Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao 266021, China.
Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266200, China.
ACS Chem Neurosci. 2021 Dec 15;12(24):4535-4545. doi: 10.1021/acschemneuro.1c00568. Epub 2021 Nov 5.
Nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated ion channels that are abundantly expressed in the central and peripheral nervous systems, playing an important role in mediating neurotransmitter release and inter-synaptic signaling. Dysfunctional nAChRs are associated with neurological disorders, and studying the structure and function of nAChRs is essential for development of drugs or strategies for treatment of related diseases. α-Conotoxins are selective antagonists of the nAChR and are an important class of drug leads. So far, the antagonistic mechanism of α-conotoxins toward the nAChRs is still unclear. In this study, we built an α3β2 nAChR homology model and investigated its conformational transition mechanism upon binding with a highly potent inhibitor, α-conotoxin BuIA, through μs molecular dynamic simulations and site-directed mutagenesis studies. The results suggested that the α3β2 nAChR underwent global conformational transitions and was stabilized into a closed state with three hydrophobic gates present in the transmembrane domain by BuIA. Finally, the probable antagonistic mechanism of BuIA was proposed. Overall, the closed-state model of the α3β2 nAChR bound with BuIA is not only essential for understanding the antagonistic mechanism of α-conotoxins but also particularly valuable for development of therapeutic inhibitors in future.
烟碱型乙酰胆碱受体 (nAChRs) 是五聚体配体门控离子通道，在中枢和周围神经系统中大量表达，在介导神经递质释放和突触间信号传递中发挥重要作用。功能失调的 nAChRs 与神经紊乱有关，研究 nAChRs 的结构和功能对于开发治疗相关疾病的药物或策略至关重要。α-芋螺毒素是 nAChR 的选择性拮抗剂，是一类重要的药物先导物。到目前为止，α-芋螺毒素对 nAChRs 的拮抗机制仍不清楚。在这项研究中，我们构建了一个 α3β2 nAChR 同源模型，并通过 μs 分子动力学模拟和定点突变研究，研究了其与高活性抑制剂 α-芋螺毒素 BuIA 结合时的构象转变机制。结果表明，BuIA 使 α3β2 nAChR 发生整体构象转变，并通过跨膜域中的三个疏水性门稳定为关闭状态。最后，提出了 BuIA 可能的拮抗机制。总之，与 BuIA 结合的 α3β2 nAChR 的关闭状态模型不仅对于理解 α-芋螺毒素的拮抗机制至关重要，而且对于未来开发治疗性抑制剂也具有特别重要的价值。
