Molecule of the Month
September 2007
The Structural Basis for Unidirectional Rotation
of Thermoalkaliphilic F1-ATPase

F1Fo-ATP synthase is a twin rotary engine that reversibly couples ion translocation across the membrane via mechanical rotation to the formation of ATP from ADP and inorganic phosphate. The bidirectional operation mode of the F1Fo-ATP synthase requires regulation to control the direction of rotation and its velocity. A unique feature of F1Fo-ATP synthases from alkaliphilic bacilli is a built-in latency of ATP hydrolysis activity. This inhibition of ATPase activity is most pronounced in the ATP synthase from the thermoalkaliphile Bacillus sp. TA2.A1 (TA2F1Fo) and is proposed to be a necessity for the survival of the organism at alkaline pH and high temperature.
In this communication we present the X-ray structure of TA2F1 at 3.1- resolution. The data show that the asymmetrical γ stalk of the rotor is distorted within the cavity of the α3β3 cylinder, thereby preventing rotation in the ATP hydrolysis direction. A similar distortion of the γ stalk is seen in electron micrographs of the native TA2F1Fo-ATP synthase complex indicating that this is not an artifact of the isolated TA2F1 subcomplex.

This work was carried out in the group of Prof. Achim Stocker.

References:

  • A. Stocker, S. Keis, J. Vonck, G. M. Cook, P. Dimroth;
    "The Structural Basis for Unidirectional Rotation of Thermoalkaliphilic F1-ATPase"
    Structure, 15, 904-914, (2007); doi:10.1016/j.str.2007.06.009.