Mechanical coordination in motor ensembles revealed using engineered artificial myosin filaments.
Mechanical coordination in motor ensembles revealed using engineered artificial myosin filaments.
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DOI：
10.1038/nnano.2015.132
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发表时间：
2015-08
影响因子：
38.3
通讯作者：
Sivaramakrishnan S
中科院分区：
文献类型：
--
作者：
Hariadi RF;Sommese RF;Adhikari AS;Taylor RE;Sutton S;Spudich JA;Sivaramakrishnan S
肌肉的肌节由成千上万的肌球蛋白马达组成，肌球蛋白马达自组装成粗丝，并与周围的肌动蛋白为基础的细丝相互作用，形成密集的、近晶体的六边形晶格。这些肌动蛋白-肌球蛋白的相互作用使大规模运动和力量产生成为可能，这是肌肉的两个主要属性。对孤立纤维的研究为肌肉的集体性质提供了相当多的见解，但肌动蛋白-肌球蛋白相互作用如何在整体中协调仍然知之甚少。在这里，我们展示了使用DNA纳米管支架设计的人工肌球蛋白细丝，提供了对运动数量，类型和间距的精确控制。使用二聚体肌球蛋白V-和肌球蛋白VI-标记的纳米管，我们发现，既不是肌球蛋白密度也不是间距有一个显着的影响肌动蛋白丝的滑行速度。这一观察结果支持了一个简单的模型，肌球蛋白集合作为能量库，缓冲个别随机事件，带来平稳，连续的运动。此外，滑动速度增加跨桥柔度，但受到布朗效应的限制。作为重建肌肉运动的第一步，我们展示了人类β-心肌肌球蛋白驱动的肌动蛋白丝在DNA纳米管上的滑动。
The sarcomere of muscle is composed of tens of thousands of myosin motors that self-assemble into thick filaments and interact with surrounding actin-based thin filaments in a dense, near-crystalline hexagonal lattice. Together, these actin–myosin interactions enable large-scale movement and force generation, two primary attributes of muscle. Research on isolated fibres has provided considerable insight into the collective properties of muscle, but how actin–myosin interactions are coordinated in an ensemble remains poorly understood. Here, we show that artificial myosin filaments, engineered using a DNA nanotube scaffold, provide precise control over motor number, type and spacing. Using both dimeric myosin V- and myosin VI-labelled nanotubes, we find that neither myosin density nor spacing has a significant effect on the gliding speed of actin filaments. This observation supports a simple model of myosin ensembles as energy reservoirs that buffer individual stochastic events to bring about smooth, continuous motion. Furthermore, gliding speed increases with cross-bridge compliance, but is limited by Brownian effects. As a first step to reconstituting muscle motility, we demonstrate human β-cardiac myosin-driven gliding of actin filaments on DNA nanotubes.