5fgm | pdb_00005fgm
Streptomyces coelicolor SigR region 4
Structural highlights
Function[SIGR_STRCO] 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 an anti-sigma factor (RsrA) until released. Responds to thiol-oxidative stress, involved in regulation of about 30 genes and operons, including the thioredoxin system (trxB-trxA, trxC), ribosomal protein L31, RNA polymerase-binding protein RbpA and mycothiol (MSH) biosynthetic (mshA) and recycling genes (mca). In conjunction with its cognate anti-sigma factor RsrA may sense the intracellular level of reduced MSH.[1] [2] [3] [4] Publication Abstract from PubMedIn Gram-positive Streptomyces coelicolor A3(2), SigR (Sc sigma(R)) of the group IV ECF sigma factor singly activates expression of more than 30 oxidation responsive genes. Of the two promoter-binding domains - individually called region 2 and region 4 - within Sc sigma(R), we hereby report a 2.6 A resolution structure of the -35 element interacting carboxyl-terminal region 4 (Sc sigma(R)4). Structural comparison of Sc sigma(R)4 with the Escherichia coli SigE (Ec sigma(E)) in complex with Ec sigma(E) -35 element suggested that a single residue (Sc sigma(R) Met188 and Ec sigma(E) Arg171) may be responsible for distinguishing the one-base pair difference of the -35 elements - Sc sigma(R)(-31')ATTCC(-35') ((-31')A) vs. Ec sigma(E)(-31')GTTCC(-35') ((-31')G) - by interacting with the -31'-base. Further studies using expressed Sc sigma(R) indicate that the wild-type Sc sigma(R) with Met188 selectively interacted with the (-31')A sequence over the (-31')G sequence, whereas a mutation of Met188 to arginine resulted in interaction with both (-31')A and (-31')G sequences. Hence, we conclude that Met188 of Sc sigma(R) confers the (-31')A-selectivity in -35 element interaction by disfavoured interaction with the (-31')G base. In Streptomyces coelicolor SigR, methionine at the -35 element interacting region 4 confers the -31'-adenine base selectivity.,Kim KY, Park JK, Park S Biochem Biophys Res Commun. 2016 Feb 5;470(2):257-62. doi:, 10.1016/j.bbrc.2016.01.075. Epub 2016 Jan 14. PMID:26775842[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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