Treating Gram-negative bacteria with antibiotics remains difficult due to the lack of a target that is specific for this population while sparing other innocuous groups. Broad spectrum antibiotics are known to affect gut microbiome diversity which can result in secondary Clostridioides difficile infections. The Lol system, which mediates lipoprotein transport between the inner and outer membranes in Gram-negative bacteria, is viewed as an enticing target. In particular, the transporter LolCDE is required for Gram-negative pathogen growth and exhibits low sequence homology with commensal bacteria. Now, Muñoz et al. have utilized known inhibitors of the LolCDE complex and modified them to improve their anti-bacterial activity against wild-type, Gram-negative pathogens, resulting in the development of the antibiotic lolamicin. Lolamicin exhibited strong activity against multidrug resistant isolates of Gram-negative pathogens such as Escherichia coli and Klebsiella pneumoniae but was inactive against Gram-positive pathogens and commensal bacteria, and was well-tolerated in mammalian cell lines and red blood cells. Generation of spontaneous lolamicin-resistant mutants in E. coli and K. pneumoniae revealed amino acid changes in LolC and LolE, confirming that lolamicin acts on the LolCDE complex. Docking and molecular dynamics simulations using the published cryo-electron microscopy structure of LolCDE identified four potential lolamicin binding clusters in the vicinity of the identified resistance mutations, suggesting that lolamicin may competitively block lipoprotein binding. Treatment of lolamicin in mice exhibited good oral bioavailability and tolerance and was effective against infections with antibiotic-resistant strains of K. pneumoniae. Compared with broad spectrum antibiotics, lolamicin treatment did not alter the gut microbiome diversity and prevented C. difficile infection. Overall, the work from Muñoz et al. reveals a potential strategy to treat a variety of Gram-negative infections with minimal off-target effects.

Original reference: Nature 629, 429–436 (2024)

由于缺乏针对该人群的特异性靶标，同时不影响其他无害群体，用抗生素治疗革兰氏阴性菌仍然很困难。已知广谱抗生素会影响肠道微生物组多样性，从而导致继发性艰难梭菌感染。 Lol 系统介导革兰氏阴性细菌内膜和外膜之间的脂蛋白转运，被视为一个诱人的目标。特别是，转运蛋白 LolCDE 是革兰氏阴性病原体生长所必需的，并且与共生细菌表现出较低的序列同源性。现在，穆尼奥斯等人。利用已知的 LolCDE 复合物抑制剂并对其进行修饰，以提高其对野生型革兰氏阴性病原体的抗菌活性，从而开发了抗生素 lolamicin。 Lolamicin 对革兰氏阴性病原体（如大肠杆菌和肺炎克雷伯氏菌）的多重耐药分离株表现出很强的活性，但对革兰氏阳性病原体和共生细菌没有活性，并且在哺乳动物细胞系和红细胞中具有良好的耐受性。在大肠杆菌和肺炎克雷伯菌中自发产生的洛拉霉素抗性突变体揭示了 LolC 和 LolE 中的氨基酸变化，证实了洛拉霉素作用于 LolCDE 复合物。使用已发表的 LolCDE 冷冻电子显微镜结构进行对接和分子动力学模拟，在已识别的抗性突变附近确定了四个潜在的洛拉米星结合簇，表明洛拉米星可能竞争性地阻断脂蛋白结合。洛拉米星在小鼠体内的治疗表现出良好的口服生物利用度和耐受性，并且能有效对抗肺炎克雷伯菌的抗生素耐药菌株的感染。 与广谱抗生素相比，洛拉米星治疗不会改变肠道微生物群多样性并预防艰难梭菌感染。总的来说，穆尼奥斯等人的工作。揭示了一种以最小的脱靶效应治疗多种革兰氏阴性感染的潜在策略。

原始参考文献：Nature 629, 429–436 (2024)