Ji Zhongju, Fan Baolian, Chen Yidu, Yue Jingyang, Chen Jiabo, Zhang Rongrong, Tong Yi, Liu Zhongqiu, Liang Jincai, Duan Lixin
Guangdong Provincial Key Laboratory of Translational Cancer Research of Chinese Medicines, Joint International Research Laboratory of Translational Cancer Research of Chinese Medicines, International Institute for Translational Chinese Medicine, School of Pharmaceutical Sciences, Guangzhou University of Chinese Medicine, Guangzhou, China.
Synth Syst Biotechnol. 2023 Jun 25;8(3):437-444. doi: 10.1016/j.synbio.2023.06.005. eCollection 2023 Sep.
(Linn.) J. Sm., a tree fern in the Dicksoniaceae family, is an economically important industrial exported plant in China and widely used in Traditional Chinese Medicine. produces a range of bioactive triterpenes and their metabolites. However, the biosynthetic pathway of triterpenes in remains unknown. To clarify the origin of diverse triterpenes in , we conducted transcriptome sequencing and analysis of rhizomes and leaves to identify the candidate genes involved in triterpene biosynthesis. Three triterpene synthases (CbTSs) candidate genes were obtained. All of them were highly expressed in rhizomes, consisting of the accumulation pattern of triterpenes in . To characterize the function of these CbTSs, we constructed a squalene- and oxidosqualene-overproducing yeast chassis by overexpressing all the enzymes in the MVA pathway under the control of GAL-regulated promoter and disrupted the GAL80 gene in simultaneously. Heterologous expressing CbTS1, CbTS2, and CbTS3 in engineering yeast strain produced cycloartenol, dammaradiene, and diploptene, respectively. Phylogenetic analysis revealed that CbTS1 belongs to oxidosqualene cyclase, while CbTS2 and CbTS3 belong to squalene cyclase. These results decipher enzymatic mechanisms underlying the origin of diverse triterpene in .
（林奈）J. 斯迈，是蚌壳蕨科的一种树蕨，在中国是一种具有重要经济价值的工业出口植物，并且在传统中药中广泛应用。它能产生一系列生物活性三萜及其代谢产物。然而，其体内三萜的生物合成途径仍不清楚。为了阐明其多样三萜的起源，我们对其根茎和叶片进行了转录组测序与分析，以鉴定参与其萜类生物合成的候选基因。获得了三个候选基因，即三萜合酶（CbTSs）。它们在根茎中均高度表达，这与三萜在其中的积累模式相符。为了表征这些CbTSs的功能，我们通过在GAL调控启动子的控制下过表达甲羟戊酸（MVA）途径中的所有酶，构建了一个高产鲨烯和氧化鲨烯的酵母底盘，并同时破坏了酵母中的GAL80基因。在工程酵母菌株中异源表达CbTS1、CbTS2和CbTS3分别产生了环阿屯醇、达玛二烯和羽扇豆烯。系统发育分析表明，CbTS1属于氧化鲨烯环化酶，而CbTS2和CbTS3属于鲨烯环化酶。这些结果揭示了其多样三萜起源背后的酶促机制。
