Plant Mol Biol. 2014 Jan;84(1-2):227-41. doi: 10.1007/s11103-013-0131-3.
In this paper we characterize three sTPSs: a germacrene D (LaGERDS), a (E)-β-caryophyllene (LaCARS) and a τ-cadinol synthase (LaCADS). τ-cadinol synthase is reported here for the first time and its activity was studied in several biological models including transiently or stably transformed tobacco species. Three dimensional structure models of LaCADS and Ocimum basilicum γ-cadinene synthase were built by homology modeling using the template structure of Gossypium arboreum δ-cadinene synthase. The depiction of their active site organization provides evidence of the global influence of the enzymes on the formation of τ-cadinol: instead of a unique amino-acid, the electrostatic properties and solvent accessibility of the whole active site in LaCADS may explain the stabilization of the cadinyl cation intermediate. Quantitative PCR performed from leaves and inflorescences showed two patterns of expression. LaGERDS and LaCARS were mainly expressed during early stages of flower development and, at these stages, transcript levels paralleled the accumulation of the corresponding terpene products (germacrene D and (E)-β-caryophyllene). By contrast, the expression level of LaCADS was constant in leaves and flowers. Phylogenetic analysis provided informative results on potential duplication process leading to sTPS diversification in lavender.
在本文中，我们对三个 sTPS 进行了特征描述：一个是大根香叶烯 D（LaGERDS），一个是(E)-β-石竹烯（LaCARS），还有一个是 τ-杜松烯合酶（LaCADS）。 τ-杜松烯合酶是首次在此报道的，其活性在包括瞬时或稳定转化的烟草物种在内的几个生物模型中进行了研究。利用陆地棉 δ-杜松烯合酶的模板结构，通过同源建模构建了 LaCADS 和罗勒 γ-杜松烯合酶的三维结构模型。它们活性位点组织的描述为酶对 τ-杜松烯形成的全局影响提供了证据：取代独特的氨基酸，LaCADS 中整个活性位点的静电特性和溶剂可及性可能解释了卡丹基阳离子中间体的稳定性。来自叶片和花序的定量 PCR 显示了两种表达模式。LaGERDS 和 LaCARS 主要在花发育的早期阶段表达，在这些阶段，转录水平与相应萜烯产物（大根香叶烯 D 和(E)-β-石竹烯）的积累相平行。相比之下，LaCADS 的表达水平在叶片和花朵中保持不变。系统发育分析为薰衣草中 sTPS 多样化的潜在复制过程提供了有价值的结果。
