Structural Basis for KCNE Modulation of the KCNQ1 Channel

描述(申请人提供)：人的KCNQ1电压门控钾通道由与辅助亚单位KCNE1的相互作用调节，这一过程对健康的心脏和听觉功能至关重要。KCNQ1和KCNE1基因突变会导致先天性长QT综合征(LQTS)和某些形式的耳聋。KCNE1既可以减缓电压刺激的通道激活，又可以显著增强开放状态的电导。KCNE家族其他成员在KCNQ1通道功能上表现出截然不同的变化。在本项目即将到来的阶段，目标是：目的1.在KCNE1在实际脂类双层中溶解的条件下，使用核磁共振确定KCNE1的三维结构。这一目的将测试我们最近在经典胶束中确定的KCNE1的结构是否代表了蛋白质在脂质双层中的真实结构，或者所确定的结构中在形成我们的KCNE1功能工作模型中至关重要的元素是否实际上是在胶束中工作的人工制品。目的2.利用KCNE1和KCNQ1的突变、生化测量和KCNQ1通道特性的电生理记录，严格评估和完善KCNE1如何减缓KCNQ1通道开放和增强开放状态电导的现有工作模型。目的3.确定KCNE3在双分子膜中的三维结构，并建立KCNE3如何快速激活Q1通道功能的工作模型。目的4.对KCNE3快速激活KCNQ1通道功能的新模型进行结构-功能和生化测试/提炼。目的5.确定KCNE4在双分子膜中的结构，建立KCNE4抑制KCNQ1通道功能的工作模型。

DESCRIPTION (provided by applicant): The human KCNQ1 voltage-gated potassium channel is modulated by interactions with an accessory subunit, KCNE1, a process that is essential for healthy cardiac and auditory function. Mutations in KCNQ1 and KCNE1 result in congenital long QT syndrome (LQTS) and some forms of deafness. KCNE1 acts both to slow down voltages-stimulated channel activation and also dramatically enhances the conductance of the open state. Other KCNE family members exert radically different changes in KCNQ1 channel function. In the upcoming phase of this project the aims are: Aim 1. Use NMR to determine the 3-D structure of KCNE1 under conditions in which it is solubilized in actual lipid bilayers. This aim will test whether the structure of KCNE1 we recently determined in classical micelles represents the bona fide structure of the protein in lipid bilayers, or whether elements of the determined structure that were crucial in formulating our working model for KCNE1 function were, in fact, artifacts of working in micelles. Aim 2. Using mutagenesis of both KCNE1 and KCNQ1, biochemical measurements, and electrophysiological recordings of KCNQ1 channel properties, critically evaluate and refine the current working model for how KCNE1 slows down KCNQ1 channel opening and enhances open state conductance. Aim 3. Determine the 3-D structure of KCNE3 in bilayers and formulate a working model for how KCNE3 rapidly activates Q1 channel function. Aim 4. Carry out structure-function and biochemical testing/refinement of the new model for how KCNE3 rapidly activates KCNQ1 channel function. Aim 5. Determine the structure of KCNE4 in bilayers and formulate a working model for how KCNE4 inhibits KCNQ1 channel function.