Chemical Biology of Voltage-Gated Sodium and Potassium Channels

描述（由申请方提供）：电压门控钠（NaV）和钾（KV）通道蛋白是调节基本电兴奋性以及几乎所有可兴奋细胞中动作电位起始和复极化的基础。这些通道已经从原始的K+选择性孔进化成具有调节机制的多种蛋白质，使它们能够对神经、心血管和免疫系统中的特定刺激做出反应。该蛋白家族对人类健康的重要性突出表现在以下事实：NaV或Kv通道的遗传性或获得性缺陷导致癫痫、肌强直、红斑性肢痛症和心律失常;导致可兴奋组织（如心肌）中K+通道的门控动力学或表达变化的突变可导致心律失常和心源性猝死的易感性（长或短QT综合征）;并且在心脏肥大或持续性心律失常期间观察到KV和NaV通道表达的显著电重构。不幸的是，广泛的兴奋性障碍在很大程度上仍然无法治疗，如果要开发有效的治疗方法，就需要一种新的方法来缩小我们对NaV和KV门控和选择性的理解中的差距。值得注意的是，虽然离子通道（特别是电压门控离子通道超家族的离子通道）已经在宏观和原子水平上进行了表征，但这些研究缺乏识别与功能作用有关的氨基酸的基本化学性质所需的分辨率。这些信息的缺乏仍然是我们理解离子渗透和通道门控以及最终有效药物设计的重要障碍。在这里，我们建议设计和应用功能强大的合成工具，在量身定制的非天然氨基酸的形式，作为一种手段，实现假设驱动的原子级诱变，以达到一个生理终点：离子选择性和通道门控的基础的理解。此外，虽然我们期望最终能够进行基于结构的药物设计，但真核NaV还不存在结构，这里提出的工作将直接告诉我们细菌NaV的哪些特征（现在可以获得结构）与真核NaV相关。最后，我们的研究结果将消除一个重要的技术障碍，原子水平，功能的理解门控和渗透机制采用的NaV和KV通道-两个被证明的药物靶点在兴奋性障碍的管理。拟议研究的成功将使产生新的氨基酸成为可能，这些氨基酸将被研究界广泛使用。

DESCRIPTION (provided by applicant): Voltage-gated sodium (NaV)- and potassium (KV)-channel proteins underlie the regulation of basal electrical excitability and the initiation and repolarization of action potentials in virtually all excitable cells. These channels have evolved from primordial K+-selective pores into diverse proteins with regulatory mechanisms that enable them to respond to specific stimuli in the nervous, cardiovascular, and immune systems. The importance of this protein family to human health is highlighted by the facts that: inherited or acquired defects in NaV or Kv channels cause epilepsy, myotonia, erythromelalgia and cardiac arrhythmias; mutations that lead to changes in the gating kinetics or expression of K+ channels in excitable tissues such as cardiac muscle can lead to arrhythmias and susceptibility to sudden cardiac death (long or short QT syndromes); and significant electrical remodeling of KV- and NaV-channel expression is observed during cardiac hypertrophy or persistent arrhythmias. Unfortunately, a broad spectrum of excitability disorders remains largely untreatable, and a fresh approach to closing the gap in our understanding of NaV and KV gating and selectivity will be needed if effective therapeutics are to be developed. Notably, although ion channels (particularly those of the voltage-gated ion channel superfamily) have been characterized on both the macroscopic and atomic levels, these studies lack the resolution needed to identify essential chemical property(s) of the amino acids that have been implicated in functional roles. The lack of such information remains a significant block to our understanding of ion permeation and channel gating, and ultimately, effective drug design. Here we propose to design and apply powerful synthetic tools, in the form of tailor-made unnatural amino acids, as a means of achieving hypothesis-driven atomic-level mutagenesis to reach a physiological endpoint: an understanding of the basis of ion selectivity and channel gating. Further, although we expect to eventually be able to perform structure-based drug design, no structures yet exist for eukaryotic NaVs, and the work proposed here will inform us directly about which traits of bacterial NaV's (where structures are now available) are relevant to eukaryotic NaV's. Finally, the results of our study will remove a significant technical barrier to an atomic-level, functional understanding of the gating and permeation mechanisms employed by NaV and KV channels-two proven drug targets in the management of excitability disorders. Success of the proposed study will make it possible to generate novel amino acids that will be widely available to the research community.