title: L-aspartate oxidase is present in the anaerobic hyperthermophilic archaeon Pyrococcus horikoshii OT-3: characteristics and role in the de novo biosynthesis of nicotinamide adenine dinucleotide proposed by genome sequencing.
abstract: A gene encoding the L-aspartate oxidase homologue was identified via genome sequencing in the anaerobic hyperthermophilic archaeon Pyrococcus horikoshii OT-3. We succeeded in expressing the encoding gene in Escherichia coli and purified the product to homogeneity. Characterization of the protein revealed that it is the most thermostable L-aspartate oxidase detected so far. In addition to the oxidase activity, the enzyme catalyzed L-aspartate dehydrogenation in the presence of an artificial electron acceptor such as phenazine methosulfate, 2,6-dichlorophenol-indophenol, and ferricyanide. L-Aspartate oxidase is known to function as the first enzyme in the de novo NAD biosynthetic pathway in prokaryotes. By a similarity search in public databases, the genes that encode the homologue of all other enzymes involved in the pathway were identified in the P. horikoshii OT-3 genome. This suggests that P. horikoshii OT-3 may use the de novo NAD biosynthetic pathway under anaerobic conditions.
authors.affiliation: Department of Biological Science and Technology, Faculty of Engineering, University of Tokushima, Tokushima 770-8506, Japan.
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Sakuraba
authors.forename: Takenori
authors.initials: T
authors.lastname: Satomura
authors.forename: Ryushi
authors.initials: R
authors.lastname: Kawakami
authors.forename: Sanae
authors.initials: S
authors.lastname: Yamamoto
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Kawarabayasi
authors.forename: Hisasi
authors.initials: H
authors.lastname: Kikuchi
authors.forename: Toshihisa
authors.initials: T
authors.lastname: Ohshima
mesh_terms: D000594:Amino Acid Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D004795:Enzyme Stability; D029968:Escherichia coli Proteins; D020745:Genome, Archaeal; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D009243:NAD / Q000096:biosynthesis*; D019711:Pyrococcus / Q000201:enzymology* / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D029968:Escherichia coli Proteins; D011994:Recombinant Proteins; D009243:NAD; D000594:Amino Acid Oxidoreductases; C031955:L-aspartate oxidase, E coli