Structural Basis for Antiarrhythmic Drug Action

电压门控钠通道(NaV1.5)启动动作电位，电压门控钙通道(Cav1.2)启动动作电位 启动心肌细胞的兴奋/收缩偶联。它们是导致基因突变的分子靶点 用于控制和预防危及生命的心律失常的抗心律失常药物(AADS)。 我们已经确定了细菌NAV通道NAAB和模型钙通道CavAb的结构 通过X射线结晶学，我们已经确定了初级心脏NAV通道NaV1.5的结构 低温电子显微镜(Cryo-EM)的高分辨率。这项工作为我们提供了对 离子选择性过滤器和钠、钙选择性机理、电压传感器的结构和机理 电压依赖门控、激活门和失活门及其功能相互作用的受体 AADS的结合部位，以及AADS通过开放的激活门进入其受体部位的机制 毛孔两侧有开窗孔。导致遗传性心律失常的NaV1.5突变，包括 扩张型心肌病和长QT综合征，映射到毛孔模块、电压传感器、激活门、 以及NAV和CAV通道的快速失活门，为探索这些通道的病理生理开辟了道路 结构层面的突变。这里我们将研究NAV和CAV通道功能的结构基础， AADS复杂的孔道封闭机制及其病理生理作用机制 心律失常突变的可能性。目的1.我们将确定NAV1.5通道在静息、开放和 分析了开态离子选择性和电导的分子机制 NAV1.5版本。目的2.制备封闭、开放和失活的NaV1.5与AADS的络合物 束缚，我们将以高分辨率解析它们的结构。我们将调查该药物的结构差异- IA类、IB类和IC类AADS形成的受体复合体，以了解 药物作用的不同导致了它们不同的临床用途。我们将研究开窗在 IA、IB和IC AADS类的休眠状态块。目标3.我们将插入导致扩张症的突变 心肌病和长QT综合征-3型进入NAAB和NAV1.5的病理生理特征 对钠电流和门控孔电流的影响及其结构的高分辨X射线解析 结晶学和/或低温电子显微镜。目的4.我们将导致Timothy综合征的突变插入到CavAb中，并 Cav1.2，测定其对钙电流和钙电流的病理生理效应，并在较高的温度下分辨其结构 通过X射线结晶学和低温电子显微镜进行分辨。总体而言，这些研究开启了令人兴奋的可能性 了解天然构象和致病构象中心脏NAV和CaV通道的原子细节 学习如何操纵美国反兴奋剂系统的结构，使其更具体、更有效和更安全。

Voltage-gated sodium (Nav1.5) channels initiate action potentials and voltage-gated calcium (Cav1.2) channels initiate excitation/contraction coupling in cardiac myocytes. They are molecular targets for mutations that cause arrhythmias and for antiarrhythmic drugs (AADs) used in control and prevention of life-threatening arrhythmias. We have determined the structures of the bacterial Nav channel NavAb and the model calcium channel CavAb by X-ray crystallography, and we have determined the structure of the primary cardiac Nav channel Nav1.5 at high resolution by cryogenic electron microscopy (cryo-EM). This work gave new insight into the structure of the ion selectivity filter and mechanism of Na and Ca selectivity, the structure of the voltage sensors and mechanisms of voltage-dependent gating, the activation and inactivation gates and their functional interaction, the receptor sites for AADs, and the mechanism of access of AADs to their receptor site through the open activation gate and fenestrations in the sides of the pore. Mutations in Nav1.5 that cause inherited cardiac arrhythmias, including Dilated Cardiomyopathy and Long QT Syndrome, map onto the pore module, voltage sensor, activation gate, and fast inactivation gate of Nav and Cav channels, opening the way to probing the pathophysiology of these mutations at the structural level. Here we will investigate the structural basis for Nav and Cav channel function, the complex pore-blocking mechanisms of AADs, and the mechanisms underlying the pathophysiological effects of arrhythmia mutations. Aim 1. We will determine the structure of Nav1.5 channels in resting, open, and inactivated states and analyze the molecular mechanisms for ion selectivity and conductance in the open state of Nav1.5. Aim 2. We will prepare complexes of Nav1.5 in the closed, open, and inactivated states with AADs bound, and we will resolve their structures at high resolution. We will probe structural differences in the drug- receptor complexes formed by Class IA, IB, and IC AADs in order to understand the structural basis for the differences in drug action that lead to their different clinical uses. We will examine the role of the fenestrations in resting-state block by Class IA, IB, and IC AADs. Aim 3. We will insert mutations that cause Dilated Cardiomyopathy and Long QT Syndrome Type-3 into NavAb and Nav1.5, characterize their pathophysiological effects on Na currents and gating pore currents, and resolve their structures at high resolution by X-ray crystallography and/or cryo-EM. Aim 4. We will insert mutations that cause Timothy Syndrome into CavAb and Cav1.2, determine their pathophysiological effects on Ca and Ba currents, and resolve their structures at high resolution by X-ray crystallography and cryo-EM. Overall, these studies open the exciting possibility of understanding cardiac Nav and Cav channels in atomic detail in native and pathogenic conformations and learning how to manipulate the structures of AADs to make them more specific, more effective, and safer.