Defects in Efflux (oprM), β-Lactamase (ampC), and Lipopolysaccharide Transport (IptE) Genes Mediate Antibiotic Hypersusceptibility of Pseudomonas aeruginosa Strain Z61
Defects in Efflux (oprM), β-Lactamase (ampC), and Lipopolysaccharide Transport (IptE) Genes Mediate Antibiotic Hypersusceptibility of Pseudomonas aeruginosa Strain Z61
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DOI：
10.1128/aac.00784-19
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发表时间：
2019-07-01
影响因子：
4.9
通讯作者：
Dean, C. R.
中科院分区：
文献类型：
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作者：
Shen, Xiaoyu;Johnson, Nicole V.;Dean, C. R.
抗生素超敏细菌突变体（例如，Earthwork大肠杆菌IMP）用于研究内在抗性，并用于抗菌发现以追踪新抑制剂化合物的弱抗菌活性。铜绿假单胞菌Z61是一种通过化学诱变产生的药物敏感菌株，尽管敏感性的遗传基础还不完全清楚。Z61的基因组测序显示，在153个基因相对于其亲本菌株的非同义单核苷酸多态性，和三个候选突变（oprM，ampC和IptE）预测介导过敏的特点。这些突变的贡献通过在Z61背景中单独或组合的野生型序列的基因组恢复来证实。在亲本菌株中单独或一起引入IptE突变或oprM和ampC基因的遗传失活重现了药物敏感性。这表明oprM（编码主要外膜外排泵通道）的破坏增加了对泵底物抗生素的敏感性，诱导型β-内酰胺酶基因ampC的失活导致β-内酰胺敏感性，脂多糖转运蛋白基因IptE的突变强烈改变了外膜渗透屏障，导致对利福平等大抗生素和β-内酰胺类药物的敏感性。
Antibiotic hypersensitive bacterial mutants (e.g., Escherkhia coli imp) are used to investigate intrinsic resistance and are exploited in antibacterial discovery to track weak antibacterial activity of novel inhibitor compounds. Pseudomonas aeruginosa Z61 is one such drug-hypersusceptible strain generated by chemical mutagenesis, although the genetic basis for hypersusceptibility is not fully understood. Genome sequencing of Z61 revealed nonsynonymous single-nucleotide polymorphisms in 153 genes relative to its parent strain, and three candidate mutations (in oprM, ampC, and IptE) predicted to mediate hypersusceptibility were characterized. The contribution of these mutations was confirmed by genomic restoration of the wild-type sequences, individually or in combination, in the Z61 background. Introduction of the IptE mutation or genetic inactivation of oprM and ampC genes alone or together in the parent strain recapitulated drug sensitivities. This showed that disruption of oprM (which encodes a major outer membrane efflux pump channel) increased susceptibility to pump substrate antibiotics, that inactivation of the inducible beta-lactamase gene ampC contributed to beta-lactam susceptibility, and that mutation of the lipopolysaccharide transporter gene IptE strongly altered the outer membrane permeability barrier, causing susceptibility to large antibiotics such as rifampin and also to beta-lactams.