State Key Laboratory of Microbial Metabolism, and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.
PLoS One. 2011;6(8):e23507. doi: 10.1371/journal.pone.0023507. Epub 2011 Aug 17.
The human Discs Large 1 (DLG1) protein uses two of its three PDZ domains to interact with the C-terminal peptide of the Adenomatous Polyposis Coli (APC) tumor suppressor protein. The DLG1/APC complex inhibits the cell cycle progression from the G0/G1 to the S phase, regulates epithelial cell migration and morphogenesis, and is required for polarization of the microtubule cytoskeleton. However, the molecular details of how DLG1 recognizes APC is not clear. In this study, we performed biochemical and biophysical assays to investigate the interactions between PDZ domains of DLG1 and the C-terminal peptide of APC. In addition, we determined the crystal structures of the PDZ1 and PDZ2 domains of DLG1 each in complex with the C-terminal 11-residue peptide of APC. Our biochemical, biophysical, and structural results revealed structural elements and residues on PDZ1 and PDZ2 domains of DLG1 and on APC crucial for their mutual interaction. In particular, our results show that the β2/β3 loops of PDZ1 and PDZ2 play important roles in contributing to the binding affinities between PDZ domains and APC, through interacting with the residues upstream of the canonical PDZ-binding S/T-X-V motif. The results provide new insights into the binding mode of a defined C-terminal segment of APC by the PDZ domains of DLG1.
人类 Discs Large 1（DLG1）蛋白使用其三个 PDZ 结构域中的两个与腺瘤性结肠息肉病（APC）肿瘤抑制蛋白的 C 末端肽相互作用。DLG1/APC 复合物抑制细胞周期从 G0/G1 期到 S 期的进展，调节上皮细胞迁移和形态发生，并且是微管细胞骨架极化所必需的。然而，DLG1 识别 APC 的分子细节尚不清楚。在这项研究中，我们进行了生化和生物物理测定，以研究 DLG1 的 PDZ 结构域与 APC 的 C 末端肽之间的相互作用。此外，我们确定了 DLG1 的 PDZ1 和 PDZ2 结构域各自与 APC 的 C 末端 11 个残基肽复合物的晶体结构。我们的生化、生物物理和结构结果揭示了 DLG1 的 PDZ1 和 PDZ2 结构域以及 APC 上的结构元素和残基对于它们相互作用至关重要。特别是，我们的结果表明 PDZ1 和 PDZ2 的β2/β3 环通过与典型 PDZ 结合 S/T-X-V 基序上游的残基相互作用，在 PDZ 结构域与 APC 之间的结合亲和力中发挥重要作用。这些结果为 DLG1 的 PDZ 结构域与 APC 的特定 C 末端片段的结合模式提供了新的见解。
