Structural model of F 1 –ATPase and the implications for rotary catalysis

The crystal structure of bovine mitochondrial F 1 –ATPase is described. Several features of the structure are consistent with the binding change mechanism of catalysis, in which binding of substrates induces conformational changes that result in a high degree of cooperativity between the three catalytic sites. Furthermore, the structure also suggests that catalysis is accompanied by a physical rotation of the centrally placed γ–subunit relative to the approximately spherical α 3 β 3 sub–assembly.

How F o –ATPase generates rotary torque

The F–ATPases synthesize ATP using a transmembrane ionmotive force (IMF) established by the electron transport chain. This transduction involves first converting the IMF to a rotary torque in the transmembrane F o portion. This torque is communicated from F o to the F 1 portion where the energy is used to release the newly synthesized ATP from the catalytic sites according to Boyer's binding change mechanism. Here we explain the principle by which an IMF generates this rotary torque in the F o ion engine.