The structural coupling between ATPase activation and recovery stroke in the myosin II motor
The structural coupling between ATPase activation and recovery stroke in the myosin II motor
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DOI：
10.1016/j.str.2007.06.008
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发表时间：
2007-07-01
期刊：
影响因子：
5.7
通讯作者：
Fischer, Stefan
中科院分区：
文献类型：
--
作者：
Koppole, Sampath;Smith, Jeremy C.;Fischer, Stefan
在肌凝蛋白马达头可以执行下一个动力冲程之前，它经历了一个大的构象转变，其中转换器域，承载杠杆臂，旋转类似65度。与这种“恢复中风”同时，肌凝蛋白通过关闭结合ATP上的开关-2环来激活其ATP酶功能。转换结构域和40a远的Switch-2环运动之间的耦合对于避免非生产性ATP水解是必不可少的。在这里，耦合机制是通过找到一系列优化的中间体来确定的，这些中间体介于恢复行程的晶体末端结构之间，产生了原子细节上的跃迁电影。Switch-2环连续形成的两个氢键与保持转换域的继电器和SH1螺旋的连续跷跷板运动有关。SH1螺旋和Switch-2环通过一个高度保守的环进行通信，该环在Switch-2关闭时楔入SH1螺旋。
Before the myosin motor head can perform the next power stroke, it undergoes a large conformational transition in which the converter domain, bearing the lever arm, rotates similar to 65 degrees. Simultaneous with this "recovery stroke," myosin activates its ATPase function by closing the Switch-2 loop over the bound ATP. This coupling between the motions of the converter domain and of the 40 A-distant Switch-2 loop is essential to avoid unproductive ATP hydrolysis. The coupling mechanism is determined here by finding a series of optimized intermediates between crystallographic end structures of the recovery stroke (Dictyostelium discoideum), yielding movies of the transition at atomic detail. The successive formation of two hydrogen bonds by the Switch-2 loop is correlated with the successive see-saw motions of the relay and SH1 helices that hold the converter domain. SH1 helix and Switch-2 loop communicate via a highly conserved loop that wedges against the SH1-helix upon Switch-2 closing.