title: Structural analysis of 1-Cys type selenoprotein methionine sulfoxide reductase A.
abstract: Methionine sulfoxide reductase A (MsrA) reduces free and protein-based methionine-S-sulfoxide to methionine. Structures of 1-Cys MsrAs lacking a resolving Cys, which interacts with catalytic Cys, are unknown. In addition, no structural information on selenocysteine (Sec)-containing MsrA enzymes has been reported. In this work, we determined the crystal structures of 1-Cys type selenoprotein MsrA from Clostridium oremlandii at 1.6-1.8Å, including the reduced, oxidized (sulfenic acid), and substrate-bound forms. The overall structure of Clostridium MsrA, consisting of ten α-helices and six β-strands, folds into a catalytic domain and a novel helical domain absent from other known MsrA structures. The helical domain, containing five helices, tightly interacts with the catalytic domain, and is likely critical for catalytic activity due to its association with organizing the active site. This helical domain is also conserved in several selenoprotein MsrAs. Our structural analysis reveals that the side chain length of Glu55 is critical for the proton donor function of this residue. Our structures also provide insights into the architecture of the 1-Cys MsrA active site and the roles of active site residues in substrate recognition and catalysis.
authors.affiliation: Division of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Republic of Korea.
authors.forename: Eun Hye
authors.initials: EH
authors.lastname: Lee
authors.affiliation: Department of Biochemistry and Molecular Biology, Yeungnam University College of Medicine, Daegu 705-717, Republic of Korea.
authors.forename: Geun-Hee
authors.initials: GH
authors.lastname: Kwak
authors.affiliation: Department of Biochemistry and Molecular Biology, Yeungnam University College of Medicine, Daegu 705-717, Republic of Korea.
authors.forename: Moon-Jung
authors.initials: MJ
authors.lastname: Kim
authors.affiliation: Department of Biochemistry and Molecular Biology, Yeungnam University College of Medicine, Daegu 705-717, Republic of Korea. Electronic address: hykim@ynu.ac.kr.
authors.forename: Hwa-Young
authors.initials: HY
authors.lastname: Kim
authors.affiliation: Division of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Republic of Korea. Electronic address: chahong@korea.ac.kr.
authors.forename: Kwang Yeon
authors.initials: KY
authors.lastname: Hwang
mesh_terms: D001665:Binding Sites; D020134:Catalytic Domain; D003013:Clostridium / Q000737:chemistry / Q000201:enzymology*; D018360:Crystallography, X-Ray; D003545:Cysteine / Q000737:chemistry* / Q000378:metabolism; D051150:Methionine Sulfoxide Reductases / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D010084:Oxidation-Reduction; D011487:Protein Conformation; D017434:Protein Structure, Tertiary
chemical_list: D051150:Methionine Sulfoxide Reductases; D003545:Cysteine
keywords: Catalysis; Clostridium; Methionine sulfoxide reductase; MsrA; Selenocysteine; Selenoprotein