首页> 美国卫生研究院文献>Antimicrobial Agents and Chemotherapy >Enhancement of the mexAB-oprM Efflux Pump Expression by a Quorum-Sensing Autoinducer and Its Cancellation by a Regulator MexT of the mexEF-oprN Efflux Pump Operon in Pseudomonas aeruginosa
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Enhancement of the mexAB-oprM Efflux Pump Expression by a Quorum-Sensing Autoinducer and Its Cancellation by a Regulator MexT of the mexEF-oprN Efflux Pump Operon in Pseudomonas aeruginosa

机译:铜绿假单胞菌引起的群体感应自动诱导子增强mexAB-oprM外排泵表达并通过调节剂MexT取消了mexEF-oprN外排泵操纵子。

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摘要

nfxC-type cells of Pseudomonas aeruginosa that produce the MexEF-OprN efflux pump exhibit resistance to fluoroquinolones and chloramphenicol and hypersusceptibility to most classical β-lactam antibiotics. We investigated the molecular mechanism of how the nfxC mutation causes β-lactam hypersusceptibility. The MexAB-OprM extrusion pump transports and confers resistance to β-lactam antibiotics. Interestingly, expression of the mexAB-oprM operon reached the highest level during the mid-stationary growth phase in both wild-type and nfxC-type mutant strains, suggesting that expression of the mexAB-oprM operon may be controlled by cell density-dependent regulation such as quorum sensing. This assumption was verified by demonstrating that exogenous addition of the quorum-sensing autoinducer N-butyryl-l-homoserine lactone (C4-HSL) enhanced the expression of MexAB-OprM, whereas N-(3-oxododecanoyl)-l-homoserine lactone had only a slight effect. Furthermore, this C4-HSL-mediated enhancement of mexAB-oprM expression was repressed by MexT, a positive regulator of the mexEF-oprN operon. It was concluded that β-lactam hypersusceptibility in nfxC-type mutant cells is caused by MexT-mediated cancellation of C4-HSL-mediated enhancement of MexAB-OprM expression.
机译:产生MexEF-OprN外排泵的铜绿假单胞菌的nfxC型细胞表现出对氟喹诺酮类和氯霉素的抗药性,并且对大多数经典的β-内酰胺类抗生素有高度敏感性。我们研究了nfxC突变如何引起β-内酰胺高度敏感性的分子机制。 MexAB-OprM挤出泵运输并赋予对β-内酰胺抗生素的抗性。有趣的是,在野生型和nfxC型突变菌株中,mexAB-oprM操纵子的表达在中期稳定生长阶段均达到最高水平,这表明mexAB-oprM操纵子的表达可能受细胞密度依赖性调节的控制。例如群体感应。通过证明外源添加群体感应自动诱导物N-丁酰基-1-高丝氨酸内酯(C4-HSL)可以增强MexAB-OprM的表达,而N-(3-氧十二烷酰基)-1-高丝氨酸内酯具有上述表达能力,这一假设得到了证实。只有轻微的影响。此外,这种C4-HSL介导的mexAB-oprM表达增强受到了mexEF-oprN操纵子的正向调节子MexT的抑制。结论是,nfxC型突变细胞中的β-内酰胺超敏性是由MexT介导的C4-HSL介导的MexAB-OprM表达增强引起的。

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