The European Physical Journal E ( IF 1.8 ) Pub Date : 2022-03-23 , DOI: 10.1140/epje/s10189-022-00181-7 Ping Xie 1
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Abstract
During the processive stepping of a molecular motor on its polar track, a step consists of a long dwell period and a very short moving period. In single molecule optical trapping experiments to determine the load dependence of the motor dynamics, although the motor experiences a constant load during the dwell period, it experiences a varying load during the moving period. However, in previous theoretical studies to explain the single molecule optical trapping data, it was simply assumed that the motor experiences a constant load during both the dwell period and the following moving period. Thus, an important but unclear issue is whether the assumption is appropriate in the theoretical studies. Here, we take kinesin and myosin-V as examples to study theoretically the motor dynamics with the consideration of the varying load during the moving period and compare with that with the assumption of the constant load. The studies show that in the optical trapping experiments employed in the literature, for the kinesin with a small step size of about 8 nm it is a good approximation to make the theoretical studies by assuming that the motor experiences the constant load during the moving period. For the myosin-V with a large step size of about 36 nm, there are small but noticeable deviations of the results obtained by considering that the motor experiences the varying load during the moving period from those by assuming that the motor experiences the constant load.
Graphical abstract
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中文翻译：
阶跃运动期间不同载荷对分子马达动力学的影响
摘要
在分子马达在其极轨上的连续步进期间，一个步进包括一个长的停留时间和一个非常短的移动时间。在确定电机动力学负载依赖性的单分子光捕获实验中，尽管电机在停留期间承受恒定负载，但在移动期间承受变化负载。然而，在先前解释单分子光捕获数据的理论研究中，简单地假设电机在停留期间和随后的移动期间都经历恒定负载。因此，一个重要但不清楚的问题是该假设在理论研究中是否合适。这里，我们以kinesin和myosin-V为例，从理论上研究了考虑运动期间负载变化的电机动力学，并与假设负载恒定的情况进行了比较。研究表明，在文献中采用的光捕获实验中，对于步长约为 8 nm 的驱动蛋白，通过假设电机在运动期间承受恒定负载来进行理论研究是一个很好的近似值。对于具有大约 36 nm 的大步长的肌球蛋白-V，考虑到电机在移动期间承受变化的负载而获得的结果与假设电机承受恒定负载的结果存在微小但明显的偏差。研究表明，在文献中采用的光捕获实验中，对于步长约为 8 nm 的驱动蛋白，通过假设电机在运动期间承受恒定负载来进行理论研究是一个很好的近似值。对于具有大约 36 nm 的大步长的肌球蛋白-V，考虑到电机在移动期间承受变化的负载而获得的结果与假设电机承受恒定负载的结果存在微小但明显的偏差。研究表明，在文献中采用的光捕获实验中，对于步长约为 8 nm 的驱动蛋白，通过假设电机在运动期间承受恒定负载来进行理论研究是一个很好的近似值。对于具有大约 36 nm 的大步长的肌球蛋白-V，考虑到电机在移动期间承受变化的负载而获得的结果与假设电机承受恒定负载的结果存在微小但明显的偏差。
图形概要
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