Achard-Joris Maud, Bourdineaud Jean-Paul
UMR CNRS 5805, Laboratoire d'Ecophysiologie et Ecotoxicologie des Systèmes Aquatiques, Université de Bordeaux 1, Place du Dr Peyneau, 33120 Arcachon, France.
Biometals. 2006 Dec;19(6):695-704. doi: 10.1007/s10534-006-9006-2. Epub 2006 May 16.
In order to determine the role of multidrug resistance proteins in mercury and zinc resistance, human MDR1, Lactococcus lactis lmrA, and Oenococcus oeni omrA genes were expressed in an Escherichia coli tolC mutant which is hypersensitive to metals. The three transporters conferred an increased mercury and zinc resistance to E. coli as compared to the control bacteria. This improved resistance correlated with a decreased zinc and mercury bioaccumulation. Indeed, quantification of intracellular metal concentrations by atomic absorption spectrometry (AAS) showed a 2.1-, 3-, and 5.1-fold decrease in zinc in cells expressing hMDR1, omrA, and lmrA, respectively, and a 2.7-, 7.5-, and 7.7-fold decrease in mercury in cells expressing omrA, lmrA, and hMDR1, respectively, as compared to the control bacteria. This means that hMDR1, LmrA, and OmrA proteins which are specialised in xenobiotic scavenging, their main known function, are nevertheless able to confer some resistance against metals. Our results show that the tolC mutated strain is well adapted to the study of MDR transporter activity and could be used to screen substrates and competitive hMDR1 inhibitors.
为了确定多药耐药蛋白在汞和锌抗性中的作用，将人类多药耐药基因1（MDR1）、乳酸乳球菌的lmrA基因以及酒类酒球菌的omrA基因在对金属高度敏感的大肠杆菌tolC突变体中表达。与对照细菌相比，这三种转运蛋白赋予了大肠杆菌更高的汞和锌抗性。这种抗性的提高与锌和汞生物累积量的减少相关。实际上，通过原子吸收光谱法（AAS）对细胞内金属浓度进行定量分析表明，与对照细菌相比，分别表达hMDR1、omrA和lmrA的细胞中锌含量分别降低了2.1倍、3倍和5.1倍，而分别表达omrA、lmrA和hMDR1的细胞中汞含量分别降低了2.7倍、7.5倍和7.7倍。这意味着专门用于清除外源性物质（其主要已知功能）的hMDR1、LmrA和OmrA蛋白，仍然能够赋予一定的金属抗性。我们的结果表明，tolC突变菌株非常适合用于研究多药耐药转运蛋白的活性，并且可用于筛选底物和竞争性hMDR1抑制剂。
