Heterologously expressed bacterial and human multidrug resistance proteins confer cadmium resistance to Escherichia coli
Heterologously expressed bacterial and human multidrug resistance proteins confer cadmium resistance to Escherichia coli
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DOI：
10.1021/bi047700r
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发表时间：
2005-04-19
期刊：
影响因子：
2.9
通讯作者：
Bourdineaud, JP
中科院分区：
文献类型：
--
作者：
Achard-Joris, M;van Saparoea, HBV;Bourdineaud, JP
人类MDR 1基因是由镉暴露诱导的，尽管在过表达hMDR 1的人类细胞中没有观察到对这种金属的抗性。为了获得MDR蛋白在镉抗性中的作用，在大肠杆菌tolC突变株中表达人MDR 1、乳酸乳球菌lmrA和酒类酒球菌omrA，该突变株被证明对镉过敏。人和细菌的MDR基因都赋予了大肠杆菌对镉的抗性。大肠杆菌中，最高达0.4 mM浓度。100 μ M维拉帕米可消除保护作用。用原子吸收光谱法定量测定细胞内镉浓度表明，表达MDR基因的细胞中镉积累减少。L.内翻外膜囊泡。过表达lmrA的乳酸菌表现出ATP依赖性的Cd-109（2+）吸收，并受到谷胱甘肽的刺激。一个进化模型进行了讨论，其中MDR蛋白质已经独立地从一个祖先的蛋白质显示有机异生质和二价金属挤压能力。
The human MDR1 gene is induced by cadmium exposure although no resistance to this metal is observed in human cells overexpressing hMDR1. To access the role of MDR proteins in cadmium resistance, human MDR1, Lactococcus lactis lmrA, and Oenococcus oeni omrA were expressed in an Escherichia coli tolC mutant strain which proved to be hypersensitive to cadmium. Both the human and bacterial MDR genes conferred cadmium resistance to E. coli up to 0.4 mM concentration. Protection was abolished by 100 mu M verapamil. Quantification of intracellular cadmium concentration by atomic absorption spectrometry showed a reduced cadmium accumulation in cells expressing the MDR genes. Inside-out membrane vesicles of L. lactis overexpressing lmrA displayed an ATP-dependent Cd-109(2+) uptake that was stimulated by glutathione. An evolutionary model is discussed in which MDR proteins have evolved independently from an ancestor protein displaying both organic xenobiotic- and divalent metal-extrusion abilities.