A UDP-Glucose:Monoterpenol Glucosyltransferase Adds to the Chemical Diversity of the Grapevine Metabolome.
Terpenoids represent one of the major classes of natural products and serve different biological functions. In grape (Vitis vinifera), a large fraction of these compounds is present as nonvolatile terpene glycosides. We have extracted putative glycosyltransferase (GT) sequences from the grape genome database that show similarity to Arabidopsis (Arabidopsis thaliana) GTs whose encoded proteins glucosylate a diversity of terpenes. Spatial and temporal expression levels of the potential VvGT genes were determined in five different grapevine varieties. Heterologous expression and biochemical assays of candidate genes led to the identification of a UDP-glucose:monoterpenol β-d-glucosyltransferase (VvGT7). The VvGT7 gene was expressed in various tissues in accordance with monoterpenyl glucoside accumulation in grape cultivars. Twelve allelic VvGT7 genes were isolated from five cultivars, and their encoded proteins were biochemically analyzed. They varied in substrate preference and catalytic activity. Three amino acids, which corresponded to none of the determinants previously identified for other plant GTs, were found to be important for enzymatic catalysis. Site-specific mutagenesis along with the analysis of allelic proteins also revealed amino acids that impact catalytic activity and substrate tolerance. These results demonstrate that VvGT7 may contribute to the production of geranyl and neryl glucoside during grape ripening.
Biotechnology of Natural Products, Technische Universität München, 85354 Freising, Germany (F.B., W.S.);Geisenheim University, Department of Grape Breeding, 65366 Geisenheim, Germany (J.F., E.R., O.B.); andFood Chemistry Research Unit, Institute of Nutrition and Food Sciences, University of Bonn, D-53115 Bonn, Germany (S.S., M.W.).
Friedericke
F
Bönisch
Biotechnology of Natural Products, Technische Universität München, 85354 Freising, Germany (F.B., W.S.);Geisenheim University, Department of Grape Breeding, 65366 Geisenheim, Germany (J.F., E.R., O.B.); andFood Chemistry Research Unit, Institute of Nutrition and Food Sciences, University of Bonn, D-53115 Bonn, Germany (S.S., M.W.).
Johanna
J
Frotscher
Biotechnology of Natural Products, Technische Universität München, 85354 Freising, Germany (F.B., W.S.);Geisenheim University, Department of Grape Breeding, 65366 Geisenheim, Germany (J.F., E.R., O.B.); andFood Chemistry Research Unit, Institute of Nutrition and Food Sciences, University of Bonn, D-53115 Bonn, Germany (S.S., M.W.).
Sarah
S
Stanitzek
Biotechnology of Natural Products, Technische Universität München, 85354 Freising, Germany (F.B., W.S.);Geisenheim University, Department of Grape Breeding, 65366 Geisenheim, Germany (J.F., E.R., O.B.); andFood Chemistry Research Unit, Institute of Nutrition and Food Sciences, University of Bonn, D-53115 Bonn, Germany (S.S., M.W.).
Ernst
E
Rühl
Biotechnology of Natural Products, Technische Universität München, 85354 Freising, Germany (F.B., W.S.);Geisenheim University, Department of Grape Breeding, 65366 Geisenheim, Germany (J.F., E.R., O.B.); andFood Chemistry Research Unit, Institute of Nutrition and Food Sciences, University of Bonn, D-53115 Bonn, Germany (S.S., M.W.).
Matthias
M
Wüst
Biotechnology of Natural Products, Technische Universität München, 85354 Freising, Germany (F.B., W.S.);Geisenheim University, Department of Grape Breeding, 65366 Geisenheim, Germany (J.F., E.R., O.B.); andFood Chemistry Research Unit, Institute of Nutrition and Food Sciences, University of Bonn, D-53115 Bonn, Germany (S.S., M.W.).
Oliver
O
Bitz
Biotechnology of Natural Products, Technische Universität München, 85354 Freising, Germany (F.B., W.S.);Geisenheim University, Department of Grape Breeding, 65366 Geisenheim, Germany (J.F., E.R., O.B.); andFood Chemistry Research Unit, Institute of Nutrition and Food Sciences, University of Bonn, D-53115 Bonn, Germany (S.S., M.W.) schwab@wzw.tum.de.
Wilfried
http://orcid.org/0000-0002-9753-3967
W
Schwab