VpsR and cyclic di-GMP together drive transcription initiation to activate biofilm formation in Vibrio cholerae.

ABSTRACT: The small molecule cyclic di-GMP (c-di-GMP) is known to affect bacterial gene expression in myriad ways. In Vibrio cholerae in vivo, the presence of c-di-GMP together with the response regulator VpsR results in transcription from PvpsL, a promoter of biofilm biosynthesis genes. VpsR shares homology with enhancer binding proteins that activate ?54-RNA polymerase (RNAP), but it lacks conserved residues needed to bind to ?54-RNAP and to hydrolyze adenosine triphosphate, and PvpsL transcription does not require ?54 in vivo. Consequently, the mechanism of this activation has not been clear. Using an in vitro transcription system, we demonstrate activation of PvspL in the presence of VpsR, c-di-GMP and ?70-RNAP. c-di-GMP does not significantly change the affinity of VpsR for PvpsL DNA or the DNase I footprint of VpsR on the DNA, and it is not required for VpsR to dimerize. However, DNase I and KMnO4 footprints reveal that the ?70-RNAP/VpsR/c-di-GMP complex on PvpsL adopts a different conformation from that formed by ?70-RNAP alone, with c-di-GMP or with VpsR. Our results suggest that c-di-GMP is required for VpsR to generate the specific protein-DNA architecture needed for activated transcription, a previously unrecognized role for c-di-GMP in gene expression.

SUBMITTER: Hsieh ML 

PROVIDER: S-EPMC6158489 | biostudies-literature | 2018 Sep

REPOSITORIES: biostudies-literature