Mechanical inhibition of isolated V(o) from V/A-ATPase for proton conductance

V-ATPase is an energy converting enzyme, coupling ATP hydrolysis/synthesis in the hydrophilic V(1) domain, with proton flow through the V(o) membrane domain, via rotation of the central rotor complex relative to the surrounding stator apparatus. Upon dissociation from the V(1) domain, the V(o) domain of the eukaryotic V-ATPase can adopt a physiologically relevant auto-inhibited form in which proton conductance through the V(o) 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 holo V/A-ATPase and isolated V(o) at near-atomic resolution, respectively. These structures clarify how the isolated V(o) domain adopts the auto-inhibited form and how the holo complex prevents formation of the inhibited V(o) form.