School of Forestry and Resource Conservation, National Taiwan University, Taipei, Taiwan.
Department of Forestry, National Chung-Hsing University, Taichung, Taiwan.
Plant Sci. 2022 Aug;321:111315. doi: 10.1016/j.plantsci.2022.111315. Epub 2022 May 18.
Terpene synthase (TPS) analysis may contribute to a better understanding of terpenoids biosynthesis and the evolution of phylogenetic taxonomy. Chamaecyparis formosensis Matsumura is an endemic and valuable conifer of Taiwan. Its excellent wood quality, fragrance, and durability make it become the five precious conifers in Taiwan. In this study, three sesquiterpene synthase genes that belong to the TPS-d2 clade were isolated and characterized through in vitro reaction of recombinant protein and in vivo reaction of Escherichia coli heterologous expression system. The main product of Cf-GerA was germacrene A using GC/MS analysis, while the product of Cf-Aco and Cf-Gor were identified as acora-4(14),8-diene and (5R,6R,10S)-α-gorgonene by using NMR analysis. These are the first reported enzymes that biosynthesize acora-4(14),8-diene and (5 R,6 R,10 S)-α-gorgonene. Both sesquiterpene synthases may isomerize the farnesyl pyrophosphate substrate to nerolidyl pyrophosphate for further cyclization. Cf-Aco may catalyze 1,6-cyclization of nerolidyl cation while Cf-Gor may catalyze through an uncharged intermediate, isogermacrene A.
萜烯合酶（TPS）分析可能有助于更好地理解萜类生物合成和系统发育分类学的进化。台湾扁柏是台湾特有的一种珍贵针叶树。其优良的木材质量、香气和耐久性使其成为台湾的五种珍贵针叶树之一。本研究通过体外重组蛋白反应和大肠杆菌异源表达系统的体内反应，分离并鉴定了三个属于 TPS-d2 分支的倍半萜合酶基因。Cf-GerA 的主要产物通过 GC/MS 分析鉴定为大根香叶烯 D，而 Cf-Aco 和 Cf-Gor 的产物通过 NMR 分析鉴定为 acora-4(14),8-二烯和 (5R,6R,10S)-α-高烯。这些是首次报道能够生物合成 acora-4(14),8-二烯和 (5R,6R,10S)-α-高烯的酶。两种倍半萜合酶可能将法呢基焦磷酸底物异构化为香叶基焦磷酸，以进一步环化。Cf-Aco 可能催化 nerolidyl 阳离子的 1,6-环化，而 Cf-Gor 可能通过不带电荷的中间体异大根香叶烯 D 进行催化。
