从单个单体的分子性质模拟驱动蛋白二聚体的运动性
Modeling Motility of the Kinesin Dimer from Molecular Properties of Individual Monomers
摘要：
传统的驱动蛋白是一种同源二聚体的马达蛋白，通过水解ATP分子沿丝状微管（MT）单向运输细胞器。这项研究表明，ATP周转率和头部扩散的负荷调制都是必不可少的，在确定负载下的二聚体的性能。据发现，连续运行长度的二聚体严重依赖于几个途径，导致个别头部从MT的脱离。修改这些脱离途径的速率改变了运行长度，但不是二聚体的速度，与突变体实验一致。行程长度可以随或不随ATP浓度而增加，这取决于纯机械分离的单一速率。这一发现提供了一个解释，以前的争论有关ATP的运行长度的依赖性，本研究的相关定量预测可以通过未来的实验进行测试。本研究亦发现，辅助负载的实验观测结果可以用负载偏置头部扩散来定量解释。因此，我们得出结论，二聚体运动下抵抗以及辅助负荷是由基本上相同的机制。
英文摘要：
Conventional kinesin is a homodimeric motor protein that unidirectionally transports organelles along filamentous microtubule (MT) by hydrolyzing ATP molecules. This study shows that the load modulations of ATP turnover and head diffusion are both essential in determining the performance of the dimer under loads. It is found that the consecutive run length of the dimer critically depends upon a few pathways, leading to the detachment of individual heads from MT. Modifying rates for these detachment pathways changes the run length but not the velocity of the dimer, consistent with mutant experiments. The run length may increase with or without the ATP concentration, depending upon a single rate for pure mechanical detachment. This finding provides an explanation to a previous controversy concerning ATP dependence of the run length, and related quantitative predictions of this study can be tested by a future experiment. This study also finds that the experimental observations for assisting loads can be quantitatively explained by load-biased head diffusion. We thus conclude that the dimer motility under resisting as well as assisting loads is governed by essentially the same mechanisms.
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