Dynamics of single-motor molecules: the thermal ratchet model.
We present a model for single-motor molecules--myosin, dynein, or kinesin--that is powered either by thermal fluctuations or by conformational change. In the thermally driven model, the cross-bridge fluctuates about its equilibrium position against an elastic restoring force. The attachment and detachment of the cross-bridge are determined by modeling the electrostatic attraction between the cross-bridge and the fiber binding sites, so that binding depends on the strain in the cross-bridge and its velocity with respect to the fiber. The model correctly predicts the empirical force-velocity characteristics for populations of motor molecules. For a single motor, the apparent cross-bridge step size per ATP hydrolysis depends nonlinearly on the load. When the elastic energy driving the cross-bridge is generated by a conformational change, the velocity and duty cycle are much larger than is observed experimentally for myosin.
Córdova
N J
NJ
Department of Applied Mathematics and Computer Science, Weizmann Institute of Science, Rehovot, Israel.
Ermentrout
B
B
Oster
G F
GF
D000205:Actomyosin / Q000502:physiology; D000255:Adenosine Triphosphate / Q000378:metabolism; D004398:Dyneins / Q000502:physiology*; D016547:Kinesins / Q000502:physiology*; D046911:Macromolecular Substances; D008962:Models, Theoretical; D009068:Movement; D009218:Myosins / Q000502:physiology*; D011485:Protein Binding; D011487:Protein Conformation; D013696:Temperature; D013816:Thermodynamics; D014404:Tubulin / Q000502:physiology
D046911:Macromolecular Substances; D014404:Tubulin; D000255:Adenosine Triphosphate; D000205:Actomyosin; D009218:Myosins; D004398:Dyneins; D016547:Kinesins