From the Institute of Biochemistry, Faculty of Biosciences, Pharmacy and Psychology, Universität Leipzig, 04103 Leipzig, Germany and.
J Biol Chem. 2014 Feb 28;289(9):5846-59. doi: 10.1074/jbc.M113.502021. Epub 2013 Dec 27.
Structural characterization of the human Y4 receptor (hY4R) interaction with human pancreatic polypeptide (hPP) is crucial, not only for understanding its biological function but also for testing treatment strategies for obesity that target this interaction. Here, the interaction of receptor mutants with pancreatic polypeptide analogs was studied through double-cycle mutagenesis. To guide mutagenesis and interpret results, a three-dimensional comparative model of the hY4R-hPP complex was constructed based on all available class A G protein-coupled receptor crystal structures and refined using experimental data. Our study reveals that residues of the hPP and the hY4R form a complex network consisting of ionic interactions, hydrophobic interactions, and hydrogen binding. Residues Tyr(2.64), Asp(2.68), Asn(6.55), Asn(7.32), and Phe(7.35) of Y4R are found to be important in receptor activation by hPP. Specifically, Tyr(2.64) interacts with Tyr(27) of hPP through hydrophobic contacts. Asn(7.32) is affected by modifications on position Arg(33) of hPP, suggesting a hydrogen bond between these two residues. Likewise, we find that Phe(7.35) is affected by modifications of hPP at positions 33 and 36, indicating interactions between these three amino acids. Taken together, we demonstrate that the top of transmembrane helix 2 (TM2) and the top of transmembrane helices 6 and 7 (TM6-TM7) form the core of the peptide binding pocket. These findings will contribute to the rational design of ligands that bind the receptor more effectively to produce an enhanced agonistic or antagonistic effect.
研究人类胰多肽（hPP）与人类 Y4 受体（hY4R）相互作用的结构特征至关重要，这不仅有助于理解其生物学功能，还为针对这种相互作用的肥胖治疗策略的测试提供了依据。在此，通过双循环诱变研究了受体突变体与胰多肽类似物的相互作用。为了指导诱变并解释结果，根据所有可用的 A 类 G 蛋白偶联受体晶体结构构建了 hY4R-hPP 复合物的三维比较模型，并使用实验数据进行了优化。我们的研究表明，hPP 和 hY4R 的残基形成了一个由离子相互作用、疏水相互作用和氢键组成的复杂网络。发现 Y4R 的残基 Tyr(2.64)、Asp(2.68)、Asn(6.55)、Asn(7.32)和 Phe(7.35)在 hPP 激活受体中起重要作用。具体来说，Tyr(2.64)通过疏水接触与 hPP 的 Tyr(27)相互作用。Asn(7.32)受 hPP 中 Arg(33)位置修饰的影响，表明这两个残基之间存在氢键。同样，我们发现 Phe(7.35)受 hPP 在位置 33 和 36 修饰的影响，表明这三个氨基酸之间存在相互作用。综上所述，我们证明了跨膜螺旋 2（TM2）的顶部和跨膜螺旋 6 和 7（TM6-TM7）的顶部形成了肽结合口袋的核心。这些发现将有助于设计更有效地结合受体的配体，从而产生增强的激动或拮抗作用。
