ATP synthase motor components: Proposal and animation of two dynamic models for stator function

Recent research indicates that ATP synthases (F₀F₁) contain two distinct nanomotors, one an electrochemically driven proton motor contained within F₀ that drives an ATP hydrolysis-driven motor (F₁) in reverse during ATP synthesis. This is depicted in recent models as involving a series of events in which each of the three αβ pairs comprising F₁ is induced via a centrally rotating subunit (γ) to undergo the sequential binding changes necessary to synthesize ATP (binding change mechanism). Stabilization of this rotary process (i.e., to minimize "wobble" of F₁) is provided in current models by a peripheral stalk or "stator" that has recently been shown to extend from near the bottom of the ATP synthase molecule to the very top of F₁. Although quite elegant, these models envision the stator as fixed during ATP synthesis, i.e., bound to only a single αβ pair. This is despite the fact that the binding change mechanism views each αβ pair as going through the same sequential order of conformational changes which demonstrate a chemical equivalency among them. For this reason, we propose here two different dynamic models for stator function during ATP synthesis. Both models have been designed to maintain chemical equivalency among the three αβ pairs during ATP synthesis and both have been animated.