Effect of anisotropic inhibitors of ATP synthesis in mitochondria of Saccharomyces cerevisiae. Comparison between a wild-type and a mutant strain altered in the stoichiometry of the MT DNA encoded proteolipids of ATP synthase.

The effect of a group of non-usual inhibitors of ATP synthesis was investigated in yeast mitochondria. Tetraphenylphosphonium, tetraphenylarsonium and ethidium decreased the rate of ATP synthesis but did not decrease the ATP/O ratio. They did not inhibit the ATPase activity and the translocase, and did not decrease the proton-motive force. They inhibited phosphate transport under conditions in which it was strictly energy-dependent, but did not under conditions in which it was energy-independent. These inhibitors had a poor effect on ATP synthesis in mitochondria isolated from a nuclear mutant which contained a reduced amount of the subunits 8 and 6 of the Fo part of the ATP synthase as compared to wild-type and which were unable to support any energy-dependent phosphate-transport. Thus, it appeared that the phosphate-dependence of ATP synthesis was altered in the same way by both tetraphenylphosphonium and the mutation.