Glucose polyester biosynthesis. Purification and characterization of a glucose acyltransferase

Li, AX Eannetta, N Ghangas, GS Steffens, JC

Ax. Li et al., Glucose polyester biosynthesis. Purification and characterization of a glucose acyltransferase, PLANT PHYSL, 121(2), 1999, pp. 453-460

40

INGLESE

Article

Plant Sciences","Animal & Plant Sciences

PLANT PHYSIOLOGY

0032-0889 → ACNP

121

2

1999

453 - 460

ISI

0032-0889(199910)121:2<453:GPBPAC>2.0.ZU;2-O

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.