Published online 2017 Aug 30. doi: 10.1038/s41467-017-00419-5
Tuberculosis remains one of the world's deadliest communicable diseases, novel anti-tuberculosis agents are urgently needed due to severe drug resistance and the co-epidemic of tuberculosis/human immunodeficiency virus. Here, we show the isolation of six anti-mycobacterial ilamycin congeners (1-6) bearing rare L-3-nitro-tyrosine and L-2-amino-4-hexenoic acid structural units from the deep sea-derived Streptomyces atratus SCSIO ZH16. The biosynthesis of the rare L-3-nitrotyrosine and L-2-amino-4-hexenoic acid units as well as three pre-tailoring and two post-tailoring steps are probed in the ilamycin biosynthetic machinery through a series of gene inactivation, precursor chemical complementation, isotope-labeled precursor feeding experiments, as well as structural elucidation of three intermediates (6-8) from the respective mutants. Most impressively, ilamycins E1/E2, which are produced in high titers by a genetically engineered mutant strain, show very potent anti-tuberculosis activity with an minimum inhibitory concentration value ≈9.8 nM to Mycobacterium tuberculosis H37Rv constituting extremely potent and exciting anti-tuberculosis drug leads.Tuberculosis (TB) remains one of the world's deadliest communicable diseases, novel anti-TB agents are urgently needed due to severe drug resistance and the co-epidemic of TB/HIV. Here, the authors show that anti-mycobacterial ilamycin congeners bearing unusual structural units possess extremely potent anti-tuberculosis activities.
研究背景
受细菌强耐药性影响,人类在与肺结核病斗争的道路上步履维艰。新型抗生素的发现与生产成为攻克这一疾病的迫切需求。
2017年8月30日,Nature Communication(《自然通讯》)发表了中国科学院南海海洋研究所鞠建华团队在抗生素发现及生物合成研究方面取得的最新成果。报道以“Biosynthesis of Ilamycins featuring unusual building blocks and engineered production of enhanced anti-tuberculosis agents”为题,展开介绍了该团队对肺结核治疗新型抗生素怡莱霉素(ilamycins)的发现过程、生物合成机制研究及基因工程改造工作。
作者利用“深海微生物在严苛的生存条件下,会产生抗生素拮抗周边微生物生长”这一化学生态学原理,从深海放线菌Streptomyces atratus SCSIO ZH16菌株中分离到具有显著抗结核分枝杆菌活性的怡莱霉素(ilamycins)。该抗生素对结核分枝杆菌M.Tuberculosis H37Rv的抑制活性为9.8nM,是经典抗结核药物利福平活性的30倍,且对正常细胞的毒性较低,安全性较好,是理想的抗结核抗生素,具有成药的潜力。此外,通过基因工程改造,研发团队成功实现了该化合物在基因工程菌株中的高效生产。
云生物对作者分离获得此新型抗生素的放线菌Streptomyces atratus SCSIO ZH16(9.64Mb)菌株进行了基因组完成图构建。基因组水平研究显示,一段长约57.1kb,含有20个开放阅读框的片段可能与怡莱霉素的生物合成相关。通过深度挖掘基因组信息,研究获得了参与怡莱霉素生物合成过程的基因簇,并进行了相应的功能注释,阐明了怡莱霉素的生物合成通路(下图)。对放线菌Streptomyces atratus SCSIO ZH16菌株开展的基因组测序工作,为新型抗结核抗生素怡莱霉素的药理、毒理研究奠定了基础,也为进一步开展基因工程改造菌研究用于该抗生素的生产提供了理论依据。