Structure of intact Thermus thermophilus V-ATPase by cryo-EM reveals organization of the membrane-bound VO motor

The eubacterium Thermus thermophilus uses a macromolecular assembly closely related to eukaryotic V-ATPase to produce its supply of ATP. This simplified V-ATPase offers several advantages over eukaryotic V-ATPases for structural analysis and investigation of the mechanism of the enzyme. Here we report the structure of the complex at similar to 16 angstrom resolution as determined by single particle electron cryomicroscopy (cryo-EM). The resolution of the map and our use of cryo-EM, rather than negative stain EM, reveals detailed information about the internal organization of the assembly. We could separate the map into segments corresponding to subunits A and B, the threefold pseudosymmetric C-subunit, a central rotor consisting of subunits D and F, the L-ring, the stator subcomplex consisting of subunits I, E, and G, and a micelle of bound detergent. The architecture of the V-O region shows a remarkably small area of contact between the I-subunit and the ring of L-subunits and is consistent with a two half-channel model for proton translocation. The arrangement of structural elements in V-O gives insight into the mechanism of torque generation from proton translocation.