Crystal structure and mechanism of CO dehydrogenase, a molybdo iron-sulfur flavoprotein containing S-selanylcysteine.
CO dehydrogenase from the aerobic bacterium Oligotropha carboxidovorans catalyzes the oxidation of CO with H(2)O, yielding CO(2), two electrons, and two H(+). Its crystal structure in the air-oxidized form has been determined to 2.2 A. The active site of the enzyme, which contains molybdenum with three oxygen ligands, molybdopterin-cytosine dinucleotide and S-selanylcysteine, delivers the electrons to an intramolecular electron transport chain composed of two types of [2Fe-2S] clusters and flavin-adenine dinucleotide. CO dehydrogenase is composed of an 88.7-kDa molybdoprotein (L), a 30. 2-kDa flavoprotein (M), and a 17.8-kDa iron-sulfur protein (S). It is organized as a dimer of LMS heterotrimers and resembles xanthine dehydrogenase/oxidase in many, but not all, aspects. A mechanism based on a structure with the bound suicide-substrate cyanide is suggested and displays the necessity of S-selanylcysteine for the catalyzed reaction.
Dobbek
H
H
Max-Planck-Institut für Biochemie, Abteilung Strukturforschung, D-82152 Martinsried, Germany. dobbek@biochem.mpg.de
Gremer
L
L
Meyer
O
O
Huber
R
R
D000445:Aldehyde Oxidoreductases / Q000737:chemistry* / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D018360:Crystallography, X-Ray; D003901:Desulfovibrio / Q000201:enzymology; D019281:Dimerization; D007506:Iron-Sulfur Proteins / Q000737:chemistry* / Q000378:metabolism*; D008024:Ligands; D046911:Macromolecular Substances; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008982:Molybdenum / Q000378:metabolism; D009097:Multienzyme Complexes / Q000737:chemistry* / Q000378:metabolism*; D017433:Protein Structure, Secondary; D017279:Selenocysteine; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014969:Xanthine Oxidase / Q000737:chemistry
D007506:Iron-Sulfur Proteins; D008024:Ligands; D046911:Macromolecular Substances; D009097:Multienzyme Complexes; D017279:Selenocysteine; D008982:Molybdenum; D014969:Xanthine Oxidase; D000445:Aldehyde Oxidoreductases; C019823:carbon monoxide dehydrogenase