Acceleration of the ATP-binding rate of F1-ATPase by forcible forward rotation

F-1-ATPase (F-1) is a reversible ATP-driven rotary motor protein. When its rotary shaft is reversely rotated, F-1 produces ATP against the chemical potential of ATP hydrolysis, suggesting that F-1 modulates the rate constants and equilibriums of catalytic reaction steps depending on the rotary angle of the shaft. Although the chemomechanical coupling scheme of F-1 has been determined, it is unclear how individual catalytic reaction steps depend on its rotary angle. Here, we report direct evidence that the ATP-binding rate of F-1 increases upon the forward rotation of the rotor, and its binding affinity to ATP is enhanced by rotation. (C) 2009 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.