title: Arabidopsis thaliana IRX10 and two related proteins from psyllium and Physcomitrella patens are xylan xylosyltransferases.
abstract: The enzymatic mechanism that governs the synthesis of the xylan backbone polymer, a linear chain of xylose residues connected by β-1,4 glycosidic linkages, has remained elusive. Xylan is a major constituent of many kinds of plant cell walls, and genetic studies have identified multiple genes that affect xylan formation. In this study, we investigate several homologs of one of these previously identified xylan-related genes, IRX10 from Arabidopsis thaliana, by heterologous expression and in vitro xylan xylosyltransferase assay. We find that an IRX10 homolog from the moss Physcomitrella patens displays robust activity, and we show that the xylosidic linkage formed is a β-1,4 linkage, establishing this protein as a xylan β-1,4-xylosyltransferase. We also find lower but reproducible xylan xylosyltransferase activity with A. thaliana IRX10 and with a homolog from the dicot plant Plantago ovata, showing that xylan xylosyltransferase activity is conserved over large evolutionary distance for these proteins.
authors.affiliation: Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA; DOE Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: Jacob Krüger
authors.initials: JK
authors.lastname: Jensen
authors.forename: Nathan Robert
authors.initials: NR
authors.lastname: Johnson
authors.forename: Curtis Gene
authors.initials: CG
authors.lastname: Wilkerson
mesh_terms: D017360:Arabidopsis / Q000145:classification / Q000201:enzymology / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D019068:Bryopsida / Q000378:metabolism*; D010430:Pentosyltransferases / Q000378:metabolism*; D010802:Phylogeny; D011620:Psyllium / Q000378:metabolism*; D000097608:UDP Xylose-Protein Xylosyltransferase
chemical_list: D029681:Arabidopsis Proteins; D010430:Pentosyltransferases; D011620:Psyllium; D000097608:UDP Xylose-Protein Xylosyltransferase
keywords: Arabidopsis thaliana; IRX10; Physcomitrella patens; Pichia pastoris; Plantago ovata; psyllium; xylan synthase; xylosyltransferase