The quorum sensing transcription factor AphA directly regulates natural competence in Vibrio cholerae

PLoS Genet. 2019 Oct 28;15(10):e1008362. doi: 10.1371/journal.pgen.1008362. eCollection 2019 Oct.

Abstract

Many bacteria use population density to control gene expression via quorum sensing. In Vibrio cholerae, quorum sensing coordinates virulence, biofilm formation, and DNA uptake by natural competence. The transcription factors AphA and HapR, expressed at low and high cell density respectively, play a key role. In particular, AphA triggers the entire virulence cascade upon host colonisation. In this work we have mapped genome-wide DNA binding by AphA. We show that AphA is versatile, exhibiting distinct modes of DNA binding and promoter regulation. Unexpectedly, whilst HapR is known to induce natural competence, we demonstrate that AphA also intervenes. Most notably, AphA is a direct repressor of tfoX, the master activator of competence. Hence, production of AphA markedly suppressed DNA uptake; an effect largely circumvented by ectopic expression of tfoX. Our observations suggest dual regulation of competence. At low cell density AphA is a master repressor whilst HapR activates the process at high cell density. Thus, we provide deep mechanistic insight into the role of AphA and highlight how V. cholerae utilises this regulator for diverse purposes.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biofilms / growth & development
  • Cholera / genetics*
  • Cholera / microbiology
  • DNA-Binding Proteins / genetics*
  • Gene Expression Regulation, Bacterial / genetics
  • Host-Pathogen Interactions / genetics
  • Humans
  • Promoter Regions, Genetic / genetics
  • Quorum Sensing / genetics
  • Trans-Activators / genetics*
  • Transcription Factors / genetics
  • Vibrio cholerae / genetics*
  • Vibrio cholerae / pathogenicity

Substances

  • AphA protein, Vibrio cholerae
  • DNA-Binding Proteins
  • Trans-Activators
  • Transcription Factors