Itakura S, Yamakawa H, Toyoshima Y Y, Ishijima A, Kojima T, Harada Y, Yanagida T, Wakabayashi T, Sutoh K
Department of Pure and Applied Sciences, College of Arts and Sciences, University of Tokyo, Japan.
Biochem Biophys Res Commun. 1993 Nov 15;196(3):1504-10. doi: 10.1006/bbrc.1993.2422.
To understand the underlying mechanism of force generation by myosin motor, it is crucial to know which part of the molecule is essential for the process. Recent structure determination of myosin motor domain at atomic resolution has revealed that the domain comprises two smaller domains, the "ATPase domain" consisting of only an N-terminal segment of the heavy chain and the "neck domain" consisting of a long alpha-helix of the heavy chain and two light chains. This atomic structure begs the question of whether both domains are required for force generation. To answer it, we genetically truncated the head to generate a recombinant fragment composed of the "ATPase domain" alone. The truncated head drove sliding movement of actin filaments and generated force in a novel in vitro assay system, which allows us to hold a specific site of the head on a glass surface. These results indicate that the compact ATPase domain functions as a force-generating machinery of the myosin motor.
为了理解肌球蛋白马达产生力的潜在机制，关键在于了解分子的哪一部分对这一过程至关重要。最近以原子分辨率测定的肌球蛋白马达结构域表明，该结构域由两个较小的结构域组成，即仅由重链的N端片段构成的“ATP酶结构域”和由重链的一个长α螺旋及两条轻链构成的“颈部结构域”。这种原子结构引发了一个问题，即这两个结构域对于产生力是否都是必需的。为了回答这个问题，我们通过基因手段截短头部，以产生仅由“ATP酶结构域”组成的重组片段。在一种新型的体外检测系统中，截短的头部驱动肌动蛋白丝的滑动运动并产生力，该系统能让我们将头部的特定部位固定在玻璃表面。这些结果表明，紧凑的ATP酶结构域起着肌球蛋白马达产生力的机制的作用。
