Affiliation:
1. Department of Environmental Toxicology, University of California, Santa Cruz,
Santa Cruz, California 95064
Abstract
ABSTRACT
Vibrio cholerae
undergoes phenotypic variation that generates two
morphologically different variants, termed smooth and rugose. The transcriptional profiles of the two variants differ greatly, and many of the differentially regulated genes are controlled by a complex regulatory circuitry that includes the transcriptional regulators VpsR, VpsT, and HapR. In this study, we identified the VpsT regulon and
compared the VpsT and VpsR regulons to elucidate the contribution of each positive regulator to the rugose variant transcriptional profile and associated phenotypes. We have found that although the VpsT and VpsR regulons are very similar, the magnitude of the gene regulation accomplished by each regulator is different. We also determined that
cdgA
, which encodes a GGDEF domain protein, is partially responsible for the altered
vps
gene expression between the
vpsT
and
vpsR
mutants. Analysis of epistatic
relationships among
hapR
,
vpsT
, and
vpsR
with respect to a whole-genome expression profile, colony morphology, and biofilm formation revealed that
vpsR
is epistatic to
hapR
and
vpsT
. Expression of virulence genes was increased in a
vpsR hapR
double mutant relative to a
hapR
mutant, suggesting that VpsR negatively regulates
virulence gene expression in the
hapR
mutant. These results show that a complex regulatory interplay among VpsT, VpsR, HapR, and GGDEF/EAL family proteins controls transcription of the genes required for
Vibrio
polysaccharide and virulence factor production in
V.
cholerae
.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology