Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
Eur Biophys J. 2019 Oct;48(7):609-619. doi: 10.1007/s00249-019-01386-z. Epub 2019 Jul 5.
Available single-molecule data have shown that some mammalian cytoplasmic dynein dimers move on microtubules with a constant step size of about 8.2 nm. Here, a model is presented for the chemomechanical coupling of these mammalian cytoplasmic dynein dimers. In contrast to the previous models, a peculiar feature of the current model is that the rate constants of ATPase activity are independent of the external force. Based on this model, analytical studies of the motor dynamics are presented. With only four adjustable parameters, the theoretical results reproduce quantitatively diverse available single-molecule data on the force dependence of stepping ratio, velocity, mean dwell time, and dwell-time distribution between two mechanical steps. Predicted results are also provided for the force dependence of the number of ATP molecules consumed per mechanical step, indicating that under no or low force the motors exhibit a tight chemomechanical coupling, and as the force increases the number of ATPs consumed per step increases greatly.
现有的单分子数据表明，一些哺乳动物细胞质动力蛋白二聚体在微管上以约 8.2nm 的恒定步长移动。本文提出了一种用于这些哺乳动物细胞质动力蛋白二聚体的化学机械偶联的模型。与之前的模型相比，当前模型的一个特殊特征是，ATP 酶活性的速率常数与外力无关。基于该模型，对马达动力学进行了分析研究。仅用四个可调参数，理论结果就定量再现了各种现有的单分子数据，这些数据涉及步长比、速度、平均停留时间以及两个力学步骤之间的停留时间分布对力的依赖性。还提供了预测结果，表明在无外力或低外力下，马达表现出紧密的化学机械偶联，而随着外力的增加，每一步消耗的 ATP 分子数量大大增加。
