武汉植物园表明PlUGT1是催化异黄酮7-O-糖苷形成的关键酶分子

糖苷是天然药物的修饰基团，增强了小分子药物的水溶性与制剂成药的可操作性。野葛是一种豆科植物，其根富含多种异黄酮糖苷类化合物，具有降血脂、抗肿瘤、预防骨质疏松和女性更年期综合症等功效。挖掘野葛根中催化异黄酮糖苷形成的糖基转移酶，对于新药合成与老药糖基化改造具有重要的应用价值。

中国科学院武汉植物园天然产物合成生物学学科组助理研究员黎佳和博士研究生李兆波在章焰生研究员的指导下，从野葛根中分离了7个根中高量表达的糖基转移酶基因，并利用酵母与原核生物蛋白表达系统对这些基因的功能进行了分析，结果表明糖基转移酶PlUGT1(UGT88E12)和PlUGT13(UGT88H1)分别催化大豆苷元、染料木素和芒柄花素转化成大豆苷、染料木苷和芒柄花苷，其中PlUGT1的活性明显高于PlUGT13;PlUGT1对异黄酮底物具有较高的专一性，而PlUGT13对异黄酮和其它黄酮类物质的催化活性无显著差异;借助野葛植物悬浮细胞系，该研究组还分析了PIUGT基因表达与大豆苷物质代谢积累的相关性，结果显示PIUGT1基因的表达与大豆苷的生物合成呈正相关，而PIUGT13的表达与大豆苷的积累无明显相关。这些结果均表明PlUGT1是催化异黄酮7-O-糖苷形成的关键酶分子。

该研究得到国家自然基金(31170284)、中国科学院“百人计划”(Y129441R01)和中国科学院知识创新工程(KSCX2-EW-J-20)的支持，相关研究结果已在国际学术期刊plant cell reports上在线发表。

原文摘要：

Molecular cloning and characterization of an isoflavone 7-O-glucosyltransferase from Pueraria lobata

Jia Li, Zhaobo Li, Changfu Li, Junbo Gou, Yansheng Zhang

Pueraria lobata roots are traditionally consumed as a rich source of isoflavone glycosides that have various human health benefits. However, to date, the genes encoding isoflavone UDP-glycosyltransferases (UGTs) have only been isolated from the roots of soybean seedlings (GmIF7GT), soybean seeds (UGT73F2) and Glycyrrhiza echinata cell suspension cultures (GeIF7GT). To investigate the isoflavone metabolism in P. lobata, 40 types of partial UGT cDNAs were isolated from P. lobata, and seven full-length UGT candidates with preferential expression in roots were identified. Functional assays in yeast (Saccharomyces cerevisiae) revealed that one of these UGT candidates, designated PlUGT1 (official UGT designation UGT88E12), efficiently glycosylated isoflavone aglycones at the 7-hydroxy group. Recombinant PlUGT1 purified fromEscherichia coli cells was characterized and shown to be relatively specific for isoflavone aglycones, while flavonoid substrates were poorly accepted. The biochemical results suggested that PlUGT1 was an isoflavone 7-O-glucosyltransferase. The deduced amino acid sequence of PlUGT1 shared only 26 % identity with GeIF7GT, 27 % with UGT73F2 and 63 % with GmIF7GT. The PlUGT1 gene was highly expressed in P. lobata roots relative to other organs and strongly induced by methyl jasmonate signal in P. lobata cell suspension culture. The transcript abundance of PlUGT1 was correlated with the accumulation pattern of isoflavone glycosides such as daidzin in P. lobata plants or in cell suspension culture. The biochemical properties and gene expression profile supported the idea that PlUGT1 could play a role in isoflavone glycosylation in P. lobata.

标签: 糖基转移酶 PlUGT1 异黄酮7-O-糖苷

作者：中科院

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