Identification and functional analysis of glycosyltransferase catalyzing the synthesis of phlorizin and trilobatin in Lithocarpus polystachyus Rehd

• Published in: Industrial crops and products Vol. 192; p. 116056
• Main Authors: Zhang, Jie, Jiao, Mengying, Cheng, Wenwen, Song, Xin, Wang, Shuo, Zhao, Xuelei, Dong, Jing, Zhang, Xuemei, Long, Yuehong, Xing, Zhaobin
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2023
• Subjects: Lithocarpus polystachyus Rehd; LpP2`GT; LpP4`GT; UDP-glucosyltransferase; LpP2`GT; PSPG motif; UGT; P2`GT; Lithocarpus polystachyus Rehd; UDP-glucose; P4`GT; UDP-glucosyltransferase; LpP4`GT
• ISSN: 0926-6690; 1872-633X
• DOI: 10.1016/j.indcrop.2022.116056

The leaves of Lithocarpus polystachyus Rehd. are rich in dihydrochalcone compounds phlorizin and trilobatin, which are substances of great medicinal importance and may serve as potential sources for apple-derived phlorizin and trilobatin substitutes. In this study, the uridine diphosphate-glycosyltransferase (UGT) gene family in the L. polystachyus transcriptome was identified and analyzed at different developmental stages, and 107 UGTs were obtained, containing 16 subfamilies. The comparative analysis confirmed that a more complete UGT gene family was obtained for L. polystachyus. Following the comparative analysis of UGT gene expression and metabolite content, four candidate phloretin 2'-O-glucosyltransferase (LpP2`GT) genes catalyzing phlorizin synthesis and three phloretin 4'-O-glucosyltransferase (LpP4`GT) genes catalyzing trilobatin synthesis were screened in the E and L subgroups of the L. polystachyus UGT gene family. The functions of LpP2`GT (Cluster-6439.143031, Cluster-6439.111627) and LpP4`GT (Cluster-6439.98883) were expressed and validated in vitro; enzyme kinetic analysis showed that the affinity and catalytic efficiency of Cluster-6439.143031 recombinant for phloretin were higher than Cluster-6439.98883. Molecular docking results suggest that this may have been caused by a difference in the efficiency of the LpUGT proteins in catalyzing sugar donor protonation, which affected the nucleophilic substitution reaction with uridine diphosphate-glucose (UDP-glucose), leading to differences in activity. [Display omitted] •Sweet tea serve as potential substitutes for apple-derived phlorizin and trilobatin.•Two type uridine diphosphate glycosyltransferase catalyzed phloretin were identified.•Molecular docking explains mechanism in difference activities of glycosyltransferase.•This work enable pure phloretin glycosides to be synthesized in vitro.