Probing the Potassium Channel Inhibitor Binding Site

描述（由申请人提供）： 钾通道含有保守的离子传导孔，其含有能够结合多种药物的混杂配体结合位点。 确定该位点的精确位置以及结合发生的机制一直是难以捉摸的。 通道中的小序列差异影响疏水性、芳香性、空腔大小和通道门控，这些都被认为影响配体结合亲和力。 KcsA是一种结构已知的细菌通道，由于其相对容易突变、高度表达和结晶，是研究钾通道家族孔区的合适模型。我建议建立一个使用KcsA钾通道的系统，使用诱变沿着结构生物学和电生理学方法来研究通道腔的特征。 我还将表达和结晶HERG（人类ether-a-go-go相关基因），这是一种存在于心肌细胞中的钾通道。HERG特别令人感兴趣，因为许多常见药物阻断其通道，导致功能丧失，这导致异常电信号（长QT综合征），可导致心律失常性尖端扭转型室性心动过速，有时会突然心力衰竭。

DESCRIPTION (provided by applicant): Potassium channels contain a conserved ion conduction pore that contains a promiscuous ligand binding site able to bind a multitude of drugs. Determining the precise location of the site, and the mechanism by which binding occurs has been elusive. Small sequence differences in the channels affect hydrophobicity, aromaticity, cavity size, and channel gating which are all thought to affect ligand binding affinity. KcsA, the bacterial channel of known structure, is a suitable model for studying the pore region of the family of potassium channels due to the relative ease with which it can be mutated, highly expressed, and crystallized, I propose to establish a system using the KcsA potassium channel to study the features of the channel cavity using mutagenesis along with both structural biology and electrophysiology methods. I will also express and crystallize HERG (human ether-a-go-go-related gene), a potassium channel present in heart muscle cells. HERG is of particular interest because many common drugs block its channel causing loss of function, which results in an abnormal electrical signal (long-QT syndrome) that can lead to the arrythmia Torsades de Pointes and sometimes sudden heart failure.