Novel chromosomally encoded multidrug efflux transporter MdeA in Staphylococcus aureus
Novel chromosomally encoded multidrug efflux transporter MdeA in Staphylococcus aureus
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DOI：
10.1128/aac.48.3.909-917.2004
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发表时间：
2004-03-01
影响因子：
4.9
通讯作者：
McDevitt, D
中科院分区：
文献类型：
--
作者：
Huang, JZ;O'Toole, PW;McDevitt, D
抗生素外排是病原菌耐药的重要机制。在这里，我们描述了一种新的染色体编码的多药耐药外排蛋白在金黄色葡萄球菌，MdeA（多药外排A）的鉴定和表征。MdeA是从筛选S.金黄色葡萄球菌开放阅读框表达文库，用于对抗生素化合物的抗性。当过表达时，MdeA赋予S.金黄色葡萄球菌对一系列季铵化合物和抗生素敏感，但对氟喹诺酮类不敏感。MdeA是一种52 kDa的蛋白质，具有14个预测的跨膜片段。它属于主要的促进剂超家族，并且在已知的外排蛋白中与枯草芽孢杆菌的LmrB和大肠杆菌的EmrB最密切相关。在S.金黄色葡萄球菌可减少溴化乙锭的摄取，增加其外排，利血平可抑制这种作用，解偶联剂可消除这种作用。通过引物延伸鉴定mdeA启动子。自发突变体选择增加耐药性的MdeA底物经历了突变的启动子mdeA，和他们的mdeA转录水平增加了多达15倍。mdeA基因存在于所有6株S.金黄色葡萄球菌检查。在S.金黄色葡萄球菌基因组，但他们的过度表达并不介导耐药性的测试。然而，在其他细菌中鉴定出MdeA同源物，包括炭疽芽孢杆菌，其中一些被证明是MdeA的功能性直系同源物。
Antibiotic efflux is an important mechanism of resistance in pathogenic bacteria. Here we describe the identification and characterization of a novel chromosomally encoded multidrug resistance efflux protein in Staphylococcus aureus, MdeA (multidrug efflux A). MdeA was identified from screening an S. aureus open reading frame expression library for resistance to antibiotic compounds. When overexpressed, MdeA confers resistance on S. aureus to a range of quaternary ammonium compounds and antibiotics, but not fluoroquinolones. MdeA is a 52-kDa protein with 14 predicted transmembrane segments. It belongs to the major facilitator superfamily and is most closely related, among known efflux proteins, to LmrB of Bacillus subtilis and EmrB of Escherichia coli. Overexpression of mdeA in S. aureus reduced ethidium bromide uptake and enhanced its efflux, which could be inhibited by reserpine and abolished by an uncoupler. The mdeA promoter was identified by primer extension. Spontaneous mutants selected for increased resistance to an MdeA substrate had undergone mutations in the promoter for mdeA, and their mdeA transcription levels were increased by as much as 15-fold. The mdeA gene was present in the genomes of all six strains of S. aureus examined. Uncharacterized homologs of MdeA were present elsewhere in the S. aureus genome, but their overexpression did not mediate resistance to the antibacterials tested. However, MdeA homologs were identified in other bacteria, including Bacillus anthracis, some of which were shown to be functional orthologs of MdeA.