title: NMR structure of the flavin domain from soluble methane monooxygenase reductase from Methylococcus capsulatus (Bath).
abstract: Soluble methane monooxygenase (sMMO) catalyzes the hydroxylation of methane by dioxygen to methanol, the first step in carbon assimilation by methanotrophs. This multicomponent system transfers electrons from NADH through a reductase component to the non-heme diiron center in the hydroxylase where O(2) is activated. The reductase component comprises three distinct domains, a [2Fe-2S] ferredoxin domain along with FAD- and NADH-binding domains. We report the solution structure of the reduced 27.6 kDa FAD- and NADH-binding domains (MMOR-FAD) of the reductase from Methylococcus capsulatus (Bath). The FAD-binding domain consists of a six-stranded antiparallel beta-barrel and one alpha-helix, with the first 10 N-terminal residues unstructured. In the interface between the two domains, the FAD cofactor is tightly bound in an unprecedented extended conformation. The NADH-binding domain consists of a five-stranded parallel beta-sheet with four alpha-helices packing closely around this sheet. MMOR-FAD is structurally homologous to other FAD-containing oxidoreductases, and we expect similar structures for the FAD/NADH-binding domains of reductases that occur in other multicomponent monooxygenases.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA.
authors.forename: Lisa L
authors.initials: LL
authors.lastname: Chatwood
authors.forename: Jens
authors.initials: J
authors.lastname: Müller
authors.forename: John D
authors.initials: JD
authors.lastname: Gross
authors.forename: Gerhard
authors.initials: G
authors.lastname: Wagner
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Lippard
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D005182:Flavin-Adenine Dinucleotide / Q000737:chemistry / Q000378:metabolism; D005415:Flavins / Q000737:chemistry* / Q000378:metabolism*; D020619:Methylococcus capsulatus / Q000201:enzymology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009243:NAD / Q000737:chemistry / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D010088:Oxidoreductases / Q000737:chemistry* / Q000378:metabolism*; D010105:Oxygenases / Q000737:chemistry* / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D012995:Solubility
chemical_list: D005415:Flavins; D009243:NAD; D005182:Flavin-Adenine Dinucleotide; D010088:Oxidoreductases; D010105:Oxygenases; C021555:methane monooxygenase