Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, MI, USA.
Advanced Photon Source, Argonne National Lab, Argonne, IL, USA.
Biochem Biophys Res Commun. 2014 May 30;448(2):169-74. doi: 10.1016/j.bbrc.2014.04.085. Epub 2014 Apr 24.
The formation of CXCR2-NHERF1-PLCβ2 macromolecular complex in neutrophils regulates CXCR2 signaling and plays a key role in neutrophil chemotaxis and transepithelial neutrophilic migration. However, NHERF1 by itself, with only two PDZ domains, has a limited capacity in scaffolding the multiprotein-complex formation. Here we report the crystal structure of the NHERF1 PDZ2 domain in complex with the C-terminal CXCR2 sequence. The structure reveals that the PDZ2-CXCR2 binding specificity is achieved by numerous hydrogen bonds and hydrophobic contacts with the last four CXCR2 residues contributing to specific interactions. The structure also reveals two probable modes of PDZ2 dimerization where the two canonical ligand-binding pockets are well separated and orientated in a unique parallel fashion. This study provides not only the structural basis for the PDZ-mediated NHERF1-CXCR2 interaction, but also an additional example of how PDZ domains may dimerize, which both could prove valuable in understanding NHERF1 complex-scaffolding function in neutrophils.
中性粒细胞中 CXCR2-NHERF1-PLCβ2 大分子复合物的形成调节 CXCR2 信号转导，并在中性粒细胞趋化和跨上皮中性粒细胞迁移中发挥关键作用。然而，NHERF1 本身只有两个 PDZ 结构域，其形成多蛋白复合物的能力有限。在这里，我们报告了 NHERF1 PDZ2 结构域与 CXCR2 C 端序列复合物的晶体结构。该结构揭示了 PDZ2-CXCR2 结合特异性是通过与最后四个 CXCR2 残基的众多氢键和疏水相互作用实现的，这些残基有助于特定相互作用。该结构还揭示了 PDZ2 二聚体的两种可能模式，其中两个规范的配体结合口袋很好地分离，并以独特的平行方式定向。这项研究不仅为 PDZ 介导的 NHERF1-CXCR2 相互作用提供了结构基础，还为 PDZ 结构域如何二聚体提供了另一个例子，这两者都可能有助于理解 NHERF1 复合物在中性粒细胞中的支架功能。
