Chloroplast ATP Synthase

6FKF

Hahn et al., 2018 (PDB 6FKF) — complete spinach chloroplast F₁Fₒ ATP synthase.

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Reaction cycle

1Fₒ · Lumen protons cross the membrane and spin the c-ring rotor
2F₁ · The turning γ-stalk drives the α₃β₃ head — 3 ATP per revolution

Moving parts

Rotor — c-ring + γ/ε central stalk
Stator — α₃β₃ head, a/b subunits, peripheral stalkanchored

How it works

The whole rotary engine of photosynthesis. Protons built up in the thylakoid lumen flow through the membrane Fₒ motor, spinning a rotor — the 14-subunit c-ring plus the central γ/ε stalk (shown in colour). The stator (the α₃β₃ catalytic head, the a- and b-subunits and the peripheral stalk, shown in grey) is held still, so the turning γ-stalk inside the head forces each β-subunit through its cycle: one full revolution makes three ATP. Here the entire complex is shown with its rotor turning continuously inside the stator.