A change in the radius of rotation of F1-ATPase indicates a tilting motion of the central shaft.

ABSTRACT: F(1)-ATPase is a water-soluble portion of F(o)F(1)-ATP synthase and rotary molecular motor that exhibits reversibility in chemical reactions. The rotational motion of the shaft subunit ? has been carefully scrutinized in previous studies, but a tilting motion of the shaft has never been explicitly postulated. Here we found a change in the radius of rotation of the probe attached to the shaft subunit ? between two different intermediate states in ATP hydrolysis: one waiting for ATP binding, and the other waiting for ATP hydrolysis and/or subsequent product release. Analysis of this radial difference indicates a ~4° outward tilting of the ?-subunit induced by ATP binding. The tilt angle is a new parameter, to our knowledge, representing the motion of the ?-subunit and provides a new constraint condition of the ATP-waiting conformation of F(1)-ATPase, which has not been determined as an atomic structure from x-ray crystallography.

SUBMITTER: Sugawa M 

PROVIDER: S-EPMC3207153 | biostudies-literature | 2011 Nov

REPOSITORIES: biostudies-literature