title: Su e of the yeast F1Fo-ATP synthase forms homodimers.
abstract: The yeast F(1)F(o)-ATP synthase forms a dimeric complex in the mitochondrial inner membrane. Dimerization of two F(1)F(o) monomeric complexes involves the physical association of two membrane-embedded F(o) sectors and in a manner, which is dependent on the F(o) subunit, Su e. Sequence analysis of Su e protein family members indicated the presence of a conserved coiled-coil motif. As this motif is often the basis for protein homodimerization events, it was hypothesized that Su e forms homodimers in the inner membrane and that formation of Su e dimers between two neighboring F(o) complexes would facilitate dimerization of the F(1)F(o)-ATP synthase complex (Arnold, I., Pfeiffer, K., Neupert, W., Stuart, R. A., and Schägger, H. (1998) EMBO J. 17, 7170-7178). Using a histidine-tagged derivative of yeast Su e, Su e-His(12), combined with cross-linking and affinity purification approaches, we have directly demonstrated the ability of the yeast Su e protein to form homodimers. Functionality of the Su e-His(12) derivative was confirmed by its ability to assemble into the ATP synthase complex and to support its dimerization in the Deltasu e null mutant yeast cells. The close association of two neighboring Su e proteins was also demonstrated using cross-linking with Cu(2+), which binds and cross-links a unique Cys residue in neighboring Su e proteins. Finally, we propose a model for the molecular basis of the homodimerization of the Su e proteins.
authors.affiliation: Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin 53233, USA.
authors.forename: Susanne
authors.initials: S
authors.lastname: Brunner
authors.forename: Valerie
authors.initials: V
authors.lastname: Everard-Gigot
authors.forename: Rosemary A
authors.initials: RA
authors.lastname: Stuart
mesh_terms: D019281:Dimerization; D006180:Proton-Translocating ATPases / Q000737:chemistry / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*
chemical_list: D006180:Proton-Translocating ATPases