Entropy rectifies the Brownian steps of kinesin
Entropy rectifies the Brownian steps of kinesin
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DOI：
10.1038/nchembio741
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发表时间：
2005-11-01
影响因子：
14.8
通讯作者：
Yanagida, T
中科院分区：
文献类型：
--
作者：
Taniguchi, Y;Nishiyama, M;Yanagida, T
驱动蛋白是一种步进马达，沿着微管连续地产生向前和向后的8 nm的步长。在生理条件下，驱动蛋白的动力步骤偏向一个方向，并驱动各种生物运动过程。驱动蛋白步骤的单向偏置的物理机制尚未完全理解。在这里，我们探讨了机械动力学和热力学的向前和向后驱动步骤，通过分析它们的温度和负载的依赖性。结果表明，前向步和后向步之间的频率不对称性是由熵引起的。此外，熵不对称的大小为6 k（B）T，比从当前模型预期的大三倍多，其中驱动蛋白分子结构内的机械构象变化直接使驱动蛋白向前移动。我们建议，驱动蛋白的步进方向优选地是由熵不对称性导致的驱动蛋白和微管之间的相互作用基于它们的极性结构的兼容性。
Kinesin is a stepping motor that successively produces forward and backward 8-nm steps along microtubules. Under physiological conditions, the steps powering kinesin's motility are biased in one direction and drive various biological motile processes. The physical mechanism underlying the unidirectional bias of the kinesin steps is not fully understood. Here we explored the mechanical kinetics and thermodynamics of forward and backward kinesin steps by analyzing their temperature and load dependence. Results show that the frequency asymmetry between forward and backward steps is produced by entropy. Furthermore, the magnitude of the entropic asymmetry is 6 k(B)T, more than three times greater than expected from a current model, in which a mechanical conformational change within the kinesin molecular structure directly biases the kinesin steps forward. We propose that the stepping direction of kinesin is preferably caused by an entropy asymmetry resulting from the compatibility between the kinesin and microtubule interaction based on their polar structures.