Active efflux of fluoroquinolones in Mycobacterium smegmatis mediated by LfrA, a multidrug efflux pump
Active efflux of fluoroquinolones in Mycobacterium smegmatis mediated by LfrA, a multidrug efflux pump
复制标题
DOI：
10.1128/jb.178.13.3791-3795.1996
复制
发表时间：
1996-07-01
影响因子：
3.2
通讯作者：
Nikaido, H
中科院分区：
文献类型：
--
作者：
Liu, J;Takiff, HE;Nikaido, H
从耐喹诺酮类的耻垢分枝杆菌mc(2)-552染色体DNA中克隆的lfrA基因，当存在于多拷贝质粒上时，赋予对氟喹诺酮类药物的低水平耐药性。序列分析表明，LfrA编码主要易化子家族的一种膜外排泵（H. E. 塔基夫，M. 奇米诺，M. C. 穆索，T. 韦斯布罗德，R. 马蒂内，M. B. 德尔加多，L. 萨拉查，B. R. 布卢姆和W. R. 雅各布斯，《美国国家科学院院刊》93:362 - 366，1996）。在这项工作中，我们研究了LfrA在耻垢分枝杆菌对氟喹诺酮类药物积累中的作用。携带含有lfrA基因质粒的耻垢分枝杆菌对亲水性喹诺酮类药物诺氟沙星的稳态积累水平约为亲本菌株的50%，但通过添加质子导体羰基氰化物间氯苯腙可增加到与亲本菌株相同的水平。由LfrA介导的诺氟沙星外排受到环丙沙星的强烈竞争，但不受萘啶酸的影响。此外，我们表明饥饿细胞积累的部分诺氟沙星在细胞重新获得能量时被泵出，并且在药物的细胞内浓度较高时，这种外排速率显示出饱和的迹象。这些结果表明，LfrA多肽催化几种喹诺酮类药物的主动外排。
The lfrA gene cloned from chromosomal DNA of quinolone-resistant Mycobacterium smegmatis mc(2)-552 conferred low-level resistance to fluoroquinolones when present on multicopy plasmids. Sequence analysis suggested that IfrA encodes a membrane efflux pump of the major facilitator family (H. E. Takiff M. Cimino, M. C. Musso, T. Weisbrod, R. Martinet, M. B. Delgado, L. Salazar, B. R. Bloom, and W. R. Jacbos, Jr., Proc. Natl. Acad, Sci, USA 93:362-366, 1996). In this work, we studied the role of LfrA in the accumulation of fluoroquinolones by M. smegmatis. The steady-state accumulation level of a hydrophilic quinolone, norfloxacin, by M. smegmatis harboring a plasmid carrying the IfrA gene was about 50% of that by the parent strain but was increased to the same level as that of the parent strain by addition of a proton conductor, carbonyl cyanide m-chorophenylhydrazone. Norfloxacin efflux mediated by LfrA was competed for strongly by ciprofloxacin but not by nalidixic acid, Furthermore, we showed that portions of norfloxacin accumulated by starved cells were pumped out upon reenergization of the cells, and the rates of this efflux showed evidence of saturation at higher intracellular concentrations of the drug. These results suggest that the LfrA polypeptide catalyzes the active efflux of several quinolones.