1H-Benzo[d]Imidazole Derivatives Affect MmpL3 in Mycobacterium tuberculosis
1H-Benzo[d]Imidazole Derivatives Affect MmpL3 in Mycobacterium tuberculosis
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DOI：
10.1128/aac.00441-19
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发表时间：
2019-10-01
影响因子：
4.9
通讯作者：
Dziadek, Jaroslaw
中科院分区：
文献类型：
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作者：
Korycka-Machala, Malgorzata;Viljoen, Albertus;Dziadek, Jaroslaw
1H-苯并[d]咪唑类化合物在体外表现出纳摩尔浓度范围内的抗结核活性，对人体细胞无毒，但其作用机制尚不清楚。在这里，我们证明了这些化合物对细胞内结核分枝杆菌具有活性。为了确定他们的靶标，我们选择了耐药结核分枝杆菌突变株，然后使用全基因组测序来揭示必需的mmpL3基因的突变，该基因编码催化输出海藻糖单菌酯的完整膜蛋白，海藻糖二甲醇酸(TDM)是分枝杆菌外膜成分海藻糖二肌酸(TDM)的前体，以及与阿拉伯半乳糖结合的真菌酸。在携带耐药突变的高表达MMPL3等位基因的亲本菌株中也观察到了耐药表型。然而，1H-苯并[d]咪唑类化合物与另一种MmpL3抑制剂SQ109或其他一线抗结核药物之间没有交叉耐药性。代谢标记和定量薄层色谱(TLC)分析表明，经苯并咪唑处理的结核分枝杆菌培养物中的放射性标记脂抑制了海藻糖二肌醇酸(TDM)的合成，并降低了霉菌半乳糖的水平，这与抑制MmpL3的活性一致。总体而言，这项研究强调了1H-苯并[d]咪唑衍生物在干扰霉菌酸代谢方面的显著活性，以及它们在抗击结核病方面的治疗应用潜力。
1H-benzo[d]imidazole derivatives exhibit antitubercular activity in vitro at a nanomolar range of concentrations and are not toxic to human cells, but their mode of action remains unknown. Here, we showed that these compounds are active against intracellular Mycobacterium tuberculosis. To identify their target, we selected drug-resistant M. tuberculosis mutants and then used whole-genome sequencing to unravel mutations in the essential mmpL3 gene, which encodes the integral membrane protein that catalyzes the export of trehalose monomycolate, a precursor of the mycobacterial outer membrane component trehalose dimycolate (TDM), as well as mycolic acids bound to arabinogalactan. The drug-resistant phenotype was also observed in the parental strain overexpressing the mmpL3 alleles carrying the mutations identified in the resistors. However, no cross-resistance was observed between 1H-benzo[d]imidazole derivatives and SQ109, another MmpL3 inhibitor, or other first-line antitubercular drugs. Metabolic labeling and quantitative thin-layer chromatography (TLC) analysis of radiolabeled lipids from M. tuberculosis cultures treated with the benzoimidazoles indicated an inhibition of trehalose dimycolate (TDM) synthesis, as well as reduced levels of mycolylated arabinogalactan, in agreement with the inhibition of MmpL3 activity. Overall, this study emphasizes the pronounced activity of 1H-benzo[d]imidazole derivatives in interfering with mycolic acid metabolism and their potential for therapeutic application in the fight against tuberculosis.