Evidence for chloramphenicol/H+ antiport in Cmr (MdfA) system of Escherichia coli and properties of the antiporter
Evidence for chloramphenicol/H+ antiport in Cmr (MdfA) system of Escherichia coli and properties of the antiporter
复制标题
DOI：
10.1093/oxfordjournals.jbchem.a022078
复制
发表时间：
1998-07-01
影响因子：
2.7
通讯作者：
Tsuchiya, T
中科院分区：
文献类型：
--
作者：
Mine, T;Morita, Y;Tsuchiya, T
我们检测了大肠杆菌膜囊中氯霉素/H+的反转运活性，并从大肠杆菌染色体DNA中克隆了一个反转运基因。将该基因引入大肠杆菌细胞后，大肠杆菌对氯霉素和乙锭产生了耐药性。还观察到对吖啶橙的抗性略有增加。在携带该基因的质粒的细胞中观察到氯霉素和乙锭外排升高。在测定混合物中加入氯霉素可减少乙锭的流出。在含有质粒的细胞制备的膜泡中观察到氯霉素/H+的抗转运活性升高。最适pH为6.5。我们对该基因进行了测序，并推导出其产物的氨基酸序列。序列同源性与Cmr（或MdfA）相同。因此，很明显Cmr （MdfA）是氯霉素（和乙锭）/H+反向转运蛋白。
We detected chloramphenicol/H+ antiport activity in membrane vesicles of Escherichia coli and cloned a gene for the antiporter from chromosomal DNA of E. coli. introduction of the gene into E. coli cells conferred resistance to chloramphenicol and ethidium. A slight increase in resistance to acridine orange was also observed. Elevated chloramphenicol efflux and ethidium efflux were observed in cells harboring a plasmid carrying the gene. Addition of chloramphenicol to the assay mixture reduced the efflux of ethidium. Elevated chloramphenicol/H+ antiport activity was observed in membrane vesicles prepared from cells harboring the plasmid. The pH optimum for the activity was 6.5. We sequenced the gene and deduced the amino acid sequence of its product. A sequence homology search revealed that it was same as that of Cmr (or MdfA). Thus, it became clear that Cmr (MdfA) is the chloramphenicol(and ethidium)/H+ antiporter.