The Functional Expression of a Rat cDNA Encoding OSCP in the Yeast Saccharomyces cerevisiae

The oligomycin sensitivity conferring protein (OSCP) of Saccharomyces cerevisiae is a component of the stalk F A sector of the mitochondrial F 1F O-ATP synthase complex (mtATPase). The subunits comprising this sector have been implicated in the coupling of proton flux through the membrane F O sector to ATP synthesis on the catalytic F 1 sector. We tested whether the yeast subunit encoded by the ATP5 gene could be functionally replaced by a mammalian homologue, rat OSCP. The yeast and rat OSCP proteins have 58% homology in terms of conserved amino acids. A vector-borne rat cDNA encoding the OSCP precursor was introduced into a yeast strain lacking endogenous OSCP as a result of its disrupted ATP5 gene. The resultant yeast cells showed essentially a wildtype growth rate at 18, 28 and 35°C, on nonfermentable substrates. Expression of mammalian F A subunit homologues in yeast should provide a productive new approach to generating information on the structure and function of mtATPase.