Voltage Sensor Movement in the HERG Potassium Channel

HEG 钾通道中的电压传感器移动

• 批准号: 6993663
• 负责人: MARTIN TRISTANI-FIROUZI
• 金额: $ 36.5万
• 依托单位: UNIVERSITY OF UTAH
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-01-15 至 2008-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6993663
• 关键词: Xenopus oocyte; action potentials; arrhythmia; cardiovascular function; clinical research; electrophysiology; heart rhythm; membrane potentials; potassium channel; site directed mutagenesis; slow potential; voltage /patch clamp; voltage gated channel

DESCRIPTION (provided by applicant): The overall goals of this proposal are to define the structural basis of voltage sensor movement and the mechanism of coupling sensor movement to opening of HERG delayed rectifier K+ channels. HERG is one of several voltage-gated IC channels that mediate repolarization of the cardiac action potential. HERG channel dysfunction, caused by mutations or commonly prescribed medications, is associated with life-threatening arrhythmias. The critical role of HERG in the maintenance of normal cardiac electrical activity derives from its unusual gating properties: slow channel activation and fast inactivation. Activation and inactivation gating are voltage dependent, implying that these processes are coupled to movement of charged residues within the membrane. The structural basis of voltage sensor movement and mechanism of coupling sensor movement to HERG channel opening are not known. In this proposal, we provide the first description of HERG voltage sensor movement as measured by gating current. We hypothesize (1) the domains surrounding the S4 domain (the putative voltage sensor) influence the rate of S4 movement and account for the slow activation of HERG ionic current, (2) inactivation and activation gating are coupled to the same fundamental voltage sensing mechanism and (3) voltage sensor movement is coupled to channel opening via a direct interaction between the intracellular S4-S5 linker and the S6 domain. The aims of this proposal are to determine the structural basis of slow activation in HERG channels, to define the voltage sensor movement associated with fast HERG inactivation and to determine the mechanism whereby movement of the voltage sensor is coupled to channel opening. These aims will be accomplished using site-directed mutagenesis, chimeric constructs between HERG and the structurally related EAG channel, biochemical assays, two microelectrode voltage clamp and cut-open oocyte voltage clamp techniques. Insight into the molecular basis of voltage sensing in the HERG channel will advance our understanding of how this channel contributes to normal electrical stability in the heart and may advance our understanding of arrhythmia susceptibility.

描述（由申请人提供）：该提案的总体目标是定义电压传感器运动的结构基础以及耦合传感器运动的机制，以开放HERG延迟整流器K+通道。 HERG是介导心脏作用电位复极化的几个电压门控的IC通道之一。由突变或普遍处方药引起的HERG通道功能障碍与威胁生命的心律不齐有关。 HERG在维持正常心脏电活动中的关键作用源自其异常的门控特性：慢速通道激活和快速失活。激活和灭活门控为电压取决于电压，这意味着这些过程与膜内带电残基的运动耦合。电压传感器运动的结构基础和耦合传感器向HERG通道开口的机理尚不清楚。在此提案中，我们提供了通过门控电流衡量的HERG电压传感器运动的第一个描述。 We hypothesize (1) the domains surrounding the S4 domain (the putative voltage sensor) influence the rate of S4 movement and account for the slow activation of HERG ionic current, (2) inactivation and activation gating are coupled to the same fundamental voltage sensing mechanism and (3) voltage sensor movement is coupled to channel opening via a direct interaction between the intracellular S4-S5 linker and the S6域。该提案的目的是确定HERG通道中缓慢激活的结构基础，定义与快速HERG失活相关的电压传感器运动，并确定电压传感器移动与通道打开的机制。这些目标将使用定位的诱变，HERG和与结构相关的EAG通道之间的嵌合构建，生化测定，两个微电极电压夹和切开的卵母细胞电压夹具技术。洞悉HERG通道中电压传感的分子基础，将促进我们对此通道如何有助于心脏正常的电稳定性的理解，并可能提高我们对心律不齐的敏感性的理解。