Contributions of MexAB-OprM and an EmrE homolog to intrinsic resistance of Pseudomonas aeruginosa to aminoglycosides and dyes
Contributions of MexAB-OprM and an EmrE homolog to intrinsic resistance of Pseudomonas aeruginosa to aminoglycosides and dyes
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DOI：
10.1128/aac.47.1.27-33.2003
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发表时间：
2003-01-01
影响因子：
4.9
通讯作者：
Nikaido, H
中科院分区：
文献类型：
--
作者：
Li, XZ;Poole, K;Nikaido, H
在铜绿假单胞菌的6个可能的小多药耐药(SMR)家族蛋白中，由PA4990基因编码的蛋白EmRE(PAE)与大肠杆菌EmRE外排转运蛋白的同源性最高。逆转录-聚合酶链式反应证实了Emre(Pae)在铜绿假单胞菌野生型菌株中的表达。利用等基因Emre(PAE)、mexAB-oprM和/或mexB缺失突变体，在低离子强度的Difco营养肉汤中进行药敏试验，评估EmRE蛋白和MexAB-oprM外排系统在铜绿假单胞菌耐药性中的作用。我们发现，Emre(Pae)不仅对溴化乙锭和吖啶黄素有内在抗性，而且对氨基糖苷类化合物也有抗性。在这种低离子强度的介质中，MexAB-OprM也被证明对氨基糖苷类药物耐药有贡献，推测是通过主动外排。这两种泵引起的氨基糖苷类耐药性不能在高离子强度的介质中表现出来，如Luria肉汤或Mueller-Hinton肉汤。连续荧光实验证实了溴化乙锭的外排依赖于EmRE。
Of the six putative small multidrug resistance (SMR) family proteins of Pseudomonas aeruginosa, a protein encoded by the PA4990 gene (emrE(Pae) shows the highest identity to the well-characterized EmrE efflux transporter of Escherichia coli. Reverse transcription-PCR confirmed the expression of emrE(Pae) in the wild-type strain of P. aeruginosa. Using isogenic emrE(Pae)., mexAB-oprM, and/or mexB deletion mutants, the contributions of the EmrE protein and the MexAB-OprM efflux system to drug resistance in P. aeruginosa were assessed by a drug susceptibility test carried out in a low-ionic-strength medium, Difco nutrient broth. We found that EmrE(Pae) contributed to intrinsic resistance not only to ethidium bromide and acriflavine but also to amino-glycosides. In this low-ionic-strength medium, MexAB-OprM was also shown to contribute to aminoglycoside resistance, presumably via active efflux. Aminoglycoside resistance caused by these two pumps could not be demonstrated in high-ionic-strength media, such as Luria broth or Mueller-Hinton broth. The EmrE-dependent efflux of ethidium bromide was confirmed by a continuous fluorescence assay.