title: An unusual xylan in Arabidopsis primary cell walls is synthesised by GUX3, IRX9L, IRX10L and IRX14.
abstract: Xylan is a crucial component of many plant primary and secondary cell walls. However, the structure and function of xylan in the dicotyledon primary cell wall is not well understood. Here, we characterized a xylan that is specific to tissues enriched in Arabidopsis primary cell walls. Unlike previously described xylans, this xylan carries a pentose linked 1-2 to the α-1,2-d-glucuronic acid (GlcA) side chains on the β-1,4-Xyl backbone. The frequent and precisely regular spacing of GlcA substitutions every six xylosyl residues along the backbone is also unlike that previously observed in secondary cell wall xylan. Molecular genetics, in vitro assays, and expression data suggest that IRX9L, IRX10L and IRX14 are required for xylan backbone synthesis in primary cell wall synthesising tissues. IRX9 and IRX10 are not involved in the primary cell wall xylan synthesis but are functionally exchangeable with IRX9L and IRX10L. GUX3 is the only glucuronyltransferase required for the addition of the GlcA decorations on the xylan. The differences in xylan structure in primary versus secondary cell walls might reflect the different roles in cross-linking and interaction with other cell wall components.
authors.affiliation: Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK.|Physical Biosciences Division, Lawrence Berkeley National Laboratory, Joint BioEnergy Institute, Berkeley, CA, 94720, USA.
authors.forename: Jenny C
authors.initials: JC
authors.lastname: Mortimer
authors.affiliation: Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK.
authors.forename: Nuno
authors.initials: N
authors.lastname: Faria-Blanc
authors.affiliation: Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK.
authors.forename: Xiaolan
authors.initials: X
authors.lastname: Yu
authors.affiliation: Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK.
authors.forename: Theodora
authors.initials: T
authors.lastname: Tryfona
authors.affiliation: Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK.
authors.forename: Mathias
authors.initials: M
authors.lastname: Sorieul
authors.affiliation: Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK.
authors.forename: Yao Z
authors.initials: YZ
authors.lastname: Ng
authors.affiliation: Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK.
authors.forename: Zhinong
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK.
authors.forename: Katherine
authors.initials: K
authors.lastname: Stott
authors.affiliation: Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK.
authors.forename: Nadine
authors.initials: N
authors.lastname: Anders
authors.affiliation: Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Dupree
mesh_terms: D017360:Arabidopsis / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002473:Cell Wall / Q000737:chemistry*; D016695:Glycosyltransferases / Q000378:metabolism*; D010430:Pentosyltransferases / Q000378:metabolism*; D014990:Xylans / Q000737:chemistry* / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D014990:Xylans; D016695:Glycosyltransferases; C000603650:IRX9L protein, Arabidopsis; C571990:IRX14 protein, Arabidopsis; D010430:Pentosyltransferases
keywords: Arabidopsis thaliana; GUX3; IRX10L; IRX14; IRX9L; Xylan; primary wall