AbstractThe development of novel anti‐infectives requires unprecedented strategies targeting pathways which are solely present in pathogens but absent in humans. Following this principle, we developed inhibitors of lipoic acid (LA) salvage, a crucial pathway for the survival of LA auxotrophic bacteria and parasites but non‐essential in human cells. An LA‐based probe was selectively transferred onto substrate proteins via lipoate protein ligase (LPL) in intact cells, and their binding sites were determined by mass spectrometry. Probe labeling served as a proxy of LPL activity, enabling in situ screenings for cell‐permeable LPL inhibitors. Profiling a focused compound library revealed two substrate analogs (LAMe and C3) as inhibitors, which were further validated by binding studies and co‐crystallography. Importantly, LAMe exhibited low toxicity in human cells and achieved killing of Plasmodium falciparum in erythrocytes with an EC50 value of 15 μM, making it the most effective LPL inhibitor reported to date.
摘要新型抗感染药物的开发需要采用前所未有的策略,以病原体中存在而人类中不存在的途径为目标。根据这一原则,我们开发了硫辛酸(LA)挽救抑制剂,这是硫辛酸辅助细菌和寄生虫生存的关键途径,但在人体细胞中却不是必需的。在完整细胞中,一种基于 LA 的探针通过硫辛酸蛋白连接酶(LPL)选择性地转移到底物蛋白上,并通过质谱测定其结合位点。探针标记可作为 LPL 活性的替代物,从而实现原位筛选细胞渗透性 LPL 抑制剂。通过对重点化合物库的分析,发现了两种底物类似物(LAMe 和 C3)作为抑制剂,并通过结合研究和共晶体学进一步验证了这两种类似物。重要的是,LAMe 在人体细胞中表现出低毒性,对红细胞中的恶性疟原虫有杀伤作用,EC50 值为 15 μM,是迄今为止报道的最有效的 LPL 抑制剂。