title: Rhamnogalacturonan-II cross-linking of plant pectins via boron bridges occurs during polysaccharide synthesis and/or secretion.
abstract: Rhamnogalacturonan-II (RG-II), a domain of plant cell wall pectins, is able to cross-link with other RG-II domains through borate diester bridges. Although it is known to affect mechanical properties of the cell wall, the biochemical requirements and lifecycle of this cross-linking remain unclear. We developed a PAGE methodology to allow separation of monomeric and dimeric RG-II and used this to study the dynamics of cross-linking in vitro and in vivo. Rosa cells grown in medium with no added boron contained no RG-II dimers, although these re-appeared after addition of boron to the medium. However, other Rosa cultures which were unable to synthesize new polysaccharides did not show dimer formation. We conclude that RG-II normally becomes cross-linked intraprotoplasmically or during secretion, but not post-secretion.
authors.affiliation: The Edinburgh Cell Wall Group; Institute of Molecular Plant Sciences; School of Biological Sciences; The University of Edinburgh; The King's Buildings; Edinburgh, UK; Current address: INRA PACA Domaine Saint-Paul-Site Agroparc; Avignon, France.
authors.forename: Dimitra
authors.initials: D
authors.lastname: Chormova
authors.affiliation: The Edinburgh Cell Wall Group; Institute of Molecular Plant Sciences; School of Biological Sciences; The University of Edinburgh; The King's Buildings; Edinburgh, UK; Current address: Unilever R&D; Colworth Science Park; Sharnbrook, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Messenger
authors.affiliation: The Edinburgh Cell Wall Group; Institute of Molecular Plant Sciences; School of Biological Sciences; The University of Edinburgh; The King's Buildings; Edinburgh, UK.
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Fry
mesh_terms: D017360:Arabidopsis; D001881:Borates / Q000378:metabolism*; D001895:Boron / Q000378:metabolism*; D002478:Cells, Cultured; D010368:Pectins / Q000378:metabolism*; D027826:Rosa / Q000378:metabolism*
chemical_list: D001881:Borates; C042492:rhamnogalacturonan II; D010368:Pectins; D001895:Boron
keywords: Arabidopsis thaliana; Rosasp.; boron; cell wall; cross-linking; gel electrophoresis; pectin; radiolabelling; rhamnogalacturonan-II