α-Catenin Structure and Nanoscale Dynamics in Solution and in Complex with F-Actin
α-Catenin Structure and Nanoscale Dynamics in Solution and in Complex with F-Actin
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DOI：
10.1016/j.bpj.2018.07.005
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发表时间：
2018-08-21
影响因子：
3.4
通讯作者：
Bu, Zimei
中科院分区：
文献类型：
--
作者：
Nicholl, Iain D.;Matsui, Tsutomu;Bu, Zimei
作为粘附连接的核心组分，α-连环蛋白稳定钙粘蛋白/连环蛋白复合物与肌动蛋白细胞骨架，用于细胞-细胞粘附的机械偶联。α-连环蛋白还调节肌动蛋白动力学、细胞极性和细胞迁移功能，这些功能不依赖于粘附连接。我们已经确定了解决方案的α-连环蛋白单体和二聚体的结构，使用在线尺寸排阻色谱小角X-射线散射，以及结构的α-连环蛋白二聚体在复杂的F-肌动蛋白丝使用选择性氘化和对比度匹配的小角中子散射。我们进一步提出的第一个观察，据我们所知，α-连环蛋白的纳米级动力学的中子自旋回波光谱，复制，明确揭示了移动的地区的α-连环蛋白是至关重要的结合F-肌动蛋白。在溶液中，α-连环蛋白单体比晶体结构二聚体中所示的任何一种原聚体都更膨胀，其中粘着斑蛋白结合M片段和肌动蛋白结合结构域能够采用不同的构型。溶液中的α-连环蛋白二聚体也比二聚体晶体结构显著更多地扩展，具有比晶体结构更少的结构域间和亚基间接触。当与F-肌动蛋白复合时，α-连环蛋白二聚体具有比在溶液中更开放和延伸的构象，肌动蛋白结合结构域进一步与二聚体的主体分离。随着α-连环蛋白/F-肌动蛋白摩尔比的增加，α-连环蛋白组装的F-肌动蛋白束发展成有序的细丝堆积排列。总之，结构和动态研究表明，α-连环蛋白具有动态分子构象，该蛋白质作为机械传感器蛋白发挥作用。
As a core component of the adherens junction, alpha-catenin stabilizes the cadherin/catenin complexes to the actin cytoskeleton for the mechanical coupling of cell-cell adhesion. alpha-catenin also modulates actin dynamics, cell polarity, and cell-migration functions that are independent of the adherens junction. We have determined the solution structures of the alpha-catenin monomer and dimer using in-line size-exclusion chromatography small-angle X-ray scattering, as well as the structure of alpha-catenin dimer in complex to F-actin filament using selective deuteration and contrast-matching small angle neutron scattering. We further present the first observation, to our knowledge, of the nanoscale dynamics of alpha-catenin by neutron spin-echo spectros-copy, which explicitly reveals the mobile regions of alpha-catenin that are crucial for binding to F-actin. In solution, the alpha-catenin monomer is more expanded than either protomer shown in the crystal structure dimer, with the vinculin-binding M fragment and the actin-binding domain being able to adopt different configurations. The alpha-catenin dimer in solution is also significantly more expanded than the dimer crystal structure, with fewer interdomain and intersubunit contacts than the crystal structure. When in complex to F-actin, the alpha-catenin dimer has an even more open and extended conformation than in solution, with the actin-binding domain further separated from the main body of the dimer. The alpha-catenin-assembled F-actin bundle develops into an ordered filament packing arrangement at increasing alpha-catenin/F-actin molar ratios. Together, the structural and dynamic studies reveal that alpha-catenin possesses dynamic molecular conformations that prime this protein to function as a mechanosensor protein.