Chemical biology of voltage-gated sodium and potassium channels

描述（由申请人提供）：电压门控钠（NaV）和钾（KV）通道蛋白在几乎所有可兴奋细胞的基础电兴奋性和动作电位的起始和复极化调节中起着重要作用。这些通道已经从原始的K+选择性孔进化为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。NaV或Kv通道的遗传或获得性缺陷导致癫痫、肌强直、红斑性肢痛和心律失常，这些事实突出了该蛋白质家族对人类健康的重要性；导致门控动力学或可兴奋组织（如心肌）中K+通道表达改变的突变可导致心律失常和心源性猝死易感性（长QT综合征或短QT综合征）；在心肌肥厚或持续性心律失常时，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差距。值得注意的是，尽管离子通道（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强大的合成工具，以定制的非天然氨基酸的形式，作为实现假设驱动的原子水平诱变的一种手段，以达到生理终点：理解离子选择性和通道门控的基础。此外，尽管我们期望最终能够进行基于结构的药物设计，但真核NaV的结构尚不存在，本文提出的工作将直接告诉我们细菌NaV的哪些特征（哪些结构现在可用）与真核NaV相关。最后，我们的研究结果将消除对NaV和KV通道门控和渗透机制的原子水平和功能理解的重大技术障碍，NaV和KV通道是管理兴奋性障碍的两个已证实的药物靶点。这项研究的成功将使产生新的氨基酸成为可能，这些氨基酸将被广泛地提供给研究界。

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.