Multi-Ion, Free Energy Study of Effect of Ba2+ Blockage on KcsA Ion Selectivity

Ba2 阻断对 KcsA 离子选择性影响的多离子、自由能研究

• 批准号: 8526779
• 负责人: Karen Michelle Callahan
• 金额: $ 5.22万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-01 至 2014-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8526779
• 关键词: Accounting; Arrhythmia; Barium; Binding; Binding Sites; Charge; Computing Methodologies; Diffusion; Dissociation; Electronics; Electrophysiology (science); Ensure; Epilepsy; Equilibrium; Free Energy; Goals; Health; Immune response; Ion Channel; Ions; Kinetics; Knowledge; Length; Ligands; Measures; Mechanics; Membrane Lipids; Membrane Proteins; Methods; Migraine; Modeling; Molecular; Molecular Conformation; Multiple Sclerosis; Nerve; Play; Positioning Attribute; Potassium; Potassium Channel; Potassium Channel Blockers; Process; Relative (related person); Reporting; Research; Resolution; Roentgen Rays; Role; Site; Structure; Testing; Time; Water; base; computer studies; drug discovery; molecular dynamics; mutant; nanosecond; public health relevance; quantum; research study; simulation; voltage

DESCRIPTION (provided by applicant): The goal of the proposed research is to elucidate the mechanism of barium blockade of the selectivity filter of potassium channels and to determine the effects of barium blockade upon ion selectivity in the E71A mutant of the KcsA potassium channel. Since the selectivity filter of potassium channels is highly conserved, all knowledge gained from these studies is immediately applicable to a wide range of potassium channels. Voltage-activated potassium (K+) channels are membrane proteins that play a key role in the propagation of the nerve impulse. It is critical to their function that they maintain very high K+ o Na+ selectivity, but also conduct ions at a rate that approaches the diffusion limit. Currently, barium blockade electrophysiological experiments are one of the most reliable methods to determine ion selectivity in highly-selective potassium channels. However, little is known in detail about the positioning of the barium and potassium in the channels during these experiments or the effect of a barium blockade on the selectivity of the binding sites in the channel. Recently, and for the first time, experimental studies took place that investigated barium blockade in a potassium channel of known structure, the E71A mutant of KcsA. Slow inactivation is suppressed in the E71A mutant of KcsA, therefore that all information obtained about ion selectivity pertains to the conductive form of the selectivity filter. The existence of many structural studies of KcsA and additionally several studies of ion selectivity in KcsA make it uniquely suited for a detailed computational studies based on explicitly polarizable all-atom molecular dynamics simulations. Equilibrium and non-equilibrium molecular dynamics methods (free energy perturbation) will be used to determine the mechanism of barium blockade in the E71A mutant of the KcsA potassium channel and the effects of barium blockade on ion selectivity.

描述（由申请方提供）：拟定研究的目的是阐明钾通道选择性过滤器的钡阻断机制，并确定钡阻断对KcsA钾通道E71A突变体离子选择性的影响。由于钾通道的选择性过滤器是高度保守的，因此从这些研究中获得的所有知识都可以立即应用于广泛的钾通道。电压激活钾（K+）通道是在神经冲动的传播中起关键作用的膜蛋白。对于它们的功能至关重要的是，它们保持非常高的K+或Na+选择性，但也以接近扩散极限的速率传导离子。目前，钡阻滞电生理实验是确定高选择性钾通道离子选择性的最可靠方法之一。然而，很少有人知道在这些实验过程中的钡和钾的通道中的定位或钡封锁的效果上的选择性的结合位点的通道中的详细信息。最近，第一次进行了实验研究，研究了已知结构的钾通道（KcsA的E71A突变体）中的钡阻滞。在KcsA的E71A突变体中，缓慢失活受到抑制，因此，获得的所有关于离子选择性的信息都与选择性过滤器的导电形式有关。KcsA的许多结构研究的存在和另外几个研究的离子选择性KcsA使其唯一适合于一个详细的计算研究的基础上明确极化的全原子分子动力学模拟。将使用平衡和非平衡分子动力学方法（自由能微扰）确定KcsA钾通道E71A突变体中钡阻断的机制以及钡阻断对离子选择性的影响。