title: Mesocarp localization of a bi-functional resveratrol/hydroxycinnamic acid glucosyltransferase of Concord grape (Vitis labrusca).
abstract: Resveratrol is a stilbene with well-known health-promoting effects in humans that is produced constitutively or accumulates as a phytoalexin in several plant species including grape (Vitis sp.). Grape berries accumulate stilbenes in the exocarp as cis- and trans-isomers of resveratrol, together with their respective 3-O-monoglucosides. An enzyme glucosylating cis- and trans-resveratrol was purified to apparent homogeneity from Concord (Vitis labrusca) grape berries, and peptide sequencing associated it to an uncharacterized Vitis vinifera full-length clone (TC38971, tigr database). A corresponding gene from Vitis labrusca (VLRSgt) had 98% sequence identity to clone TC38971 and 92% sequence identity to a Vitis viniferap-hydroxybenzoic acid glucosyltransferase that produces glucose esters. The recombinant enzyme was active over a broad pH range (5.5-10), producing glucosides of stilbenes, flavonoids and coumarins at higher pH and glucose esters of several hydroxybenzoic and hydroxycinnamic acids at low pH. Vitis labrusca grape berries accumulated both stilbene glucosides and hydroxycinnamic acid glucose esters, consistent with the bi-functional role of VLRSgt in stilbene and hydroxycinnamic acid modification. While phylogenetic analysis of VLRSgt and other functionally characterized glucosyltransferases places it with other glucose ester-producing enzymes, the present results indicate broader biochemical activities for this class of enzymes.
authors.affiliation: Department of Biological Sciences, Brock University, 500 Glenridge Avenue, St Catharines, Ontario, Canada, L2S 3A1.
authors.forename: Dawn
authors.initials: D
authors.lastname: Hall
authors.forename: Vincenzo
authors.initials: V
authors.lastname: De Luca
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D003373:Coumaric Acids / Q000737:chemistry / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D005960:Glucosides / Q000737:chemistry / Q000378:metabolism; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010802:Phylogeny; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D000077185:Resveratrol; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D013267:Stilbenes / Q000737:chemistry / Q000378:metabolism*; D013379:Substrate Specificity; D027843:Vitis / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
chemical_list: D003373:Coumaric Acids; D005960:Glucosides; D011994:Recombinant Proteins; D013267:Stilbenes; D000217:Acyltransferases; C022674:stilbene synthase; D005964:Glucosyltransferases; D000077185:Resveratrol