title: Stringent factor and proteolysis control of sigma factor RpoS expression in Vibrio cholerae.
abstract: Vibrio cholerae can colonize the gastrointestinal track of humans and cause the disease cholera. During colonization, the alternative sigma factor, RpoS, controls a process known as "mucosal escape response," defining a specific spatial and temporal response and effecting chemotaxis and motility. In this report, the expression and proteolytic control of RpoS in V. cholerae was characterized. To date, aspects of proteolysis control, the involved components, and proteolysis regulation have not been addressed for RpoS in V. cholerae. Similar to Escherichia coli, we find that the RpoS protein is subjected to regulated intracellular proteolysis, which is mediated by homologues of the proteolysis-targeting factor RssB and the protease complex ClpXP. As demonstrated, RpoS expression transiently peaks after cells are shifted from rich to minimal growth medium. This peak level is dependent on (p)ppGpp-activated rpoS transcription and controlled RpoS proteolysis. The RpoS peak level also correlates with induction of a chemotaxis gene, encoding a methyl-accepting chemotaxis protein, earlier identified to belong to the mucosal escape response pathway. These results suggest that the RpoS expression peak is linked to (p)ppGpp alarmone increase, leading to enhanced motility and chemotaxis, and possibly contributing to the mucosal escape response.
authors.affiliation: University of Graz, Institute of Molecular Biosciences, Molecular Enzymology and Physiology, Humboldtstraße 50, A-8010 Graz, Austria.
authors.forename: Philipp
authors.initials: P
authors.lastname: Wurm
authors.affiliation: University of Graz, Institute of Molecular Biosciences, Molecular Enzymology and Physiology, Humboldtstraße 50, A-8010 Graz, Austria.
authors.forename: Sarah
authors.initials: S
authors.lastname: Tutz
authors.affiliation: University of Graz, Institute of Molecular Biosciences, Molecular Enzymology and Physiology, Humboldtstraße 50, A-8010 Graz, Austria.
authors.forename: Beatrice
authors.initials: B
authors.lastname: Mutsam
authors.affiliation: University of Graz, Institute of Molecular Biosciences, Molecular Enzymology and Physiology, Humboldtstraße 50, A-8010 Graz, Austria.
authors.forename: Dina
authors.initials: D
authors.lastname: Vorkapic
authors.affiliation: University of Graz, Institute of Molecular Biosciences, Molecular Enzymology and Physiology, Humboldtstraße 50, A-8010 Graz, Austria.
authors.forename: Barbara
authors.initials: B
authors.lastname: Heyne
authors.affiliation: University of Graz, Institute of Molecular Biosciences, Molecular Enzymology and Physiology, Humboldtstraße 50, A-8010 Graz, Austria.
authors.forename: Claudia
authors.initials: C
authors.lastname: Grabner
authors.affiliation: University of Graz, Institute of Molecular Biosciences, Molecular Enzymology and Physiology, Humboldtstraße 50, A-8010 Graz, Austria.
authors.forename: Katharina
authors.initials: K
authors.lastname: Kleewein
authors.affiliation: University of Graz, Institute of Molecular Biosciences, Molecular Enzymology and Physiology, Humboldtstraße 50, A-8010 Graz, Austria.
authors.forename: Anja
authors.initials: A
authors.lastname: Halscheidt
authors.affiliation: University of Graz, Institute of Molecular Biosciences, Molecular Enzymology and Physiology, Humboldtstraße 50, A-8010 Graz, Austria; BioTechMed-Graz, Austria; NAWI Graz, Austria.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schild
authors.affiliation: University of Graz, Institute of Molecular Biosciences, Molecular Enzymology and Physiology, Humboldtstraße 50, A-8010 Graz, Austria; BioTechMed-Graz, Austria; NAWI Graz, Austria. Electronic address: joachim.reidl@uni-graz.at.
authors.forename: Joachim
authors.initials: J
authors.lastname: Reidl
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D002633:Chemotaxis; D003470:Culture Media / Q000737:chemistry; D049071:Endopeptidase Clp / Q000378:metabolism*; D001277:GTP Pyrophosphokinase / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D059748:Proteolysis; D012808:Sigma Factor / Q000378:metabolism*; D014734:Vibrio cholerae / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D012808:Sigma Factor; C069567:sigma factor KatF protein, Bacteria; D001277:GTP Pyrophosphokinase; D049071:Endopeptidase Clp