title: Quorum Sensing Regulators Are Required for Metabolic Fitness in Vibrio parahaemolyticus.
abstract: Quorum sensing (QS) is a process by which bacteria alter gene expression in response to cell density changes. InVibriospecies, at low cell density, the sigma 54-dependent response regulator LuxO is active and regulates the two QS master regulators AphA, which is induced, and OpaR, which is repressed. At high cell density the opposite occurs: LuxO is inactive, and therefore OpaR is induced while AphA is repressed. InVibrio parahaemolyticus, a significant enteric pathogen of humans, the roles of these regulators in pathogenesis are less known. We examined deletion mutants ofluxO,opaR, andaphAforin vivofitness using an adult mouse model. We found that theluxOandaphAmutants were defective in colonization compared to levels in the wild type. TheopaRmutant did not show any defectin vivoColonization was restored to wild-type levels in aluxO opaRdouble mutant and was also increased in anopaR aphAdouble mutant. These data suggest that AphA is important and that overexpression ofopaRis detrimental toin vivofitness. Transcriptome sequencing (RNA-Seq) analysis of the wild type andluxOmutant grown in mouse intestinal mucus showed that 60% of the genes that were downregulated in theluxOmutant were involved in amino acid and sugar transport and metabolism. These data suggest that theluxOmutant has a metabolic disadvantage, which was confirmed by growth pattern analysis using phenotype microarrays. Bioinformatics analysis revealed OpaR binding sites in the regulatory region of 55 carbon transporter and metabolism genes. Biochemical analysis of five representatives of these regulatory regions demonstrated direct binding of OpaR in all five tested. These data demonstrate the role of OpaR in carbon utilization and metabolic fitness, an overlooked role in the QS regulon.
authors.affiliation: Department of Biological Sciences, University of Delaware, Newark, Delaware, USA.
authors.forename: Sai Siddarth
authors.initials: SS
authors.lastname: Kalburge
authors.affiliation: Department of Biological Sciences, University of Delaware, Newark, Delaware, USA.
authors.forename: Megan R
authors.initials: MR
authors.lastname: Carpenter
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware, USA.
authors.forename: Sharon
authors.initials: S
authors.lastname: Rozovsky
authors.affiliation: Department of Biological Sciences, University of Delaware, Newark, Delaware, USA fboyd@udel.edu.
authors.forename: E Fidelma
authors.initials: EF
authors.lastname: Boyd
mesh_terms: D000222:Adaptation, Physiological; D001426:Bacterial Proteins / Q000235:genetics; D001665:Binding Sites; D001692:Biological Transport; D004734:Energy Metabolism / Q000235:genetics; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D007413:Intestinal Mucosa / Q000382:microbiology; D009154:Mutation; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D053038:Quorum Sensing; D015398:Signal Transduction; D014736:Vibrio parahaemolyticus / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins
keywords: Vibrio parahaemolyticus; carbon metabolism; intestinal colonization; quorum sensing