On chemomechanical coupling of the F(1)-ATPase molecular motor.
F(1)-ATPase catalyzes ATP hydrolysis to drive the central gamma-shaft rotating inside a hexameric cylinder composed of alternating alpha and beta subunits. Experiments showed that the rotation of gamma-shaft proceeds in steps of 120 degrees and each 120 degrees -rotation is composed of an 80 degrees substep and a 40 degrees substep. Here, based on the previously proposed models, an improved physical model for chemomechanical coupling of F(1)-ATPase is presented, with which the two-substep rotation is well explained. One substep is driven by the power stroke upon ATP binding, while the other one resulted from the passage of gamma-shaft from previous to next adjacent beta subunits via free diffusion. Using the model, the dynamics and kinetics of F(1)-ATPase, such as the rotating time of each substep, the dwell time at each pause and the rotation rate, are analytically studied. The theoretical results obtained with only three adjustable parameters reproduce the available experimental data well.
Xie
Ping
P
Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China. pxie@aphy.iphy.ac.cn
D002384:Catalysis; D019281:Dimerization; D007700:Kinetics; D008956:Models, Chemical; D020409:Molecular Motor Proteins / Q000378:metabolism*; D011485:Protein Binding; D021122:Protein Subunits / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000737:chemistry / Q000378:metabolism*; D012399:Rotation; D013997:Time Factors
D020409:Molecular Motor Proteins; D021122:Protein Subunits; D006180:Proton-Translocating ATPases