Electrostatic tuning of ion conductance in potassium channels
Electrostatic tuning of ion conductance in potassium channels
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DOI：
10.1021/bi0348720
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发表时间：
2003-08-12
期刊：
影响因子：
2.9
通讯作者：
Miller, C
中科院分区：
文献类型：
--
作者：
Nimigean, CM;Chappie, JS;Miller, C
K+通道家族的成员显示出显著的序列保守性和离子选择性过滤器的结构，而K+周转率在家族内变化很大。在这里，我们表明，通道电导的强烈影响，在通道的细胞内口电荷。在细菌K+通道KcsA的这个位置引入负电荷环，以pH依赖性方式增加电导。这些结果解释了一个简单的静电效应的基础上已知的通道结构，其中的负电荷用于改变内口的电位，从而增加局部K+浓度。此外，去除高电导真核细胞K+通道中等同位置的保守负电荷会导致电导降低。
Members of the K+ channel family display remarkable conservation of sequence and structure of the ion selectivity filter, whereas the rates of K+ turnover vary widely within the family. Here we show that channel conductance is strongly influenced by charge at the channel's intracellular mouth. Introduction of a ring of negative charges at this position in KcsA, a bacterial K+ channel, augments the conductance in a pH-dependent manner. These results are explained by a simple electrostatic effect based on known channel structures, where the negative charges serve to alter the electrical potential at the inner mouth and, thus, to increase the local K+ concentration. In addition, removal of the conserved negative charges at equivalent positions in a high-conductance eukaryotic K+ channel leads to a decrease in conductance.