Cryo-EM structure of a human cytoplasmic actomyosin complex at near-atomic resolution
Cryo-EM structure of a human cytoplasmic actomyosin complex at near-atomic resolution
复制标题
DOI：
10.1038/nature18295
复制
发表时间：
2016-06-30
期刊：
影响因子：
64.8
通讯作者：
Raunser, Stefan
中科院分区：
文献类型：
--
作者：
von der Ecken, Julian;Heissler, Sarah M.;Raunser, Stefan
肌球蛋白与肌动蛋白细丝的相互作用是肌肉收缩(1)和货物沿细胞骨架的肌动蛋白细丝移动(2)的主要特征。这些运动的能量是在一个复杂的机械力化学反应循环(3，4)中产生的。肌球蛋白在不同状态下的晶体结构为肌球蛋白从F-肌动蛋白(5-7)中分离出来时肌球蛋白摩托车提供了重要的结构信息。然而，获得衍射晶的困难阻碍了通过肌动球蛋白复合体的结晶学来确定结构。因此，尽管在F-肌动蛋白与各种肌球蛋白(8-11)的复合体中存在结构模型，但缺少F-肌动蛋白-肌球蛋白复合体的高分辨率结构。在这里，使用电子冷冻显微镜，我们展示了一个人类僵直肌球蛋白复合体的结构，平均分辨率为3.9埃。该结构揭示了肌动球蛋白界面的细节，该界面主要由疏水相互作用稳定。肌动蛋白带负电荷的氨基末端与肌球蛋白环2中保守的基本基序相互作用，促进肌球蛋白裂隙的闭合。令人惊讶的是，在没有F-肌动蛋白的情况下，肌球蛋白的整体结构类似于僵直的肌球蛋白结构，这表明F-肌动蛋白结合只会导致肌球蛋白的微小构象变化。通过与PowerStroke前和中间(P-I-释放)(7)状态的比较，我们可以讨论肌球蛋白与F-肌动蛋白结合的一般机制。我们的结果为从分子水平理解细胞骨架疾病奠定了坚实的基础，如常染色体显性听力损失和影响骨骼肌和心肌的疾病，特别是线虫性肌病和肥厚性心肌病。
The interaction of myosin with actin filaments is the central feature of muscle contraction(1) and cargo movement along actin filaments of the cytoskeleton(2). The energy for these movements is generated during a complex mechanochemical reaction cycle(3,4). Crystal structures of myosin in different states have provided important structural insights into the myosin motor cycle when myosin is detached from F-actin(5-7). The difficulty of obtaining diffracting crystals, however, has prevented structure determination by crystallography of actomyosin complexes. Thus, although structural models exist of F-actin in complex with various myosins(8-11), a high-resolution structure of the F-actin-myosin complex is missing. Here, using electron cryomicroscopy, we present the structure of a human rigor actomyosin complex at an average resolution of 3.9 angstrom. The structure reveals details of the actomyosin interface, which is mainly stabilized by hydrophobic interactions. The negatively charged amino (N) terminus of actin interacts with a conserved basic motif in loop 2 of myosin, promoting cleft closure in myosin. Surprisingly, the overall structure of myosin is similar to rigor-like myosin structures in the absence of F-actin, indicating that F-actin binding induces only minimal conformational changes in myosin. A comparison with pre-powerstroke and intermediate (P-i-release)(7) states of myosin allows us to discuss the general mechanism of myosin binding to F-actin. Our results serve as a strong foundation for the molecular understanding of cytoskeletal diseases, such as autosomal dominant hearing loss and diseases affecting skeletal and cardiac muscles, in particular nemaline myopathy and hypertrophic cardiomyopathy.