Actin activates a cryptic dimerization potential of the vinculin tail domain
Actin activates a cryptic dimerization potential of the vinculin tail domain
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DOI：
10.1074/jbc.275.1.95
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发表时间：
2000-01-07
影响因子：
4.8
通讯作者：
Craig, SW
中科院分区：
文献类型：
--
作者：
Johnson, RP;Craig, SW
vinculin的尾部结构域（V-t）是一个肌动蛋白结合模块，包含两个与f -肌动蛋白相互作用的区域。虽然从细菌表达系统中纯化的完整V-t是一个球形单体，但每个肌动蛋白结合区在单独表达时都是二聚的，这表明存在着受调节的隐性自结合位点。我们发现肌动蛋白通过诱导或稳定V-t的构象变化来调节V-t自结合，从而允许二聚化。化学交联研究表明，肌动蛋白结合区域之一在肌动蛋白存在时介导二聚化。肌动蛋白诱导的V-t二聚体可能在该蛋白的丝交联活性中起作用。肌动蛋白诱导的V-t二聚体与酸性磷脂（如磷脂酰肌醇4,5-二磷酸）诱导的V-t二聚体和更高的低聚体在生物化学上是不同的，这表明V-t与这两种配体结合的结构差异可能为磷脂酰肌醇4,5-二磷酸抑制f -肌动蛋白的结合提供了机制基础。肌动蛋白调节肌动蛋白结合蛋白二聚化状态的能力表明，肌动蛋白细丝可能直接参与信号转导和其他已知依赖于细胞骨架完整性的细胞事件，而不是充当被动的结构角色。
The tail domain of vinculin (V-t) is an actin binding module containing two regions that interact with F-actin. Although intact V-t purified from a bacterial expression system is a globular monomer, each actin binding region dimerizes when expressed individually, suggesting the presence of cryptic self-association sites whose exposure is regulated. We show that actin modulates V-t self-association by inducing or stabilizing a conformational change in V-t that allows dimerization. Chemical cross-linking studies implicate one of the actin binding regions in mediating dimerization in the presence of actin. Actin induced V-t dimers may play a role in the filament cross-linking activity of this protein. The V-t dimers induced by actin are biochemically distinct from the V-t dimers and higher oligomers induced by acidic phospholipids such as phosphatidylinositol 4,5-bisphosphate, suggesting structural differences in V-t bound to these two ligands that may provide a mechanistic basis for inhibition of F-actin binding by phosphatidylinositol 4,5-bisphosphate. The ability of actin to regulate the dimerization state of an actin binding protein suggests that, rather than serving a passive structural role, actin filaments may directly participate in signal transduction and other cellular events that are known to depend on cytoskeletal integrity.