甘草鲨烯合酶1基因多态性及其与β-香树脂醇合成酶共表达对β-香树脂醇积累的影响研究(英文)

Enhancing the accumulation of β-amyrin in Saccharomyces cerevisiae by co-expression of Glycyrrhiza uralensis squalene synthase 1 and β-amyrin synthase genes

甘草是我国最常用的大宗药材之一。甘草中最主要的活性成分为甘草酸,其生物合成途径受到很多酶的调节。鲨烯合酶(squalene synthase,SQS)及β-香树脂醇合成酶(β-amyrin synthase,β-AS)是其中的两种关键酶。为了揭示鲨烯合酶基因多态性及其与β-香树脂醇合成酶共表达对MVA代谢途径的影响,本文构建了7种载体,分别含有3种不同的SQS1基因和β-AS基因,将其在酿酒酵母(Saccharomyces cerevisiae)中表达,通过TLC及GC-MS检测代谢产物β-香树脂醇的含量。结果显示SQS1基因与β-AS基因共表达有助于代谢产物β-香树脂醇的积累,在3种不同的SQS1基因中,以SQS12为最好。本文为进一步研究功能基因对甘草酸代谢途径的影响以及提高甘草酸的含量奠定了理论基础。

Glycyrrhiza uralensis Fisch. ex DC is widely used in traditional Chinese medicine （TCM）. Among its various active components, glycyrrhizic acid is believed to be the marker component. Squalene synthase （SQS） and β-amyrin synthase （β-AS） are key enzymes in the biosynthetic pathway of glycyrrhizic acid in G uralensis. To reveal the effects of co-expression of SQS1 and β-AS genes on this pathway, 7 yeast expression vectors harboring different SQS1 variants and β-AS were constructed and expressed in Saccharomyces cerevisiae as fusion proteins. TLC and GC-MS results showed that co-expression of SQS1 and β-AS enhanced the accumulation of β-amyrin. The effects of SQS12 were more obvious than the other two SQS1 variants. This study is significant for further investigations concerned with exploring the biosynthesis of glycyrrhizic acid in vitro and strengthening the efficacy of G uralensis by means of increasing the content of glycyrrhizic acid.