Bio-fermentation of modified flavonoids: an example of in vivo diversification of secondary metabolites

Mutational Analysis of the Medicago Glycosyltransferase UGT71G1 Reveals Residues That Control Regioselectivity for (Iso)flavonoid Glycosylation

“…Trp 360 forms a hydrogen bond with the sugar donor through its main chain nitrogen atom (37). The W360G mutant would be expected to maintain this same interaction, unless this mutation altered the overall conformation of the donor binding pocket due to the large difference in size between Gly and Trp.…”

“…Recently, there has been increasing interest in biocatalytic synthesis of glucosides of quercetin (27,37) and other phenolic compounds (38) due to their potential therapeutic value in cardiovascular disease and cancer, and their antimicrobial properties. Specific quercetin mono-or diglucosides have been successfully produced in an E. coli fermentation system employing regiospecific glycosyltransferases (27,37) The majority of the soluble glucoside products are secreted to the medium that facilitates their purification. We have now demonstrated that new glycosyltransferases with altered regioselectivity for quercetin can be obtained through targeted mutagenesis.…”

Assessing the Biosynthetic Capabilities of Secretory Glands inCitrusPeel

“…A gene of the CYP82C subfamily, members of which have been demonstrated to be involved in the biosynthesis of 5-hydroxylated coumarins (Kruse et al, 2008), was found to be highly enriched in ECs (Table II). Polymethoxylated flavonoids are formed by successive hydroxylations and O-methylations (Willits et al, 2004;Schmidt et al, 2011), and candidate genes for enzymes involved in these steps were also found to be highly enriched in ECs (Supplemental Table S5). These observations indicate that our gene expression data from Citrus glandular ECs reflect their specialization for essential oil biosynthesis and present an excellent resource for gene discovery related to the biosynthesis of oil constituents.…”

A Set of Regioselective O-Methyltransferases Gives Rise to the Complex Pattern of Methoxylated Flavones in Sweet Basil

“…Whereas the total PMF amount is probably controlled by the activity of early phenylpropanoid-acetate pathway enzymes, the relative amounts of compounds differing from each other by a methyl or a methoxyl group depend on the late, "decorative" steps, such as 6-, 7-, 8-, 39-, or 49-methylations and 6-, 8-, or 39-hydroxylations. Nothing is known about the flavonoid 6-and 8-hydroxylases in the Lamiaceae, while flavonoid O-methyltransferases (FOMTs) from this plant family have received some attention. Five FOMTs from peppermint (Mentha 3 piperita) were used for in vivo diversification studies (Willits et al, 2004). However, due to the intended biotechnological application in that study, the potential substrates chosen represented a broad range of flavonoid aglycones rather than physiologically relevant compounds.…”