Structure, mechanism, and regulation of the chloroplast ATP synthase.

Abstract

The chloroplast adenosine triphosphate (ATP) synthase uses the electrochemical proton gradient generated by photosynthesis to produce ATP, the energy currency of all cells. Protons conducted through the membrane-embedded F_o motor drive ATP synthesis in the F₁ head by rotary catalysis. We determined the high-resolution structure of the complete cF₁F_o complex by cryo-electron microscopy, resolving side chains of all 26 protein subunits, the five nucleotides in the F₁ head, and the proton pathway to and from the rotor ring. The flexible peripheral stalk redistributes differences in torsional energy across three unequal steps in the rotation cycle. Plant ATP synthase is autoinhibited by a β-hairpin redox switch in subunit γ that blocks rotation in the dark.