title: Disulfide bond formation and ToxR activity in Vibrio cholerae.
abstract: Virulence factor production in Vibrio cholerae is complex, with ToxRS being an important part of the regulatory cascade. Additionally, ToxR is the transcriptional regulator for the genes encoding the major outer membrane porins OmpU and OmpT. ToxR is a transmembrane protein and contains two cysteine residues in the periplasmic domain. This study addresses the influence of the thiol-disulfide oxidoreductase system DsbAB, ToxR cysteine residues and ToxR/ToxS interaction on ToxR activity. The results show that porin production correlates with ToxR intrachain disulfide bond formation, which depends on DsbAB. In contrast, formation of ToxR intrachain or interchain disulfide bonds is dispensable for virulence factor production and in vivo colonization. This study further reveals that in the absence of ToxS, ToxR interchain disulfide bond formation is facilitated, whereat cysteinyl dependent homo- and oligomerization of ToxR is suppressed if ToxS is coexpressed. In summary, new insights into gene regulation by ToxR are presented, demonstrating a mechanism by which ToxR activity is linked to a DsbAB dependent intrachain disulfide bond formation.
authors.affiliation: Institute of Molecular Biosciences, University of Graz, Humboldtstrasse, Graz, Austria.
authors.forename: Vera H I
authors.initials: VH
authors.lastname: Fengler
authors.forename: Eva C
authors.initials: EC
authors.lastname: Boritsch
authors.forename: Sarah
authors.initials: S
authors.lastname: Tutz
authors.forename: Andrea
authors.initials: A
authors.lastname: Seper
authors.forename: Hanna
authors.initials: H
authors.lastname: Ebner
authors.forename: Sandro
authors.initials: S
authors.lastname: Roier
authors.forename: Stefan
authors.initials: S
authors.lastname: Schild
authors.forename: Joachim
authors.initials: J
authors.lastname: Reidl
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002771:Cholera / Q000235:genetics / Q000382:microbiology; D003545:Cysteine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D015151:Immunoblotting; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation; D019897:Periplasm / Q000378:metabolism; D018272:Porins / Q000235:genetics / Q000378:metabolism; D019704:Protein Disulfide-Isomerases / Q000235:genetics / Q000378:metabolism; D055503:Protein Multimerization; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014734:Vibrio cholerae / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D014774:Virulence / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D004220:Disulfides; C079503:DsbB protein, Bacteria; D008565:Membrane Proteins; D018272:Porins; D014157:Transcription Factors; C499324:toxR protein, Vibrio cholerae; C066828:ToxS protein, Vibrio cholerae; D019704:Protein Disulfide-Isomerases; D003545:Cysteine