Molecular switch of F0F1-ATP synthase, G-protein, and other ATP-driven enzymes

Abstract
Exchange-out of amide tritium from labeled γ-subunit of α3β3γ complex of F0F1-ATP synthase was not accelerated by ATP, suggesting that hemagglutinin-type transition of coiled-coil structure did not occur in γ-subunit. Local topology of nucleotide binding site and “switch II” region of G-protein α resemble those of F1-β subunit and other proteins which catalyze ATP-triggered reactions. Probably, binding of nucleotide to F0F1-ATP synthase induces conformational change of the switch II-like region with transforming β subunit structure from “open” to “closed” form and this transformation results in loss of hydrogen bonds with the γ subunit, thus enabling the γ subunit to move.