Mechanical inhibition of isolated V from V/A-ATPase for proton conductance.

V-ATPase is an energy converting enzyme, coupling ATP hydrolysis/synthesis in the hydrophilic V domain, with proton flow through the V membrane domain, via rotation of the central rotor complex relative to the surrounding stator apparatus. Upon dissociation from the V domain, the V domain of the eukaryotic V-ATPase can adopt a physiologically relevant auto-inhibited form in which proton conductance through the V domain is prevented, however the molecular mechanism of this inhibition is not fully understood. Using cryo-electron microscopy, we determined the structure of both the V/A-ATPase and isolated V at near-atomic resolution, respectively. These structures clarify how the isolated V domain adopts the auto-inhibited form and how the complex prevents formation of the inhibited V form.