title: A role for mechanosensitive channels in survival of stationary phase: regulation of channel expression by RpoS.
abstract: The mechanosensitive (MS) channels MscS and MscL are essential for the survival of hypoosmotic shock by Escherichia coli cells. We demonstrate that MscS and MscL are induced by osmotic stress and by entry into stationary phase. Reduced levels of MS proteins and reduced expression of mscL- and mscS-LacZ fusions in an rpoS mutant strain suggested that the RNA polymerase holoenzyme containing sigmaS is responsible, at least in part, for regulating production of MS channel proteins. Consistent with the model that the effect of sigmaS is direct, the MscS and MscL promoters both use RNA polymerase containing sigmaS in vitro. Conversely, clpP or rssB mutations, which cause enhanced levels of sigmaS, show increased MS channel protein synthesis. RpoS null mutants are sensitive to hypoosmotic shock upon entry into stationary phase. These data suggest that MscS and MscL are components of the RpoS regulon and play an important role in ensuring structural integrity in stationary phase bacteria.
authors.affiliation: Department of Molecular and Cell Biology, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, Scotland, United Kingdom.
authors.forename: Neil R
authors.initials: NR
authors.lastname: Stokes
authors.forename: Heath D
authors.initials: HD
authors.lastname: Murray
authors.forename: Chandrasekaran
authors.initials: C
authors.lastname: Subramaniam
authors.forename: Richard L
authors.initials: RL
authors.lastname: Gourse
authors.forename: Petra
authors.initials: P
authors.lastname: Louis
authors.forename: Wendy
authors.initials: W
authors.lastname: Bartlett
authors.forename: Samantha
authors.initials: S
authors.lastname: Miller
authors.forename: Ian R
authors.initials: IR
authors.lastname: Booth
mesh_terms: D001426:Bacterial Proteins / Q000502:physiology*; D001483:Base Sequence; D017931:DNA Primers; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics*; D017930:Genes, Reporter; D007473:Ion Channels / Q000235:genetics* / Q000502:physiology*; D040542:Mechanotransduction, Cellular / Q000235:genetics / Q000502:physiology*; D010957:Plasmids / Q000235:genetics; D012808:Sigma Factor / Q000502:physiology*; D014158:Transcription, Genetic; D001616:beta-Galactosidase / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D017931:DNA Primers; D029968:Escherichia coli Proteins; D007473:Ion Channels; C086596:MscL protein, E coli; C469542:MscS protein, E coli; D012808:Sigma Factor; C069567:sigma factor KatF protein, Bacteria; D001616:beta-Galactosidase