title: Glucose polyester biosynthesis. Purification and characterization of a glucose acyltransferase.
abstract: Glandular trichomes of the wild tomato species Lycopersicon pennellii secrete 2,3,4-O-tri-acyl-glucose (-Glc), which contributes to insect resistance. A Glc acyltransferase catalyzes the formation of diacyl-Glc by disproportionating two equivalents of 1-O-acyl-beta-Glc, a high-energy molecule formed by a UDP-Glc dependent reaction. The acyltransferase was purified 4,900-fold from L. pennellii leaves by polyethylene glycol fractionation, diethylaminoethyl chromatography, concanavalin A affinity chromatography, and chromatofocusing. The acyltransferase possesses an isoelectric point of 4.8, a relative molecular mass around 110 kD, and is composed of 34- and 24-kD polypeptides as a heterotetramer. The 34- and 24-kD proteins were partially sequenced. The purified enzyme catalyzes both the disproportionation of 1-O-acyl-beta-Glcs to generate 1,2-di-O-acyl-beta-Glc and anomeric acyl exchange between 1-O-acyl-beta-Glc and Glc.
authors.affiliation: Department of Plant Breeding, Cornell University, Ithaca, New York 14853, USA.
authors.forename: A X
authors.initials: AX
authors.lastname: Li
authors.forename: N
authors.initials: N
authors.lastname: Eannetta
authors.forename: G S
authors.initials: GS
authors.lastname: Ghangas
authors.forename: J C
authors.initials: JC
authors.lastname: Steffens
mesh_terms: D000085:Acetates / Q000378:metabolism*; D000217:Acyltransferases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D000595:Amino Acid Sequence; D002846:Chromatography, Affinity; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D005947:Glucose / Q000031:analogs & derivatives*; D007202:Indicators and Reagents; D007700:Kinetics; D018551:Solanum lycopersicum / Q000201:enzymology*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification
chemical_list: D000085:Acetates; D007202:Indicators and Reagents; D010446:Peptide Fragments; D000217:Acyltransferases; D005947:Glucose