Purification, molecular cloning and functional characterization of flavonoid C-glucosyltransferases from Fagopyrum esculentum M. (buckwheat) cotyledon

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Abstract

C-Glycosides are characterized by their C-C bonds in which the anomeric carbon of the sugar moieties is directly bound to the carbon atom of aglycon. C-Glycosides are remarkably stable, as their C-C bonds are resistant to glycosidase or acid hydrolysis. A variety of plant species are known to accumulate C-glycosylflavonoids

however, the genes encoding for enzymes that catalyze C-glycosylation of flavonoids have been identified only from Oryza sativa (rice) and Zea mays (maize), and have not been identified from dicot plants. In this study, we identified the C-glucosyltransferase gene from the dicot plant Fagopyrum esculentumM. (buckwheat). We purified two isozymes from buckwheat seedlings that catalyze C-glucosylation of 2-hydroxyflavanones, which are expressed specifically in the cotyledon during seed germination. Following purification we isolated the cDNA corresponding to each isozyme [FeCGTa (UGT708C1) and FeCGTb (UGT708C2)]. When expressed in Escherichia coli, both proteins demonstrated C-glucosylation activity towards 2-hydroxyflavanones, dihydrochalcone, trihydroxyacetophenones and other related compounds with chemical structures similar to 2,4,6-trihydroxyacetophenone. Molecular phylogenetic analysis of plant glycosyltransferases shows that flavonoid C-glycosyltransferases form a different clade with other functionally analyzed plant glycosyltransferases.

Article

PLANT JOURNAL. 80(3):437-448 (2014)

Journal

  • PLANT JOURNAL

    PLANT JOURNAL 80 (3), 437-448, 2014-11

    WILEY-BLACKWELL

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