Stochastic rotational catalysis of proton pumping F-ATPase

Abstract

F-ATPases synthesize ATP from ADP and phosphate coupled with an electrochemical proton gradient in bacterial or mitochondrial membranes and can hydrolyse ATP to form the gradient. F-ATPases consist of a catalytic F1and proton channel F0formed from the α3β3γδϵ andab2c10subunit complexes, respectively. The rotation of γϵc10couples catalyses and proton transport. Consistent with the threefold symmetry of the α3β3catalytic hexamer, 120° stepped revolution has been observed, each step being divided into two substeps. The ATP-dependent revolution exhibited stochastic fluctuation and was driven by conformation transmission of the β subunit (phosphate-binding P-loop/α-helix B/loop/β-sheet4). Recent results regarding mechanically driven ATP synthesis finally proved the role of rotation in energy coupling.