title: Biosynthesis of two quercetin O-diglycosides in Escherichia coli.
abstract: Various flavonoid glycosides are found in nature, and their biological activities are as variable as their number. In some cases, the sugar moiety attached to the flavonoid modulates its biological activities. Flavonoid glycones are not easily synthesized chemically. Therefore, in this study, we attempted to synthesize quercetin 3-O-glucosyl (1→2) xyloside and quercetin 3-O-glucosyl (1→6) rhamnoside (also called rutin) using two uridine diphosphate-dependent glycosyltransferases (UGTs) in Escherichia coli. To synthesize quercetin 3-O-glucosyl (1→2) xyloside, sequential glycosylation was carried out by regulating the expression time of the two UGTs. AtUGT78D2 was subcloned into a vector controlled by a Tac promoter without a lacI operator, while AtUGT79B1 was subcloned into a vector controlled by a T7 promoter. UDP-xyloside was supplied by concomitantly expressing UDP-glucose dehydrogenase (ugd) and UDP-xyloside synthase (UXS) in the E. coli. Using these strategies, 65.0 mg/L of quercetin 3-O-glucosyl (1→2) xyloside was produced. For the synthesis of rutin, one UGT (BcGT1) was integrated into the E. coli chromosome and the other UGT (Fg2) was expressed in a plasmid along with RHM2 (rhamnose synthase gene 2). After optimization of the initial cell concentration and incubation temperature, 119.8 mg/L of rutin was produced. The strategies used in this study thus show promise for the synthesis of flavonoid diglucosides in E. coli.
authors.affiliation: Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, Seoul, 05029, Korea.
authors.forename: Dae Gyun
authors.initials: DG
authors.lastname: An
authors.affiliation: Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, Seoul, 05029, Korea.
authors.forename: So Mi
authors.initials: SM
authors.lastname: Yang
authors.affiliation: Department of Forest Resources, Gyeongnam National University of Science and Technology, 33 Dongjin-ro, Jinju-si, Gyeongsangman-do, 660-758, Republic of Korea.
authors.forename: Bong Gyu
authors.initials: BG
authors.lastname: Kim
authors.affiliation: Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, Seoul, 05029, Korea. jhahn@konkuk.ac.kr.
authors.forename: Joong-Hoon
authors.initials: JH
authors.lastname: Ahn
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D005419:Flavonoids / Q000096:biosynthesis; D006027:Glycosides / Q000096:biosynthesis*; D006031:Glycosylation; D016695:Glycosyltransferases / Q000378:metabolism; D010957:Plasmids; D011794:Quercetin / Q000096:biosynthesis*
chemical_list: D001426:Bacterial Proteins; D005419:Flavonoids; D006027:Glycosides; D011794:Quercetin; D016695:Glycosyltransferases
keywords: Flavonoid diglycosides; Glycosyltransferase; Metabolic engineering