Three New O-Methyltransferases Are Sufficient for All O-Methylation Reactions of Ipecac Alkaloid Biosynthesis in Root Culture of Psychotria ipecacuanha
作者:Taiji Nomura、Toni M. Kutchan
DOI:10.1074/jbc.m109.086157
日期:2010.3
ipecacuanha produces ipecac alkaloids, a series of monoterpenoid-isoquinoline alkaloids such as emetine and cephaeline, whose biosynthesis derives from condensation of dopamine and secologanin. Here, we identified three cDNAs, IpeOMT1-IpeOMT3, encoding ipecac alkaloid O-methyltransferases (OMTs) from P. ipecacuanha. They were coordinately transcribed with the recently identified ipecac alkaloid beta-glucosidase
药用植物Psychotria ipecacuanha 产生吐根生物碱,这是一系列单萜-异喹啉生物碱,如依米丁和头孢碱,其生物合成来源于多巴胺和secologanin 的缩合。在这里,我们鉴定了三个 cDNA,即 IpeOMT1-IpeOMT3,它们编码来自吐根假单胞菌的吐根生物碱 O-甲基转移酶 (OMT)。它们与最近发现的吐根生物碱 β-葡萄糖苷酶 Ipeglu1 协同转录。它们的氨基酸序列彼此密切相关,而不是与参与苄基异喹啉生物碱生物合成的 OMT 相关,而不是与类黄酮 OMT 相关。重组 IpeOMT 酶的表征与 IpeGlu1 的酶学特性的整合表明,通过 IpeOMT1 的 6-O-甲基化,emetine 生物合成从 N-脱乙酰异胡椒苷分枝出来,IpeOMT2 的贡献较小,然后是 IpeGlu1 的去糖基化。苷元异喹啉骨架的 7-羟基在形成与第二个多巴胺分子缩合的原甲基化之前被 IpeOMT3