MOLECULAR-CLONING AND CDNA SEQUENCING OF ENDOXYLOGLUCAN TRANSFERASE, A NOVEL CLASS OF GLYCOSYLTRANSFERASE THAT MEDIATES MOLECULAR GRAFTING BETWEEN MATRIX POLYSACCHARIDES IN PLANT-CELL WALLS

Endoxyloglucan transferase is a novel class of glycosyltransferase rec ently purified from Vigna angularis (Nishitani, K., and Tominaga, R. ( 1992) J. Biol. Chem. 267, 21058-21064). This enzyme is the first trans ferase identified that catalyzes molecular grafting between polysaccha ride cross-links in the cell wall matrix and participates in reconstru ction of the network structure in the cell wall. Based on the NH2-term inal amino acid sequence information of the purified transferase, we h ave here cloned and sequenced cDNAs derived from five different plant species, V angularis, Triticum aestivum, Arabidopsis thaliana, Lycoper sicon esculentum, and Glycine max. In the five plant species, the amin o acid sequence of the mature proteins is conserved in the range of 71 -90% throughout their length. The consensus sequence for N-linked glyc osylation, and four cysteine residues are all conserved in the five sp ecies. Thus, the endoxyloglucan transferase protein is ubiquitous amon g higher plants. The highly conserved DNA sequence will serve as a pro mising tool for exploring the molecular process by which cell wall con struction, and hence cell growth, is regulated.