Open

This item appears in the following Collection(s)

Show full item record

Search DSpace

Advanced Search