title: Formation of the yeast F1F0-ATP synthase dimeric complex does not require the ATPase inhibitor protein, Inh1.
abstract: The yeast F1F0-ATP synthase forms dimeric complexes in the mitochondrial inner membrane and in a manner that is supported by the F0-sector subunits, Su e and Su g. Furthermore, it has recently been demonstrated that the binding of the F1F0-ATPase natural inhibitor protein to purified bovine F1-sectors can promote their dimerization in solution (Cabezon, E., Arechaga, I., Jonathan P., Butler, G., and Walker J. E. (2000) J. Biol. Chem. 275, 28353-28355). It was unclear until now whether the binding of the inhibitor protein to the F1 domains contributes to the process of F1F0-ATP synthase dimerization in intact mitochondria. Here we have directly addressed the involvement of the yeast inhibitor protein, Inh1, and its known accessory proteins, Stf1 and Stf2, in the formation of the yeast F1F0-ATP synthase dimer. Using mitochondria isolated from null mutants deficient in Inh1, Stf1, and Stf2, we demonstrate that formation of the F(1)F(0)-ATP synthase dimers is not adversely affected by the absence of these proteins. Furthermore, we demonstrate that the F1F0-ATPase monomers present in su e null mutant mitochondria can be as effectively inhibited by Inh1, as its dimeric counterpart in wild-type mitochondria. We conclude that dimerization of the F1F0-ATP synthase complexes involves a physical interaction of the membrane-embedded F0 sectors from two monomeric complexes and in a manner that is independent of inhibitory activity of the Inh1 and accessory proteins.
authors.affiliation: Department of Biology, Marquette University, Milwaukee, Wisconsin 53233, USA.
authors.forename: Mary
authors.initials: M
authors.lastname: Dienhart
authors.forename: Kathy
authors.initials: K
authors.lastname: Pfeiffer
authors.forename: Hermann
authors.initials: H
authors.lastname: Schagger
authors.forename: Rosemary A
authors.initials: RA
authors.lastname: Stuart
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D019281:Dimerization; D004591:Electrophoresis, Polyacrylamide Gel; D005656:Fungal Proteins / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins; D011485:Protein Binding; D006180:Proton-Translocating ATPases / Q000737:chemistry* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism*; D013997:Time Factors
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D005656:Fungal Proteins; D024101:Mitochondrial Proteins; C469352:STF1 protein, S cerevisiae; C469353:STF2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D006180:Proton-Translocating ATPases