Antibiotic-resistant pose a major threat to healthcare systems worldwide, necessitating the development of novel strategies to fight such hard-to-kill bacteria. One potential approach is to develop molecules that force bacteria to hyper-activate prodrug antibiotics, thus rendering them more effective. In the present work, we aimed to obtain proof-of-concept data to support that small molecules targeting transcriptional regulators can potentiate the antibiotic activity of the prodrug metronidazole (MTZ) against under aerobic conditions. By screening a chemical library of small molecules, a series of structurally related molecules were identified that had little inherent antibiotic activity but showed substantial activity in combination with ineffective concentrations of MTZ. Transcriptome analyses, functional genetics, thermal shift assays, and electrophoretic mobility shift assays were then used to demonstrate that these MTZ boosters target the transcriptional repressor MarR, resulting in the upregulation of the operon and its downstream MarA regulon. The associated upregulation of the flavin-containing nitroreductase, NfsA, was then shown to be critical for the booster-mediated potentiation of MTZ antibiotic activity. Transcriptomic studies, biochemical assays, and electron paramagnetic resonance measurements were then used to show that under aerobic conditions, NfsA catalyzed 1-electron reduction of MTZ to the MTZ radical anion which in turn induced lethal DNA damage in . This work reports the first example of prodrug boosting in by transcriptional modulators and highlights that MTZ antibiotic activity can be chemically induced under anaerobic growth conditions.

中文翻译：

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小分子 MarR 调节剂通过诱导硝基还原酶 NfsA 的激活来增强需氧大肠杆菌中的甲硝唑抗生素活性


抗生素耐药性对全世界的医疗系统构成重大威胁，因此需要制定新的策略来对抗这种难以杀死的细菌。一种潜在的方法是开发迫使细菌过度激活前药抗生素的分子，从而使它们更有效。在目前的工作中，我们的目的是获得概念验证数据，以支持靶向转录调节因子的小分子可以增强前药甲硝唑（MTZ）在有氧条件下的抗生素活性。通过筛选小分子化学文库，鉴定出一系列结构相关的分子，这些分子几乎没有固有的抗生素活性，但与无效浓度的 MTZ 结合时显示出显着的活性。然后使用转录组分析、功能遗传学、热位移分析和电泳迁移率变化分析来证明这些 MTZ 增强剂靶向转录抑制子 MarR，导致操纵子及其下游 MarA 调节子的上调。含黄素硝基还原酶 NfsA 的相关上调被证明对于增强剂介导的 MTZ 抗生素活性增强至关重要。然后使用转录组学研究、生化测定和电子顺磁共振测量表明，在有氧条件下，NfsA 催化 MTZ 的 1-电子还原为 MTZ 自由基阴离子，进而诱导致命的 DNA 损伤。这项工作报告了转录调节剂增强前药作用的第一个例子，并强调了 MTZ 抗生素活性可以在厌氧生长条件下通过化学方法诱导。