UGT85A84 Catalyzes the Glycosylation of Aromatic Monoterpenes in Osmanthus fragrans Lour. Flowers
UGT85A84 Catalyzes the Glycosylation of Aromatic Monoterpenes in Osmanthus fragrans Lour. Flowers
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DOI：
10.3389/fpls.2019.01376
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发表时间：
2019-11
影响因子：
5.6
通讯作者：
R. Zheng;Zhenyin Zhu;Yanli Wang;Shiyang Hu;W. Xi;Wei Xiao;Xiaolu Qu;Linlin Zhong;Q. Fu;Caiyun Wang
中科院分区：
文献类型：
--
作者：
R. Zheng;Zhenyin Zhu;Yanli Wang;Shiyang Hu;W. Xi;Wei Xiao;Xiaolu Qu;Linlin Zhong;Q. Fu;Caiyun Wang
芳樟醇及其氧化物是桂花中主要的芳香活性化合物。花。这些单萜苷在整个开花过程中积累，导致大量潜在香气成分的储存，这些成分占非挥发性香气化合物的大部分。然而，负责芳樟醇及其氧化物糖基化的udp -糖基转移酶（UGT）尚未明确。通过转录组测序筛选出4个与已知萜类UGTs具有高度同源性的候选ofuts （UGT85A82、UGT85A83、UGT85AF3和UGT85A84）。候选OfUGTs在烟草中的过表达表明，UGT85A84使植物中的芳樟醇氧化物糖基化。由于UGT85A84的转录水平与糖苷积累呈正相关，因此重组UGT85A84蛋白与苷元和糖供体发生反应。通过液相色谱-质谱分析（LC-MS），在芳樟醇和芳樟醇氧化物反应中，UDP-Glc中只检测到两种甲酸加合物，表明UDP-Glc是特定的糖供体。动力学参数表明，UGT85A84在体外均能使芳樟醇和联樟醇氧化物糖基化。进一步分析表明，MEP通路基因的转录水平可能在介导萜类糖基化过程中发挥重要作用。我们的发现揭示了花中基本香气化合物糖基化的机制。该研究将促进潜在香气贡献者在未来工业中的应用。
The monoterpenes linalool and its oxides are the key aroma-active compounds in Osmanthus fragrans Lour. flowers. The glycosides of these monoterpenes accumulate throughout flowering, leading to considerable storage of potential aroma constituents that account for the majority of non-volatile aroma compounds. However, the UDP-glycosyltransferase (UGT) responsible for the glycosylation of linalool and its oxides has not been clarified. Four candidate OfUGTs (UGT85A82, UGT85A83, UGT85AF3, and UGT85A84) with high homology to the known terpenoid UGTs were screened by transcriptome sequencing. Over-expression of the candidate OfUGTs in tobacco showed that UGT85A84 glycosylated linalool oxides in planta. Since the transcript levels of UGT85A84 were positively correlated with glycoside accumulation, the recombinant UGT85A84 protein was subjected to reactions with aglycones and sugar donors. Two formate adducts were exclusively detected in UDP-Glc with linalool and linalool oxide reactions by liquid chromatography-mass spectrometry (LC-MS), indicating that UDP-Glc was the specific sugar donor. The kinetic parameters demonstrated that UGT85A84 glycosylated both linalool and lianlool oxides in vitro. Further analysis demonstrated that the transcription levels of MEP pathway genes might play an important role in mediating terpenoid glycosylation. Our findings unraveled the mechanism underlying the glycosylation of essential aroma compounds in flowers. This study will facilitate the application of potential aroma contributors in future industries.