Binding of Vinculin to Lipid Membranes in Its Inhibited and Activated States
Binding of Vinculin to Lipid Membranes in Its Inhibited and Activated States
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DOI：
10.1016/j.bpj.2016.08.019
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发表时间：
2016-10-04
影响因子：
3.4
通讯作者：
Winter, Roland
中科院分区：
文献类型：
--
作者：
Dwivedi, Mridula;Winter, Roland
磷酸肌醇是一类重要的磷脂，参与了从细胞信号到运动和黏附的无数细胞过程。纽蛋白(vinculin，VN)是一种主要的调节蛋白，它与PIP2一起调节脂质膜和其他细胞骨架成分中的局部粘连。VN在膜界面的结合和解离转变是理解细胞信号和运动协调的重要环节。利用不同的生物物理手段，包括原子力显微镜、共聚焦荧光显微镜和傅里叶变换红外光谱，我们研究了VN的激活和自抑制状态与脂膜的纳米相互作用。我们假设VN和脂膜之间发生了弱相互作用，这导致自抑制的VN与支撑的脂双层结合，并在独立的脂泡中解离。可能的驱动力可能包括C末端与脂膜的连接，以及疏水性螺旋-膜相互作用。相反，活化的VN通过与嵌入在脂膜中的PIP2簇发生特定的相互作用而强烈地与膜结合。PIP2簇上活化的VN可能会为进一步的相互作用伙伴形成小分子相互作用平台，这是焦点粘附点正常发挥功能所必需的。
Phosphoinositols are an important class of phospholipids that are involved in a myriad of cellular processes, from cell signaling to motility and adhesion. Vinculin (Vn) is a major adaptor protein that regulates focal adhesions in conjunction with PIP2 in lipid membranes and other cytoskeletal components. The binding and unbinding transitions of Vn at the membrane interface are an important link to understanding the coordination of cell signaling and motility. Using different biophysical tools, including atomic force microscopy combined with confocal fluorescence microscopy and Fourier transform infrared spectroscopy, we studied the nanoscopic interactions of activated and autoinhibited states of Vn with lipid membranes. We hypothesize that a weak interaction occurs between Vn and lipid membranes, which leads to binding of autoinhibited Vn to supported lipid bilayers, and to unbinding in freestanding lipid vesicles. Likely driving forces may include tethering of the C-terminus to the lipid membrane, as well as hydrophobic helix-membrane interactions. Conversely, activated Vn binds strongly to membranes through specific interactions with clusters of PIP2 embedded in lipid membranes. Activated Vn harbored on PIP2 clusters may form small oligomeric interaction platforms for further interaction partners, which is necessary for the proper function of focal adhesion points.