Actin age orchestrates myosin-5 and myosin-6 run lengths.
Actin age orchestrates myosin-5 and myosin-6 run lengths.
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DOI：
10.1016/j.cub.2015.06.033
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发表时间：
2015-08-03
期刊：
影响因子：
--
通讯作者：
Rock RS
中科院分区：
文献类型：
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作者：
Zimmermann D;Santos A;Kovar DR;Rock RS
与静态和固定的骨架不同，肌动蛋白细胞骨架是一种高度动态的丝状肌动蛋白（F-肌动蛋白）聚合物网络，不断翻转。除了产生机械力和感知机械变形外，动态F-肌动蛋白网络还充当肌球蛋白运动交通的细胞轨道。然而，我们对进行性肌球蛋白的机械理解大部分来自体外研究，其中在预组装和人工稳定的静态F-肌动蛋白轨道上研究了运动性。在这项工作中，我们研究肌动蛋白动力学在单分子肌球蛋白运动中的作用，使用组装F-肌动蛋白和两个高度进行性的电机，肌球蛋白-5和肌球蛋白-6。这两种肌球蛋白在细胞中具有不同的功能，并沿沿着肌动蛋白丝以相反的方向运动。肌球蛋白-5走向F-肌动蛋白的倒刺末端，移动到细胞周边的肌动蛋白聚合位点。肌球蛋白-6向F-肌动蛋白的尖端移动，沿着沿着肌动蛋白丝的较老片段向细胞中心移动。我们发现肌球蛋白5在ADP·Pi（年轻）F-肌动蛋白上的运行时间延长了1.3至1.5倍，而肌球蛋白6在ADP·Pi（年老）F-肌动蛋白上的运行时间延长了沿着1.7至3.6倍。这些结果表明，ADP·Pi和ADP F-肌动蛋白之间的构象差异使这些肌球蛋白向其优选的肌动蛋白丝末端走得更远。总之，这些实验定义了一个新的机制，肌球蛋白交通可能会排序不同的F-肌动蛋白网络取决于丝的年龄。
Unlike a static and immobile skeleton, the actin cytoskeleton is a highly dynamic network of filamentous actin (F-actin) polymers that continuously turn over. In addition to generating mechanical forces and sensing mechanical deformation, dynamic F-actin networks serve as cellular tracks for myosin motor traffic. However, much of our mechanistic understanding of processive myosins comes from in vitro studies where motility was studied on pre-assembled and artificially stabilized, static F-actin tracks. In this work, we examine the role of actin dynamics in single-molecule myosin motility using assembling F-actin and the two highly processive motors, myosin-5 and myosin-6. These two myosins have distinct functions in the cell and travel in opposite directions along actin filaments. Myosin-5 walks towards the barbed ends of F-actin, traveling to sites of actin polymerization at the cell periphery. Myosin-6 walks towards the pointed end of F-actin, traveling towards the cell center along older segments of the actin filament. We find that myosin-5 takes 1.3 to 1.5-fold longer runs on ADP•Pi (young) F-actin, while myosin-6 takes 1.7 to 3.6-fold longer runs along ADP (old) F-actin. These results suggest that conformational differences between ADP•Pi and ADP F-actin tailor these myosins to walk farther toward their preferred actin filament end. Taken together, these experiments define a new mechanism by which myosin traffic may sort to different F-actin networks depending on filament age.