Pinto-Anwandter Bernardo I
Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois.
Biophys J. 2025 Jun 24. doi: 10.1016/j.bpj.2025.06.029.
The generation and propagation of action potentials in neurons relies on the coordinated activation of voltage-dependent sodium and potassium channels. The Kv1 (Shaker) family of potassium channels drives the repolarization phase of the action potential by opening and closing their pore, a process controlled by a voltage sensor domain. However, a molecular description of how the voltage sensor domain drives pore gating has been constrained by a lack of closed-state structures. Here, we present a structural model of the closed Shaker channel that reveals the structural basis of voltage gating. Using AlphaFold2-based conformational sampling, we identified a partially activated state of the voltage sensor which, when modeled with the full channel, produced a closed state. Based on this model we demonstrate that breaking a backbone hydrogen bond between the S4-S5 linker and S5 helices is a critical part of the activation pathway. Docking studies revealed a hydrophobic cavity in the closed pore that binds 4-aminopyridine, a potassium channel inhibitor used to enhance nerve conduction in multiple sclerosis. Our results demonstrate how the voltage sensor movement drives pore opening and provide a structural framework for developing new therapeutic agents targeting the closed state. We anticipate that the novel methods used in this work will allow the characterization of conformational dynamics in voltage-gated ion channels, enabling drug design efforts focused on state-dependent modulation of ion channels for neurological disorders treatment.
神经元中动作电位的产生和传播依赖于电压依赖性钠通道和钾通道的协同激活。钾通道的Kv1(震荡器)家族通过打开和关闭其孔道来驱动动作电位的复极化阶段,这一过程由电压传感器结构域控制。然而,由于缺乏关闭状态的结构,关于电压传感器结构域如何驱动孔道门控的分子描述受到了限制。在此,我们展示了关闭状态的震荡器通道的结构模型,揭示了电压门控的结构基础。使用基于AlphaFold2的构象采样,我们确定了电压传感器的一个部分激活状态,当与完整通道一起建模时,产生了一个关闭状态。基于该模型,我们证明破坏S4-S5连接体与S5螺旋之间的主链氢键是激活途径的关键部分。对接研究揭示了关闭孔道中的一个疏水腔,该腔结合4-氨基吡啶,一种用于增强多发性硬化症神经传导的钾通道抑制剂。我们的结果展示了电压传感器的运动如何驱动孔道开放,并为开发针对关闭状态的新型治疗药物提供了结构框架。我们预计,这项工作中使用的新方法将能够表征电压门控离子通道中的构象动力学,从而使药物设计工作聚焦于针对神经疾病治疗的离子通道状态依赖性调节。