{"title":"Secondary structure transitions and dual PIP2 binding define cardiac KCNQ1-KCNE1 channel gating.","authors":"Ling Zhong, Xiaoqing Lin, Xinyu Cheng, Shuangyan Wan, Yaoguang Hua, Weiwei Nan, Bin Hu, Xiangjun Peng, Zihan Zhou, Qiansen Zhang, Huaiyu Yang, Frank Noé, Zhenzhen Yan, Dexiang Jiang, Hangyu Zhang, Fengjiao Liu, Chenxin Xiao, Zhuo Zhou, Yimin Mou, Haijie Yu, Lijuan Ma, Chen Huang, Vincent Kam Wai Wong, Sookja Kim Chung, Bing Shen, Zhi-Hong Jiang, Erwin Neher, Wandi Zhu, Jin Zhang, Panpan Hou","doi":"10.1038/s41422-025-01182-9","DOIUrl":null,"url":null,"abstract":"<p><p>The KCNQ1 + KCNE1 potassium channel complex produces the slow delayed rectifier current (I<sub>Ks</sub>) critical for cardiac repolarization. Loss-of-function mutations in KCNQ1 and KCNE1 cause long QT syndrome (LQTS) types 1 and 5 (LQT1/LQT5), accounting for over one-third of clinical LQTS cases. Despite prior structural work on KCNQ1 and KCNQ1 + KCNE3, the structural basis of KCNQ1 + KCNE1 remains unresolved. Using cryo-electron microscopy and electrophysiology, we determined high-resolution (2.5-3.4 Å) structures of human KCNQ1<sub>APO</sub>, and KCNQ1 + KCNE1 in both closed and open states. KCNE1 occupies a pivotal position at the interface of three KCNQ1 subunits, inducing six helix-to-loop transitions in KCNQ1 transmembrane segments. Three of them occur at both ends of the S4-S5 linker, maintaining a loop conformation during I<sub>Ks</sub> gating, while the other three, in S6 and helix A, undergo dynamic helix-loop transitions during I<sub>Ks</sub> gating. These structural rearrangements: (1) stabilize the closed pore and the conformation of the intermediate state voltage-sensing domain, thereby determining channel gating, ion permeation, and single-channel conductance; (2) enable a dual-PIP2 modulation mechanism, where one PIP2 occupies the canonical site, while the second PIP2 bridges the S4-S5 linker, KCNE1, and the adjacent S6', stabilizing channel opening; (3) create a fenestration capable of binding compounds specific for KCNQ1 + KCNE1 (e.g., AC-1). Together, these findings reveal a previously unrecognized large-scale secondary structural transition during ion channel gating that fine-tunes I<sub>Ks</sub> function and provides a foundation for developing targeted LQTS therapy.</p>","PeriodicalId":9926,"journal":{"name":"Cell Research","volume":" ","pages":""},"PeriodicalIF":25.9000,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Cell Research","FirstCategoryId":"99","ListUrlMain":"https://doi.org/10.1038/s41422-025-01182-9","RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CELL BIOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
The KCNQ1 + KCNE1 potassium channel complex produces the slow delayed rectifier current (IKs) critical for cardiac repolarization. Loss-of-function mutations in KCNQ1 and KCNE1 cause long QT syndrome (LQTS) types 1 and 5 (LQT1/LQT5), accounting for over one-third of clinical LQTS cases. Despite prior structural work on KCNQ1 and KCNQ1 + KCNE3, the structural basis of KCNQ1 + KCNE1 remains unresolved. Using cryo-electron microscopy and electrophysiology, we determined high-resolution (2.5-3.4 Å) structures of human KCNQ1APO, and KCNQ1 + KCNE1 in both closed and open states. KCNE1 occupies a pivotal position at the interface of three KCNQ1 subunits, inducing six helix-to-loop transitions in KCNQ1 transmembrane segments. Three of them occur at both ends of the S4-S5 linker, maintaining a loop conformation during IKs gating, while the other three, in S6 and helix A, undergo dynamic helix-loop transitions during IKs gating. These structural rearrangements: (1) stabilize the closed pore and the conformation of the intermediate state voltage-sensing domain, thereby determining channel gating, ion permeation, and single-channel conductance; (2) enable a dual-PIP2 modulation mechanism, where one PIP2 occupies the canonical site, while the second PIP2 bridges the S4-S5 linker, KCNE1, and the adjacent S6', stabilizing channel opening; (3) create a fenestration capable of binding compounds specific for KCNQ1 + KCNE1 (e.g., AC-1). Together, these findings reveal a previously unrecognized large-scale secondary structural transition during ion channel gating that fine-tunes IKs function and provides a foundation for developing targeted LQTS therapy.
期刊介绍:
Cell Research (CR) is an international journal published by Springer Nature in partnership with the Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences (CAS). It focuses on publishing original research articles and reviews in various areas of life sciences, particularly those related to molecular and cell biology. The journal covers a broad range of topics including cell growth, differentiation, and apoptosis; signal transduction; stem cell biology and development; chromatin, epigenetics, and transcription; RNA biology; structural and molecular biology; cancer biology and metabolism; immunity and molecular pathogenesis; molecular and cellular neuroscience; plant molecular and cell biology; and omics, system biology, and synthetic biology. CR is recognized as China's best international journal in life sciences and is part of Springer Nature's prestigious family of Molecular Cell Biology journals.