Increased drug permeability of a stiffened mycobacterial outer membrane in cells lacking MFS transporter Rv1410 and lipoprotein LprG
Increased drug permeability of a stiffened mycobacterial outer membrane in cells lacking MFS transporter Rv1410 and lipoprotein LprG
复制标题
DOI：
10.1111/mmi.14220
复制
发表时间：
2019-05-01
影响因子：
3.6
通讯作者：
Seeger, Markus A.
中科院分区：
文献类型：
--
作者：
Hohl, Michael;Remm, Sille;Seeger, Markus A.
主要促进剂超家族转运蛋白Rv1410和脂蛋白LprG(Rv1411)由一个保守的双基因操纵子编码，与结核分枝杆菌的毒力有关。Rv1410最初被认为是一个药物外排泵，但最近的研究表明，Rv1410和LprG协同工作，将三酰甘油和阿拉伯甘露聚糖插入外膜。在这里，我们对缺乏操纵子的污垢分枝杆菌进行了显微分析，观察到了细胞分离缺陷，而原子力显微镜测量的表面刚性被发现增加。而在乳酸乳球菌中表达的Rv1410不会产生耐药性，而脓肿分枝杆菌和耻垢分枝杆菌中操纵子的缺失会导致对万古霉素、新诺比星和利福平的敏感性增加。Rv1410的同源模型揭示了一个周质环和一个高度保守的天冬氨酸，它们被发现对操纵子的功能是必不可少的。有趣的是，荧光染料BCECF-AM和Calcein-AM在去能耻垢分枝杆菌细胞中的流入速度在缺失突变体中更快。我们的结果明确地表明，缺失突变体中药物敏感性的增加是由通过有缺陷的分枝杆菌细胞膜的药物内流增加引起的，而不是由Rv1410介导的药物外流引起的。
The major facilitator superfamily transporter Rv1410 and the lipoprotein LprG (Rv1411) are encoded by a conserved two-gene operon and contribute to virulence in Mycobacterium tuberculosis. Rv1410 was originally postulated to function as a drug efflux pump, but recent studies suggested that Rv1410 and LprG work in concert to insert triacylglycerides and lipoarabinomannans into the outer membrane. Here, we conducted microscopic analyses of Mycobacterium smegmatis lacking the operon and observed a cell separation defect, while surface rigidity measured by atomic force microscopy was found to be increased. Whereas Rv1410 expressed in Lactococcus lactis did not confer drug resistance, deletion of the operon in Mycobacterium abscessus and M. smegmatis resulted in increased susceptibility toward vancomycin, novobiocin and rifampicin. A homology model of Rv1410 revealed a periplasmic loop as well as a highly conserved aspartate, which were found to be essential for the operon's function. Interestingly, influx of the fluorescent dyes BCECF-AM and calcein-AM in de-energized M. smegmatis cells was faster in the deletion mutant. Our results unambiguously show that elevated drug susceptibility in the deletion mutant is caused by increased drug influx through a defective mycobacterial cell envelope and not by drug efflux mediated by Rv1410.