Jones P, Messner B, Nakajima J-I, Schäffner AR, Saito K UGT73C6 and UGT78D1, Glycosyltransferases Involved in Flavonol Glycoside Biosynthesis in Arabidopsis thaliana Journal of Biological Chemistry278 (2003)
43910-43918
Publication DOI:10.1074/jbc.M303523200 Journal NLM ID:2985121R Publisher: Baltimore, MD: American Society for Biochemistry and Molecular Biology Correspondence: ksaitop.chiba-u.ac.jp Institutions: Department of Molecular Biology and Biotechnology, Graduate school of Pharmaceutical Sciences, Chiba University, Core Research for Evolutional Science and Techology of Japan Science and Technology Corporation (JST), Yayoi-cho 1-33, Inage-ku, Chiba 263-8522, Japan, Institute of Biochemical Plant Pathology, GSF-National Research Center for Environment and Health, Ingolstädter Landstrasse 1, D-85764 Neuherberg, Germany
Flavonol glycosides constitute one of the most prominent plant natural product classes that accumulate in the model plant Arabidopsis thaliana. To date there are no reports of functionally characterized flavonoid glycosyltransferases in Arabidopsis, despite intensive research efforts aimed at both flavonoids and Arabidopsis. In this study, flavonol glycosyltransferases were considered in a functional genomics approach aimed at revealing genes involved in determining the flavonol-glycoside profile. Candidate glycosyltransferase-encoding genes were selected based on homology to other known flavonoid glycosyltransferases and two T-DNA knockout lines lacking flavonol-3-O-rhamnoside-7-O-rhamnosides (ugt78D1) and quercetin-3-O-rhamnoside-7-O-glucoside (ugt73C6 and ugt78D1) were identified. To confirm the in planta results, cDNAs encoding both UGT78D1 and UGT73C6 were expressed in vitro and analyzed for their qualitative substrate specificity. UGT78D1 catalyzed the transfer of rhamnose from UDP-rhamnose to the 3-OH position of quercetin and kaempferol, whereas UGT73C6 catalyzed the transfer of glucose from UDP-glucose to the 7-OH position of kaempferol-3-O-rhamnoside and quercetin-3-O-rhamnoside, respectively. The present results suggest that UGT78D1 and UGT73C6 should be classified as UDP-rhamnose:flavonol-3-Orhamnosyltransferase and UDP-glucose:flavonol-3-O-glycoside-7-O-glucosyltransferase, respectively.
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