title: Involvement of sulfide:quinone oxidoreductase in sulfur oxidation of an acidophilic iron-oxidizing bacterium, Acidithiobacillus ferrooxidans NASF-1.
abstract: The effects of cyanide, azide, and 2-n-Heptyl-4-hydroxy-quinoline-N-oxide (HQNO) on the oxidation of ferrous ion or elemental sulfur with Acidithiobacillus ferrooxidans NASF-1 cells grown in iron- or sulfur-medium were examined. The iron oxidation of both iron- and sulfur-grown cells was strongly inhibited by cyanide and azide, but not by HQNO. Sulfur oxidation was relatively resistant to cyanide and azide, and inhibited by HQNO. Higher sulfide oxidation, ubiquinol dehydrogenase activity, and sulfide:quinone oxidoreductase (SQR) activity were observed in sulfur-grown cells more than in iron-grown cells. Sulfide oxidation in the presence of ubiquinone with the membrane fraction was inhibited by HQNO, but not by cyanide, azide, antimycin A, and myxothiazol. The transcription of three genes, encoding an aa(3)-type cytochrome c oxidase (coxB), a bd-type ubiquinol oxidase (cydA), and an sqr, were measured by real-time reverse transcription polymerase chain reaction. The transcriptional levels of coxB and cydA genes were similar in sulfur- and iron-grown cells, but that of sqr was 3-fold higher in sulfur-grown cells than in iron-grown cells. A model is proposed for the oxidation of reduced inorganic sulfur compounds in A. ferrooxidans NASF-1 cells.
authors.affiliation: Division of Science and Technology for Energy Conversion, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-Naka, Okayama 700-8530, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Wakai
authors.forename: Mei
authors.initials: M
authors.lastname: Kikumoto
authors.forename: Tadayoshi
authors.initials: T
authors.lastname: Kanao
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kamimura
mesh_terms: D042763:Acidithiobacillus / Q000201:enzymology*; D001386:Azides / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D003486:Cyanides / Q000494:pharmacology; D003576:Electron Transport Complex IV / Q000235:genetics; D006912:Hydroxyquinolines / Q000494:pharmacology; D007501:Iron / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D010088:Oxidoreductases / Q000235:genetics; D011808:Quinone Reductases / Q000235:genetics / Q000378:metabolism*; D013455:Sulfur / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D001386:Azides; D001426:Bacterial Proteins; D003486:Cyanides; D006912:Hydroxyquinolines; C001333:2-(n-heptyl)-4-hydroxyquinoline N-oxide; D013455:Sulfur; D007501:Iron; D010088:Oxidoreductases; C432586:ubiquinol oxidase; D011808:Quinone Reductases; C073412:sulfide quinone reductase; D003576:Electron Transport Complex IV