Regulation of KCNH ion channels

描述（由申请人提供）：离子通道是大脑和心脏所有电兴奋性的基础，离子通道缺陷是许多人类疾病的原因。KCNH通道家族，包括ERG、ELK和EAG，是电压依赖性钾通道，它们在塑造神经元和心肌细胞的电活动中起着特殊的作用。KCNH通道缺陷已被证明与认知缺陷、精神分裂症、心律失常和癌症风险增加有关。最近已经清楚地表明，KCNH通道的特化门控来自其独特的细胞内结构域，n端eag结构域和c端c连接子/CNBHD。在本提案中，我们将验证KCNH通道的c -link /CNBHD是介导eag结构域和其他细胞内调节作用的关键调控结构域的假设。我们将以三个令人兴奋的新的x射线晶体结构为基础，我们已经解决了三个不同的KCNH通道的细胞内结构域：1)ELK的c -连接体/CNBHD， 2) ERG的c -连接体/CNBHD，以及3)eag的CNBHD和eag结构域的复合物。这些新结构揭示了意想不到的特征，如eag结构域和CNBHD之间的直接相互作用，以及CNBHD结合位点上调节门控的内在配体。它们为更好地理解KCNH通道的门控和调控机制提供了一个框架。为了实现这一目标，我们将利用x射线晶体学、电生理学和荧光的力量来研究KCNH通道门控过程中eag结构域和c -连接体/CNBHD的结构和重排。

DESCRIPTION (provided by applicant): Ion channels underlie all electrical excitability in the brain and heart, and defects in ion channels are the cause of many human disorders. The KCNH family of channels, ERG, ELK, and EAG, are voltage-dependent potassium channels that are specialized for their role in shaping the electrical activity of neurons and cardiomyocytes. Defects in KCNH channels have been shown to be linked to cognitive defects, increased risk of schizophrenia, cardiac arrhythmias, and cancer. Recently it has become clear that the specialized gating of KCNH channels arises from their unique intracellular domains, the N-terminal eag domain, and the C-terminal C-linker/CNBHD. In this proposal, we will test the hypothesis that the C-linker/CNBHD of KCNH channels is a key regulatory domain that mediates the action of the eag domain and other intracellular regulators. We will build on three exciting new X-ray crystal structures we have solved of the intracellular domains of three different KCNH channels: 1) the C-linker/CNBHD of ELK, 2) the C-linker/CNBHD of ERG, and 3) a complex of the CNBHD and eag domain of EAG. These new structures reveal unexpected features like a direct interaction between the eag domain and the CNBHD, and an intrinsic ligand in the binding site of the CNBHD that regulates gating. They provide a framework to better understand the mechanisms of the gating and regulation of KCNH channels. Toward this goal, we will leverage the power of X-ray crystallography, electrophysiology, and fluorescence to study the structure and rearrangements of the eag domain and C-linker/CNBHD during gating of KCNH channels.