8twd
From Proteopedia
Structure of IraM-bound RssB
Structural highlights
FunctionW8SRD3_ECOLX Inhibits RpoS proteolysis by regulating RssB activity, thereby increasing the stability of the sigma stress factor RpoS during magnesium starvation.[HAMAP-Rule:MF_01199] Publication Abstract from PubMedUpon Mg(2+) starvation, a condition often associated with virulence, enterobacteria inhibit the ClpXP-dependent proteolysis of the master transcriptional regulator, sigma(s), via IraM, a poorly understood anti-adaptor that prevents RssB-dependent loading of sigma(s) onto ClpXP. This inhibition results in sigma(s) accumulation, and expression of stress resistance genes. Here we report on the structural analysis of RssB bound to IraM, which reveals that IraM induces two folding transitions within RssB, amplified via a segmental helical linker. These conformational changes result in an open, yet inhibited RssB structure in which IraM associates with both the C-terminal and N-terminal domains of RssB and prevents binding of sigma(s) to the 4-5-5 face of the N-terminal receiver domain. This work highlights the remarkable structural plasticity of RssB and reveals how a stress specific RssB antagonist modulates a core stress response pathway that could be leveraged to control biofilm formation, virulence, and the development of antibiotic resistance. IraM Remodels the RssB Segmented Helical Linker to Stabilize sigma(s) Against Degradation by ClpXP.,Brugger C, Srirangam S, Deaconescu AM J Biol Chem. 2023 Dec 14:105568. doi: 10.1016/j.jbc.2023.105568. PMID:38103640[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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