Burkholderia thailandensis has emerged as a nonpathogenic surrogate for Burkholderia pseudomallei , the causative agent of melioidosis, and an important Gram-negative model bacterium for studying the biosynthesis and regulation of secondary metabolism. We recently reported that subinhibitory concentrations of trimethoprim induce vast changes in both the primary and secondary metabolome of B. thailandensis . In the current work, we show that the folate biosynthetic enzyme FolE2 is permissive under standard growth conditions but essential for B. thailandensis in the presence of subinhibitory doses of trimethoprim. Reasoning that FolE2 may serve as an attractive drug target, we screened for and identified ten inhibitors, including dehydrocostus lactone (DHL), parthenolide, and β-lapachone, all of which are innocuous individually but form a chemical-synthetic lethal combination with subinhibitory doses of trimethoprim. We show that DHL is a mechanism-based inhibitor of FolE2 and capture the structure of the covalently inhibited enzyme using X-ray crystallography. In vitro, the combination of subinhibitory trimethoprim and DHL is more potent than Bactrim, the current standard of care against melioidosis. Moreover, unlike Bactrim, this combination does not affect the growth of most commensal and beneficial gut bacteria tested, thereby providing a degree of specificity against B. pseudomallei . Our work provides a path for identifying antimicrobial drug targets and for utilizing binary combinations of molecules that form a toxic cocktail based on metabolic idiosyncrasies of specific pathogens.

中文翻译：

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用化学合成致死性对抗类鼻疽


泰国伯克霍尔德菌已成为类鼻疽病原体类鼻疽伯克霍尔德菌的非致病性替代物，也是研究次生代谢生物合成和调节的重要革兰氏阴性模型细菌。我们最近报道了甲氧苄啶的亚抑制浓度会诱导泰国双歧杆菌的初级和次级代谢组发生巨大变化。在目前的工作中，我们表明叶酸生物合成酶 FolE2 在标准生长条件下是允许的，但在甲氧苄啶亚抑制剂量存在下对泰国芽孢杆菌至关重要。推断 FolE2 可能是一个有吸引力的药物靶点，我们筛选并确定了 10 种抑制剂，包括脱氢肋内酯 （DHL）、小白菊内酯和 β-lapachone，所有这些抑制剂单独都是无害的，但与亚抑制剂量的甲氧苄啶形成化学合成致死组合。我们表明 DHL 是一种基于机制的 FolE2 抑制剂，并使用 X 射线晶体学捕获共价抑制酶的结构。在体外，亚抑制性甲氧苄啶和 DHL 的组合比 Bactrim 更有效，Bactrim 是目前针对类鼻疽的护理标准。此外，与 Bactrim 不同的是，这种组合不会影响大多数测试的共生和有益肠道细菌的生长，从而对类鼻疽芽孢杆菌具有一定程度的特异性。我们的工作为识别抗菌药物靶点和利用分子的二元组合提供了一条途径，这些分子组合根据特定病原体的代谢特性形成有毒鸡尾酒。