Structural basis of the binding of blockers to potassium channels

描述（由申请人提供）：本项目的目的是使用X射线晶体学和电生理学技术阐明小有机阻滞剂与K+通道中央腔结合的结构基础。钾通道在调节许多不同类型细胞的膜兴奋性中起关键作用。许多K+通道被其孔内的小分子结合所阻断。这些阻断剂中的一些是内源性的，并在生理通道功能中发挥作用，而另一些是外源性分子-许多具有重要的药理学意义。我们将使用电生理学和X射线晶体学技术来研究两种类型的小的有机阻断剂的结合机制：季铵（QA）离子和药物，阻止hERG K+通道。了解K+通道阻滞剂在原子细节上的相互作用将为理解K+通道的功能和调节提供关键信息。此外，它可能有助于在药物开发的早期阶段识别和消除或重新设计可能导致危及生命的副作用（如长QT综合征）的药物。我们将使用细菌K+通道KcsA作为模型系统，通过合理地突变它来模拟其他K+通道。我们将进行电生理学研究，并解决与阻滞剂复杂的模型的3-D结构。

DESCRIPTION (provided by applicant): The objective of this project is to elucidate the structural basis of the binding of small organic blockers to the central cavity of K+ channels, using X-ray crystallographic and electrophysiological techniques. Potassium channels play critical roles in regulating membrane excitability of many diverse cell types. Many K+ channels are blocked by the binding of small molecules within their pores. Some of these blockers are endogenous and play roles in physiological channel function, while others are exogenous molecules-many of great pharmacological importance. We will use electrophysiological and X-ray crystallographic techniques to study the binding mechanisms of two types of small organic blockers: quaternary ammonium (QA) ions and drugs that block the hERG K+ channel. Understanding the K+ channel-blocker interactions at atomic detail will provide critical information for understanding of K+ channel function and regulation. Moreover, it may help to identify and eliminate or re-design drugs that may cause life-threatening side effects such as the long QT syndrome at early stages of drug development. We will use the bacterial K+ channel KcsA as a model system by rationally mutating it to mimic other K+ channels. We will perform electrophysiological studies, and solve the 3-D structures of the model in complex with the blockers.