Pressure-Dependent Chemical Shifts in the R3 Domain of Talin Show that It Is Thermodynamically Poised for Binding to Either Vinculin or RIAM
Pressure-Dependent Chemical Shifts in the R3 Domain of Talin Show that It Is Thermodynamically Poised for Binding to Either Vinculin or RIAM
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DOI：
10.1016/j.str.2017.10.008
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发表时间：
2017-12-05
期刊：
影响因子：
5.7
通讯作者：
Williamson, Mike P.
中科院分区：
文献类型：
--
作者：
Baxter, Nicola J.;Zacharchenko, Thomas;Williamson, Mike P.
踝蛋白介导细胞与细胞外基质的附着。它被 Rap1 效应器 RIAM 靶向粘着斑位点，随后经历力诱导的构象打开以招募肌动蛋白相互作用蛋白纽蛋白。构象转换涉及talin R3结构域，该结构域在关闭时结合RIAM，在打开时结合纽蛋白。在这里，我们对 R3 施加压力并测量 H-1、N-15 和 C-13 化学位移变化，这些变化使用简单的模型进行拟合，并表明 R3 仅 50% 闭合：闭合形式是四螺旋束，而在开放状态下，螺旋 1 被扭曲。引人注目的是，R3 的突变体与 RIAM 的结合亲和力与野生型相似，但与纽蛋白的亲和力更弱，在闭合时表现出更稳定 0.84 kJ mol(-1)。这些结果表明，R3 在热力学上能够结合 RIAM 或纽蛋白，从而构成良好的机械敏感开关。
Talin mediates attachment of the cell to the extracellular matrix. It is targeted by the Rap1 effector RIAM to focal adhesion sites and subsequently undergoes force-induced conformational opening to recruit the actin-interacting protein vinculin. The conformational switch involves the talin R3 domain, which binds RIAM when closed and vinculin when open. Here, we apply pressure to R3 and measure H-1, N-15, and C-13 chemical shift changes, which are fitted using a simple model, and indicate that R3 is only 50% closed: the closed form is a four-helix bundle, while in the open state helix 1 is twisted out. Strikingly, a mutant of R3 that binds RIAM with an affinity similar to wild-type but more weakly to vinculin is shown to be 0.84 kJ mol(-1) more stable when closed. These results demonstrate that R3 is thermodynamically poised to bind either RIAM or vinculin, and thus constitutes a good mechanosensitive switch.