2q1z
From Proteopedia
Crystal Structure of Rhodobacter sphaeroides SigE in complex with the anti-sigma ChrR
Structural highlights
Function[RPOE_RHOS4] Sigma factors are initiation factors that promote the attachment of RNA polymerase to specific initiation sites and are then released. Extracytoplasmic function (ECF) sigma factors are held in an inactive form by a cognate anti-sigma factor until released. Sigma-E controls a transcriptional response to singlet oxygen, a by-product of photosynthesis; its continuous activity requires constant exposure to singlet oxygen. The regulon has about 180 genes that protect against or repair damage induced by singlet oxygen, including itself and rpoH2, a heat shock-responsive sigma factor.[1] [2] [3] [CHRR_RHOS4] Anti-sigma factor that inhibits the activity of the extracytoplasmic function (ECF) sigma-E factor (RpoE), thereby indirectly regulating the transcription of the cycA and rpoE genes. ECF sigma factors are held in an inactive form by a cognate anti-sigma factor.[4] [5] [6] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedA transcriptional response to singlet oxygen in Rhodobacter sphaeroides is controlled by the group IV sigma factor sigma(E) and its cognate anti-sigma ChrR. Crystal structures of the sigma(E)/ChrR complex reveal a modular, two-domain architecture for ChrR. The ChrR N-terminal anti-sigma domain (ASD) binds a Zn(2+) ion, contacts sigma(E), and is sufficient to inhibit sigma(E)-dependent transcription. The ChrR C-terminal domain adopts a cupin fold, can coordinate an additional Zn(2+), and is required for the transcriptional response to singlet oxygen. Structure-based sequence analyses predict that the ASD defines a common structural fold among predicted group IV anti-sigmas. These ASDs are fused to diverse C-terminal domains that are likely involved in responding to specific environmental signals that control the activity of their cognate sigma factor. A conserved structural module regulates transcriptional responses to diverse stress signals in bacteria.,Campbell EA, Greenwell R, Anthony JR, Wang S, Lim L, Das K, Sofia HJ, Donohue TJ, Darst SA Mol Cell. 2007 Sep 7;27(5):793-805. PMID:17803943[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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