Cloning, Prokaryotic Expression, and Enzyme Activity of a UDP‑Glucose Flavonoid 3‑O‑Glycosyltransferase from Mulberry (Morus alba L.) Leaves

Objectives: In this article, MaUFGT, a cDNA encoding the UFGT from mulberry leaves, was cloned, codon optimized, and expressed in Escherichia coli to study its effect in vitro. Materials and Methods: Mulberry UDP- Glucose flavonoid‑3‑O‑glucanotransferase (MaUFGT) gene was reverse transcription‑polymerase chain reaction amplified using the cDNA obtained from young leaves of mulberry, and the full‑length MaUFGT gene was synthesized by codon‑optimized whole‑gene synthetic method. Then, the plasmid pCzn1/MaUFGT was constructed and heterologously expressed in E. coli. After denatured, renatured, and purified, the recombinant protein was used to evaluate its function in vitro by determining the final product by high‑performance liquid chromatography. Results: The target protein was in the range of 45–66 KD and mainly present in the form of inclusion bodies. The obtained protein was found to transfer UDP‑glucose glycosyl moieties to the 3‑hydroxyl group of quercetin or kaempferol to form the corresponding products in vitro. Conclusion: The MaUFGT was preliminarily proved to be involved in flavonoid 3‑O‑glucoside biosynthesis.