Miller Rebecca L, Thompson Aaron A, Trapella Claudio, Guerrini Remo, Malfacini Davide, Patel Nilkanth, Han Gye Won, Cherezov Vadim, Caló Girolamo, Katritch Vsevolod, Stevens Raymond C
Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
Department of Chemical and Pharmaceutical Sciences and LTTA (Laboratorio per le Tecnologie delle Terapie Avanzate), University of Ferrara, 44121 Ferrara, Italy.
Structure. 2015 Dec 1;23(12):2291-2299. doi: 10.1016/j.str.2015.07.024. Epub 2015 Oct 29.
Understanding the mechanism by which ligands affect receptor conformational equilibria is key in accelerating membrane protein structural biology. In the case of G protein-coupled receptors (GPCRs), we currently pursue a brute-force approach for identifying ligands that stabilize receptors and facilitate crystallogenesis. The nociceptin/orphanin FQ peptide receptor (NOP) is a member of the opioid receptor subfamily of GPCRs for which many structurally diverse ligands are available for screening. We observed that antagonist potency is correlated with a ligand's ability to induce receptor stability (Tm) and crystallogenesis. Using this screening strategy, we solved two structures of NOP in complex with top candidate ligands SB-612111 and C-35. Docking studies indicate that while potent, stabilizing antagonists strongly favor a single binding orientation, less potent ligands can adopt multiple binding modes, contributing to their low Tm values. These results suggest a mechanism for ligand-aided crystallogenesis whereby potent antagonists stabilize a single ligand-receptor conformational pair.
了解配体影响受体构象平衡的机制是加速膜蛋白结构生物学研究的关键。就G蛋白偶联受体（GPCR）而言，我们目前采用一种强力方法来鉴定能够稳定受体并促进结晶的配体。孤啡肽/孤啡肽FQ肽受体（NOP）是GPCR阿片受体亚家族的成员，有许多结构多样的配体可供筛选。我们观察到拮抗剂效力与配体诱导受体稳定性（熔解温度）和结晶的能力相关。使用这种筛选策略，我们解析了NOP与顶级候选配体SB - 612111和C -35形成复合物的两种结构。对接研究表明，虽然强效、稳定的拮抗剂强烈倾向于单一结合取向，但效力较弱的配体可以采用多种结合模式，这导致了它们较低的熔解温度值。这些结果提示了一种配体辅助结晶的机制，即强效拮抗剂稳定单一的配体 - 受体构象对。
