title: Local differentiation of sugar donor specificity of flavonoid glycosyltransferase in Lamiales.
abstract: Flavonoids are most commonly conjugated with various sugar moieties by UDP-sugar:glycosyltransferases (UGTs) in a lineage-specific manner. Generally, the phylogenetics and regiospecificity of flavonoid UGTs are correlated, indicating that the regiospecificity of UGT differentiated prior to speciation. By contrast, it is unclear how the sugar donor specificity of UGTs evolved. Here, we report the biochemical, homology-modeled, and phylogenetic characterization of flavonoid 7-O-glucuronosyltransferases (F7GAT), which is responsible for producing specialized metabolites in Lamiales plants. All of the Lamiales F7GATs were found to be members of the UGT88-related cluster and specifically used UDP-glucuronic acid (UDPGA). We identified an Arg residue that is specifically conserved in the PSPG box in the Lamiales F7GATs. Substitution of this Arg with Trp was sufficient to convert the sugar donor specificity of the Lamiales F7GATs from UDPGA to UDP-glucose. Homology modeling of the Lamiales F7GAT suggested that the Arg residue plays a critical role in the specific recognition of anionic carboxylate of the glucuronic acid moiety of UDPGA with its cationic guanidinium moiety. These results support the hypothesis that differentiation of sugar donor specificity of UGTs occurred locally, in specific plant lineages, after establishment of general regiospecificity for the sugar acceptor. Thus, the plasticity of sugar donor specificity explains, in part, the extraordinary structural diversification of phytochemicals.
authors.affiliation: Institute for Health Care Science, Suntory Ltd., Suntory Research Center, Shimamoto, Mishima, Osaka 618-8503, Japan.
authors.forename: Akio
authors.initials: A
authors.lastname: Noguchi
authors.forename: Manabu
authors.initials: M
authors.lastname: Horikawa
authors.forename: Yuko
authors.initials: Y
authors.lastname: Fukui
authors.forename: Masako
authors.initials: M
authors.lastname: Fukuchi-Mizutani
authors.forename: Asako
authors.initials: A
authors.lastname: Iuchi-Okada
authors.forename: Masaji
authors.initials: M
authors.lastname: Ishiguro
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Kiso
authors.forename: Toru
authors.initials: T
authors.lastname: Nakayama
authors.forename: Eiichiro
authors.initials: E
authors.lastname: Ono
mesh_terms: D000595:Amino Acid Sequence; D050260:Carbohydrate Metabolism; D003001:Cloning, Molecular; D017124:Conserved Sequence; D005419:Flavonoids / Q000737:chemistry / Q000378:metabolism*; D016695:Glycosyltransferases / Q000737:chemistry / Q000145:classification / Q000378:metabolism*; D019686:Lamiaceae / Q000201:enzymology; D019684:Magnoliopsida / Q000201:enzymology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D010943:Plantago / Q000201:enzymology; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D013379:Substrate Specificity
chemical_list: D005419:Flavonoids; D016695:Glycosyltransferases