Structural basis for the functions of dopamine receptors, neurotransmitter transporters, and sigma 1 receptor

多巴胺受体、神经递质转运蛋白和 sigma 1 受体功能的结构基础

• 批准号: 10699660
• 负责人: Lei Shi
• 金额: $ 218.05万
• 依托单位: NATIONAL INSTITUTE ON DRUG ABUSE
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10699660
• 关键词: Agonist; Amphetamines; Analgesics; Arrestins; Bar Codes; Binding; Binding Sites; Biological Models; Brain; COVID-19 pandemic; Carrier Proteins; Characteristics; Cocaine; Consensus; Crystallization; Development; Dopamine Receptor; Drug Targeting; Event; Fentanyl; Free Energy; G-Protein-Coupled Receptors; GTP-Binding Proteins; Goals; Heroin; Human; Image; Investigation; Lead; Ligand Binding; Ligands; Mediating; Molecular Conformation; N Domain; Nervous System; Neurons; Neurotransmitters; Opioid Receptor; Opioid Receptor Binding; Overdose; Pattern; Pharmaceutical Preparations; Pharmacology; Pharmacotherapy; Phosphopeptides; Phosphorylation; Play; Proteins; Receptor Activation; Recreational Drugs; Research; Research Subjects; Role; Signal Pathway; Signal Transduction; Signaling Protein; Specificity; Structure; Structure-Activity Relationship; Substance Use Disorder; Tail; Therapeutic; Therapeutic Intervention; Toxic effect; addiction; analog; computer studies; conformational conversion; design; dopamine transporter; drug discovery; drug market; drug of abuse; extracellular; insight; molecular dynamics; nervous system disorder; novel; opioid epidemic; receptor; scaffold; serotonin transporter; sigma-1 receptor; simulation; single-molecule FRET; small molecule; synergism; synthetic cannabinoid; synthetic opioid; therapeutic development; therapeutically effective; therapy development

Fentanyl and its analogs are selective agonists of the micro-opioid receptor (MOR). Among novel synthetic opioids (NSOs), they dominate the recreational drug market and are the main culprits for the opioid crisis, which has been exacerbated by the COVID-19 pandemic. By taking advantage of the crystal structures of the MOR, several groups have investigated the binding mechanism of fentanyl, but have not reached a consensus, in terms of both the binding orientation and the fentanyl conformation. Thus, the binding mechanism of fentanyl at the MOR remains an unsolved and challenging question. Here, we carried out a systematic computational study to investigate the preferred fentanyl conformations, and how these conformations are being accommodated in the MOR binding pocket. We characterized the free energy landscape of fentanyl conformations with metadynamics simulations, and compared and evaluated several possible fentanyl binding conditions in the MOR with long-timescale molecular dynamics simulations. Our results indicate that the most preferred binding pose in the MOR binding pocket corresponds well with the global minimum on the energy landscape of fentanyl in the absence of the receptor, while the energy landscape can be reconfigured by modifying the fentanyl scaffold. The interactions with the receptor may stabilize a slightly unfavored fentanyl conformation in an alternative binding pose. By extending similar investigations to fentanyl analogs, our findings establish a structure-activity relationship of fentanyl binding at the MOR. In addition to providing a structural basis to understand the potential toxicity of the emerging NSOs, such insights will contribute to developing new, safer analgesics. -arrestins bind GPCRs to terminate G protein signaling and to facilitate other downstream signaling pathways. Using single-molecule fluorescence resonance energy transfer imaging, we show that -arrestin is strongly autoinhibited in its basal state. Its engagement with a phosphopeptide mimicking phosphorylated receptor tail efficiently releases the -arrestin tail from its N domain to assume distinct conformations. Unexpectedly, we find that -arrestin binding to phosphorylated receptor, with a phosphorylation barcode identical to the isolated phosphopeptide, is highly inefficient and that agonist-promoted receptor activation is required for -arrestin activation, consistent with the release of a sequestered receptor C tail. These findings, together with focused cellular investigations, reveal that agonism and receptor C-tail release are specific determinants of the rate and efficiency of -arrestin activation by phosphorylated receptor. We infer that receptor phosphorylation patterns, in combination with receptor agonism, synergistically establish the strength and specificity with which diverse, downstream -arrestin-mediated events are directed.

芬太尼及其类似物是微阿片受体（MOR）的选择性激动剂。在新型合成阿片类药物（nso）中，它们主导了娱乐性药物市场，是阿片类药物危机的主要罪魁祸首，这种危机因COVID-19大流行而加剧。利用MOR的晶体结构，一些研究小组研究了芬太尼的结合机理，但无论是结合取向还是芬太尼的构象，都没有达成共识。因此，芬太尼在MOR的结合机制仍然是一个未解决的和具有挑战性的问题。在这里，我们进行了系统的计算研究，以研究芬太尼的首选构象，以及这些构象是如何在MOR结合口袋中被容纳的。我们通过元动力学模拟表征了芬太尼构象的自由能格局，并通过长时间分子动力学模拟比较和评估了几种可能的芬太尼在MOR中的结合条件。我们的研究结果表明，在没有受体的情况下，MOR结合口袋中最优选的结合姿态与芬太尼能量格局的全局最小值相吻合，而能量格局可以通过修改芬太尼支架来重新配置。与受体的相互作用可以在另一种结合姿势中稳定稍微不利的芬太尼构象。通过将类似的研究扩展到芬太尼类似物，我们的发现建立了芬太尼在MOR上结合的结构-活性关系。除了为了解新兴nso的潜在毒性提供结构基础外，这些见解将有助于开发新的，更安全的镇痛药。