Journal article
Directional loading of the kinesin motor molecule as it buckles a microtubule
Biophysical journal, Vol.70(1), pp.418-429
01/1996
Handle:
https://hdl.handle.net/2376/107570
PMCID: PMC1224940
PMID: 8770218
Abstract
Single kinesin motor molecules were observed to buckle the microtubules along which they moved in a modified in vitro gliding assay. In this assay a central portion of the microtubule was clamped to the glass substrate via biotin-streptavidin bonds, while the plus end of the microtubule was free to interact with motors adsorbed at low density to the substrate. A statistical analysis of the length of microtubules buckled by single motors showed a decreasing probability of buckling for loads greater than 4-6 pN parallel to the filament. This is consistent with kinesin stalling forces found in other experiments. A detailed analysis of some buckling events allowed us to estimate both the magnitude and direction of the loading force as it developed a perpendicular component tending to pull the motor away from the microtubule. We also estimated the motor speed as a function of this changing vector force. The kinesin motors consistently reached unexpectedly high speeds as the force became nonparallel to the direction of motor movement. Our results suggest that a perpendicular component of load does not hinder the kinesin motor, but on the contrary causes the motor to move faster against a given parallel load. Because the perpendicular force component speeds up the motor but does no net work, perpendicular force acts as a mechanical catalyst for the reaction. A simple explanation is that there is a spatial motion of the kinesin molecule during its cycle that is rate-limiting under load; mechanical catalysis results if this motion is oriented away from the surface of the microtubule.
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Details
- Title
- Directional loading of the kinesin motor molecule as it buckles a microtubule
- Creators
- F Gittes - Department of Physiology and Biophysics, University of Washington, Seattle 98195-7290, USAE Meyhöfer - Department of Physiology and Biophysics, University of Washington, Seattle 98195-7290, USAS Baek - Department of Physiology and Biophysics, University of Washington, Seattle 98195-7290, USAJ Howard - Department of Physiology and Biophysics, University of Washington, Seattle 98195-7290, USA
- Publication Details
- Biophysical journal, Vol.70(1), pp.418-429
- Academic Unit
- Physics and Astronomy, Department of
- Identifiers
- 99900547247001842
- Language
- English
- Resource Type
- Journal article