Oligomycin Resistance of Mitochondrial Adenosine Triphosphatase in a Pleiotropic Chromosomal Mutant of a “Petite-Negative” Yeast, Schizosaccharomyces pombe

A chromosomal pleiotropic respiratory-deficient mutant has been obtained by x-irradiation of a petite-negative yeast species: Schizosaccharomyces pombe 972h-. This mutant, called M126, does not grow on glycerol medium and lacks antimycin A-sensitive respiration. It possesses the following mitochondrial enzymes: cytochrome c, cytochrome c1, succinate:phenazine methosulfate oxidoreductase (EC 1.3.99.1), and Dio-9-sensitive ATPase (ATP phosphohydrolase, EC 3.6.13). There was a decrease of more than 95% in cytochrome oxidase (ferricytochrome c:oxygen oxidoreductase, EC 1.9.3.1), succinate:cytochrome c oxidoreductase (EC 1.3.99.1), and oligomycin-sensitive ATPase. The cytochrome a + a3 absorption peak was not detectable. The cytochrome b 560 absorption peak was markedly decreased but detectable in the mutant. The mutant Dio-9-sensitive ATPase activity was recovered mainly in the postribosomal supernatant, suggesting that the binding of ATPase to the mitochondrial membrane is weakened. The Dio-9-sensitive ATPase purified from mutant submitochondrial particles reacts like the wild type enzyme to anions, cations, inhibitors, and low temperature. Both purified ATPases show five subunits of the following molecular weights: 61,000, 58,000 32,000, 14,000, and 8,000. The addition of chloramphenicol and ethidium bromide to the wild type produces pleiotropic phenotypes which show several similarities to that of the mutant. However, the cycloheximide-resistant incorporation of leucine by the mutant is significantly decreased by ethidium bromide. Genetic analyses show that the mutation is of chromosomal origin and that only one gene or a few closely linked genes are modified. These data suggest that the mutation affects a chromosomal DNA product involved in a central process of mitochondrial biogenesis.