膜荚黄芪黄酮糖基转移酶AmGT90的功能表征  

Functional characterization of flavonoid glycosyltransferase AmGT90 in Astragalus membranaceus

作　　者：彭国情 徐冰艳 黄建萍 余志银 黄胜雄 PENG Cuo-qing;XU Bing-yan;HUANG Jian-png;YU Zhi-yin;HUANG Sheng-xiong(School of Pharmacy,Chengdu University of Traditional Chinese Medicine,Chengdu 611137,China;Innovative Institute of Chinese Medicine and Pharmacy,Chengdu University of Traditional Chinese Medicine,Chengdu 611137,China;Key Laboratory of Phytochemistry and Natural Medicines,Kunming Institute of Botany,Chinese Academy of Sciences,Kunming 650201,China)

机构地区：[1]成都中医药大学药学院,四川成都611137 [2]成都中医药大学中医药创新研究院,四川成都611137 [3]中国科学院昆明植物研究所植物化学与天然药物重点实验室,云南昆明650201

出　　处：《中国中药杂志》2025年第6期1534-1543,共10页China Journal of Chinese Materia Medica

基　　金：国家自然科学基金杰出青年基金项目(82225043)。

摘　　要：黄芪作为一种传统补益中药,黄酮类化合物是其主要药效成分和质量标准检测成分之一,它们在植物体内经糖基化修饰后多以糖苷的形式存在。目前已报道的膜荚黄芪黄酮糖基转移酶的反应产物多为单糖苷,只有AmUGT28催化木犀草素生成双糖苷。该研究从膜荚黄芪中克隆得到1条糖基转移酶基因AmGT90,其ORF长度为1335 bp,编码444个氨基酸,蛋白相对分子质量50.5 kDa。系统发育树分析表明,AmGT90属于UGT74家族。体外酶促反应发现,AmGT90具有宽泛的底物识别性,可催化异黄酮、黄酮、二氢黄酮和查尔酮等黄酮类化合物的糖基化。AmGT90不仅能催化生成单糖苷,还能催化生成双糖苷。此外,该研究还对AmGT90催化木犀草素生成双糖苷的机制进行了初步探究,结果表明AmGT90优先识别木犀草素的C4′-OH后识别C7-OH生成双糖苷。综上,该研究报道了膜荚黄芪中能催化黄酮类化合物生成单糖苷和双糖苷的糖基转移酶AmGT90,为认识和了解膜荚黄芪中黄酮苷类有效成分的生物合成途径奠定基础,也为利用合成生物学生产糖苷类物质提供了新的生物元件。Astragalus membranaceus(A.membranaceus),a traditional tonic,contains flavonoids as one of its main bioactive components and key indicators for quality standard detection.These compounds predominantly exist in glycosylated forms after glycosylation modification within the plant.The catalytic products of flavonoid glycosyltransferases in A.membranaceus have been reported to be mostly monoglycosides,and only AmUGT28 catalyzes luteolin to form diglycosides.In this study,we cloned a glycosyltransferase gene,AmGT90,from A.membranaceus,with an ORF length of 1335 bp,encoding 444 amino acids,and the protein had a relative molecular mass of 50.5 kDa.Phylogenetic tree analysis indicated that AmGT90 belongs to the UGT74 family.In vitro enzymatic reaction showed that AmGT90 had broad substrate specificity and could catalyze the glycosylation of various flavonoids,including isoflavones,flavones,flavanones,and chalcones.AmGT90 not only catalyzed the formation of monoglycosides but also diglycosides.In addition,the mechanism of AmGT90 catalyzing the formation of diglycosides from luteolin was preliminarily explored.The experimental results showed that AmGT90 may preferentially recognize C4′-OH of luteolin and then recognize C7-OH to form diglycosides.This study reported a glycosyltransferase from A.membranaceus capable of converting flavonoids into monoglycosides and diglycosides.This finding not only enhances our understanding of the biosynthetic pathways of flavonoid glycosides in A.membranaceus but also introduces a new component for glycoside production through synthetic biology.

关 键 词：膜荚黄芪 糖基转移酶 黄酮 UGT74 功能鉴定 

分 类 号：R284[医药卫生—中药学]