Kinesin Crouches to Sprint but Resists Pushing

Recent optical trap experiments have applied resisting, assisting, and sideways loads to conventional kinesin moving on microtubules at fixed [ATP]. To gain insight into intermediate motions when the motor protein takes its 8.2-nm steps, the velocity and randomness data have been analyzed by using d...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2005-11, Vol.102 (45), p.16209-16214
Main Authors: Fisher, Michael E., Kim, Young C.
Format: Article
Language:English
Subjects:
Adenosine Triphosphate - metabolism
Asymmetry
Biochemistry
Biological Sciences
Biophysical Phenomena
Biophysics
Data lines
Kinesin - chemistry
Kinetics
Microtubules
Motors
Optics
Parametric models
Proteins
Randomness
Stochastic models
Velocity
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Summary:Recent optical trap experiments have applied resisting, assisting, and sideways loads to conventional kinesin moving on microtubules at fixed [ATP]. To gain insight into intermediate motions when the motor protein takes its 8.2-nm steps, the velocity and randomness data have been analyzed by using discrete-state stochastic models with a three-dimensional "energy landscape." The bead size and tether angle play a crucial role. The analysis implies that on binding ATP the motor "crouches," the point of attachment of the tether at the necklinker junction moving downward toward the microtubule by 0.5-0.7 nm, while inching forward by only 0.1-0.2 nm, before completing the step from a transition state by a unitary "sprint" of ~7.8 nm. These inferences accord with high-resolution observations that exclude a previously predicted substep of 1.8-2.1 nm. Assisting and leftward loads are opposed in that the perpendicular component of the tension in the tether is enhanced by ~2 pN, which reduces the velocity, but sideways lurching is not supported.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0507802102