title: Structural organization of mitochondrial ATP synthase.
abstract: Specific modules and subcomplexes like F(1) and F(0)-parts, F(1)-c subcomplexes, peripheral and central stalks, and the rotor part comprising a ring of c-subunits with attached subunits gamma, delta, and epsilon can be identified in yeast and mammalian ATP synthase. Four subunits, alpha(3)beta(3), OSCP, and h, seem to form a structural entity at the extramembranous rotor/stator interface (gamma/alpha(3)beta(3)) to hold and stabilize the rotor in the holo-enzyme. The intramembranous rotor/stator interface (c-ring/a-subunit) must be dynamic to guarantee unhindered rotation. Unexpectedly, a c(10)a-assembly could be isolated with almost quantitive yield suggesting that an intermediate step in the rotating mechanism was frozen under the conditions used. Isolation of dimeric a-subunit and (c(10))(2)a(2)-complex from dimeric ATP synthase suggested that the a-subunit stabilizes the same monomer-monomer interface that had been shown to involve also subunits e, g, b, i, and h. The natural inhibitor protein Inh1 does not favor oligomerization of yeast ATP synthase. Other candidates for the oligomerization of dimeric ATP synthase building blocks are discussed, e.g. the transporters for inorganic phosphate and ADP/ATP that had been identified as constituents of ATP synthasomes. Independent approaches are presented that support previous reports on the existence of ATP synthasomes in the mitochondrial membrane.
authors.affiliation: Molecular Bioenergetics Group, Cluster of Excellence Frankfurt Macromolecular Complexes, Medical School, Johann Wolfgang Goethe-Universität, Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany. wittig@zbc.kgu.de
authors.forename: Ilka
authors.initials: I
authors.lastname: Wittig
authors.forename: Hermann
authors.initials: H
authors.lastname: Schägger
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D020134:Catalytic Domain; D002417:Cattle; D008322:Mammals; D025261:Mitochondrial Proton-Translocating ATPases / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D010446:Peptide Fragments / Q000737:chemistry; D011487:Protein Conformation; D011499:Protein Processing, Post-Translational; D021122:Protein Subunits / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: D010446:Peptide Fragments; D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins; D025261:Mitochondrial Proton-Translocating ATPases