Functional Analysis of an Uridine Diphosphate Glycosyltransferase Involved in the Biosynthesis of Polyphenolic Glucoside in Tea Plants (&ITCamellia sinensis&IT)
Functional Analysis of an Uridine Diphosphate Glycosyltransferase Involved in the Biosynthesis of Polyphenolic Glucoside in Tea Plants (&ITCamellia sinensis&IT)
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参与茶树多酚葡萄糖苷生物合成的尿苷二磷酸糖基转移酶的功能分析（
DOI：
10.1021/acs.jafc.7b04969
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发表时间：
2017
影响因子：
6.1
通讯作者：
Wang Yunsheng
中科院分区：
文献类型：
--
作者：
Zhao Xuecheng;Dai Xinlong;Gao Liping;Guo Lina;Zhuang Juhua;Liu Yajun;Ma Xiubing;Wang Rui;Xia Tao;Wang Yunsheng
多酚是对植物和人类健康有益的最大化合物组之一。黄酮醇苷是茶树多酚类物质的主要成分。黄酮醇-3-O-糖苷是茶浸液中的特征性涩味化合物。从茶树中分离到一种多酚糖基转移酶（CsUGT 72 AM 1），属于簇IIIb。CsUGT 72 AM 1的cDNA全长为1416 bp。它编码472个氨基酸，计算分子量为50.92 kDa，等电点为5.21。重组CsUGT 72 AM 1蛋白在大肠杆菌中表达，并对多种黄酮和松柏醛具有催化活性。酶活性测定结果表明，rCsUGT 72 AM 1在体外可分别与黄酮醇和松柏醇糖苷化生成3-O-葡萄糖苷和4-O-葡萄糖苷。有趣的是，这种酶也有活性，并进行多位点糖苷化对黄烷酮。经核磁共振分析，确定了产物为柚皮素-7-O-葡萄糖苷和-4′-O-葡萄糖苷。此外，在以花青素为底物的酶活性测定中，高浓度的花青素对CsUGT 72 AM 1的糖基化活性有明显的抑制作用。以上结果表明，CsUGT 72 AM 1可能参与了黄酮醇、二氢黄酮、花色素苷和木质素的代谢。
Polyphenols are one of the largest groups of compounds that confer benefits to the health of plants and humans. Flavonol glycosides are a major ingredient of polyphenols inCamellia sinensis. Flavonol-3-O-glycosides are characteristic astringent taste compounds in tea infusion. A polyphenolic glycosyltransferase (CsUGT72AM1) belonging to cluster IIIb was isolated from the tea plant. The full-length cDNA ofCsUGT72AM1is 1416 bp. It encodes 472 amino acids with a calculated molecular mass of 50.92 kDa and an isoelectric point of 5.21. The recombinantCsUGT72AM1 protein was expressed inEscherichia coliand exhibited catalytic activity toward multiple flavonoids and coniferyl aldehyde. The enzyme assay indicated that rCsUGT72AM1 could perform glycosidation of flavonols or coniferyl aldehydein vitroto form 3-O-glucoside or 4-O-glucoside, respectively. Interestingly, this enzyme also had activities and performed multisite glycosidation toward flavanones. The consistent products were confirmed to be naringenin-7-O-glucoside and -4′-O-glucoside by the nuclear magnetism assay. In addition, in the enzyme assay with cyanidin as the substrate, the results suggested that the glycosylated activity ofCsUGT72AM1 was remarkably inhibited by a high concentration of anthocyanins. The above results indicate thatCsUGT72AM1 may be involved in the metabolism of flavonol, flavanone, anthocyanin, and lignin.