The crystal structure of Ac-AChBP in complex with α-conotoxin LvlA reveals the mechanism of its selectivity towards different nAChR subtypes  

作　　者：Manyu Xu Xiaopeng Zhu Jinfang Yu Jinpeng Yu Sulan Luo Xinquan Wang 

机构地区：[1]The Ministry of Education Key Laboratory of Protein Science, School of Life Sciences, Beijing Advanced Innovation Center for Structural Biology, Collaborative Innovation Center for Biotherapy, Tsinghua University, Beijing 100084, China [2]Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, Hainan University, Haikou 570228, China

出　　处：《Protein & Cell》2017年第9期675-685,共11页蛋白质与细胞（英文版）

基　　金：ACKNOWLEDGEMENTS We thank scientists at SSRF BL17U beam line for assistance in diffraction data collection. This work was supported by the National Natural Science Foundation of China （Grant Nos. 31470751 and U1405228 to Xinquan Wang） and the Beijing Advanced Innovation Center for Structural Biology. This work was also supported, in part, by the Major Intemational Joint Research Project of National Natural Science Foundation of China （81420108028）, and Changjiang Scholars and Innovative Research Teams in Universities Grant （IRT_I 5R15）.

摘　　要：The a3＊ nAChRs, which are considered to be promising drug targets for problems such as pain, addiction, cardiovascular function, cognitive disorders etc., are found throughout the central and peripheral nervous system. The α-conotoxin （α-CTx） LvlA has been identified as the most selective inhibitor of α3β2 nAChRs known to date, and it can distinguish the α3132 nAChR subtype from the α6/α3β2β3 and α3β4 nAChR subtypes. However, the mechanism of its selectivity towards α3132, α6/α3β2β3, and α3β4 nAChRs remains elusive. Here we report the co-crystal structure of LvlA in complex with Aplysia californica acetylcholine binding protein （Ac-AChBP） at a resolution of 3.4 A. Based on the structure of this complex, together with homology modeling based on other nAChR subtypes and binding affinity assays, we conclude that Asp-11 of LvlA plays an important role in the selectivity of LvlA towards α3132 and α31o6132133 nAChRs by making a salt bridge with Lys-155 of the rat α3 subunit. Asn-9 lies within a hydrophobic pocket that is formed by Met-36, Thr-59, and Phe-119 of the rat β2 subunit in the α3β2 nAChR model, revealing the reason for its more potent selectivity towards the a3β2 nAChR subtype. These results provide molecular insights that can be used to design ligands that selectively target α3β2 nAChRs, with significant implications for the design of new therapeutic a-CTxs.The a3＊ nAChRs, which are considered to be promising drug targets for problems such as pain, addiction, cardiovascular function, cognitive disorders etc., are found throughout the central and peripheral nervous system. The α-conotoxin （α-CTx） LvlA has been identified as the most selective inhibitor of α3β2 nAChRs known to date, and it can distinguish the α3132 nAChR subtype from the α6/α3β2β3 and α3β4 nAChR subtypes. However, the mechanism of its selectivity towards α3132, α6/α3β2β3, and α3β4 nAChRs remains elusive. Here we report the co-crystal structure of LvlA in complex with Aplysia californica acetylcholine binding protein （Ac-AChBP） at a resolution of 3.4 A. Based on the structure of this complex, together with homology modeling based on other nAChR subtypes and binding affinity assays, we conclude that Asp-11 of LvlA plays an important role in the selectivity of LvlA towards α3132 and α31o6132133 nAChRs by making a salt bridge with Lys-155 of the rat α3 subunit. Asn-9 lies within a hydrophobic pocket that is formed by Met-36, Thr-59, and Phe-119 of the rat β2 subunit in the α3β2 nAChR model, revealing the reason for its more potent selectivity towards the a3β2 nAChR subtype. These results provide molecular insights that can be used to design ligands that selectively target α3β2 nAChRs, with significant implications for the design of new therapeutic a-CTxs.

关 键 词：base editor high-fidelity mouse embryos proximal-site deamination whole-genome sequencing 

分 类 号：Q422[生物学—神经生物学] Q577[生物学—生理学]