Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA.
Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA.
Structure. 2014 Jan 7;22(1):82-93. doi: 10.1016/j.str.2013.09.019. Epub 2013 Nov 7.
PDZ domain interactions are involved in signaling and trafficking pathways that coordinate crucial cellular processes. Alignment-based PDZ binding motifs identify the few most favorable residues at certain positions along the peptide backbone. However, sequences that bind the CAL (CFTR-associated ligand) PDZ domain reveal only a degenerate motif that overpredicts the true number of high-affinity interactors. Here, we combine extended peptide-array motif analysis with biochemical techniques to show that non-motif "modulator" residues influence CAL binding. The crystallographic structures of 13 CAL:peptide complexes reveal defined, but accommodating stereochemical environments at non-motif positions, which are reflected in modulator preferences uncovered by multisequence substitutional arrays. These preferences facilitate the identification of high-affinity CAL binding sequences and differentially affect CAL and NHERF PDZ binding. As a result, they also help determine the specificity of a PDZ domain network that regulates the trafficking of CFTR at the apical membrane.
PDZ 结构域相互作用参与信号转导和运输途径，协调关键的细胞过程。基于对齐的 PDZ 结合基序可以确定肽主链上某些位置的少数最有利残基。然而，与 CAL（CFTR 相关配体）PDZ 结构域结合的序列仅显示出一个退化的基序，该基序过高预测了高亲和力相互作用物的真实数量。在这里，我们将扩展的肽阵列基序分析与生化技术相结合，表明非基序“调节剂”残基会影响 CAL 结合。13 个 CAL：肽复合物的晶体结构揭示了在非基序位置处定义但具有适应性的立体化学环境，这反映在多序列取代阵列中揭示的调节剂偏好中。这些偏好有助于确定高亲和力的 CAL 结合序列，并对 CAL 和 NHERF PDZ 结合产生不同的影响。因此，它们还有助于确定调节 CFTR 在顶膜运输的 PDZ 结构域网络的特异性。
