Kinesin moves by an asymmetric hand-over-hand mechanism
Kinesin moves by an asymmetric hand-over-hand mechanism
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DOI：
10.1126/science.1092985
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发表时间：
2003-12-19
期刊：
影响因子：
56.9
通讯作者：
Block, SM
中科院分区：
文献类型：
--
作者：
Asbury, CL;Fehr, AN;Block, SM
驱动蛋白是一种双头运动蛋白，它以8纳米的步长沿沿着运动。两大类模型已被调用来解释驱动蛋白运动：手在手和尺蠖。在双手交替模型中，每走一步，头部都会交换领导和尾随的角色，而在尺蠖模型中，没有这样的交换，其中一个头部总是领导。通过测量单个酶的步进运动，我们发现一些驱动蛋白分子在连续步骤之间的停留时间中表现出明显的交替，导致这些马达沿着微管“跛行”。跛行意味着驱动蛋白分子在两种不同的构象之间严格交替，因为它们的步骤，指示一个不对称的，手在手的机制。
Kinesin is a double-headed motor protein that moves along microtubules in 8-nanometer steps. Two broad classes of model have been invoked to explain kinesin movement: hand-over-hand and inchworm. In hand-over-hand models, the heads exchange leading and trailing roles with every step, whereas no such exchange is postulated for inchworm models, where one head always leads. By measuring the stepwise motion of individual enzymes, we find that some kinesin molecules exhibit a marked alternation in the dwell times between sequential steps, causing these motors to "limp" along the microtubule. Limping implies that kinesin molecules strictly alternate between two different conformations as they step, indicative of an asymmetric, hand-over-hand mechanism.