title: Transient accumulation of elastic energy in proton translocating ATP synthase.
abstract: ATP synthase is conceived as a rotatory engine with two reversible drives, the proton-transporting membrane portion, F0, and the catalytic peripheral portion, F1. They are mounted on a central shaft (subunit gamma) and held together by an eccentric bearing. It is established that the hydrolysis of three molecules of ATP in F1 drives the shaft over a full circle in three steps of 120 degrees each. Proton flow through F0 probably generates a 12-stepped rotation of the shaft so that four proton-translocating steps of 30 degrees each drive the synthesis of one molecule of ATP. We addressed the elasticity of the transmission between F0 and F1 in a model where the four smaller steps in F0 load a torsional spring which is only released under liberation of ATP from F1. The kinetic model of an elastic ATP synthase described a wealth of published data on the synthesis/hydrolysis of ATP by F0F1 and on proton conduction by F0 as function of the pH and the protonmotive force. The pK values of the proton-carrying group interacting with the acidic and basic sides of the membrane were estimated as 5.3-6.4 and 8.0-8.3, respectively.
authors.affiliation: Division of Biophysics, Faculty of Biology/Chemistry, University of Osnabrück, Germany.
authors.forename: D A
authors.initials: DA
authors.lastname: Cherepanov
authors.forename: A Y
authors.initials: AY
authors.lastname: Mulkidjanian
authors.forename: W
authors.initials: W
authors.lastname: Junge
mesh_terms: D004734:Energy Metabolism; D008954:Models, Biological; D006180:Proton-Translocating ATPases / Q000378:metabolism*
chemical_list: D006180:Proton-Translocating ATPases