Stepping and stretching - How kinesin uses internal strain to walk processively
Stepping and stretching - How kinesin uses internal strain to walk processively
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DOI：
10.1074/jbc.m300849200
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发表时间：
2003-05-16
影响因子：
4.8
通讯作者：
Block, SM
中科院分区：
文献类型：
--
作者：
Rosenfeld, SS;Fordyce, PM;Block, SM
驱动蛋白在微管轨道上长距离移动而不解离的能力导致了各种模型来解释这种显着程度的持续合成能力是如何维持的。所有这些都要求两个马达结构域保持酶促“异相”，这一行为将确保在任何给定时间，一个马达牢固地附着在微管上。这种协调在许多机械化学循环中的维持从未得到解释，因为循环中的关键步骤无法直接观察到。我们已经解决了这个问题，通过应用几种新的光谱方法来监测电机解离，磷酸盐释放，并在进行性运动过程中的二聚驱动蛋白构建核苷酸结合。我们的数据表明，当驱动蛋白的两个马达结构域结合微管时产生的内部应变的主要作用是阻止ATP与主导马达结合。这种效应保证了两个运动域在许多机械化学循环中保持异相，并为维持进行性运动提供了有效和适应性强的机制。
The ability of kinesin to travel long distances on its microtubule track without dissociating has led to a variety of models to explain how this remarkable degree of processivity is maintained. All of these require that the two motor domains remain enzymatically "out of phase," a behavior that would ensure that, at any given time, one motor is strongly attached to the microtubule. The maintenance of this coordination over many mechanochemical cycles has never been explained, because key steps in the cycle could not be directly observed. We have addressed this issue by applying several novel spectroscopic approaches to monitor motor dissociation, phosphate release, and nucleotide binding during processive movement by a dimeric kinesin construct. Our data argue that the major effect of the internal strain generated when both motor domains of kinesin bind the microtubule is to block ATP from binding to the leading motor. This effect guarantees the two motor domains remain out of phase for many mechanochemical cycles and provides an efficient and adaptable mechanism for the maintenance of processive movement.