title: Biological synthesis of quercetin 3-O-N-acetylglucosamine conjugate using engineered Escherichia coli expressing UGT78D2.
abstract: Biotransformation of flavonoids using Escherichia coli harboring nucleotide sugar-dependent uridine diphosphate-dependent glycosyltransferases (UGTs) commonly results in the production of a glucose conjugate because most UGTs are specific for UDP-glucose. The Arabidopsis enzyme AtUGT78D2 prefers UDP-glucose as a sugar donor and quercetin as a sugar acceptor. However, in vitro, AtUGT78D2 could use UDP-N-acetylglucosamine as a sugar donor, and whole cell biotransformation of quercetin using E. coli harboring AtUGT78D2 produced quercetin 3-O-N-acetylglucosamine. In order to increase the production of quercetin 3-O-N-acetylglucosamine via biotransformation, two E. coli mutant strains deleted in phosphoglucomutase (pgm) or glucose-1-phosphate uridylyltransferase (galU) were created. The galU mutant produced up to threefold more quercetin 3-O-N-acetylglucosamine than wild type, resulting in the production of 380-mg/l quercetin 3-O-N-acetylglucosamine and a negligible amount of quercetin 3-O-glucoside. These results show that construction of bacterial strains for the synthesis of unnatural flavonoid glycosides is possible through rational selection of the nucleotide sugar-dependent glycosyltransferase and engineering of the nucleotide sugar metabolic pathway in the host strain.
authors.affiliation: Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, Seoul, South Korea.
authors.forename: Bong-Gyu
authors.initials: BG
authors.lastname: Kim
authors.forename: Su Hyun
authors.initials: SH
authors.lastname: Sung
authors.forename: Joong-Hoon
authors.initials: JH
authors.lastname: Ahn
mesh_terms: D000117:Acetylglucosamine / Q000378:metabolism*; D017360:Arabidopsis / Q000201:enzymology*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D005818:Genetic Engineering; D016695:Glycosyltransferases / Q000235:genetics* / Q000378:metabolism; D011794:Quercetin / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D011794:Quercetin; D016695:Glycosyltransferases; D000117:Acetylglucosamine