Evidence of a subunit 4 (subunit b) dimer in favor of the proximity of ATP synthase complexes in yeast inner mitochondrial membrane

Yeast mitochondria having either the D54C or E55C mutations in subunit 4 (subunit b), which is a component of the ATP synthase stator, displayed a spontaneous disulfide bridge between two subunits 4. This dimer was not soluble upon Triton X-100 extraction either at concentrations which extract the yeast ATP synthase or at higher concentrations. increasing detergent concentrations led to a lack of the oligomycin-sensitive ATPase activity, thus showing an uncoupling between the two sectors of the mutated enzymes due to the dissociation of the subunit 4 dimer from the mutant enzyme. There is only one subunit 4 (subunit b) per eukaryotic ATP synthase. As a consequence, the results are interpreted as the proximity of ATP synthase complexes within the inner mitochondrial membrane. (C) 1998 Elsevier Science B.V. All rights reserved.