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Functional Characterization of the Stringent Response Regulatory Gene dksA of Vibrio cholerae and Its Role in Modulation of Virulence Phenotypes

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Title Functional Characterization of the Stringent Response Regulatory
Gene dksA of Vibrio cholerae and Its Role in Modulation of Virulence
Phenotypes
 
Creator Pal, Ritesh Ranjan
Bag, Satyabrata
Dasgupta, Shreya
Das, Bhabatosh
Bhadra, Rupak K
 
Subject Infectious Diseases and Immunology
 
Description In bacteria, nutrient deprivation evokes the stringent response, which is mediated by the small intracellular signaling molecule
ppGpp. In Gram negatives, the RelA enzyme synthesizes and SpoT hydrolyzes ppGpp, although the latter protein also has weak
synthetase activity. DksA, a recently identified RNA polymerase binding transcription factor, acts as a coregulator along with
ppGpp for controlling the stringent response. Recently, we have shown that three genes, relA, spoT, and relV, govern cellular levels
of ppGpp during various starvation stresses in the Gram-negative cholera pathogen Vibrio cholerae. Here we report functional
characterization of the dksA gene of V. cholerae (dksAVc), coding for the protein DksAVc. Extensive genetic analyses of the
�dksAVc mutants suggest that DksAVc is an important component involved in the stringent response in V. cholerae. Further
analysis of mutants revealed that DksAVc positively regulates various virulence-related processes, namely, motility, expression of
the major secretory protease, called hemagglutinin protease (HAP), and production of cholera toxin (CT), under in vitro conditions.
We found that DksAVc upregulates expression of the sigma factor FliA (�28), a critical regulator of motility in V. cholerae.
Altogether, it appears that apart from stringent-response regulation, DksAVc also has important roles in fine regulation of virulence-
related phenotypes of V. cholerae
 
Publisher American Society for Microbiology
 
Date 2012
 
Type Article
PeerReviewed
 
Format application/pdf
 
Identifier http://www.eprints.iicb.res.in/1717/1/JOURNAL_OF_BACTERIOLOGY___194_(20_)5638%2D5648_;2012[31].pdf
Pal, Ritesh Ranjan and Bag, Satyabrata and Dasgupta, Shreya and Das, Bhabatosh and Bhadra, Rupak K (2012) Functional Characterization of the Stringent Response Regulatory Gene dksA of Vibrio cholerae and Its Role in Modulation of Virulence Phenotypes. Journal of Bacteriology, 194 (20). pp. 5638-5648.
 
Relation http://dx.doi.org/10.1128/JB.00518-12
http://www.eprints.iicb.res.in/1717/