EVIDENCE FOR MULTIPLE K+ EXPORT SYSTEMS IN ESCHERICHIA-COLI
EVIDENCE FOR MULTIPLE K+ EXPORT SYSTEMS IN ESCHERICHIA-COLI
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DOI：
10.1128/jb.169.8.3743-3749.1987
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发表时间：
1987-08-01
影响因子：
3.2
通讯作者：
GAJEWSKA, A
中科院分区：
文献类型：
--
作者：
BAKKER, EP;BOOTH, IR;GAJEWSKA, A
研究了大肠杆菌kefB（原trkB）和kefC（原trkC）基因编码的K+转运系统在K+外排中的作用。由N-乙基马来酰亚胺（NEM），增加膨压，碱化的细胞质，或2，4-二硝基苯酚在两个kef基因的无效突变的突变体中产生的外排率与外排率在野生型菌株kef进行了比较。结果表明，这两个基因编码NEM刺激外排的主要途径。然而，这两种外排系统似乎都不是由高膨压、细胞质碱化或添加高浓度2，4-二硝基苯酚产生的K+外排的重要途径。因此，除了kefB和kefC编码的系统外，该物种必须至少有一个其他系统，能够介导高速率的K+流出。当菌株用NEM处理时，KefC 121突变特征的高自发K+流出率进一步增加。 因此，在该菌株中导致自发外排的突变缺陷不会消除负责NEM作用的位点。
The role of the K+ transport systems encoded by the kefB (formerly trkB) and kefC (formerly trkC) genes of Escherichia coli in K+ efflux has been investigated. The rate of efflux produced by N-ethylmaleimide (NEM), increased turgor pressure, alkalinization of the cytoplasm, or 2,4-dinitrophenol in a mutant with null mutations in both kef genes was compared with the rate of efflux in a wild-type strain for kef. The results show that these two genes encode the major paths for NEM-stimulated efflux. However, neither efflux system appears to be a significant path of K+ efflux produced by high turgorpressure, by alkalinization of the cytoplasm, or by additon of high concentrations of 2,4-dinitrophenol. Therefore, this species must have at least one other system, besides those encoded by kefB and kefC, capable of mediating a high rate of K+ efflux. The high, spontaneous rate of K+ efflux characteristic of the kefC121 mutation increases further when the strain is treated with NEM. Therefore, the mutational defect that leads to spontaneous efflux in this strain does not abolish the site(s) responsible for the action of NEM.