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Structure of the Vacuolar H + -ATPase Rotary Motor Reveals New Mechanistic Insights

2015; Elsevier BV; Volume: 23; Issue: 3 Linguagem: Inglês

10.1016/j.str.2014.12.016

1878-4186

Shaun Rawson, Clair Phillips, Markus Huss, Felix Tiburcy, Helmut Wieczorek, John Trinick, Michael A. Harrison, Stephen P. Muench,

Photosynthetic Processes and Mechanisms

Vacuolar H(+)-ATPases are multisubunit complexes that operate with rotary mechanics and are essential for membrane proton transport throughout eukaryotes. Here we report a ∼ 1 nm resolution reconstruction of a V-ATPase in a different conformational state from that previously reported for a lower-resolution yeast model. The stator network of the V-ATPase (and by implication that of other rotary ATPases) does not change conformation in different catalytic states, and hence must be relatively rigid. We also demonstrate that a conserved bearing in the catalytic domain is electrostatic, contributing to the extraordinarily high efficiency of rotary ATPases. Analysis of the rotor axle/membrane pump interface suggests how rotary ATPases accommodate different c ring stoichiometries while maintaining high efficiency. The model provides evidence for a half channel in the proton pump, supporting theoretical models of ion translocation. Our refined model therefore provides new insights into the structure and mechanics of the V-ATPases.