Diffusion Biased by a Soft Neck Linker Regulates Kinesin Stepping.

Huijuan Xu, Ruizheng Hou, Tong Tong, Hongrong Li

The journal of physical chemistry. B 2021 Mar 18

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Conventional kinesin is a high-performance motor that moves primarily toward the plus end of microtubules and occasionally toward the opposite direction. The physical mechanism of this directional stepping remains unclear. Here we develop a kinetic two-cycle model incorporating kinesin forward and backward stepping, in which the neck linker zippering and ATP catalysis process are conserved in backward steps. This model is quantitatively validated by a variety of experimental data, including load dependence of velocity, stepping ratio, and dwell time. The physical mechanism of kinesin stepping regulated by a biased diffusion process is identified by analyzing the load dependence and relevant thermodynamic properties of the model. Furthermore, the model suggests the kinesin directionality is optimized resulting from fulfilling a thermodynamic constraint. Our modeling provides a chemomechanical coupling mechanism that connects the flexibility of the neck linker zippering effect for direction rectification and the measured performance into a consistent frame.

Citation

Huijuan Xu, Ruizheng Hou, Tong Tong, Hongrong Li. Diffusion Biased by a Soft Neck Linker Regulates Kinesin Stepping. The journal of physical chemistry. B. 2021 Mar 18;125(10):2627-2635