The scr circuit in Vibrio parahaemolyticus: output targets and transcriptional regulation by a c-di-GMP responsive protein

ABSTRACT: Vibrio parahaemolyticus scr genes modulate expression of gene sets pertinent to swarming and biofilm formation. They do so by affecting the level of the second messenger c-di-GMP. Here we explore the extent of this regulation by comparing the transcriptomes of a scrABC mutant and its wild-type parental strain. The scope of transcriptional effects modulated by c-di-GMP includes ~100 genes that are positively and negatively regulated. An elevated cellular level of c-di-GMP represses the surface sensing regulon including the genes encoding the lateral flagellar and type three secretion systems while inducing expression of genes encoding cell surface molecules and capsular polysaccharide. Expression of a few transcriptional regulators was also affected, and here we describe the role of one, CpsQ. CpsQ is one of four V. parahaemolyticus homologs in the CsgD/VpsT family of regulators, members of which have been implicated in c-di-GMP signaling. Mutations in cpsQ, like defects in another previously identified capsule regulator, cpsR, suppress the sticky phenotype of scr mutants. By using a combination of mutant and reporter analyses in Vibrio and E. coli, CpsQ is shown to be the direct positive regulator of cpsA transcription and its cpsA-activating ability is found to be responsive to the cellular level of c-di-GMP. Unexpectedly, we find that a low level of this nucleotide diminishes the stability of CpsQ. The molecular interplay in this signaling circuit is further defined by demonstrating that CpsQ is epistatic to CpsS, a negative regulator of capsule. CpsR activates cpsQ, and CpsQ can also regulate its own transcription. Wildtype Vibrio parahaemolyticus (LM5674) and scrABC mutant (LM6567) were grown on rich mediim agar plates and gene expression profiles were compared.

ORGANISM(S): Vibrio parahaemolyticus

SUBMITTER: Linda McCarter 

PROVIDER: E-GEOD-30508 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress