Crystal structure of yeast V‐ATPase subunit C reveals its stator function

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Abstract
Vacuolar H+‐ATPase (V‐ATPase) has a crucial role in the vacuolar system of eukaryotic cells. It provides most of the energy required for transport systems that utilize the proton‐motive force that is generated by ATP hydrolysis. Some, but not all, of the V‐ATPase subunits are homologous to those of F‐ATPase and the nonhomologous subunits determine the unique features of V‐ATPase. We determined the crystal structure of V‐ATPase subunit C (Vma5p), which does not show any homology with F‐ATPase subunits, at 1.75 Å resolution. The structural features suggest that subunit C functions as a flexible stator that holds together the catalytic and membrane sectors of the enzyme. A second crystal form that was solved at 2.9 Å resolution supports the flexible nature of subunit C. These structures provide a framework for exploring the unique mechanistic features of V‐ATPases.