Myosin-V is a mechanical ratchet
Myosin-V is a mechanical ratchet
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DOI：
10.1073/pnas.0510191103
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发表时间：
2006-06-06
影响因子：
11.1
通讯作者：
Rief, Matthias
中科院分区：
文献类型：
--
作者：
Gebhardt, J. Christof M.;Clemen, Anabel E. -M.;Rief, Matthias
肌球蛋白-V是一个线性分子马达，水解ATIP向肌动蛋白丝的正端移动。最近在各种单分子测定中研究了这种马达在低力下的运动。在本文中，我们表明，肌球蛋白V的反应，高的力量作为一个机械棘轮。高的反向载荷可以诱导沿着肌动蛋白丝的快速和进行性的反向步骤。这种运动完全独立于ATP结合和水解。相反，前向力不能诱导ATP独立的前向步骤。我们可以解释这种明显的机械不对称性的模型中，肌动蛋白结合的电机头的强度调制的杠杆臂构象。了解分子马达的完整力-速度依赖性对于理解它们在细胞环境中的功能是很重要的。
Myosin-V is a linear molecular motor that hydrolyzes ATIP to move processively toward the plus end of actin filaments. Motion of this motor under low forces has been studied recently in various single-molecule assays. In this paper we show that myosin-V reacts to high forces as a mechanical ratchet. High backward loads can induce rapid and processive backward steps along the actin filament. This motion is completely independent of ATP binding and hydrolysis. In contrast, forward forces cannot induce ATP-independent forward steps. We can explain this pronounced mechanical asymmetry by a model in which the strength of actin binding of a motor head is modulated by the lever arm conformation. Knowledge of the complete force-velocity dependence of molecular motors is important to understand their function in the cellular environment.