Propofol, one of the most commonly used intravenous general anesthetics, modulates neuronal function by interacting with ion channels. The mechanisms that link propofol binding to the modulation of distinct ion channel states, however, are not understood. To tackle this problem, we investigated prokaryotic ancestors of eukaryotic voltage-gated Na+ channels (Navs) using unbiased photoaffinity labeling with a photoacitivatable propofol analog (AziPm), electrophysiological methods and mutagenesis. The results directly demonstrate conserved propofol binding sites involving the S4 voltage sensors and the S4-S5 linkers in NaChBac and NavMs, and also suggest state-dependent changes at these sites. Then, using molecular dynamics simulations to elucidate the structural basis of propofol modulation, we show that the S4 voltage sensors and the S4-S5 linkers shape two distinct propofol binding sites in a conformation-dependent manner. These interactions help explain how propofol binding promotes activation-coupled inactivation to inhibit Nav channel function.

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原核电压门控钠通道的异丙酚结合位点

丙泊酚是最常用的静脉全身麻醉剂之一，它通过与离子通道相互作用来调节神经元功能。然而，将异丙酚结合至不同离子通道状态的调节的机制尚不清楚。为了解决这个问题，我们使用可光活化的异丙酚类似物（AziPm），电生理方法和诱变技术，使用无偏光亲和标记法，研究了真核电压门控Na +通道（Navs）的原核祖先。结果直接证明了在NaChBac和NavMs中涉及S4电压传感器和S4-S5接头的保守的异丙酚结合位点，并且还暗示了这些位点的状态依赖性变化。然后，使用分子动力学模拟阐明丙泊酚调节的结构基础，我们表明，S4电压传感器和S4-S5连接子以构象依赖性方式形成两个不同的异丙酚结合位点。这些相互作用有助于解释丙泊酚结合如何促进激活偶联的失活以抑制Nav通道功能。