Yeast mitochondrial F1F0-ATP synthase exists as a dimer: identification ofthree dimer-specific subunits

Using the technique of blue native gel electrophoresis, the oligomeric stat e of the yeast mitochondrial F1F0-ATP synthase was analysed. Solubilization of mitochondrial membranes with low detergent to protein ratios led to the identification of the dimeric state of the ATP synthase, Analysis of the s ubunit composition of the dimer, in comparison with the monomer, revealed t he presence of three additional small proteins. These dimer-specific subuni ts of the ATP synthase were identified as the recently described subunit e/ Tim11 (Su e/Tim11), the putative subunit g homolog (Su g) and a new compone nt termed subunit k (Su k), Although, as shown here, these three proteins a re not required for the formation of enzymatically active ATP synthase, Su e/Tim11 and Su g are essential for the formation of the dimeric state, Su e /Tim11 appears to play a central role in this dimerization process. The dim er-specific subunits are associated with the membrane bound F-0-sector. The F-0-sector may thereby be involved in the dimerization of two monomeric F1 F0-ATP synthase complexes. We speculate that the F1F0-ATP synthase of yeast , like the other complexes of oxidative phosphorylation, form supracomplexe s to optimize transduction of energy and to enhance the stability of the co mplex in the membrane.