title: Electron cryomicroscopy observation of rotational states in a eukaryotic V-ATPase.
abstract: Eukaryotic vacuolar H(+)-ATPases (V-ATPases) are rotary enzymes that use energy from hydrolysis of ATP to ADP to pump protons across membranes and control the pH of many intracellular compartments. ATP hydrolysis in the soluble catalytic region of the enzyme is coupled to proton translocation through the membrane-bound region by rotation of a central rotor subcomplex, with peripheral stalks preventing the entire membrane-bound region from turning with the rotor. The eukaryotic V-ATPase is the most complex rotary ATPase: it has three peripheral stalks, a hetero-oligomeric proton-conducting proteolipid ring, several subunits not found in other rotary ATPases, and is regulated by reversible dissociation of its catalytic and proton-conducting regions. Studies of ATP synthases, V-ATPases, and bacterial/archaeal V/A-ATPases have suggested that flexibility is necessary for the catalytic mechanism of rotary ATPases, but the structures of different rotational states have never been observed experimentally. Here we use electron cryomicroscopy to obtain structures for three rotational states of the V-ATPase from the yeast Saccharomyces cerevisiae. The resulting series of structures shows ten proteolipid subunits in the c-ring, setting the ATP:H(+) ratio for proton pumping by the V-ATPase at 3:10, and reveals long and highly tilted transmembrane α-helices in the a-subunit that interact with the c-ring. The three different maps reveal the conformational changes that occur to couple rotation in the symmetry-mismatched soluble catalytic region to the membrane-bound proton-translocating region. Almost all of the subunits of the enzyme undergo conformational changes during the transitions between these three rotational states. The structures of these states provide direct evidence that deformation during rotation enables the smooth transmission of power through rotary ATPases.
authors.affiliation: 1] Molecular Structure and Function Program, The Hospital for Sick Children Research Institute, 686 Bay Street, Toronto, Ontario M5G 0A4, Canada [2] Department of Medical Biophysics, The University of Toronto, Toronto Medical Discovery Tower, MaRS Centre, 101 College Street, Toronto, Ontario M5G 1L7, Canada.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Molecular Structure and Function Program, The Hospital for Sick Children Research Institute, 686 Bay Street, Toronto, Ontario M5G 0A4, Canada.
authors.forename: Samir
authors.initials: S
authors.lastname: Benlekbir
authors.affiliation: 1] Molecular Structure and Function Program, The Hospital for Sick Children Research Institute, 686 Bay Street, Toronto, Ontario M5G 0A4, Canada [2] Department of Medical Biophysics, The University of Toronto, Toronto Medical Discovery Tower, MaRS Centre, 101 College Street, Toronto, Ontario M5G 1L7, Canada [3] Department of Biochemistry, The University of Toronto, 1 King's College Circle, Medical Sciences Building, Toronto, Ontario M5S 1A8, Canada.
authors.forename: John L
authors.initials: JL
authors.lastname: Rubinstein
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D055162:Biocatalysis; D002462:Cell Membrane / Q000737:chemistry / Q000201:enzymology / Q000378:metabolism; D020285:Cryoelectron Microscopy; D008051:Lipid Bilayers / Q000378:metabolism; D008958:Models, Molecular; D018583:Pliability; D011487:Protein Conformation; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D011522:Protons; D012399:Rotation; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D012995:Solubility; D025262:Vacuolar Proton-Translocating ATPases / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure*
chemical_list: D008051:Lipid Bilayers; D021122:Protein Subunits; D011522:Protons; D000255:Adenosine Triphosphate; D025262:Vacuolar Proton-Translocating ATPases