期刊
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
卷 70, 期 13, 页码 4076-4085出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.jafc.2c01029
关键词
quercetin 3-O-N-acetylgalactosamine; hyperoside; flavonoid 3-O-glycosyltransferase; donor promiscuity; quercetin
资金
- Beijing Natural Science Foundation [7212183]
- CAMS Innovation Fund for Medical Sciences (CIFMS) [2021-I2M-1-029]
- National Key Research and Development Program of China [2020YFA0908000]
In this study, Quercetin 3-O-N-acetylgalactosamine (Q3GalNAc), a compound that had never been enzymatically synthesized before, was successfully produced. The enzyme PhUGT was identified to have quercetin GalNAc-T activity and was engineered to enhance the conversion rate. The study also revealed the donor promiscuity of PhUGT and provided a potent biocatalyst for glycodiversifying quercetin.
Quercetin 3-O-N-acetylgalactosamine (Q3GalNAc), a derivative of dietary hyperoside, had never been enzymaticallysynthesized due to the lack of well-identifiedN-acetylgalactosamine-transferase (GalNAc-T). Herein, PhUGT, an identifiedflavonoid 3-O-galactosyltransferase fromPetunia hybrida, was demonstrated to display quercetin GalNAc-T activity, transferring aN-acetylgalactosamine (GalNAc) from UDP-N-acetylgalactosamine (UDP-GalNAc) to the 3-OH of quercetin to form Q3GalNAc witha low conversion of 11.7% at 40 degrees C for 2 h. Protein engineering was thus performed, and the resultant PhUGT variant F368T got anenhanced conversion of 75.5% toward UDP-GalNAc. The enzymatically synthesized Q3GalNAc exhibited a comparable antioxidantactivity with other quercetin 3-O-glycosides. Further studies revealed that PhUGT was a donor promiscuous glycosyltransferase(GT), recognizing seven sugar donors. Thisfinding overturned a previous notion that PhUGT exclusively recognized UDP-galactose(UDP-Gal). The reason why PhUGT was mistaken for a UDP-Gal-specific GT was demonstrated to be a shorter reaction time, inwhich many quercetin 3-O-glycosides, except hyperoside, could not be effectively synthesized. The fact that the microbial cell factoryexpressing PhUGT could yield an array of Q3Gs further confirmed the donor promiscuity of PhUGT. This study laid a foundationfor the scale production of Q3GalNAc and provided a potent biocatalyst capable of glycodiversifying quercetin as well.
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