Oligomycin Sensitivity of ATPase Studied as a Function of Mitochondrial Biogenesis, using Mitochondrially Determined Oligomycin‐Resistant Mutants of Saccharomyces cerevisiae

The quantitative comparison of oligomycin sensitivity of ATPase from two mitochondrially determined oligomycin‐resistant mutants (locus O I and O II ) and the wild‐type strain (all three isonuclear), as a function of mitochondrial biogenesis, gave the following results:1 The mutations at the loci O I and O II confer distinctly different oligomycin resistance on mitochondrial ATPase, O I being more resistant than O II , and both more resistant than the ATPase from the wild‐type strain. 2 In spite of these differences in oligomycin resistance, the binding of the ATPase to the mitochondrial membranes does not appear to be modified. 3 The phenotypic oligomycin resistance of mitochondrial ATPase, produced by growth of the wild type strain in the presence of chloramphenicol, is notably higher than the highest genotypic oligomycin resistance. 4 The oligomycin sensitivity or resistance of ATPase is strictly identical in anaerobic promitochondria and aerobic mitochondria, i.e. the difference between the oligomycin sensitivity of the ATPase from these strains is maintained in such extremely different physiological states. 5 In contrast, the ATPase isolated during respiratory adaptation of the wild‐type strain had distinctly higher oligomycin resistance than the promitochondria or the aerobic mitochondria. This “transient” resistance displayed by the wild‐type ATPase during adaptation (in the absence of growth) was very similar to the genotypic resistance of the ATPase from the mutant at locus O I .