Anti-adaptors provide multiple modes for regulation of the RssB adaptor protein

• Published in: Genes & development 2013-12, Vol.27 (24), p.2722-2735
• Main Authors: Battesti, Aurelia, Hoskins, Joel R, Tong, Song, Milanesio, Paola, Mann, Jessica M, Kravats, Andrea, Tsegaye, Yodit M, Bougdour, Alexandre, Wickner, Sue, Gottesman, Susan
• Format: Article
• Language: English
• Subjects: Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriology; Biochemistry; Biochemistry, Molecular Biology; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Escherichia coli; Escherichia coli K12 - genetics; Escherichia coli K12 - metabolism; Escherichia coli Proteins - genetics; Escherichia coli Proteins - metabolism; Gene Expression Regulation, Bacterial; Life Sciences; Microbiology and Parasitology; Molecular biology; Mutation; Phosphorylation; Protein Structure, Tertiary - genetics; Research Paper; Transcription Factors - genetics; Transcription Factors - metabolism; Virology
• ISSN: 0890-9369; 1549-5477
• DOI: 10.1101/gad.229617.113

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.