Várkuti Boglárka H, Yang Zhenhui, Malnasi-Csizmadia Andras
From the Department of Biochemistry, Institute of Biology and.
From the Department of Biochemistry, Institute of Biology and the ELTE-HAS Molecular Biophysics Research Group, Eötvös Loránd University, H-1117 Budapest and Optopharma Ltd., H-1015 Budapest, Hungary
J Biol Chem. 2015 Jan 16;290(3):1679-88. doi: 10.1074/jbc.M114.606665. Epub 2014 Nov 21.
We present the first in silico model of the weak binding actomyosin in the initial powerstroke state, representing the actin binding-induced major structural changes in myosin. First, we docked an actin trimer to prepowerstroke myosin then relaxed the complex by a 100-ns long unrestrained molecular dynamics. In the first few nanoseconds, actin binding induced an extra primed myosin state, i.e. the further priming of the myosin lever by 18° coupled to a further closure of switch 2 loop. We demonstrated that actin induces the extra primed state of myosin specifically through the actin N terminus-activation loop interaction. The applied in silico methodology was validated by forming rigor structures that perfectly fitted into an experimentally determined EM map of the rigor actomyosin. Our results unveiled the role of actin in the powerstroke by presenting that actin moves the myosin lever to the extra primed state that leads to the effective lever swing.
我们展示了处于初始动力冲程状态的弱结合肌动球蛋白的首个计算机模拟模型，该模型代表了肌动蛋白结合诱导的肌球蛋白主要结构变化。首先，我们将一个肌动蛋白三聚体与预动力冲程肌球蛋白对接，然后通过100纳秒的无约束分子动力学使复合物松弛。在最初的几纳秒内，肌动蛋白结合诱导了一种额外的预激活肌球蛋白状态，即肌球蛋白杠杆进一步预激活18°，同时开关2环进一步闭合。我们证明肌动蛋白通过肌动蛋白N端-激活环相互作用特异性地诱导肌球蛋白的额外预激活状态。通过形成与实验确定的强直肌动球蛋白的电子显微镜图谱完美匹配的强直结构，验证了所应用的计算机模拟方法。我们的结果揭示了肌动蛋白在动力冲程中的作用，即肌动蛋白将肌球蛋白杠杆移动到额外的预激活状态，从而导致有效的杠杆摆动。
