Wang Xiaoxia, Fukuda Koichi, Byeon In-Ja, Velyvis Algirdas, Wu Chuanyue, Gronenborn Angela, Qin Jun
Structural Biology Program, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
J Biol Chem. 2008 Jul 25;283(30):21113-9. doi: 10.1074/jbc.M801270200. Epub 2008 May 28.
Alpha-parvin is an essential component of focal adhesions (FAs), which are large multiprotein complexes that link the plasma membrane and actin cytoskeleton. Alpha-parvin contains two calponin homology (CH) domains and its C-terminal CH2 domain binds multiple targets including paxillin LD motifs for regulating the FA network and signaling. Here we describe the solution structure of alpha-parvin CH2 bound to paxillin LD1. We show that although CH2 contains the canonical CH-fold, a previously defined N-terminal linker forms an alpha-helix that packs unexpectedly with the C-terminal helix of CH2, resulting in a novel variant of the CH domain. Importantly, such packing generates a hydrophobic surface that recognizes the Leu-rich face of paxillin-LD1, and the binding pattern differs drastically from the classical paxillin-LD binding to four-helix bundle proteins such as focal adhesion kinase. These results define a novel modular recognition mode and reveal how alpha-parvin associates with paxillin to mediate the FA assembly and signaling.
α-帕文蛋白是粘着斑（FAs）的重要组成部分，粘着斑是连接质膜和肌动蛋白细胞骨架的大型多蛋白复合物。α-帕文蛋白包含两个钙调蛋白同源（CH）结构域，其C端CH2结构域结合多个靶点，包括桩蛋白的LD基序，以调节粘着斑网络和信号传导。在此，我们描述了与桩蛋白LD1结合的α-帕文蛋白CH2的溶液结构。我们发现，尽管CH2含有典型的CH折叠，但先前定义的N端连接子形成了一个α-螺旋，该螺旋意外地与CH2的C端螺旋堆积在一起，从而产生了一种新型的CH结构域变体。重要的是，这种堆积产生了一个疏水表面，该表面识别桩蛋白-LD1富含亮氨酸的表面，并且其结合模式与经典的桩蛋白-LD与四螺旋束蛋白（如粘着斑激酶）的结合模式截然不同。这些结果定义了一种新型的模块化识别模式，并揭示了α-帕文蛋白如何与桩蛋白结合以介导粘着斑组装和信号传导。
