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A torque component in the kinesin-1 power stroke.
Junichiro Yajima1, Robert A Cross
1Molecular Motors Group, Marie Curie Research Institute, The Chart, Oxted, Surrey RH8 0TL, UK.
Nature Chemical Biology
|January 13, 2006
Summary
Kinesin-1 monomers generate rotational motion in microtubules, suggesting a novel force-generating mechanism. This molecular motor
Area of Science:
- Molecular biology
- Biophysics
- Cellular mechanics
Background:
- Kinesin-1 is a molecular motor that moves along microtubules.
- Its walking action involves alternating head interactions.
- Previous studies suggested directional force generation via binding site selection or conformational changes.
Purpose of the Study:
- To investigate the force-generating mechanism of kinesin-1 monomers.
- To understand the relationship between axial and torsional motion in kinesin-1 activity.
Main Methods:
- Utilizing surface-attached rat kinesin-1 monomers.
- Observing the rotation of sliding microtubules around their axes.
- Manipulating assay geometry to isolate motion components.
Main Results:
- Kinesin-1 monomers induced counterclockwise rotation of microtubules.
- Torsional motion could be reduced or blocked by altering assay geometry.
- Axial motion remained largely unaffected by these geometric changes.
Conclusions:
- Kinesin-1's force generation involves a mechanism beyond simple amplification.
- A biasing process shifting diffusion-to-capture by ~1 nm towards the microtubule plus end is proposed.
- This model accounts for both axial and torsional motion observed in kinesin-1 activity.