title: Structures of dimeric dihydrodiol dehydrogenase apoenzyme and inhibitor complex: probing the subunit interface with site-directed mutagenesis.
abstract: Dimeric dihydrodiol dehydrogenase (DD) catalyses the nicotinamide adenine dinucleotide phosphate (NADP+)-dependent oxidation of trans-dihydrodiols of aromatic hydrocarbons to their corresponding catechols. This is the first report of the crystal structure of the dimeric enzyme determined at 2.0 A resolution. The tertiary structure is formed by a classical dinucleotide binding fold comprising of two betaalphabetaalphabeta motifs at the N-terminus and an eight-stranded, predominantly antiparallel beta-sheet at the C-terminus. The active-site of DD, occupied either by a glycerol molecule or the inhibitor 4-hydroxyacetophenone, is located in the C-terminal domain of the protein and maintained by a number of residues including Lys97, Trp125, Phe154, Leu158, Val161, Asp176, Leu177, Tyr180, Trp254, Phe279, and Asp280. The dimer interface is stabilized by a large number of intermolecular contacts mediated by the beta-sheet of each monomer, which includes an intricate hydrogen bonding network maintained in principal by Arg148 and Arg202. Site-directed mutagenesis has demonstrated that the intact dimer is not essential for catalytic activity. The similarity between the quaternary structures of mammalian DD and glucose-fructose oxidoreductase isolated from the prokaryotic organism Zymomonas mobilis suggests that both enzymes are members of a unique family of oligomeric proteins and may share a common ancestral gene.
authors.affiliation: Department of Medicinal Chemistry, Victorian College of Pharmacy, Monash University, Parkville, Victoria 3052, Australia.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Carbone
authors.forename: Satoshi
authors.initials: S
authors.lastname: Endo
authors.forename: Rie
authors.initials: R
authors.lastname: Sumii
authors.forename: Roland P-T
authors.initials: RP
authors.lastname: Chung
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Matsunaga
authors.forename: Akira
authors.initials: A
authors.lastname: Hara
authors.forename: Ossama
authors.initials: O
authors.lastname: El-Kabbani
mesh_terms: D000818:Animals; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D018076:DNA, Complementary; D019281:Dimerization; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000494:pharmacology; D006801:Humans; D006860:Hydrogen Bonding; D008958:Models, Molecular; D015335:Molecular Probes; D016297:Mutagenesis, Site-Directed; D010088:Oxidoreductases / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics; D017433:Protein Structure, Secondary
chemical_list: D018076:DNA, Complementary; D004791:Enzyme Inhibitors; D015335:Molecular Probes; D010088:Oxidoreductases; C048338:trans-1,2-dihydrobenzene-1,2-diol dehydrogenase