Glandular trichomes of the wild tomato species Lycopersicon pennellii secre
te 2,3,4-O-tri-acyl-glucose (-Glc), which contributes to insect resistance.
A Glc acyltransferase catalyzes the formation of diacyl-Glc by disproporti
onating 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-fo
ld from L. pennellii leaves by polyethylene glycol fractionation, diethylam
inoethyl chromatography, concanavalin A affinity chromatography, and chroma
tofocusing. The acyltransferase possesses an isoelectric point of 4.8, a re
lative molecular mass around 110 kD, and is composed of 34- and 24-kD polyp
eptides as a heterotetramer. The 34- and 24-kD proteins were partially sequ
enced. The purified enzyme catalyzes both the disproportionation of 1-O-acy
l-beta-Glcs to generate 1,2-di-O-acyl-beta-Glc and anomeric acyl exchange b
etween 1-O-acyl-beta-Glc and Glc.