The cytochrome bc1 and cytochrome c oxidase complexes associate to form a single supracomplex in yeast mitochondria

The mitochondrial electron transport chain complexes are large multisubunit complexes embedded in the inner membrane. We report here that in the yeast Saccharomyces cerevisiae, the cytochrome be, and cytochrome c oxidase complexes co-exist as a larger complex of similar to 1000 kDa in the mitochondrial membrane. Following solubilization with a mild detergent, the cytochrome bc(1)-cytochrome c oxidase complex remains stable. It was analyzed using the techniques of gel filtration and blue native-polyacrylamide gel electrophoresis. Direct physical. association of subunits of the cytochrome be, complex with those of the cytochrome c oxidase complex was verified by co-immunoprecipitation analysis. Our data indicate that the cytochrome be, complex is exclusively in association with the cytochrome c oxidase complex in yeast mitochondria. We term this complex the cytochrome bc(1)-cytochrome c oxidase supracomplex.