Stochastic rotational catalysis of proton pumping F-ATPase

摘要

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 F-1 and proton channel F-0 formed from the alpha(3)beta(3)gamma delta epsilon and ab(2)c(10) subunit complexes, respectively. The rotation of gamma epsilon c(10) couples catalyses and proton transport. Consistent with the threefold symmetry of the alpha(3)beta(3) catalytic hexamer, 1208 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 beta subunit (phosphate-binding P-loop/alpha-helix B/loop/beta-sheet4). Recent results regarding mechanically driven ATP synthesis finally proved the role of rotation in energy coupling.