Antimicrobials Research Group, Institute of Microbiology and Infection, College of Medical and Dental Sciences, The University of Birmingham, Birmingham, United Kingdom
School of Biosciences, The University of Birmingham, Birmingham, United Kingdom.
mBio. 2021 Mar 30;12(2):e00109-21. doi: 10.1128/mBio.00109-21.
In the fight against antibiotic resistance, drugs that target resistance mechanisms in bacteria can be used to restore the therapeutic effectiveness of antibiotics. The multidrug resistance efflux complex AcrAB-TolC is the most clinically relevant efflux pump in and is a target for drug discovery. Inhibition of the pump protein AcrB allows the intracellular accumulation of a wide variety of antibiotics, effectively restoring their therapeutic potency. To facilitate the development of AcrB efflux inhibitors, it is desirable to discover the native substrates of the pump, as these could be chemically modified to become inhibitors. We analyzed the native substrate profile of AcrB in MG1655 and serovar Typhimurium SL1344 using an untargeted metabolomics approach. We analyzed the endo- and exometabolome of the wild-type strain and their respective AcrB loss-of-function mutants (AcrB D408A) to determine the metabolites that are native substrates of AcrB. Although there is 95% homology between the AcrB proteins of Typhimurium and , we observed mostly different metabolic responses in the exometabolomes of the Typhimurium and AcrB D408A mutants relative to those in the wild type, potentially indicating a differential metabolic adaptation to the same mutation in these two species. Additionally, we uncovered metabolite classes that could be involved in virulence of Typhimurium and a potential natural substrate of AcrB common to both species. Multidrug-resistant Gram-negative bacteria pose a global threat to human health. The AcrB efflux pump confers inherent and evolved drug resistance to , including and serovar Typhimurium. We provide insights into the physiological role of AcrB: (i) we observe that loss of AcrB function in two highly related species, and Typhimurium, has different biological effects despite AcrB conferring drug resistance to the same groups of antibiotics in both species, and (ii) we identify potential natural substrates of AcrB, some of which are in metabolite classes implicated in the virulence of Typhimurium. Molecules that inhibit multidrug efflux potentiate the activity of old, licensed, and new antibiotics. The additional significance of our research is in providing data about the identity of potential natural substrates of AcrB in both species. Data on these will facilitate the discovery of, and/or could be chemically modified to become, new efflux inhibitors.
在对抗抗生素耐药性的斗争中，可以使用针对细菌耐药机制的药物来恢复抗生素的治疗效果。多药耐药外排复合物 AcrAB-TolC 是 中最具临床相关性的外排泵，也是药物发现的目标。抑制泵蛋白 AcrB 可以使各种抗生素在细胞内积累，从而有效地恢复其治疗效力。为了促进 AcrB 外排抑制剂的开发，理想情况下是发现泵的天然底物，因为这些底物可以被化学修饰以成为抑制剂。我们使用非靶向代谢组学方法分析了 MG1655 和 血清型鼠伤寒 SL1344 中 AcrB 的天然底物谱。我们分析了野生型菌株及其各自的 AcrB 功能丧失突变体（AcrB D408A）的内、外代谢组，以确定 AcrB 的天然底物代谢物。尽管 鼠伤寒和 之间的 AcrB 蛋白有 95%的同源性，但我们观察到 鼠伤寒和 AcrB D408A 突变体的外代谢组中大多数代谢反应与野生型不同，这可能表明这两种物种对同一突变的代谢适应性存在差异。此外，我们还发现了可能与 鼠伤寒毒力有关的代谢物类别和两种物种共有的 AcrB 潜在天然底物。多药耐药革兰氏阴性菌对人类健康构成全球性威胁。AcrB 外排泵赋予 固有和进化的耐药性，包括 和 血清型鼠伤寒。我们深入了解了 AcrB 的生理作用：（i）我们观察到，在两个高度相关的物种 和 鼠伤寒中，AcrB 功能的丧失具有不同的生物学效应，尽管 AcrB 使这两个物种的相同抗生素组产生耐药性；（ii）我们确定了 AcrB 的潜在天然底物，其中一些是在 鼠伤寒毒力涉及的代谢物类别中。抑制多药外排的分子可以增强旧的、已获许可的和新的抗生素的活性。我们研究的额外意义在于提供了两种物种中 AcrB 潜在天然底物的身份数据。这些数据将有助于发现新的外排抑制剂，或者可以对其进行化学修饰以成为新的外排抑制剂。
