title: Anti-adaptors provide multiple modes for regulation of the RssB adaptor protein.
abstract: RpoS, an RNA polymerase σ factor, controls the response of Escherichia coli and related bacteria to multiple stress responses. During nonstress conditions, RpoS is rapidly degraded by ClpXP, mediated by the adaptor protein RssB, a member of the response regulator family. In response to stress, RpoS degradation ceases. Small anti-adaptor proteins--IraP, IraM, and IraD, each made under a different stress condition--block RpoS degradation. RssB mutants resistant to either IraP or IraM were isolated and analyzed in vivo and in vitro. Each of the anti-adaptors is unique in its interaction with RssB and sensitivity to RssB mutants. One class of mutants defined an RssB N-terminal region close to the phosphorylation site and critical for interaction with IraP but unnecessary for IraM and IraD function. A second class, in the RssB C-terminal PP2C-like domain, led to activation of RssB function. These mutants allowed the response regulator to act in the absence of phosphorylation but did not abolish interaction with anti-adaptors. This class of mutants is broadly resistant to the anti-adaptors and bears similarity to constitutively activated mutants found in a very different PP2C protein. The mutants provide insight into how the anti-adaptors perturb RssB response regulator function and activation.
authors.affiliation: Laboratory of Molecular Biology, National Cancer Institute, Bethesda, Maryland 20892, USA.
authors.forename: Aurelia
authors.initials: A
authors.lastname: Battesti
authors.forename: Joel R
authors.initials: JR
authors.lastname: Hoskins
authors.forename: Song
authors.initials: S
authors.lastname: Tong
authors.forename: Paola
authors.initials: P
authors.lastname: Milanesio
authors.forename: Jessica M
authors.initials: JM
authors.lastname: Mann
authors.forename: Andrea
authors.initials: A
authors.lastname: Kravats
authors.forename: Yodit M
authors.initials: YM
authors.lastname: Tsegaye
authors.forename: Alexandre
authors.initials: A
authors.lastname: Bougdour
authors.forename: Sue
authors.initials: S
authors.lastname: Wickner
authors.forename: Susan
authors.initials: S
authors.lastname: Gottesman
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D048168:Escherichia coli K12 / Q000235:genetics* / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D009154:Mutation; D010766:Phosphorylation; D017434:Protein Structure, Tertiary / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C529084:IraM protein, E coli; C522786:IraP protein, E coli; D014157:Transcription Factors; C098923:rssB protein, E coli
keywords: ClpX; IraP; RpoS; RsbP; response regulator