title: Cytochrome bd-type quinol oxidase in a mutant of Bacillus stearothermophilus deficient in caa3-type cytochrome c oxidase.
abstract: Gram-positive thermophilic Bacillus species contain cytochrome caa3-type cytochrome c oxidase as a terminal oxidase in the respiratory chain. To identify alternative oxidases, we isolated B. stearothermophilus mutants defective in the caa3-type oxidase activity. One mutant contained little cytochrome a and had low cytochrome c oxidase activity. However, growth and the respiratory activity of membranes in the presence of NADH were close to normal, suggesting that the mutant contains an alternative electron transfer pathway. A novel oxidase was isolated from the membrane fraction of the mutant. The enzyme is a cytochrome bd-type quinol oxidase composed of two subunits of 52 and 40 kDa, whose N-terminal regions show sequence similarity to polypeptides of the bd-type oxidase from Escherichia coli and Azotobacter vinelandii. This is the first report of a bd-type terminal oxidase purified from a Gram-positive bacterium.
authors.affiliation: Department of Biochemical Engineering and Science, Kyushu Institute of Technology, Fukuoka-ken, Japan. sakamoto@bse.kyutech.ac.jp
authors.forename: J
authors.initials: J
authors.lastname: Sakamoto
authors.forename: A
authors.initials: A
authors.lastname: Matsumoto
authors.forename: K
authors.initials: K
authors.lastname: Oobuchi
authors.forename: N
authors.initials: N
authors.lastname: Sone
mesh_terms: D000595:Amino Acid Sequence; D003573:Cytochrome b Group; D030401:Cytochrome-c Oxidase Deficiency; D003580:Cytochromes / Q000378:metabolism; D004579:Electron Transport; D045222:Electron Transport Chain Complex Proteins; D003576:Electron Transport Complex IV / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins; D001411:Geobacillus stearothermophilus / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009154:Mutation; D010088:Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010089:Oxidoreductases, N-Demethylating / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid
chemical_list: D003573:Cytochrome b Group; D003580:Cytochromes; D045222:Electron Transport Chain Complex Proteins; D029968:Escherichia coli Proteins; D010088:Oxidoreductases; C020094:duroquinol oxidase; D010089:Oxidoreductases, N-Demethylating; C022726:tetramethylphenylenediamine oxidase; C040077:cytochrome bd terminal oxidase complex, E coli; D003576:Electron Transport Complex IV