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 recently purified from Vigna angularis (Nishitani, K,, and Tominaga, R. (1992) J. Biol. Chem. 267, 21058-21064). This enzyme is the first transferase identified that catalyzes molecular grafting between polysaccharide cross-links in the cell wall matrix and participates in reconstruction of the network structure in the cell wall. Based on the NH2-terminal amino acid sequence information of the purified transferase, we have here cloned and sequenced cDNAs derived from five different plant species, V. angularis, Triticum aestivum, Arabidopsis thaliana, Lycopersicon esculentum, and Glycine max. In the five plant species, the amino acid sequence of the mature proteins is conserved in the range of 71-90% throughout their length. The consensus sequence for N-linked glycosylation, and four cysteine residues are all conserved in the five species. Thus, the endoxyloglucan transferase protein is ubiquitous among higher plants. The highly conserved DNA sequence will serve as a promising tool for exploring the molecular process by which cell wall construction, and hence cell growth, is regulated.