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

Recent research indicates that ATP synthases (F0F1) contain two distinct na nomotors, one an electrochemically driven proton motor contained within F-0 that drives an ATP hydrolysis-driven motor (F-1) in reverse during ATP syn thesis. This is depicted in recent models as involving a series of events i n which each of the three alpha beta pairs comprising F-1 is induced via a centrally rotating subunit (gamma) to undergo the sequential binding change s necessary to synthesize ATP (binding change mechanism). Stabilization of this rotary process (i.e., to minimize "wobble" of F-1) is provided in curr ent models by a peripheral stalk or "stator" that has recently been shown t o extend from near the bottom of the ATP synthase molecule to the very top of F-1. Although quite elegant, these models envision the stator as fixed d uring ATP synthesis, i.e., bound to only a single alpha beta pair. This is despite the fact that the binding change mechanism views each alpha beta pa ir as going through the same sequential order of conformational changes whi ch demonstrate a chemical equivalency among them. For this reason, we propo se here two different dynamic models for stator function during ATP synthes is. Both models have been designed to maintain chemical equivalency among t he three alpha beta pairs during ATP synthesis and both have been animated. (C) 2001 Academic Press.