Department of Cancer Biology, Cell Adhesion Laboratory, The Scripps Research Institute, FL 33458, USA.
Global Phasing Ltd., Sheraton House, Castle Park, Cambridge CB3 0AX, UK.
J Mol Biol. 2012 Oct 5;422(5):697-704. doi: 10.1016/j.jmb.2012.06.015. Epub 2012 Jun 15.
Vinculin is a key regulator of the actin cytoskeleton attachment to the cell membrane at cellular adhesion sites, which is crucial for processes such as cell motility and migration, development, survival, and wound healing. Vinculin loss results in embryonic lethality, cardiovascular diseases, and cancer. Its tail domain, Vt, is crucial for vinculin activation and focal adhesion turnover and binds to the actin cytoskeleton and acidic phospholipids upon which it unfurls. The RNA binding protein raver1 regulates the assembly of focal adhesions transcriptionally by binding to vinculin. The muscle-specific splice form, metavinculin, is characterized by a 68-residue insert in the tail domain (MVt) and correlates with hereditary idiopathic dilated cardiomyopathy. Here, we report that metavinculin can bind to raver1 in its inactive state. Our crystal structure explains this permissivity, where an extended coil unique to MVt is unfurled in the MVtΔ954:raver1 complex structure. Our binding assays show that raver1 forms a ternary complex with MVt and vinculin mRNA. These findings suggest that the metavinculin:raver1:RNA complex is constitutively recruited to adhesion complexes.
粘着斑蛋白是细胞黏附部位细胞骨架与细胞膜附着的关键调节因子，对于细胞运动、迁移、发育、存活和伤口愈合等过程至关重要。粘着斑蛋白缺失会导致胚胎致死、心血管疾病和癌症。其尾部结构域 Vt 对于粘着斑蛋白的激活和焦点黏附的转化至关重要，并与肌动蛋白细胞骨架和其上展开的酸性磷脂结合。RNA 结合蛋白 raver1 通过与粘着斑蛋白结合，从转录水平上调节焦点黏附的形成。肌特异性剪接形式 metavinculin 的尾部结构域插入了 68 个残基（MVt），与遗传性特发性扩张型心肌病相关。在这里，我们报告 metavinculin 可以在非活性状态下与 raver1 结合。我们的晶体结构解释了这种允许性，其中独特的 MVt 延伸线圈在 MVtΔ954:raver1 复合物结构中展开。我们的结合实验表明，raver1 与 MVt 和粘着斑蛋白 mRNA 形成三元复合物。这些发现表明，metavinculin:raver1:RNA 复合物是连续招募到黏附复合物中的。
