Mechercharmycin A (MCM-A) is a marine natural product belonging to a family of polyazole cyclopeptides with remarkable bioactivities and unique structures. Identification, heterologous expression, and genetic characterizations of the MCM biosynthetic gene cluster in Bacillus subtilis revealed that it is a ribosomally synthesized and post-translationally modified peptide (RiPP) possessing complex with distinctive modifications. Based on this heterologous expression system, two MCM analogs with comparable antitumor activity are generated by engineering the biosynthetic pathway. Combinatorial co-production of a precursor peptide with different modifying enzymes in Escherichia coli identifies a different timing of modifications, showing that a tRNA^Glu-dependent highly regioselective dehydration is the first modification step, followed by polyazole formation through heterocyclization and dehydrogenation in an N- to C-terminal direction. Therefore, a rational biosynthetic pathway of MCMs is proposed, which unveils a subfamily of azol(in)e-containing RiPPs and sets the stage for further investigations of the enzymatic mechanism and synthetic biology.

Mechercharmycin A (MCM-A) 是一种海洋天然产物，属于聚唑环肽家族，具有显着的生物活性和独特的结构。枯草芽孢杆菌中 MCM 生物合成基因簇的鉴定、异源表达和遗传特征表明，它是一种核糖体合成和翻译后修饰的肽 (RiPP)，具有具有独特修饰的复合物。基于这种异源表达系统，通过改造生物合成途径产生了两种具有相当抗肿瘤活性的 MCM 类似物。前体肽与不同修饰酶在大肠杆菌中的组合共生产确定了不同的修饰时间，表明 tRNA ^Glu依赖的高度区域选择性脱水是第一个修饰步骤，然后是通过杂环化和 N 到 C 末端方向的脱氢形成聚唑。因此，提出了一种合理的 MCMs 生物合成途径，揭示了一个含有 azol(in)e 的 RiPPs 亚家族，并为进一步研究酶促机制和合成生物学奠定了基础。