Regensburg 2007 – scientific programme

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BP: Fachverband Biologische Physik

BP 22: Molecular Machines

BP 22.4: Talk

Thursday, March 29, 2007, 10:30–10:45, H43

Kinesin's network of chemomechanical motor cycles — •Steffen Liepelt and Reinhard Lipowsky — Max-Planck-Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam

Using the chemical energy released by the hydrolysis of ATP, the molecular motor kinesin moves processively along microtubules. A single motor step is caused by the coupling of conformational changes and filament-binding that is described by the chemomechanical cycle.

We will discuss a general network theory that is based on the distinct chemical states of the motor and on the recent observation that stepping occurs as a single event and is not built up by sub-steps. The necessity of a network theory including several motor cycles comes with the fact, that kinesin is able to walk backwards even at small concentrations of the ATP hydrolysis product ADP, which is inconsistent with the conventional picture of a single chemomechanical cycle.

In our theory, the motor's behavior is governed by the competition of two chemomechanical motor cycles which determine the motor's stall force. A third cycle becomes important for large ADP concentrations. The theory provides a quantitative description for the functional dependencies of different motor properties as observed in single molecule experiments.