title: Structure of the cobalamin-binding protein of a putative O-demethylase from Desulfitobacterium hafniense DCB-2.
abstract: This study describes the identification and the structural and spectroscopic analysis of a cobalamin-binding protein (termed CobDH) implicated in O-demethylation by the organohalide-respiring bacterium Desulfitobacterium hafniense DCB-2. The 1.5 Å resolution crystal structure of CobDH is presented in the cobalamin-bound state and reveals that the protein is composed of an N-terminal helix-bundle domain and a C-terminal Rossmann-fold domain, with the cobalamin coordinated in the base-off/His-on conformation similar to other cobalamin-binding domains that catalyse methyl-transfer reactions. EPR spectroscopy of CobDH confirms cobalamin binding and reveals the presence of a cob(III)alamin superoxide, indicating binding of oxygen to the fully oxidized cofactor. These data provide the first structural insights into the methyltransferase reactions that occur during O-demethylation by D. hafniense.
authors.affiliation: Manchester Institute of Biotechnology, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, England.
authors.forename: Hanno
authors.initials: H
authors.lastname: Sjuts
authors.forename: Mark S
authors.initials: MS
authors.lastname: Dunstan
authors.forename: Karl
authors.initials: K
authors.lastname: Fisher
authors.forename: David
authors.initials: D
authors.lastname: Leys
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D045858:Desulfitobacterium / Q000737:chemistry* / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D008969:Molecular Sequence Data; D010090:Oxidoreductases, O-Demethylating / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D013056:Spectrophotometry, Ultraviolet; D014155:Transcobalamins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014805:Vitamin B 12 / Q000378:metabolism
chemical_list: D014155:Transcobalamins; D010090:Oxidoreductases, O-Demethylating; D014805:Vitamin B 12
keywords: Desulfitobacterium hafniense; O-demethylation; cobalamin-binding proteins
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