Dynamic recognition of naloxone, morphine and endomorphin1 in the same pocket of µ-opioid receptors.
Dynamic recognition of naloxone, morphine and endomorphin1 in the same pocket of µ-opioid receptors.
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µ-阿片受体同一口袋中纳洛酮、吗啡和内啡肽1的动态识别
DOI：
10.3389/fmolb.2022.925404
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发表时间：
2022
影响因子：
5
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中科院分区：
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吗啡是最广泛使用的镇痛剂，通过激活μ-阿片受体（莫尔）来缓解严重疼痛，而纳洛酮与吗啡相比仅具有轻微的结构变化，表现出抑制作用，并用于治疗阿片类药物滥用。莫尔区分两者的机制尚不清楚。分子动力学（MD）模拟在1 μs的时间尺度和代谢动力学增强的构象采样在这里被用来确定不同的相互作用，这两个配体与莫尔：吗啡调整其姿势不断翻转到口袋里更深，而纳洛酮未能渗透更深，因为它的烯丙基与莫尔的几个残基冲突。内源性肽配体内吗啡肽-1（EM-1）在分子动力学模拟过程中几乎没有发生显著的构象变化。为了验证这些过程，我们采用GIRK 4S 143 T，一种MOR激活的Gβγ蛋白效应子，结合诱变和电生理记录。我们验证了一些关键残基在纳洛酮和吗啡的动态识别中的作用，并确定了关键残基I322，其导致吗啡和纳洛酮的差异识别，同时帮助EM-1激活莫尔。减小I322（MORI 322 A）的侧链大小将纳洛酮从抑制剂直接转化为莫尔的激动剂，并且I322 A还显著减弱了莫尔对EM-1的效力，证实了袋中的深层结合对于莫尔的激动作用至关重要。这一发现揭示了莫尔对不同配体响应的动力学机制，为在原子水平上发现莫尔的新配体提供了基础。
Morphine, the most widely used analgesic, relieves severe pain by activating the μ-opioid receptor (MOR), whereas naloxone, with only slight structural changes compared to morphine, exhibits inhibitory effect, and is used to treat opioid abuse. The mechanism by which the MOR distinguishes between the two is unclear. Molecular dynamics (MD) simulations on a 1-μs time scale and metadynamics-enhanced conformational sampling are used here to determine the different interactions of these two ligands with MOR: morphine adjusted its pose by continuously flipping deeper into the pocket, whereas naloxone failed to penetrate deeper because its allyl group conflicts with several residues of MOR. The endogenous peptide ligand endomorphin-1 (EM-1) underwent almost no significant conformational changes during the MD simulations. To validate these processes, we employed GIRK4S143T, a MOR-activated Gβγ-protein effector, in combination with mutagenesis and electrophysiological recordings. We verified the role of some key residues in the dynamic recognition of naloxone and morphine and identified the key residue I322, which leads to differential recognition of morphine and naloxone while assisting EM-1 in activating MOR. Reducing the side chain size of I322 (MORI322A) transformed naloxone from an inhibitor directly into an agonist of MOR, and I322A also significantly attenuated the potency of MOR on EM-1, confirming that binding deep in the pocket is critical for the agonistic effect of MOR. This finding reveals a dynamic mechanism for the response of MOR to different ligands and provides a basis for the discovery of new ligands for MOR at the atomic level.