title: H-NS regulation of IraD and IraM antiadaptors for control of RpoS degradation.
abstract: RpoS, the master sigma factor during stationary phase and under a variety of stress conditions, is regulated at multiple levels, including regulated degradation. Degradation is dependent upon ClpXP and the RssB adaptor protein. H-NS, a nucleoid-associated protein, affects the regulated degradation of RpoS; in the absence of H-NS, RpoS is stable. The mechanisms involved in this regulation were not known. We have found that H-NS inhibits the expression of iraD and iraM, the genes coding for two antiadaptor proteins that stabilize RpoS when overexpressed. The regulation by H-NS of iraM is independent from the previously demonstrated regulation by the PhoP/PhoQ two-component system. Moreover, differences in the behavior of several hns alleles are explained by a role for StpA, an H-NS-like protein, in the regulation of RpoS stability. This finding parallels recent observations for a role of StpA in regulation of RpoS stability in Salmonella.
authors.affiliation: Laboratory of Molecular Biology, National Cancer Institute, Bethesda, Maryland, USA.
authors.forename: A
authors.initials: A
authors.lastname: Battesti
authors.forename: Y M
authors.initials: YM
authors.lastname: Tsegaye
authors.forename: D G
authors.initials: DG
authors.lastname: Packer
authors.forename: N
authors.initials: N
authors.lastname: Majdalani
authors.forename: S
authors.initials: S
authors.lastname: Gottesman
mesh_terms: D000483:Alleles; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D036781:Fimbriae Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D059748:Proteolysis; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C529458:FimG protein, E coli; C535006:IraD protein, E coli; C529084:IraM protein, E coli; C465562:PhoP protein, E coli; C079792:PhoQ protein, Bacteria; D012808:Sigma Factor; C069567:sigma factor KatF protein, Bacteria; D036781:Fimbriae Proteins