Crystal Structure of DMSO Reductase: Redox-Linked Changes in Molybdopterin Coordination

• DOI: 10.1126/science.272.5268.1615
• Publication Date: 2006-10-27T18:30:41Z
• Authors: Hermann Schindelin; Caroline Kisker; James Hilton; K. V. Rajagopalan; Douglas C. Rees
• Keywords: Iron-Sulfur Proteins; Models, Molecular; 570; 0303 health sciences; Binding Sites; Sequence Homology, Amino Acid; Protein Conformation; Pteridines; Molecular Sequence Data; Coenzymes; Rhodobacter sphaeroides; Crystallography, X-Ray; 03 medical and health sciences; Metalloproteins; Amino Acid Sequence; Oxidoreductases; Molybdenum Cofactors; Oxidation-Reduction

The molybdoenzyme dimethylsulfoxide (DMSO) reductase contributes to the release of dimethylsulfide, a compound that has been implicated in cloud nucleation and global climate regulation. The crystal structure of DMSO reductase from Rhodobacter sphaeroides reveals a monooxo molybdenum cofactor containing two molybdopterin guanine dinucleotides that asymmetrically coordinate the molybdenum through their dithiolene groups. One of the pterins exhibits different coordination modes to the molybdenum between the oxidized and reduced states, whereas the side chain oxygen of Ser 147 coordinates the metal in both states. The change in pterin coordination between the Mo(VI) and Mo(IV) forms suggests a mechanism for substrate binding and reduction by this enzyme. Sequence comparisons of DMSO reductase with a family of bacterial oxotransferases containing molybdopterin guanine dinucleotide indicate a similar polypeptide fold and active site with two molybdopterins within this family.