ESX-5分泌系统对于缓慢生长的致病性分枝杆菌物种的生存力和毒力至关重要。在这项研究中,我们确定1,2,4-恶二唑衍生物是ESX-5分泌系统的假定效应物。我们证实,这种1,2,4-恶二唑和几种新合成的衍生物抑制了海洋分枝杆菌对活性脂肪酶LipY的ESX-5依赖性分泌(M.marinum)。尽管脂肪酶活性降低,我们没有观察到LipY分泌本身的缺陷。此外,我们发现其他几种ESX-5底物,特别是高分子量的PE_PGRSMMAR_5294,由几种1,2,4-恶二唑处理的马氏支原体分泌更多。对在不同恶二唑衍生物存在下生长的M.marinum的分析表明,LipY的分泌和PE_PGRS分泌的诱导是,事实上,两个独立的表型,因为我们能够鉴定仅特异性诱导这些表型之一的化合物的结构特征。尽管三种最有效的1,2,4-恶二唑对培养物中的M.marinum或结核分枝杆菌的生长仅显示出温和的影响,这些化合物可显着降低M.marinum感染斑马鱼模型中的细菌负担。总之,我们报道了一种1,2,4-恶二唑支架,其对ESX-5蛋白分泌的失调。
The ESX-5 secretion system is essential for the viability and virulence of slow-growing pathogenic mycobacterial species. In this study, we identified a 1,2,4-oxadiazole derivative as a putative effector of the ESX-5 secretion system. We confirmed that this 1,2,4-oxadiazole and several newly synthesized derivatives inhibited the ESX-5-dependent secretion of active lipase LipY by Mycobacterium marinum (M. marinum). Despite reduced lipase activity, we did not observe a defect in LipY secretion itself. Moreover, we found that several other ESX-5 substrates, especially the high molecular-weight PE_PGRS MMAR_5294, were even more abundantly secreted by M. marinum treated with several 1,2,4-oxadiazoles. Analysis of M. marinum grown in the presence of different oxadiazole derivatives revealed that the secretion of LipY and the induction of PE_PGRS secretion were, in fact, two independent phenotypes, as we were able to identify structural features in the compounds that specifically induced only one of these phenotypes. Whereas the three most potent 1,2,4-oxadiazoles displayed only a mild effect on the growth of M. marinum or M. tuberculosis in culture, these compounds significantly reduced bacterial burden in M. marinum-infected zebrafish models. In conclusion, we report a 1,2,4-oxadiazole scaffold that dysregulates ESX-5 protein secretion.