Myosin active site elements (i.e., switch‐1) bind both ATP and a divalent metal to coordinate ATP hydrolysis. ATP hydrolysis at the active site is linked via allosteric communication to the actin polymer binding site and lever arm movement, thus coupling the free energy of ATP hydrolysis to force generation. How active site motifs are functionally linked to actin binding and the power stroke is still poorly understood. We hypothesize that destabilizing switch‐1 movement at the active site will negatively affect the tight coupling of the ATPase catalytic cycle to force production. Using a metal‐switch system, we tested the effect of interfering with switch‐1 coordination of the divalent metal cofactor on force generation. We found that while ATPase activity increased, motility was inhibited. Our results demonstrate that a single atom change that affects the switch‐1 interaction with the divalent metal directly affects actin binding and productive force generation. Even slight modification of the switch‐1 divalent metal coordination can decouple ATP hydrolysis from motility. Switch‐1 movement is therefore critical for both structural communication with the actin binding site, as well as coupling the energy of ATP hydrolysis to force generation.

中文翻译：

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活性位点的 Switch-1 不稳定性使 ATP 水解与肌球蛋白 II 中的力产生分离

肌球蛋白活性位点元素（即 switch-1）结合 ATP 和二价金属以协调 ATP 水解。活性位点的 ATP 水解通过变构通讯连接到肌动蛋白聚合物结合位点和杠杆臂运动，从而将 ATP 水解的自由能与力的产生结合起来。活性位点基序如何在功能上与肌动蛋白结合和动力冲程联系在一起，仍然知之甚少。我们假设在活性位点不稳定的 switch-1 运动将对 ATPase 催化循环的紧密耦合产生负面影响，以强制产生。使用金属开关系统，我们测试了干扰二价金属辅因子的开关 1 配位对力产生的影响。我们发现，虽然 ATPase 活性增加，但运动受到抑制。我们的结果表明，影响 switch-1 与二价金属相互作用的单个原子变化直接影响肌动蛋白结合和生产力的产生。即使对 switch-1 二价金属配位稍作修改，也可以使 ATP 水解与运动分离。因此，Switch-1 的运动对于与肌动蛋白结合位点的结构交流以及将 ATP 水解的能量与力的产生耦合都至关重要。