title: In Streptomyces coelicolor SigR, methionine at the -35 element interacting region 4 confers the -31'-adenine base selectivity.
abstract: In Gram-positive Streptomyces coelicolor A3(2), SigR (Sc σ(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 σ(R), we hereby report a 2.6 Å resolution structure of the -35 element interacting carboxyl-terminal region 4 (Sc σ(R)4). Structural comparison of Sc σ(R)4 with the Escherichia coli SigE (Ec σ(E)) in complex with Ec σ(E) -35 element suggested that a single residue (Sc σ(R) Met188 and Ec σ(E) Arg171) may be responsible for distinguishing the one-base pair difference of the -35 elements--Sc σ(R)(-31')ATTCC(-35') ((-31')A) vs. Ec σ(E)(-31')GTTCC(-35') ((-31')G)--by interacting with the -31'-base. Further studies using expressed Sc σ(R) indicate that the wild-type Sc σ(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 σ(R) confers the (-31')A-selectivity in -35 element interaction by disfavoured interaction with the (-31')G base.
authors.affiliation: School of Systems Biomedical Science, Soongsil University, Seoul 06978, South Korea.
authors.forename: Keon Young
authors.initials: KY
authors.lastname: Kim
authors.affiliation: School of Systems Biomedical Science, Soongsil University, Seoul 06978, South Korea.
authors.forename: Jeong Kuk
authors.initials: JK
authors.lastname: Park
authors.affiliation: School of Systems Biomedical Science, Soongsil University, Seoul 06978, South Korea. Electronic address: psy@ssu.ac.kr.
authors.forename: SangYoun
authors.initials: S
authors.lastname: Park
mesh_terms: D000225:Adenine / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics*; D001665:Binding Sites; D008715:Methionine / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding; D012808:Sigma Factor / Q000235:genetics*; D048372:Streptomyces coelicolor / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D012808:Sigma Factor; D008715:Methionine; D000225:Adenine
keywords: ECF sigma factors; Promoter -35 element; SigR (σ(R)); Sigma factor region 4 (σ(4)); Streptomyces coelicolor