Atomic model for the dimeric F_O region of mitochondrial ATP synthase

Mitochondrial adenosine triphosphate (ATP) synthase produces the majority of ATP in eukaryotic cells, and its dimerization is necessary to create the inner membrane folds, or cristae, characteristic of mitochondria. Proton translocation through the membrane-embedded F_O region turns the rotor that drives ATP synthesis in the soluble F₁ region. Although crystal structures of the F₁ region have illustrated how this rotation leads to ATP synthesis, understanding how proton translocation produces the rotation has been impeded by the lack of an experimental atomic model for the F_O region. Using cryo-electron microscopy, we determined the structure of the dimeric F_O complex from Saccharomyces cerevisiae at a resolution of 3.6 angstroms. The structure clarifies how the protons travel through the complex, how the complex dimerizes, and how the dimers bend the membrane to produce cristae.