Chan Aaron N, Quach Co D, Handlin Lucas J, Lessie Erin N, Tajkhorshid Emad, Dai Gucan
Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Visualization, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Champaign, IL, USA.
Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO, USA.
Nat Commun. 2025 Aug 3;16(1):7126. doi: 10.1038/s41467-025-62472-9.
Voltage sensors are essential for electromechanical coupling in hERG K channels, critical to cardiac rhythm. These sensors respond to membrane potential changes by moving within the transmembrane electric field. Mutations in hERG voltage-sensing arginines, associated with Long-QT syndrome, alter channel gating, though underlying mechanisms remain unclear. Using live-cell fluorescence lifetime imaging microscopy, transition metal FRET, an improved dual stop-codon-mediated strategy for noncanonical amino-acid incorporation, and molecular dynamics simulations, we identify intermediate voltage-sensor conformations induced by neutralizing key arginines in the charge transfer center. Phasor plot analysis of lifetime data reveals multiple voltage-dependent FRET states in these mutants, in contrast to the single high-FRET state observed in controls. These intermediate FRET states reflect distinct conformations of the voltage sensor, corresponding to predicted structures of voltage sensors in molecular dynamics simulations. This study provides insights into cardiac channelopathies, highlighting a structural mechanism that impairs voltage sensing in cardiac arrhythmias.
电压传感器对于hERG钾通道中的机电耦合至关重要，而这对心律起着关键作用。这些传感器通过在跨膜电场中移动来响应膜电位变化。与长QT综合征相关的hERG电压感应精氨酸突变会改变通道门控，但其潜在机制仍不清楚。我们使用活细胞荧光寿命成像显微镜、过渡金属荧光共振能量转移、一种改进的用于非天然氨基酸掺入的双终止密码子介导策略以及分子动力学模拟，确定了通过中和电荷转移中心的关键精氨酸所诱导的中间电压传感器构象。对寿命数据的相量图分析揭示了这些突变体中多个电压依赖性荧光共振能量转移状态，这与在对照中观察到的单一高荧光共振能量转移状态形成对比。这些中间荧光共振能量转移状态反映了电压传感器的不同构象，与分子动力学模拟中预测的电压传感器结构相对应。这项研究为心脏通道病提供了见解，突出了一种损害心律失常中电压感应的结构机制。
