title: Repression by H-NS of genes required for the biosynthesis of the Vibrio cholerae biofilm matrix is modulated by the second messenger cyclic diguanylic acid.
abstract: Expression of Vibrio cholerae genes required for the biosynthesis of exopolysacchide (vps) and protein (rbm) components of the biofilm matrix is enhanced by cyclic diguanylate (c-di-GMP). In a previous study, we reported that the histone-like nucleoid structuring (H-NS) protein represses the transcription of vpsA, vpsL and vpsT. Here we demonstrate that the regulator VpsT can disrupt repressive H-NS nucleoprotein complexes at the vpsA and vpsL promoters in the presence of c-di-GMP, while H-NS could disrupt the VpsT-promoter complexes in the absence of c-di-GMP. Chromatin immunoprecipitation-Seq showed a remarkable trend for H-NS to cluster at loci involved in biofilm development such as the rbmABCDEF genes. We show that the antagonistic relationship between VpsT and H-NS regulates the expression of the rbmABCDEF cluster. Epistasis analysis demonstrated that VpsT functions as an antirepressor at the rbmA/F, vpsU and vpsA/L promoters. Deletion of vpsT increased H-NS occupancy at these promoters while increasing the c-di-GMP pool had the opposite effect and included the vpsT promoter. The negative effect of c-di-GMP on H-NS occupancy at the vpsT promoter required the regulator VpsR. These results demonstrate that c-di-GMP activates the transcription of genes required for the biosynthesis of the biofilm matrix by triggering a coordinated VpsR- and VpsT-dependent H-NS antirepression cascade.
authors.affiliation: University of Alabama at Birmingham, Department of Microbiology, Birmingham, Alabama.|Morehouse School of Medicine, Department of Microbiology, Biochemistry and Immunology, Atlanta, Georgia.
authors.forename: Julio C
authors.initials: JC
authors.lastname: Ayala
authors.affiliation: Morehouse School of Medicine, Department of Microbiology, Biochemistry and Immunology, Atlanta, Georgia.|State Key Laboratory for Infectious Disease Prevention and Control and National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Changping, Beijing, China.
authors.forename: Hongxia
authors.initials: H
authors.lastname: Wang
authors.affiliation: Morehouse School of Medicine, Department of Microbiology, Biochemistry and Immunology, Atlanta, Georgia.
authors.forename: Anisia J
authors.initials: AJ
authors.lastname: Silva
authors.affiliation: Morehouse School of Medicine, Department of Microbiology, Biochemistry and Immunology, Atlanta, Georgia.
authors.forename: Jorge A
authors.initials: JA
authors.lastname: Benitez
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D018441:Biofilms / Q000254:growth & development*; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D011485:Protein Binding; D014176:Protein Biosynthesis; D015290:Second Messenger Systems; D014734:Vibrio cholerae / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C031908:H-NS protein, bacteria; C422325:VpsR protein, Vibrio cholerae; C062025:bis(3',5')-cyclic diguanylic acid; D006152:Cyclic GMP