title: A NAD(P)H oxidase isolated from the archaeon Sulfolobus solfataricus is not homologous with another NADH oxidase present in the same microorganism. Biochemical characterization of the enzyme and cloning of the encoding gene.
abstract: A NAD(P)H oxidase has been isolated from the archaeon Sulfolobus solfataricus. The enzyme is a homodimer with M(r) 38,000 per subunit (SsNOX38) containing 1 FAD molecule/subunit. It oxidizes NADH and, less efficiently, NADPH with the formation of hydrogen peroxide. The enzyme was resistant against chemical and physical denaturating agents. The temperature for its half-denaturation was 93 and 75 degrees C in the absence or presence, respectively, of 8 M urea. The enzyme did not show any reductase activity. The SsNOX38 encoding gene was cloned and sequenced. It accounted for a product of 36.5 kDa. The translated amino acid sequence was made of 332 residues containing two putative betaalphabeta-fold regions, typical of NAD- and FAD-binding proteins. The primary structure of SsNOX38 did not show any homology with the N-terminal amino acid sequence of a NADH oxidase previously isolated from S. solfataricus (SsNOX35) (Masullo, M., Raimo, G., Dello Russo, A., Bocchini, V. and Bannister, J. V. (1996) Biotechnol. Appl. Biochem. 23, 47-54). Conversely, it showed 40% sequence identity with a putative thioredoxin reductase from Bacillus subtilis, but it did not contain cysteines, which are essential for the activity of the reductase.
authors.affiliation: Dipartimento di Biochimica e Biotecnologie Mediche, Università di Napoli Federico II, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Arcari
authors.forename: L
authors.initials: L
authors.lastname: Masullo
authors.forename: M
authors.initials: M
authors.lastname: Masullo
authors.forename: F
authors.initials: F
authors.lastname: Catanzano
authors.forename: V
authors.initials: V
authors.lastname: Bocchini
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004795:Enzyme Stability; D005182:Flavin-Adenine Dinucleotide / Q000032:analysis; D006358:Hot Temperature; D007700:Kinetics; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000737:chemistry* / Q000378:metabolism*; D009247:NADH, NADPH Oxidoreductases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D019255:NADPH Oxidases; D011489:Protein Denaturation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D016944:Sulfolobus / Q000201:enzymology* / Q000235:genetics; D013816:Thermodynamics; D013880:Thioredoxin-Disulfide Reductase / Q000737:chemistry; D014508:Urea
chemical_list: D046911:Macromolecular Substances; D009097:Multienzyme Complexes; D011994:Recombinant Proteins; D005182:Flavin-Adenine Dinucleotide; D014508:Urea; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; D013880:Thioredoxin-Disulfide Reductase