Identification and properties of a quinol oxidase super-complex composed of a bc1 complex and cytochrome oxidase in the thermophilic bacterium PS3.
Evidence for the presence of a quinol oxidase super-complex composed of a cytochrome bc1 complex and cytochrome oxidase in the respiratory chain of a Gram-positive thermophilic bacterium PS3 is reported. On incubation with an octyl glucoside-solubilized fraction of the total membranes of PS3 anti-serum against PS3 cytochrome oxidase gave an immunoprecipitate that showed both quinol-cytochrome c reductase and cytochrome c oxidase activities. When the cholate-deoxycholate and LiCl-treated membranes of PS3 were solubilized and subjected to ion-exchange chromatography in the presence of octaethyleneglycol dodecyl ether, most of the A-, B-, and C-type cytochromes were copurified as a peak having both quinol-cytochrome c reductase and cytochrome oxidase activities. The immunoprecipitate and quinol oxidase preparation contained hemes a, b, and c in a ratio of about 2:2:3, indicating the presence of one-to-one complex of cytochrome oxidase containing 2 hemes a and one heme c, and a bc1 complex containing 2 hemes b and 2 hemes c. Gel electrophoresis in the presence of dodecyl sulfate showed that the immunoprecipitate and quinol oxidase preparation were composed of seven subunits; those of 51 (56-kDa), 38, and 22 kDa for cytochrome oxidase and those of 29, 23, 21, and 14 kDa for the bc1 complex. The 38-, 29-, and 21 kDa components possessed covalently bound heme c. The apparent molecular mass of the super complex was estimated to be as 380 kDa by gel filtration.
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Department of Biochemistry, Jichi Medical School, Tochigi-ken, Japan.
Sekimachi
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Kutoh
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D000906:Antibodies; D002850:Chromatography, Gel; D014450:Electron Transport Complex III / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000378:metabolism*; D006094:Gram-Positive Bacteria / Q000201:enzymology*; D006418:Heme / Q000032:analysis; D046911:Macromolecular Substances; D009097:Multienzyme Complexes / Q000032:analysis*; D013053:Spectrophotometry
D000906:Antibodies; D046911:Macromolecular Substances; D009097:Multienzyme Complexes; D006418:Heme; D003576:Electron Transport Complex IV; D014450:Electron Transport Complex III