Larsen Olav, Lückmann Michael, van der Velden Wijnand J C, Oliva-Santiago Marta, Brvar Matjaz, Ulven Trond, Frimurer Thomas M, Karlshøj Stefanie, Rosenkilde Mette M
Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen, Denmark.
Section for Metabolic Receptology, Novo Nordisk Foundation, Center for Basic Metabolic Research, Blegdamsvej 3, DK-2200 Copenhagen, Denmark.
ACS Pharmacol Transl Sci. 2019 Nov 13;2(6):429-441. doi: 10.1021/acsptsci.9b00059. eCollection 2019 Dec 13.
Chemokines undergo post-translational modification such as N-terminal truncations. Here, we describe how N-terminal truncation of full length CCL3 affects its activity at CCR1. Truncated CCL3 has 10-fold higher potency and enhanced efficacy in β-arrestin recruitment, but less than 2-fold increased potencies in G protein signaling determined by calcium release, cAMP and IP formation. Small positive ago-allosteric ligands modulate the two CCL3 variants differently as the metal ion chelator bipyridine in complex with zinc (ZnBip) enhances the binding of truncated, but not full length CCL3, while a size-increase of the chelator to a chloro-substituted terpyridine (ZnClTerp), eliminates its allosteric, but not agonistic action. By employing a series of receptor mutants and modeling we describe residues of importance for chemokine and small molecule binding. Notably, the chemokine receptor-conserved Glu287 interacts with the N-terminal amine of truncated CCL3 and with Zn of ZnBip, thereby bridging their binding sites and enabling the positive allosteric effect. Our study emphasizes that small allosteric molecules may act differently toward chemokine variants and thus selectively modulate interactions of specific chemokine subsets with their cognate receptors.
趋化因子会经历翻译后修饰，如N端截短。在此，我们描述全长CCL3的N端截短如何影响其在CCR1上的活性。截短的CCL3在β-抑制蛋白募集方面具有高10倍的效力和增强的功效，但在通过钙释放、cAMP和肌醇磷酸形成测定的G蛋白信号传导中，效力增加不到2倍。小的正构变构配体对两种CCL3变体的调节方式不同，因为与锌络合的金属离子螯合剂联吡啶（ZnBip）增强了截短型CCL3的结合，但未增强全长CCL3的结合，而螯合剂尺寸增加到氯代三联吡啶（ZnClTerp）则消除了其变构作用，但未消除激动作用。通过使用一系列受体突变体和建模，我们描述了趋化因子和小分子结合的重要残基。值得注意的是，趋化因子受体保守的Glu287与截短型CCL3的N端胺以及ZnBip的锌相互作用，从而桥接它们的结合位点并实现正构变构效应。我们的研究强调，小的变构分子对趋化因子变体的作用可能不同，从而选择性地调节特定趋化因子亚群与其同源受体的相互作用。
