Mechanical Rotation of the c Subunit Oligomer in ATP Synthase (F 0 F 1 ): Direct Observation

Abstract

F 0 F 1 , found in mitochondria or bacterial membranes, synthesizes adenosine 5′-triphosphate (ATP) coupling with an electrochemical proton gradient and also reversibly hydrolyzes ATP to form the gradient. An actin filament connected to a c subunit oligomer of F 0 was able to rotate by using the energy of ATP hydrolysis. The rotary torque produced by the c subunit oligomer reached about 40 piconewton-nanometers, which is similar to that generated by the γ subunit in the F 1 motor. These results suggest that the γ and c subunits rotate together during ATP hydrolysis and synthesis. Thus, coupled rotation may be essential for energy coupling between proton transport through F 0 and ATP hydrolysis or synthesis in F 1 .