State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China.
Key Laboratory of Microbial Diversity in Southwest China, Ministry of Education, College of Life Science, Yunnan University, Kunming, 650091, China.
Microb Biotechnol. 2022 Apr;15(4):1168-1177. doi: 10.1111/1751-7915.13909. Epub 2021 Sep 6.
Two phenazine compounds, diastaphenazine and izumiphenazine C, with complex structures and promising antitumour activity have been isolated from the plant endophytic actinomycete Streptomyces diastaticus W2. Their putative biosynthetic gene cluster (dap) was identified by heterologous expression and gene knockout. There are twenty genes in the dap cluster. dap14-19 related to shikimic pathway were potentially involved in the precursor chorismic acid biosynthesis, and dapBCDEFG were confirmed to be responsible for the biosynthesis of the dibenzopyrazine ring, the nuclear structure of phenazines. Two transcriptional regulatory genes dapR and dap4 played the positive regulatory roles on the phenazine biosynthetic pathway. Most notably, the dimerization of the dibenzopyrazine ring in diastaphenazine and the loading of the complex side chain in izumiphenazine C could be catalysed by the cyclase homologous gene dap5, suggesting an unusual modification strategy tailoring complex phenazine biosynthesis. Moreover, metabolite analysis of the gene deletion mutant strain S. albus::23C5Δdap2 and substrate assay of the methyltransferase Dap2 clearly revealed the biosynthetic route of the complex side chain in izumiphenazine C.
从植物内生放线菌链霉菌 diastaticus W2 中分离到两种具有复杂结构和抗肿瘤活性的吩嗪化合物：二苯并嗪和伊祖米酚嗪 C。通过异源表达和基因敲除鉴定了它们可能的生物合成基因簇（dap）。dap 簇中有二十个基因。dap14-19 与莽草酸途径有关，可能参与前体分支酸的生物合成，而 dapBCDEFG 被证实负责二苯并吡嗪环、吩嗪核结构的生物合成。两个转录调节基因 dapR 和 dap4 对吩嗪生物合成途径发挥正调控作用。值得注意的是，二苯并吡嗪环在二苯并嗪中的二聚化和伊祖米酚嗪 C 中复杂侧链的加载可以由环化酶同源基因 dap5 催化，这表明了一种独特的修饰策略，用于定制复杂的吩嗪生物合成。此外，基因缺失突变株 S. albus::23C5Δdap2 的代谢产物分析和甲基转移酶 Dap2 的底物测定清楚地揭示了伊祖米酚嗪 C 中复杂侧链的生物合成途径。
