Activation Mechanism of Elic by Propylamine
Activation Mechanism of Elic by Propylamine
复制标题
丙胺激活 Elic 的机制
DOI：
10.1016/j.bpj.2013.11.3036
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发表时间：
2014
影响因子：
3.4
通讯作者：
Marabelli A
中科院分区：
文献类型：
--
作者：
Marabelli A
五聚体配体门控通道ELIC为我们提供了高分辨率的闭合态结构。这个原核通道在响应多种胺类化合物时打开到高单通道电导。在这里，我们报告了我们对重组ELIC通道激活的动力学模型的测试。通过动力学方案的最大似然直接全局拟合（HJCFIT程序；Colquhoun et al . J Physiol 547, 699, 2003）分析了由完全激动剂丙胺（0.5-50 mM）引发的外向单通道电流。通过比较每种方案的最佳拟合预测、实验开/关时间分布和宏观丙胺激活电流的时间过程（快速θ管应用，50-600 ms, 1-50 mM）来判断方案的充分性。其他Cys-loop通道，如甘氨酸受体，通过预开放中间体激活（“翻转”模型，Burzomato等人，J Neurosci 24, 10924, 2004），当完全配体时，高效地打开到单一开放状态。与此相反，饱和丙胺下的ELIC开启时间分布呈现出多个组分。因此，对于完全配位的通道，必须可以访问一个以上的开放状态。primedmodel （Mukhtasimova et al., Nature 459, 451, 2009）通过允许通道从多个完全配位的中间体打开来解释这一点。该模型的最佳拟合表明，当3个激动剂分子结合时，ELIC的最大开放概率达到99%。完全配体分支的总疗效约为130 （α1β甘氨酸通道的cf为20；Burzomato等，2004）。
The pentameric ligand-gated channel ELIC has provided us with high resolution structures of its closed state. This prokaryotic channel opens to a high single-channel conductance in response to a variety of amine compounds. Here we report our tests of kinetic models for the activation of recombinant ELIC channels. Outside-out single channel currents elicited by the full agonist propylamine (0.5-50 mM) were analysed by maximum likelihood direct global fitting of kinetic schemes (HJCFIT program; Colquhoun et al J Physiol 547, 699, 2003). The adequacy of a scheme was judged by comparing the predictions of the best fit obtained for each, with the experimental open/shut time distributions and with the time course of macroscopic propylamine-activated currents (fast theta-tube applications, 50-600 ms, 1-50 mM).Other Cys-loop channels, such as glycine receptors, activate via a pre-opening intermediate ('flip'model, Burzomato et al., J Neurosci 24, 10924, 2004) and, when fully liganded, open with high efficacy to a single open state. In contrast with that, ELIC open time distributions at saturating propylamine showed more than one component. Thus, more than one open state must be accessible to the fully liganded channel. Theprimedmodel (Mukhtasimova et al., Nature 459, 451, 2009) accounts for that by allowing the channel to open from more than one fully liganded intermediate. The best fit of this type of model showed that ELIC maximum open probability (99%) is reached when three molecules of agonist are bound. The overall efficacy of the fully liganded branch was about 130 (cf 20 for α1β glycine channels; Burzomato et al., 2004).