The voltage-gated potassium channel KCNQ2 is responsible for M-current in neurons and is an important drug target to treat epilepsy, pain and several other diseases related to neuronal hyper-excitability. A list of synthetic compounds have been developed to directly activate KCNQ2, yet our knowledge of their activation mechanism is limited, due to lack of high-resolution structures. Here, we report cryo-electron microscopy (cryo-EM) structures of the human KCNQ2 determined in apo state and in complex with two activators, ztz240 or retigabine, which activate KCNQ2 through different mechanisms. The activator-bound structures, along with electrophysiology analysis, reveal that ztz240 binds at the voltage-sensing domain and directly stabilizes it at the activated state, whereas retigabine binds at the pore domain and activates the channel by an allosteric modulation. By accurately defining ligand-binding sites, these KCNQ2 structures not only reveal different ligand recognition and activation mechanisms, but also provide a structural basis for drug optimization and design.
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Structure coordinates and cryo-EM density maps have been deposited in the protein data bank under accession numbers 7CR0 and EMD-30443 for apo KCNQ2, 7CR3 and EMD-30446 for apo KCNQ2-CaM, 7CR1 and EMD-30444 for ztz240-bound KCNQ2-Z, 7CR4 and EMD-30447 for ztz240-bound KCNQ2-CaM-Z, 7CR2 and EMD-30445 for RTG-bound KCNQ2-R, 7CR7 and EMD-30448 for RTG-bound KCNQ2-CaM-R.
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Single-particle cryo-EM data were collected at Center of Cryo-Electron Microscopy at Zhejiang University. We are grateful to Dr. Xing Zhang, Shenghai Chang, and Xiaokang Zhang for their support in facility access and data acquisition. We thank Dr. Fan Yang and Lizhen Xu for their assistance with the noise analysis of the electrophysiological data. We thank the support of ECNU Multifunctional Platform for Innovation (001). This work was supported in part by the Ministry of Science and Technology of China (2018YFA0508100 to J.G. and Q.Z., and 2016YFA0500404 to S.Y.), the National Natural Science Foundation of China (31870724 to J.G., 31800699 to Q.Z., 31525001 and 31430019 to S.Y.), the Fundamental Research Funds for the Central Universities (to J.G. and H.Y.), the “Personalized Medicines-Molecular Signature-based Drug Discovery and Development”, the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA12040220 to H.Y.), the National Science and Technology Major Project “Key New Drug Creation and Manufacturing Program” of China (2018ZX09711002 to Q.Z.), and the “XingFuZhiHua” funding of ECNU (44300-19311-542500/006 to H.Y.).
The authors declare no competing interests.
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Li, X., Zhang, Q., Guo, P. et al. Molecular basis for ligand activation of the human KCNQ2 channel. Cell Res (2020). https://doi.org/10.1038/s41422-020-00410-8