title: A distinctive dual-channel quorum-sensing system operates in Vibrio anguillarum.
abstract: Many bacterial cells communicate using diffusible signal molecules to monitor cell population density via a process termed quorum sensing. In marine Vibrio species, the Vibrio harveyi-type LuxR protein is a key player in a quorum-sensing phosphorelay cascade, which controls the expression of virulence, symbiotic and survival genes. Previously, we characterized Vibrio anguillarum homologues of LuxR (VanT) and LuxMN (VanMN) and, in this study, we have identified homologues of LuxPQ (VanPQ) and LuxOU (VanOU). In contrast to other Vibrio species, vanT was expressed at low cell density and showed no significant induction as the cell number increased. In addition, although the loss of VanO increased vanT expression, the loss of VanU, unexpectedly, decreased it. Both VanN and VanQ were required for repression of vanT even in a vanU mutant, suggesting an alternative route for VanNQ signal transduction other than via VanU. VanT negatively regulated its own expression by binding and repressing the vanT promoter and by binding and activating the vanOU promoter. The signal relay results in a cellular response as expression of the metalloprotease, empA, was altered similar to that of vanT in all the mutants. Consequently, the V. anguillarum quorum-sensing phosphorelay systems work differently from those of V. harveyi and may be used to limit rather than induce vanT expression.
authors.affiliation: Department of Molecular Biology, Umeå University, S-901 87 Umeå, Sweden.
authors.forename: Antony
authors.initials: A
authors.lastname: Croxatto
authors.forename: John
authors.initials: J
authors.lastname: Pride
authors.forename: Andrea
authors.initials: A
authors.lastname: Hardman
authors.forename: Paul
authors.initials: P
authors.lastname: Williams
authors.forename: Miguel
authors.initials: M
authors.lastname: Cámara
authors.forename: Debra L
authors.initials: DL
authors.lastname: Milton
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000737:chemistry / Q000302:isolation & purification; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D017930:Genes, Reporter; D045726:Metalloproteases / Q000096:biosynthesis; D008969:Molecular Sequence Data; D009154:Mutation; D010750:Phosphoproteins / Q000235:genetics; D010770:Phosphotransferases / Q000235:genetics; D012329:RNA, Bacterial / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D012097:Repressor Proteins / Q000235:genetics; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D015398:Signal Transduction; D015534:Trans-Activators / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics; D014733:Vibrio / Q000235:genetics* / Q000254:growth & development / Q000502:physiology*; D014774:Virulence / Q000235:genetics; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; C088907:LuxO protein, Vibrio harveyi; C090749:LuxP protein, Vibrio; C117251:LuxU protein, Vibrio; D010750:Phosphoproteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D012097:Repressor Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C430043:VanM protein, Vibrio anguillarum; C430044:VanN protein, Vibrio anguillarum; C064778:LuxR autoinducer binding proteins; D010770:Phosphotransferases; C090750:luxQ protein, Vibrio harveyi; D001616:beta-Galactosidase; D045726:Metalloproteases