题目: Refactoring the concise biosynthetic pathway of cyanogramide unveils spirooxindole formation catalyzed by a P450 enzyme

作者: Yiguang Zhu,  Qingbo Zhang,  Chunyan Fang, Yingli Zhang, Liang Ma, Zhiwen Liu, Shilan Zhai, Jing Peng, Liping Zhang, Weiming Zhu,  and Changsheng Zhang

刊物: Angewandte Chemie International Edition

年卷期页: 2020, 59: 14065-14069

摘要：Cyanogramide (1) from the marine actinomycete Actinoalloteichus cyanogriseus WH1-2216-6 features a unique spirooxindole skeleton and exhibits significant bioactivity to efficiently reverse drug resistance in tumor cells. The biosynthetic gene cluster of 1 in A. cyanogriseus WH1-2216-6 was identified and refactored by promoter engineering for heterologous expression in Streptomyces coelicolor YF11, thereby enabling the production of 1 and five new derivatives. Interesting, four of them, including 1, were identified as enantiomeric mixtures in different ratios. The functions of tailoring enzymes, including two methyltransferases (CyaEF), and three cytochrome P450 monooxygenases (CyaGHI) were confirmed by gene inactivation and feeding experiments, leading to the elucidation of a concise biosynthetic pathway for 1. Notably, CyaH was biochemically verified to catalyze the formation of the spirooxindole skeleton in 1 through an unusual carbocation-mediated semipinacol-type rearrangement reaction.