Potassium/proton antiport system of Escherichia coli
Potassium/proton antiport system of Escherichia coli
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DOI：
10.1074/jbc.m600333200
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发表时间：
2006-07-21
影响因子：
4.8
通讯作者：
Nakamura, Tatsunosuke
中科院分区：
文献类型：
--
作者：
Radchenko, Martha V.;Tanaka, Kimihiro;Nakamura, Tatsunosuke
在大肠杆菌中，细胞内的钾（K+）水平通过多种K+转运系统进行调节。最近的数据表明，并非所有的K+挤出系统都已被确定（15）。在这里我们报告说，E. coli Na ~+（Ca ~（2+））/H ~+逆向转运蛋白ChaA-作为K ~+排出系统发挥作用。细胞表达ChaA介导的K+外流对K+浓度梯度。E.缺乏chaA基因的大肠杆菌菌株在野生型细胞排出K+的条件下不能排出K+。用French press制备的倒膜囊泡检测ChaA的K+/H+逆向转运蛋白活性。生理生长研究表明，E.大肠杆菌使用ChaA来丢弃过量的K+，这对这些细胞是有毒的。这些结果表明，ChaA K+/H+反向转运蛋白活性使E.大肠杆菌对K+胁迫的适应能力和维持K+稳态的能力。
The intracellular level of potassium (K+) in Escherichia coli is regulated through multiple K+ transport systems. Recent data indicate that not all K+ extrusion system(s) have been identified (15). Here we report that the E. coli Na+(Ca2+)/H+ antiporter ChaA-functions as a K+ extrusion system. Cells expressingChaA mediated K+ efflux against a K+ concentration gradient. E. coli strains lacking the chaA gene were unable to extrude K+ under conditions in which wild- type cells extruded K+. The K+/H+ antiporter activity of ChaA was detected by using invertedmembrane vesicles produced using a French press. Physiological growth studies indicated that E. coli uses ChaA to discard excessive K+, which is toxic for these cells. These results suggest that ChaA K+/H+ antiporter activity enables E. coli to adapt to K+ salinity stress and to maintain K+ homeostasis.