Overexpression of the MexEF-OprN multidrug efflux system affects cell-to-cell signaling in Pseudomonas aeruginosa
Overexpression of the MexEF-OprN multidrug efflux system affects cell-to-cell signaling in Pseudomonas aeruginosa
复制标题
DOI：
10.1128/jb.183.18.5213-5222.2001
复制
发表时间：
2001-09-01
影响因子：
3.2
通讯作者：
Pechere, JC
中科院分区：
文献类型：
--
作者：
Köhler, T;van Delden, C;Pechere, JC
医院内病原体铜绿假单胞菌的内在和获得性抗生素耐药性主要是由几种广泛底物特异性的外排泵的表达介导的。在这里，我们报告nfxC型突变体，过表达的MexEF-OprN外排系统，产生较低水平的细胞外毒力因子比易感野生型。这些包括绿脓菌素、弹性蛋白酶和鼠李糖脂，这三个因子由铜绿假单胞菌的las和rid群体感应系统控制。与这些观察结果一致的是在nfxC型突变体中测量的弹性蛋白酶基因lasB和鼠李糖基转移酶基因rhlAB的转录降低。lasR和rhlR调节基因的表达在nfxC型突变体中不受影响。相反，转录的C4-高丝氨酸内酯（C4-HSL）自诱导合成酶基因rhlI减少了50%，在nfxC型突变体相对于野生型。这与在nfxC型突变体的上清液中检测到的C4-HSL水平的类似降低相关。通过添加合成的C4-HSL和假单胞菌喹诺酮信号（PQS）可以部分恢复rhlAB-lacZ融合物的转录。提出MexEF-OprN外排泵影响细胞内PQS水平。
Intrinsic and acquired antibiotic resistance of the nosocomial pathogen Pseudomonas aeruginosa is mediated mainly by the expression of several efflux pumps of broad substrate specificity. Here we report that nfxC type mutants, overexpressing the MexEF-OprN efflux system, produce lower levels of extracellular virulence factors than the susceptible wild type. These include pyocyanin, elastase, and rhamnolipids, three factors controlled by the las and rid quorum-sensing systems of P. aeruginosa. In agreement with these observations are the decreased transcription of the elastase gene lasB and the rhamnosyltransferase genes rhlAB measured in nfxC type mutants. Expression of the lasR and rhlR regulator genes was not affected in the nfxC type mutant. In contrast, transcription of the C4-homoserine lactone (C4-HSL) autoinducer synthase gene rhlI was reduced by 50% in the nfxC type mutant relative to that in the wild type. This correlates with a similar decrease in C4-HSL levels detected in supernatants of the nfxC type mutant. Transcription of an rhlAB-lacZ fusion could be partially restored by the addition of synthetic C4-HSL and Pseudomonas quinolone signal (PQS). It is proposed that the MexEF-OprN efflux pump affects intracellular PQS levels.