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 FA sector of the mitochondrial F1Fo-ATP synthase complex (mtATPase). The subunits comprising this sector have been implicated in the coupling of proton flux through the membrane Fo sector to ATP synthesis on the catalytic F1 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 degrees C, on nonfermentable substrates. Expression of mammalian FA subunit homologues in yeast should provide a productive new approach to generating information on the structure and function of mtATPase.