Abstract
Escherichia coli BL21(DE3) was engineered to divert the flow of carbon flux from glucose-1-phosphate to thymidine diphosphate 4-keto 4,6-dideoxy-D-glucose (dTKDG), an intermediate of various dTDP-sugars. Glucose phosphate isomerase (pgi), glucose-6-phosphate dehydrogenase (zwf) and uridylyltransferase (galU) genes were deleted while two additional genes, dTDP-D-glucose synthase (tgs) and dTDP-D-glucose 4,6-dehydratase (dh), were overexpressed to produce a pool of dTKDG in the cell cytosol. The flow of dTKDG was further diverted to dTDP-D-viosamine, dTDP 4-amino 4,6-dideoxy-D-galactose, and dTDP 3-amino 3,6-dideoxy-D-galactose sugars using sugar aminotransferases (gerB, wecE, and fdtB, respectively) from different sources. These sugar moieties were transferred to the 3-hydroxyl position of quercetin and kaempferol with the help of Arabidopsis thaliana glycosyltransferase (ArGT3). As a result, 4-amino 4,6-dideoxy-D-galactose and 3-amino 3,6-dideoxy-D-galactose sugars conjugated to quercetin and kaempferol were biosynthesized successfully from exogenously supplemented quercetin and kaempferol. However, no D-viosamine conjugated kaempferol or quercetin derivatives were produced during the biotransformation. All the synthesized glycosides are novel unnatural compounds, which could have potent biological activities.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call