title: HQNO-sensitive NADH:quinone oxidoreductase of Bacillus cereus KCTC 3674.
abstract: The enzymatic properties of NADH:quinone oxidoreductase were examined in Triton X-100 extracts of Bacillus cereus membranes by using the artificial electron acceptors ubiquinone-1 and menadione. Membranes were prepared from B. cereus KCTC 3674 grown aerobically on a complex medium and oxidized with NADH exclusively, whereas deamino-NADH was determined to be poorly oxidized. The NADH oxidase activity was lost completely by solubilization of the membranes with Triton X-100. However, by using the artificial electron acceptors ubiquinone-1 and menadione, NADH oxidation could be observed. The activities of NADH:ubiquinone-1 and NADH:menadione oxidoreductase were enhanced approximately 8-fold and 4-fold, respectively, from the Triton X-100 extracted membranes. The maximum activity of FAD-dependent NADH:ubiquinone-1 oxidoreductase was obtained at about pH 6.0 in the presence of 0.1M NaCl, while the maximum activity of FAD-dependent NADH:menadione oxidoreductase was obtained at about pH 8.0 in the presence of 0.1 M NaCl. The activities of the NADH:ubiquinone-1 and NADH:menadione oxidoreductase were very resistant to such respiratory chain inhibitors as rotenone, capsaicin, and AgNO(3), whereas these activities were sensitive to 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO). Based on these results, we suggest that the aerobic respiratory chain-linked NADH oxidase system of B. cereus KCTC 3674 possesses an HQNO-sensitive NADH:quinone oxidoreductase that lacks an energy coupling site containing FAD as a cofactor.
authors.affiliation: Department of Microbiology, Changwon National University, Sarim-dong, Changwon, Kyungnam 641-773, Korea yjkim@changwon.ac.kr.
authors.forename: Jiwon
authors.initials: J
authors.lastname: Kang
authors.forename: Young Jae
authors.initials: YJ
authors.lastname: Kim
mesh_terms: D001409:Bacillus cereus / Q000201:enzymology*; D004579:Electron Transport / Q000187:drug effects; D042967:Electron Transport Complex I / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005486:Flavin Mononucleotide / Q000494:pharmacology; D005182:Flavin-Adenine Dinucleotide / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D006912:Hydroxyquinolines / Q000494:pharmacology*; D008565:Membrane Proteins / Q000378:metabolism; D009097:Multienzyme Complexes / Q000378:metabolism; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D012492:Salts / Q000494:pharmacology; D012834:Silver / Q000494:pharmacology
chemical_list: D006912:Hydroxyquinolines; D008565:Membrane Proteins; D009097:Multienzyme Complexes; D012492:Salts; D005182:Flavin-Adenine Dinucleotide; C001333:2-(n-heptyl)-4-hydroxyquinoline N-oxide; D012834:Silver; D005486:Flavin Mononucleotide; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases; D016660:NAD(P)H Dehydrogenase (Quinone); D042967:Electron Transport Complex I