Epimedium is used in traditional Chinese medicine and contains flavonol glycosides that exhibit multiple biological activities. These bioactive flavonol glycosides usually have a rhamnose moiety at the 3-OH position of prenylflavonols, such as icariin (9), baohuoside I (1a) and baohuoside II (2a). However, to date, no rhamnosyltransferase has been reported to catalyze the 3-O-rhamnosylation of prenylflavonols. In this article, a flavonol rhamnosyltransferase, EpPF3RT, was identified from E. pseudowushanense B. L. Guo. The recombinant enzyme regiospecifically transfers a rhamnose moiety to 8-prenylkaempferol (1) and anhydroicaritin (2) at the 3-OH position to form baohuoside II (1a) and baohuoside I (2a) in vitro. In addition, a UDP-rhamnose synthase gene, EpRhS, from E. pseudowushanense was functionally characterized and used to produce the UDP-rhamnose sugar donor. Furthermore, an engineered Escherichia coli strain containing EpPF3RT and EpRhS was established to produce baohuoside II (1a) from whole cells. These studies indicate the significant potential of an enzymatic approach for the rhamnosylation of bioactive flavonoids in Epimedium plants and will provide a promising alternative for producing bioactive rhamnosylated flavonoids combined with other genes/enzymes by synthetic biology.

中文翻译：

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假吴山淫羊Epi的一种区域特异性鼠李糖基转移酶催化异戊二烯黄酮的3- O-鼠李糖基化†

淫羊med在传统中药中使用，并含有具有多种生物活性的黄酮醇苷。这些生物活性黄酮醇糖苷通常在异戊烯基黄酮醇的3-OH位置具有鼠李糖部分，如icariin （9），baohuoside I（1a）和baohuoside II（2a）。然而，迄今为止，尚未报道鼠李糖基转移酶催化异戊烯基黄酮醇的3- O-鼠李糖基化。在本文中，从伪乌山大肠杆菌BL Guo中鉴定出黄酮醇鼠李糖基转移酶EpPF3RT。重组酶将鼠李糖部分区域特异性地转移至8-异戊二烯基山emp酚（1）和脱水脱水甘油（2））在3-OH的位置在体外形成baohuoside II（1a）和baohuoside I（2a）。另外，功能上表征了来自假乌山大肠杆菌的UDP-鼠李糖合酶基因EpRhS，并用于生产UDP-鼠李糖供体。此外，建立了包含EpPF3RT和EpRhS的工程化大肠杆菌菌株，以从全细胞中产生宝火苷II（1a）。这些研究表明酶的方法在生物活性黄酮类化合物的rhamnosylation的显著潜力淫羊藿 植物，将为通过合成生物学生产与其他基因/酶结合的生物活性鼠李糖基黄酮类化合物提供有希望的替代方法。