Coordination of kinesin's two heads studied with mutant heterodimers
Coordination of kinesin's two heads studied with mutant heterodimers
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DOI：
10.1073/pnas.252409199
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发表时间：
2002-12-10
影响因子：
11.1
通讯作者：
Hirose, K
中科院分区：
文献类型：
--
作者：
Kaseda, K;Higuchi, H;Hirose, K
一个传统的驱动蛋白分子有两个相同的催化域（头部），并被认为是使用它们交替移动proc，8纳米的步骤。为了阐明每个头部如何有助于观察到的步骤，我们构建了由两个不同头部组成的异二聚体驱动蛋白。异源二聚体中的一个头部在微管结合环中发生突变，即使当亲本突变体同二聚体在微管滑动试验中结合得太弱而不能保留微管时，异源二聚体也会向前移动。异源二聚体的速度仅略高于突变体的同源二聚体，虽然这些弱结合突变体同源二聚体和WT二聚体的混合物移动微管的速度类似于WT。因此，突变头部仅在它们在同一分子中时才影响WT头部的运动性。在光捕获纳米测量中产生的单个异源二聚体的最大力介于WT和突变体同二聚体之间，这表明两个头部同时对最大力有贡献。这些结果表明驱动蛋白的两个头部在产生力和运动性方面密切合作。
A conventional kinesin molecule has two identical catalytic domains (heads) and is thought to use them alternately to move processively, with 8-nm steps. To clarify how each head contributes to the observed steps, we have constructed heterodimeric kinesins that consist of two distinct heads. The heterodimers in which one of the heads is mutated in a microtubule-bincling loop moved processively, even when the parent mutant homodimers bound too weakly to retain microtubules in microtubule-gliding assays. The velocities of the heterodimers were only slightly higher than those of the mutant homodimers, although mixtures of these weak-binding mutant homodimers and the WT dimers moved microtubules at a velocity similar to the WT. Thus, the mutant head affects the motility of the WT head only when they are in the same molecule. The maximum force a single heterodimer produced in optical trapping nanometry was intermediate between the WT and mutant homodimers, indicating that both heads contribute to the maximum force at the same time. These results demonstrate close collaboration of kinesin's two heads in producing force and motility.