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Structure of a flavonoid glucosyltransferase reveals the basis for plant natural product modification
Author(s) -
Offen Wendy,
MartinezFleites Carlos,
Yang Min,
KiatLim Eng,
Davis Benjamin G,
Tarling Chris A,
Ford Christopher M,
Bowles Dianna J,
Davies Gideon J
Publication year - 2006
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7600970
Subject(s) - biology , flavonoid , natural product , glucosyltransferase , biochemistry , product (mathematics) , enzyme , antioxidant , geometry , mathematics
Glycosylation is a key mechanism for orchestrating the bioactivity, metabolism and location of small molecules in living cells. In plants, a large multigene family of glycosyltransferases is involved in these processes, conjugating hormones, secondary metabolites, biotic and abiotic environmental toxins, to impact directly on cellular homeostasis. The red grape enzyme UDP‐glucose:flavonoid 3‐ O ‐glycosyltransferase ( Vv GT1) is responsible for the formation of anthocyanins, the health‐promoting compounds which, in planta , function as colourants determining flower and fruit colour and are precursors for the formation of pigmented polymers in red wine. We show that Vv GT1 is active, in vitro , on a range of flavonoids. Vv GT1 is somewhat promiscuous with respect to donor sugar specificity as dissected through full kinetics on a panel of nine sugar donors. The three‐dimensional structure of Vv GT1 has also been determined, both in its ‘Michaelis’ complex with a UDP‐glucose‐derived donor and the acceptor kaempferol and in complex with UDP and quercetin. These structures, in tandem with kinetic dissection of activity, provide the foundation for understanding the mechanism of these enzymes in small molecule homeostasis.