An ensemble of cadherin-catenin-vinculin complex employs vinculin as the major F-actin binding mode
An ensemble of cadherin-catenin-vinculin complex employs vinculin as the major F-actin binding mode
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DOI：
10.1016/j.bpj.2023.04.026
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发表时间：
2023-06-20
影响因子：
3.4
通讯作者：
Bu，Zimei
中科院分区：
文献类型：
--
作者：
Shi，Bright;Matsui，Tsutomu;Bu，Zimei
细胞-细胞黏附-钙粘附素-连环蛋白复合体将纽蛋白募集到黏附连接(AJ)，以调节相邻细胞之间的机械偶联。然而，目前尚不清楚纽蛋白如何影响AJ的结构和功能。在这里，我们识别了两个盐桥，它们将纽蛋白锁定在头尾自抑制构象中，并重组了与钙粘连蛋白-连环蛋白复合体结合的全长纽蛋白激活模拟物。钙粘连蛋白-连环蛋白-纽蛋白复合体含有多个无序连接子，并且具有高度的动态性，这给结构研究带来了挑战。我们用小角X射线和选择性氚/对比度变化小角中子散射确定了该络合物的系综构象。在该复合体中，α-连环蛋白和纽蛋白都采用了一系列灵活的构象，但纽蛋白具有完全开放的构象，纽蛋白头部和肌动蛋白结合的尾部结构域相互分离。F-肌动蛋白结合实验表明，钙粘附素-连环蛋白-纽蛋白复合体与F-肌动蛋白结合成束。然而，当纽蛋白肌动蛋白结合域从复合体中移除时，只有一小部分复合体与F-肌动蛋白结合。结果表明，动态钙粘附素-连环蛋白-纽蛋白复合体以纽蛋白作为主要的F-肌动蛋白结合模式来加强AJ-细胞骨架的相互作用。
The cell-cell adhesion cadherin-catenin complexes recruit vinculin to the adherens junction (AJ) to modulate the mechanical couplings between neighboring cells. However, it is unclear how vinculin influences the AJ structure and function. Here, we identified two patches of salt bridges that lock vinculin in the head-tail autoinhibited conformation and reconstituted the full-length vinculin activation mimetics bound to the cadherin-catenin complex. The cadherin-catenin-vinculin complex contains multiple disordered linkers and is highly dynamic, which poses a challenge for structural studies. We determined the ensemble conformation of this complex using small-angle x-ray and selective deuteration/contrast variation small-angle neutron scattering. In the complex, both α-catenin and vinculin adopt an ensemble of flexible conformations, but vinculin has fully open conformations with the vinculin head and actin-binding tail domains well separated from each other. F-actin binding experiments show that the cadherin-catenin-vinculin complex binds and bundles F-actin. However, when the vinculin actin-binding domain is removed from the complex, only a minor fraction of the complex binds to F-actin. The results show that the dynamic cadherin-catenin-vinculin complex employs vinculin as the primary F-actin binding mode to strengthen AJ-cytoskeleton interactions.