Glucosylation of Smoke-Derived Volatiles in Grapevine (Vitis vinifera) is Catalyzed by a Promiscuous Resveratrol/Guaiacol Glucosyltransferase

• DOI: 10.1021/acs.jafc.7b01886
• Publication Date: 2017-06-28T09:17:24Z
• Authors: Katja Härtl; Fong-Chin Huang; Ashok P. Giri; Katrin Franz-Ober...; Johanna Frotscher; Yang Shao; Thomas Hoffmann; Wilfried Schwab
• Keywords: Guaiacol; Glucosyltransferases; Glucoside

Vinification of grapes (Vitis vinifera) exposed to forest fire smoke can yield unpalatable wine due the presence taint compounds from and release derived volatiles their respective glycosides during fermentation process or in-mouth consumption. To identify glycosyltransferases (GTs) involved in formation glycosidically bound smoke-derived we performed gene expression analysis candidate GTs different grapevine tissues. Second, substrates bushfire naturally occurring were screened with recombinant GTs. A resveratrol GT (UGT72B27) gene, highly expressed leaves berries was identified be responsible for production phenolic glucosides. UGT72B27 converted stilbene trans-resveratrol mainly 3-O-glucoside. Kinetic analyses yielded specificity constants (kcat/KM) 114, 17, 9, 8, 2 mM-1 s-1 guaiacol, trans-resveratrol, syringol, methylsyringol, methylguaiacol, respectively. This knowledge will help design strategies managing risk producing smoke-affected wines.