title: The phosphotransferase VanU represses expression of four qrr genes antagonizing VanO-mediated quorum-sensing regulation in Vibrio anguillarum.
abstract: Vibrio anguillarum utilizes quorum sensing to regulate stress responses required for survival in the aquatic environment. Like other Vibrio species, V. anguillarum contains the gene qrr1, which encodes the ancestral quorum regulatory RNA Qrr1, and phosphorelay quorum-sensing systems that modulate the expression of small regulatory RNAs (sRNAs) that destabilize mRNA encoding the transcriptional regulator VanT. In this study, three additional Qrr sRNAs were identified. All four sRNAs were positively regulated by σ(54) and the σ(54)-dependent response regulator VanO, and showed a redundant activity. The Qrr sRNAs, together with the RNA chaperone Hfq, destabilized vanT mRNA and modulated expression of VanT-regulated genes. Unexpectedly, expression of all four qrr genes peaked at high cell density, and exogenously added N-acylhomoserine lactone molecules induced expression of the qrr genes at low cell density. The phosphotransferase VanU, which phosphorylates and activates VanO, repressed expression of the Qrr sRNAs and stabilized vanT mRNA. A model is presented proposing that VanU acts as a branch point, aiding cross-regulation between two independent phosphorelay systems that activate or repress expression of the Qrr sRNAs, giving flexibility and precision in modulating VanT expression and inducing a quorum-sensing response to stresses found in a constantly changing aquatic environment.
authors.affiliation: Department of Molecular Biology, Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå SE-901 87, Sweden.
authors.forename: Barbara
authors.initials: B
authors.lastname: Weber
authors.affiliation: Department of Molecular Biology, Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå SE-901 87, Sweden.
authors.forename: Kristoffer
authors.initials: K
authors.lastname: Lindell
authors.affiliation: Department of Molecular Biology, Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå SE-901 87, Sweden.
authors.forename: Samir
authors.initials: S
authors.lastname: El Qaidi
authors.affiliation: Department of Chemistry, Faculty of Science and Technology, University of Tromsø, Tromsø 9037, Norway.
authors.forename: Erik
authors.initials: E
authors.lastname: Hjerde
authors.affiliation: Department of Chemistry, Faculty of Science and Technology, University of Tromsø, Tromsø 9037, Norway.
authors.forename: Nils-Peder
authors.initials: NP
authors.lastname: Willassen
authors.affiliation: Department of Molecular Biology, Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå SE-901 87, Sweden.
authors.forename: Debra L
authors.initials: DL
authors.lastname: Milton
mesh_terms: D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D035683:MicroRNAs / Q000235:genetics*; D008954:Models, Biological; D008969:Molecular Sequence Data; D010770:Phosphotransferases / Q000378:metabolism*; D053038:Quorum Sensing; D012097:Repressor Proteins / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000378:metabolism*; D014733:Vibrio / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D004269:DNA, Bacterial; D035683:MicroRNAs; D012097:Repressor Proteins; D014157:Transcription Factors; D010770:Phosphotransferases