Regulation by heme of the synthesis of cytochrome C oxidase subunits V and VII in yeast

The effects of heme on the synthesis of subunits V and VII of cytochrome c oxidase were examined in the heme-deficient yeast mutant, GL1. In vitro translation and immunodetection with subunit-specific antisera indicated a 50% decrease in both proteins, with RNA obtained from hemeless cells. Unsupplemented, pulse-labeled cells contained both V and VII polypeptides, but at extremely low levels as compared with those found in delta-aminolevulinic acid-supplemented cells. The data suggest that heme controls the formation of mRNAs for the two subunits, and may also have a regulatory role in translation and in the stability of the polypeptides.