Flexibility within the Rotor and Stators of the Vacuolar H+-ATPase |
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| Authors: | Chun Feng Song Kostas Papachristos Shaun Rawson Markus Huss Helmut Wieczorek Emanuele Paci John Trinick Michael A. Harrison Stephen P. Muench |
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| Affiliation: | 1. Electron Microscopy Center, Hebei Medical University, Shijiazhuang, China.; 2. School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom.; 3. School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom.; 4. Abteilung Tierphysiologie, Fachbereich Biologie/Chemie, Universität Osnabrück, Osnabrück, Germany.; University of Edinburgh, United Kingdom, |
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| Abstract: | The V-ATPase is a membrane-bound protein complex which pumps protons across the membrane to generate a large proton motive force through the coupling of an ATP-driven 3-stroke rotary motor (V1) to a multistroke proton pump (Vo). This is done with near 100% efficiency, which is achieved in part by flexibility within the central rotor axle and stator connections, allowing the system to flex to minimise the free energy loss of conformational changes during catalysis. We have used electron microscopy to reveal distinctive bending along the V-ATPase complex, leading to angular displacement of the V1 domain relative to the Vo domain to a maximum of ~30°. This has been complemented by elastic network normal mode analysis that shows both flexing and twisting with the compliance being located in the rotor axle, stator filaments, or both. This study provides direct evidence of flexibility within the V-ATPase and by implication in related rotary ATPases, a feature predicted to be important for regulation and their high energetic efficiencies. |
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