Wang Le, Zhao Shou-Jing, Cao Hao-Jie, Sun Yao
School of Biological and Agricultural Engineering, Jilin University, No.5988 Renmin Street Nanguan District, Changchun, Peoples' Republic of China.
Funct Integr Genomics. 2014 Sep;14(3):545-57. doi: 10.1007/s10142-014-0384-1. Epub 2014 Jun 15.
Panax quinquefolius is one of perennial herbs and well known for its outstanding pharmacological activity. Ginsenosides are thought to be the main active ingredients in Panax quinquefolius and exist in many kinds of plant genus Panax (ginseng). Dammarenediol synthase, which is considered as a key enzyme in ginsenoside biosynthesis pathway can convert 2, 3-oxidosqualene into dammarenediol-II. However, the dammarenediol synthase gene in Panax quinquefolius has not been identified. Here, we cloned and identified a dammarenediol synthase gene from Panax quinquefolius (PqDS, GenBank accession No. KC316048) at the first time, and reverse transcription-PCR (RT-PCR) analysis also showed an obvious transcription increase of PqDS in the methyl jasmonate (MeJA)-induced hairy roots. Ectopic expression of PqDS in yeast resulted in the production of dammarenediol-II was confirmed by liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC/APCIMS). Moreover, overexpression of PqDS in transgenic hairy roots could increase the transcription of gene PqDS and another P450 gene PqD12H (encoding protopanaxadiol synthase in Panax quinquefolius), the accumulation of ginsenosides also increased at the same time. In addition, both PqDS and PqD12H gene co-expressed in recombinant yeast result in the production of protopanaxadiol was detected by LC/APCIMS; this result also provides a new strategy for the abundant production of protopanaxadiol in vitro.
西洋参是多年生草本植物之一，以其卓越的药理活性而闻名。人参皂苷被认为是西洋参中的主要活性成分，存在于多种人参属植物中。达玛烯二醇合酶被认为是人参皂苷生物合成途径中的关键酶，可将2,3-氧化鲨烯转化为达玛烯二醇-II。然而，西洋参中的达玛烯二醇合酶基因尚未被鉴定。在此，我们首次从西洋参中克隆并鉴定了一个达玛烯二醇合酶基因（PqDS，GenBank登录号：KC316048），反转录PCR（RT-PCR）分析也表明，在茉莉酸甲酯（MeJA）诱导的毛状根中PqDS的转录明显增加。通过液相色谱-大气压化学电离质谱（LC/APCIMS）证实，PqDS在酵母中的异位表达导致了达玛烯二醇-II的产生。此外，PqDS在转基因毛状根中的过表达可以增加基因PqDS和另一个P450基因PqD12H（编码西洋参原人参二醇合酶）的转录，同时人参皂苷的积累也增加。此外，通过LC/APCIMS检测到，PqDS和PqD12H基因在重组酵母中共表达导致了原人参二醇的产生；这一结果也为体外大量生产原人参二醇提供了一种新策略。
