A biological role for prokaryotic ClC chloride channels
A biological role for prokaryotic ClC chloride channels
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DOI：
10.1038/nature01000
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发表时间：
2002-10-17
期刊：
影响因子：
64.8
通讯作者：
Miller, C
中科院分区：
文献类型：
--
作者：
Iyer, R;Iverson, TM;Miller, C
从大规模基因组分析中出现的一个意想不到的发现是，原核表达离子通道属于长期研究的神经元分子家族。现在已知细菌和古细菌携带电压门控、内向整流和钙激活类钾通道（1-3）、clc型氯通道(4)、嗜离子谷氨酸受体(5)和钠通道(6)的基因。对于两个钾离子通道和一个氯离子通道，这些同源物提供了一种直接测定结构的方法（3,7-9）。然而，这些离子通道在细菌中的作用尚不清楚。从细菌到脊椎动物的重要功能序列以及结构本身的高度保守性（10）表明，对结构生物学家来说，原核生物使用离子通道的作用比提供高质量的蛋白质更具适应性。在这里，我们发现大肠杆菌在极端的耐酸反应中使用广泛存在的ClC家族的氯离子通道。我们提出，通道的功能作为一个电子分流的向外定向的虚拟质子泵，是连接到氨基酸脱羧。
An unexpected finding emerging from large-scale genome analyses is that prokaryotesexpress ion channels belonging to molecular families long studied in neurons. Bacteria and archaea are now known to carry genes for potassium channels of the voltage-gated, inward rectifier and calcium-activated classes(1-3), ClC-type chloride channels(4), an ionotropic glutamate receptor(5) and a sodium channel(6). For two potassium channels and a chloride channel, these homologues have provided a means to direct structure determination(3,7-9). And yet the purposes of these ion channels in bacteria are unknown. Strong conservation of functionally important sequences from bacteria to vertebrates, and of structure itself(10), suggests that prokaryotes use ion channels in roles more adaptive than providing high-quality protein to structural biologists. Here we show that Escherichia coli uses chloride channels of the widespread ClC family in the extreme acid resistance response. We propose that the channels function as an electrical shunt for an outwardly directed virtual proton pump that is linked to amino acid decarboxylation.