Abstract
A quinol oxidase has been purified from the cytoplasmic membrane of Paracoccus denitrificans; its heme composition and CO binding properties identify it as a cytochrome ba3. On SDS gels, the purified enzyme complex is separated into five polypeptides. Using partial peptide sequence information for subunit II, the gene locus has been cloned and sequenced. In a typical operon pattern, four genes were identified: qoxA, -B, -C, and -D, coding for subunits II, I, III, and IV. DNA-derived amino acid sequence comparisons reveal extensive similarities to other members of the terminal oxidase superfamily.
Highlights
From the Institute of Biochemistry,Department of Molecular Genetics, Universityof Frankfurt, Biozentrum N200, Marie-Curie-Strasse 9, 0-60439 Frankfurt, Federal Republic of Germany
Cus has been cloneadnd sequenced.In a typical operon Recent sequence data analysis and functional evidence on pattern, four genes were identifieqdo:zA, -B, X, and -D, quinol and cytochrome c oxidases have linkedthe two types of coding for subunit1s1,I, 111, and W.DNA-derived amino terminal oxidases and placed them intoa superfamily (6,71.As taociodthseerqumeenmcebecrosmopfatrhiseotnesrmreinvaeal loxeixdtaesnesisvuepesirmfaimlairliyt.ihaeetsympeicsa, la feature, low spin subunit I provides the ligands for component and a high spin heme; the the two latter is inclose vicinity to a copper ion (Cu,), both togetherforming the oxygen binding site
This study identifies by enzymepurification and by DNA cloning and sequencing a terminal oxidase in I? denitrificans that catalyzes the oxidation of ubiquinol by oxygen, circumventing the cytochrome bc, complex and cytochrome c oxidase
Summary
I t is characterized as a copper-containing cytochrome ba,. Cloning and sequencing of the corresponding genelocus and comparison with sequences of other oxidases reveal an operon organization of the structural genes anda clear relationship to other memboefrtshe terminal oxidase family
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