Metabolic Diversification of Benzylisoquinoline Alkaloid Biosynthesis Through the Introduction of a Branch Pathway in Eschscholzia californica
Metabolic Diversification of Benzylisoquinoline Alkaloid Biosynthesis Through the Introduction of a Branch Pathway in Eschscholzia californica
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DOI：
10.1093/pcp/pcq063
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发表时间：
2010-06-01
影响因子：
4.9
通讯作者：
Sato, Fumihiko
中科院分区：
文献类型：
--
作者：
Takemura, Tomoya;Ikezawa, Nobuhiro;Sato, Fumihiko
高等植物产生多种次生代谢物。这些化学物质是由简单的前体通过多步反应合成的。为了了解植物细胞是如何产生如此复杂的代谢的，我们研究了异位表达黄连古戊碱-9- o -甲基转移酶（CjSMT）的转基因加利福尼亚Eschscholzia califomica细胞中苯基异喹啉生物碱生物合成的可塑性。CjSMT催化的O-methylation scoulerine生产tetrahydrocolumbamine (THC)小檗碱生物合成和没有参与在大肠californica benzophenanthridine生物碱的生物合成。虽然初步表征证实columbamine (THC的氧化产物)是生产转基因大肠californica细胞,许多新发现的山峰并不确定。在这里，我们报告了新产品的鉴定，包括异隐托碱和10-羟基车里红碱。该结果表明，CjSMT反应产物被内源性酶进一步转化为双o -甲基化化合物，而不是在原苯并苯胺生物碱的7,8位上形成一个亚二氧基环。进一步的代谢物分析显示转基因细胞中生物碱谱的多样性增强。讨论了代谢可塑性和参与代谢多样性的酶。
Higher plants produce a diverse array of secondary metabolites. These chemicals are synthesized from simple precursors through multistep reactions. To understand how plant cells developed such a complicated metabolism, we examined the plasticity of benzyl isoquinoline alkaloid biosynthesis in transgenic Eschscholzia califomica cells with the ectopic expression of Coptis japonica scoulerine-9-O-methyltransferase (CjSMT). CjSMT catalyzes the O-methylation of scoulerine to produce tetrahydrocolumbamine (THC) in berberine biosynthesis and is not involved in benzophenanthridine alkaloid biosynthesis in E. californica. While a preliminary characterization confirmed that columbamine (oxidized product of THC) was produced in transgenic E. californica cells, many newly found peaks were not identified. Here, we report the identification of novel products, including allocryptopine and 10-hydroxychelerythrine. This result indicates that CjSMT reaction products were further converted by endogenous enzymes to produce double O-methylated compounds instead of a methylenedioxy ring at the 7,8-position of the original benzophenanthridine alkaloids. Further metabolite profiling revealed the enhanced diversification of the alkaloid profile in transgenic cells. Metabolic plasticity and the enzymes involved in metabolic diversity are discussed.