Background: Glucoside natural products have been showing great medicinal values and potentials. However, the production of glucosides by plant extraction, chemical synthesis, and traditional biotransformation is insufficient to meet the fast-growing pharmaceutical demands. Microbial synthetic biology offers promising strategies for synthesis and diversification of plant glycosides.Results: In this study, the two efficient UDP-glucosyltransferases (UGTs) (UGT85A1 and RrUGT3) of plant origin, that are capable of recognizing phenolic aglycons, are characterized in vitro. The two UGTs show complementary regioselectivity towards the alcoholic and phenolic hydroxyl groups on phenolic substrates. By combining a developed alkylphenol bio-oxidation system and these UGTs, twenty-four phenolic glucosides are enzymatically synthesized from readily accessible alkylphenol substrates. Based on the bio-oxidation and glycosylation systems, a number of microbial cell factories are constructed and applied to biotransformation, giving rise to a variety of plant and plant-likeO-glucosides. Remarkably, several unnaturalO-glucosides prepared by the two UGTs demonstrate better prolyl endopeptidase inhibitory and/or anti-inflammatory activities than those of the clinically used glucosidic drugs including gastrodin, salidroside and helicid. Furthermore, the two UGTs are also able to catalyze the formation ofN- andS-glucosidic bonds to produceN- andS-glucosides.Conclusions: Two highly efficient UGTs, UGT85A1 and RrUGT3, with distinct regioselectivity were characterized in this study. A group of plant and plant-like glucosides were efficiently synthesized by cell-based biotransformation using a developed alkylphenol bio-oxidation system and these two UGTs. Many of theO-glucosides exhibited better PEP inhibitory or anti-inflammatory activities than plant-origin glucoside drugs, showing significant potentials for new glucosidic drug development.

Terminal deoxynucleotidyl transferase (TdT), a unique DNA polymerase, can elongate DNA by adding deoxynucleotides to the 3′ terminal of a DNA chain in a template-independent manner. Owing to their remarkable DNA synthesis activity, TdTs have promoted the development of numerous nucleic acid-based methods, tools, and associated applications, attracting broad interest from both academia and industry. This review summarizes and discusses the recent research on TdTs, including their biochemical characteristics, enzyme engineering, and practical applications. New insights and perspectives on the future development of TdTs are provided.