Structural analysis of myosin II subfragment 1 decorated actin filament by CryoEM

为了了解肌肉收缩的机制，有必要揭示肌球蛋白如何与肌动蛋白结合。尽管有大量的生物化学信息，肌动蛋白-肌球蛋白复合物的详细结构仍然未知。我们用CryoEM获得了肌动蛋白-肌球蛋白Ⅱ S_1刚性复合物的7 μ m分辨率密度图。密度图清楚地解析了所有二级结构，例如α-螺旋、β-结构和环，使得明确的建模和细化成为可能。该结构表明，肌球蛋白发生剧烈的构象变化后，强烈结合到肌动蛋白丝和肌球蛋白结合到两个肌动蛋白单体。高分辨率的结构给了我们一个相对的肌动蛋白和肌球蛋白之间的三维排列，这表明突变引起的肌病疾病是高度相关的肌动蛋白-肌球蛋白界面形成的残基。

To understand the mechanism of muscle contraction,it is necessary to reveal how myosin binds to actin. Despite tons of biochemical information, the detail structure of actin-myosin complex remains unknown. We have obtained 7Å resolution density map of actin-myosin II S1 rigor complex by CryoEM. The density map clearly resolves all the secondary structures, such as α-helices, β-structures and loops, having made unambiguous modeling and refinement possible. The structure suggests that myosin undergoes a drastic conformational change upon strongly binding to the actin filament and that a myosin binds to two actin monomers. The high resolution structure gave us a relative three dimensional arrangement between actin and myosin, suggesting that the mutations caused myopathic illness is highly related to the residues forming the actin-myosin interface.