title: NAD+-specific D-arabinose dehydrogenase and its contribution to erythroascorbic acid production in Saccharomyces cerevisiae.
abstract: Erythroascorbic acid (eAsA) is a five-carbon analog of ascorbic acid, and it is synthesized from D-arabinose by D-arabinose dehydrogenase (ARA) and D-arabinono-gamma-lactone oxidase. We found an NAD+-specific ARA activity which is operative under submillimolar level of d-arabinose in the extracts of Saccharomyces cerevisiae. The hypothetical protein encoded by YMR041c showed a significant homology to a l-galactose dehydrogenase which plays in plant ascorbic acid biosynthesis, and we named it as Ara2p. Recombinant Ara2p showed NAD+-specific ARA activity with Km=0.78 mM to d-arabinose, which is 200-fold lower than that for the conventional NADP+-specific ARA, Ara1p. Gene disruptant of ARA2 lost entire NAD+-specific ARA activity and the conspicuous increase in intracellular eAsA by exogenous d-arabinose feeding, while the double knockout mutant of ARA1 and ARA2 still retained measurable amount of eAsA. It demonstrates that Ara2p, not Ara1p, mainly contributes to the production of eAsA from d-arabinose in S. cerevisiae.
authors.affiliation: Faculty of Nutrition, Kobe Gakuin University, 518 Arise, Kobe, Hyogo 651-2180, Japan. amakok@nutr.kobegakuin.ac.jp
authors.forename: Katsumi
authors.initials: K
authors.lastname: Amako
authors.forename: Kazuyo
authors.initials: K
authors.lastname: Fujita
authors.forename: Taka-aki
authors.initials: TA
authors.lastname: Shimohata
authors.forename: Etsuko
authors.initials: E
authors.lastname: Hasegawa
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Kishimoto
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Goda
mesh_terms: D001089:Arabinose / Q000378:metabolism / Q000494:pharmacology; D001205:Ascorbic Acid / Q000096:biosynthesis* / Q000235:genetics; D017353:Gene Deletion; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013401:Sugar Alcohol Dehydrogenases / Q000235:genetics / Q000378:metabolism*
chemical_list: D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; C005056:isoascorbic acid; D001089:Arabinose; D013401:Sugar Alcohol Dehydrogenases; C028590:D-arabinose dehydrogenase; D001205:Ascorbic Acid