中科院上海生命科学研究院的研究人员在代谢工程酵母中确定了催化原人参三醇(Protopanaxatriol)及生物活性人参皂苷（Ginsenosides ）F1和Rh1生物合成的人参尿苷二磷酸糖基转移酶(UGT)的特征。

人参中主要的天然药物活性化合物人参皂苷主要是原人参二醇（PPD）和原人参三醇（PPT）的糖基化产物。UGT负责催化PPT生成PPT类人参皂苷，当前尚无有关UGT的研究报道。

以往的研究证实UGTPg1可区域特异性糖基化PPD的C20-OH。在这篇文章中研究人员发现，UGTPg1还可特异性糖基化PPT的C20-OH生成生物活性人参皂苷F1。他们报告称确定了分离自人参的4个新UGT基因的特征，推导出它们与UGTPg1具有高度的氨基酸同源性(>84%)。他们证实UGTPg100可特异性糖基化PPT的C6-OH生成生物活性人参皂苷Rh1，UGTPg101催化了PPT生成F1，随后F1生成了人参皂苷Rg1。而研究未检测出UGTPg102和UGTPg103对PPT有活性。

通过结构建模和位点定向突变，研究人员鉴别出了这些UGTs的一些关键氨基酸，在决定它们的活性及底物区域特异性中起重要作用。此外，他们构建出了重组酵母，通过导入遗传工程PPT生成信号通路及UGTPg1或UGTPg100生物合成出了F1和Rh1。

新研究揭示出了在人参中PPT类人参皂苷可能的生物合成信号通路，并提供了一种完善的生产方法通过合成生物学策略在酵母中生成生物活性PPT类人参皂苷。（来源： 生物通  何嫱）

Characterization of Panax ginseng UDP-Glycosyltransferases Catalyzing Protopanaxatriol and Biosyntheses of Bioactive Ginsenosides F1 and Rh1 in Metabolically Engineered Yeasts

Abstract  Ginsenosides, the main pharmacologically active natural compounds in ginseng (Panax ginseng), are mostly the glycosylated products of protopanaxadiol (PPD) and protopanaxatriol (PPT). No uridine diphosphate glycosyltransferase (UGT), which catalyzes PPT to produce PPT-type ginsenosides, has yet been reported. Here, we show that UGTPg1, which has been demonstrated to regio-specifically glycosylate the C20-OH of PPD, also specifically glycosylates the C20-OH of PPT to produce bioactive ginsenoside F1. We report the characterization of four novel UGT genes isolated from P. ginseng, sharing high deduced amino acid identity (>84%) with UGTPg1. We demonstrate that UGTPg100 specifically glycosylates the C6-OH of PPT to produce bioactive ginsenoside Rh1, and UGTPg101 catalyzes PPT to produce F1, followed by the generation of ginsenoside Rg1 from F1. However, UGTPg102 and UGTPg103 were found to have no detectable activity on PPT. Through structural modeling and site-directed mutagenesis, we identified several key amino acids of these UGTs that may play important roles in determining their activities and substrate regio-specificities. Moreover, we constructed yeast recombinants to biosynthesize F1 and Rh1 by introducing the genetically engineered PPT-producing pathway and UGTPg1 or UGTPg100. Our study reveals the possible biosynthetic pathways of PPT-type ginsenosides inPanax plants, and provides a sound manufacturing approach for bioactive PPT-type ginsenosides in yeast via synthetic biology strategies.

原文链接：http://ac.els-cdn.com/S1674205215002610/1-s2.0-S1674205215002610-main.pdf?_tid=c4c8a0ba-5693-11e5-a9c3-00000aacb361&acdnat=1441763016_70910601322fb3f9b201191d10a2c586