UGT74AF3 enzymes specifically catalyze the glucosylation of 4-hydroxy-2,5-dimethylfuran-3(2H)-one,an important volatile compound in Camellia sinensis  

作　　者：Yongxian Chen Xiangyang Guo Ting Gao Na Zhang Xiaochun Wan Wilfried Schwab Chuankui Song 

机构地区：[1]State Key Laboratory of Tea Plant Biology and Utilization,International Joint Laboratory on Tea Chemistry and Health Effects,Anhui Agricultural University,230036 Hefei,Anhui,P.R.China [2]Biotechnology of Natural Products,Technische Universität München,Liesel-Beckmann-Str.1,85354 Freising,Germany

出　　处：《Horticulture Research》2020年第1期2433-2443,共11页园艺研究（英文）

基　　金：supported by the National Natural Science Foundation of China(31961133030,31870678);National Key Research and Development Program of China(2018YFD1000601);Science Fund for Distinguished Young Scientists of Anhui Province(1908085J12).

摘　　要：4-Hydroxy-2,5-dimethylfuran-3(2H)-one(HDMF)is an important odorant in some fruits,and is proposed to play a crucial role in the caramel-like notes of some teas.However,its biosynthesis and metabolism in tea plants are still unknown.Here,HDMF glucoside was unambiguously identified as a native metabolite in tea plants.A novel glucosyltransferase UGT74AF3a and its allelic protein UGT74AF3b specifically catalyzed the glucosylation of HDMF and the commercially important structural homologues 2(or 5)-ethyl-4-hydroxy-5(or 2)-methylfuran-3(2H)-one(EHMF)and 4-hydroxy-5-methylfuran-3(2H)-one(HMF)to their correspondingβ-D-glucosides.Site-directed mutagenesis of UGT74AF3b to introduce a single A456V mutation resulted in improved HDMF and EHMF glucosylation activity and affected the sugar donor preference compared with that of the wild-type control enzyme.The accumulation of HDMF glucoside was consistent with the transcript levels of UGT74AF3 in different tea cultivars.In addition,transient UGT74AF3a overexpression in tobacco significantly increased the HDMF glucoside contents,and downregulation of UGT74AF3 transcripts in tea leaves significantly reduced the concentration of HDMF glucoside compared with the levels in the controls.The identification of HDMF glucoside in the tea plant and the discovery of a novel-specific UDP-glucose:HDMF glucosyltransferase in tea plants provide the foundation for improvement of tea flavor and the biotechnological production of HDMF glucoside.

关 键 词：metabolism VOLATILE sugar 

分 类 号：S571.1[农业科学—茶叶生产加工]