Abstract：
Nicotinic acetylcholine receptor of α7 type (α7-nAChR) presented in the nervous and immune systems and epithelium is a promising therapeutic target for cognitive disfunctions and cancer treatment. Weak toxin from Naja kaouthia venom (WTX) is a non-conventional three-finger neurotoxin, targeting α7-nAChR with weak affinity. There are no data on interaction mode of non-conventional neurotoxins with nAChRs. Using α-bungarotoxin (classical three-finger neurotoxin with high affinity to α7-nAChR), we showed applicability of cryo-EM to study complexes of α7-nAChR extracellular ligand-binding domain (α7-ECD) with toxins. Using cryo-EM structure of the α7-ECD/WTX complex, together with NMR data on membrane active site in the WTX molecule and mutagenesis data, we reconstruct the structure of α7-nAChR/WTX complex in the membrane environment. WTX interacts at the entrance to the orthosteric site located at the receptor intersubunit interface and simultaneously forms the contacts with the membrane surface. WTX interaction mode with α7-nAChR significantly differs from α-bungarotoxin\'s one, which does not contact the membrane. Our study reveals the important role of the membrane for interaction of non-conventional neurotoxins with the nicotinic receptors.
摘要：
存在于神经和免疫系统以及上皮中的α7型烟碱乙酰胆碱受体（α7-nAChR）是认知障碍和癌症治疗的有希望的治疗靶标。来自眼镜蛇毒（WTX）的弱毒素是一种非常规的三指神经毒素，以弱亲和力靶向α7-nAChR。没有关于非常规神经毒素与nAChR的相互作用模式的数据。使用α-银环蛇毒素（对α7-nAChR具有高亲和力的经典三指神经毒素），我们显示了cryo-EM用于研究α7-nAChR细胞外配体结合域（α7-ECD）与毒素的复合物的适用性。利用α7-ECD/WTX复合物的低温EM结构，连同WTX分子中膜活性位点的NMR数据和诱变数据，我们在膜环境中重建了α7-nAChR/WTX复合物的结构。WTX在位于受体亚基间界面的正构位点的入口处相互作用，同时与膜表面形成接触。WTX与α7-nAChR的相互作用模式与α-银环蛇毒素的相互作用模式明显不同，它不接触膜。我们的研究揭示了膜在非常规神经毒素与烟碱受体相互作用中的重要作用。
