Department of Medicine, Jinggangshan University, Ji'an 343009, China.
School of Food Science and Engineering, Foshan University, Foshan 528225, China.
J Agric Food Chem. 2023 Jun 14;71(23):8998-9008. doi: 10.1021/acs.jafc.3c01459. Epub 2023 Jun 1.
Plant bioactive metabolites such as flavonoids are usually present in glycosylated forms by the attachment of various sugar groups. In this study, a catalytically flexible and reversible glycosyltransferase (HtUGT72AS1) was cloned and characterized from . HtUGT72AS1 could directly accept six sugar donors (UDP-glucose/-arabinose/-galactose/-xylose/--acetylglucosamine/-rhamnose) to catalyze the 3-OH glycosylation of flavonols. It also catalyzed the 4' and 7-OH glycosylation of other types of flavonoids, which lacked the 3-OH group. Additionally, the HtUGT72AS1-catalyzed reaction was highly reversible when using 2-chloro-4-nitrophenyl glycosides as substrates, which could be used for one-pot or coupled production of bioactive glycosides. It is the first reported UGT for the synthesis of arabinosides and galactosides using a transglycosylation platform. Based on structural modeling and mutagenetic analysis, the mutation of Tyr377 to Ara enhanced the catalytic efficiency of HtUGT72AS1 toward UDP--acetylglucosamine, and the V146S mutant gained an improvement in the regioselectivity toward 7-OH of flavonoids.
植物生物活性代谢物，如类黄酮，通常通过连接各种糖基而以糖基化形式存在。在这项研究中，从 中克隆并表征了一种催化灵活且可逆的糖基转移酶（HtUGT72AS1）。HtUGT72AS1 可以直接接受六种糖供体（UDP-葡萄糖/-阿拉伯糖/-半乳糖/-木糖/-乙酰葡萄糖胺/-鼠李糖），催化黄酮醇的 3-OH 糖基化。它还催化其他类型缺乏 3-OH 基团的类黄酮的 4'和 7-OH 糖基化。此外，当使用 2-氯-4-硝基苯基糖苷作为底物时，HtUGT72AS1 催化的反应具有高度的可逆性，可用于一锅法或偶联生产生物活性糖苷。这是首次报道使用转糖基化平台合成阿拉伯糖苷和半乳糖苷的 UGT。基于结构建模和突变分析，将 Tyr377 突变为 Ara 增强了 HtUGT72AS1 对 UDP--乙酰葡萄糖胺的催化效率，而 V146S 突变体在黄酮类化合物 7-OH 的区域选择性方面得到了改善。
