The path to visualization of walking myosin V by high-speed atomic force microscopy.
The path to visualization of walking myosin V by high-speed atomic force microscopy.
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DOI：
10.1007/s12551-014-0141-7
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发表时间：
2014
影响因子：
--
通讯作者：
Ando T
中科院分区：
文献类型：
--
作者：
Kodera N;Ando T
对肌球蛋白运动机制的探索始于对肌肉收缩的研究。通过大量的研究，人们构建了这一机制的基本框架，并提出了精彩的假说。然而，关于肌动蛋白-肌球蛋白相互作用如何产生收缩力和缩短的最关键问题的争论尚未确定。为了增加“测量的直接性”，创建并使用了体外运动测定和单分子光学技术。因此，详细了解肌肉肌球蛋白的能动性的演变，这导致了挑起更多的争论，以更高的水平。随着技术的进步，细胞生物学的进步导致了许多类别的肌球蛋白的发现。与肌球蛋白II不同，肌球蛋白V被发现是一种进行性运动。持续合成能力降低了实验难度，因为它允许连续追踪单个肌球蛋白V分子的运动行为。对肌球蛋白V的广泛研究有望解决争论并建立共识，但不一定能做到这一点。最近出现的高速原子力显微镜能够以高时空分辨率直接观察生物分子的作用，进一步增强了测量的直接性。这种显微镜清楚地观察到肌球蛋白V分子在肌动蛋白丝上行走，并最终为摆动双臂运动推动分子提供了无可辩驳的证据。然而，原子力显微镜电影中也出现了一种特殊的踩踏行为，这引发了该马达和一般肌球蛋白马达中化学机械耦合的新问题。本文综述了肌球蛋白运动研究的这些变化，并提出了解决这些新问题的新思路。
The quest for understanding the mechanism of myosin-based motility started with studies on muscle contraction. From numerous studies, the basic frameworks for this mechanism were constructed and brilliant hypotheses were put forward. However, the argument about the most crucial issue of how the actin–myosin interaction generates contractile force and shortening has not been definitive. To increase the “directness of measurement”, in vitro motility assays and single-molecule optical techniques were created and used. Consequently, detailed knowledge of the motility of muscle myosin evolved, which resulted in provoking more arguments to a higher level. In parallel with technical progress, advances in cell biology led to the discovery of many classes of myosins. Myosin V was discovered to be a processive motor, unlike myosin II. The processivity reduced experimental difficulties because it allowed continuous tracing of the motor action of single myosin V molecules. Extensive studies of myosin V were expected to resolve arguments and build a consensus but did not necessarily do so. The directness of measurement was further enhanced by the recent advent of high-speed atomic force microscopy capable of directly visualizing biological molecules in action at high spatiotemporal resolution. This microscopy clearly visualized myosin V molecules walking on actin filaments and at last provided irrefutable evidence for the swinging lever-arm motion propelling the molecules. However, a peculiar foot stomp behavior also appeared in the AFM movie, raising new questions of the chemo-mechanical coupling in this motor and myosin motors in general. This article reviews these changes in the research of myosin motility and proposes new ideas to resolve the newly raised questions.