5frf

Solution structure of reduced and zinc-bound RsrA

spinqualitylabelsall models 5frf Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 5frf is a 1 chain structure with sequence from Streptomyces coelicolor. Full experimental information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Solution NMR Ligands: ZN Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function RSRA_STRCO A redox-regulated anti-sigma factor for extracytoplasmic function (ECF) sigma factor SigR, and a key sensor of disulfide stress. Holds SigR, its cognate ECF sigma factor, in an inactive form, inhibiting its sigma activity under reducing but not oxidizing conditions; oxidation and reduction of the anti-sigma factor is reversible. Mycothiol (MSH) is competent for reduction of RsrA, allowing it to bind to SigR. In conjunction with its cognate sigma factor SigR may sense the intracellular level of reduced MSH. Probably releases SigR during oxidative stress. Publication Abstract from PubMed Redox-regulated effector systems that counteract oxidative stress are essential for all forms of life. Here we uncover a new paradigm for sensing oxidative stress centred on the hydrophobic core of a sensor protein. RsrA is an archetypal zinc-binding anti-sigma factor that responds to disulfide stress in the cytoplasm of Actinobacteria. We show that RsrA utilizes its hydrophobic core to bind the sigma factor sigma(R) preventing its association with RNA polymerase, and that zinc plays a central role in maintaining this high-affinity complex. Oxidation of RsrA is limited by the rate of zinc release, which weakens the RsrA-sigma(R) complex by accelerating its dissociation. The subsequent trigger disulfide, formed between specific combinations of RsrA's three zinc-binding cysteines, precipitates structural collapse to a compact state where all sigma(R)-binding residues are sequestered back into its hydrophobic core, releasing sigma(R) to activate transcription of anti-oxidant genes. The anti-sigma factor RsrA responds to oxidative stress by reburying its hydrophobic core.,Rajasekar KV, Zdanowski K, Yan J, Hopper JT, Francis ML, Seepersad C, Sharp C, Pecqueur L, Werner JM, Robinson CV, Mohammed S, Potts JR, Kleanthous C Nat Commun. 2016 Jul 19;7:12194. doi: 10.1038/ncomms12194. PMID:27432510 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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