4nqw | pdb_00004nqw

Structure of Mycobacterium tuberculosis extracytoplasmic function sigma factor SigK in complex with the cytosolic domain of its cognate anti-sigma factor RskA

spinqualitylabelsall models 4nqw, resolution 2.40Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4nqw is a 2 chain structure with sequence from "bacillus_tuberculosis"_(zopf_1883)_klein_1884 "bacillus tuberculosis" (zopf 1883) klein 1884. This structure supersedes the now removed PDB entry 3vdo. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CD Gene: Rv0445c, sigK ("Bacillus tuberculosis" (Zopf 1883) Klein 1884), rskA, Rv0444c ("Bacillus tuberculosis" (Zopf 1883) Klein 1884) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [SIGK_MYCTU] Sigma factors are initiation factors that promote the attachment of RNA polymerase to specific initiation sites and are then released. Sigma-K controls genes such as mpt70 and mpt83. [RSKA_MYCTU] Represses SigK, the extracytoplasmic function (ECF) sigma factor K, by binding to it and inhibiting its activity. This leads to a decreased expression of SigK-regulated genes, such as mpt70 and mpt83. Publication Abstract from PubMed The host-pathogen interactions in Mycobacterium tuberculosis infection are significantly influenced by redox stimuli and alterations in the levels of secreted antigens. The extracytoplasmic function (ECF) sigma factor sigma(K) governs the transcription of the serodominant antigens MPT70 and MPT83. The cellular levels of sigma(K) are regulated by the membrane-associated anti-sigma(K) (RskA) that localizes sigma(K) in an inactive complex. The crystal structure of M. tuberculosis sigma(K) in complex with the cytosolic domain of RskA (RskAcyto) revealed a disulfide bridge in the -35 promoter-interaction region of sigma(K). Biochemical experiments reveal that the redox potential of the disulfide-forming cysteines in sigma(K) is consistent with its role as a sensor. The disulfide bond in sigma(K) influences the stability of the sigma(K)-RskAcyto complex but does not interfere with sigma(K)-promoter DNA interactions. It is noted that these disulfide-forming cysteines are conserved across homologues, suggesting that this could be a general mechanism for redox-sensitive transcription regulation. Structural basis for the redox sensitivity of the Mycobacterium tuberculosis SigK-RskA sigma-anti-sigma complex.,Shukla J, Gupta R, Thakur KG, Gokhale R, Gopal B Acta Crystallogr D Biol Crystallogr. 2014 Apr 1;70(Pt 4):1026-36. doi:, 10.1107/S1399004714000121. Epub 2014 Mar 19. PMID:24699647 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Sigma factor

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