7l9c
Receiver Domain of RssB
Structural highlights
FunctionRSSB_ECOLI Regulates the turnover of the sigma S factor (RpoS) by promoting its proteolysis in exponentially growing cells. Acts by binding and delivering RpoS to the ClpXP protease. RssB is not co-degraded with RpoS, but is released from the complex and can initiate a new cycle of RpoS recognition and degradation. In stationary phase, could also act as an anti-sigma factor and reduce the ability of RpoS to activate gene expression. Is also involved in the regulation of the mRNA polyadenylation pathway during stationary phase, probably by maintaining the association of PcnB with the degradosome.[HAMAP-Rule:MF_00958][1] [2] [3] [4] [5] [6] Publication Abstract from PubMedIn the model organism Escherichia coli and related species, the general stress response relies on tight regulation of the intracellular levels of the promoter specificity subunit RpoS. RpoS turnover is exclusively dependent on RssB, a two-domain response regulator that functions as an adaptor that delivers RpoS to ClpXP for proteolysis. Here, we report crystal structures of the receiver domain of RssB both in its unphosphorylated form and bound to the phosphomimic BeF3 (-) . Surprisingly, we find only modest differences between these two structures, suggesting that truncating RssB may partially activate the receiver domain to a "meta-active" state. Our structural and sequence analysis points to RssB proteins not conforming to either the Y-T coupling scheme for signaling seen in prototypical response regulators, such as CheY, or to the signaling model of the less understood FATGUY proteins. Phospho-dependent signaling during the general stress response by the atypical response regulator and ClpXP adaptor RssB.,Schwartz J, Son J, Brugger C, Deaconescu AM Protein Sci. 2021 Apr;30(4):899-907. doi: 10.1002/pro.4047. Epub 2021 Mar 1. PMID:33599047[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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