Gene regulation by the RcsCB two-component system and the auxiliary protein TviA in S. Typhi

ABSTRACT: In response to osmolarity, Salmonella enterica serotype Typhi (S. Typhi) regulates genes required for Vi capsular antigen expression oppositely to those required for motility and invasion. Previous studies suggest that osmoregulation of motility, invasion and capsule expression is mediated through the RcsC/RcsD/RcsB phosphorelay system. Here we performed gene expression profiling and functional studies to determine the role of TviA, an auxiliary protein of the RcsB response regulator, in controlling virulence gene expression in S. Typhi. TviA repressed expression of genes encoding flagella and the invasion associated type III secretion system (T3SS-1) through repression of the flagellar regulators flhDC and fliZ, resulting in reduced invasion and reduced expression of FliC. Both RcsB and TviA reduced expression of flhDC, but only TviA altered flhDC expression in response to osmolarity. These data suggest that the auxiliary TviA protein integrates a new regulatory input into the RcsB regulon of S. Typhi, thereby altering expression of genes encoding flagella, the Vi antigen and T3SS-1 in response to osmolarity. Gene expression profiles of the S. Typhi wild-type strain, a rcsB mutant, a (delta)tviB-vexE (tviBCDEvexABCDE) mutant, and a (delta)viaB (tviABCDEvexABCDE) mutant (lacking tviA expression) was compared. Strains were cultured in SOB broth (low salt), a condition known to induce expression of TviA and the RcsCB system. Total RNA was extracted from two independent cultures (biological replicates) of each strain. cDNA was differentially labeled with Alexa Fluor 555 and 648, respectively and competitively hybridized on S.Typhimurium arrays (PFGRC, version 4). The submitted samples are biological replicates of a competitive hybridization of cDNA from the wild-type strain (Ty2) and the rcsB mutant (SW237) (GSM395580, GSM395581) or the viaB mutant (STY2) and the tviB-vexE mutant (SW74) (GSM395582, GSM395583), respectively.

ORGANISM(S): Salmonella enterica subsp. enterica serovar Typhi

SUBMITTER: Andreas Baumler 

PROVIDER: E-GEOD-15752 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress