title: The Deconstruction of Pectic Rhamnogalacturonan I Unmasks the Occurrence of a Novel Arabinogalactan Oligosaccharide Epitope.
abstract: Rhamnogalacturonan I (RGI) is a pectic polysaccharide composed of a backbone of alternating rhamnose and galacturonic acid residues with side chains containing galactose and/or arabinose residues. The structure of these side chains and the degree of substitution of rhamnose residues are extremely variable and depend on species, organs, cell types and developmental stages. Deciphering RGI function requires extending the current set of monoclonal antibodies (mAbs) directed to this polymer. Here, we describe the generation of a new mAb that recognizes a heterogeneous subdomain of RGI. The mAb, INRA-AGI-1, was produced by immunization of mice with RGI oligosaccharides isolated from potato tubers. These oligomers consisted of highly branched RGI backbones substituted with short side chains. INRA-AGI-1 bound specifically to RGI isolated from galactan-rich cell walls and displayed no binding to other pectic domains. In order to identify its RGI-related epitope, potato RGI oligosaccharides were fractionated by anion-exchange chromatography. Antibody recognition was assessed for each chromatographic fraction. INRA-AGI-1 recognizes a linear chain of (1→4)-linked galactose and (1→5)-linked arabinose residues. By combining the use of INRA-AGI-1 with LM5, LM6 and INRA-RU1 mAbs and enzymatic pre-treatments, evidence is presented of spatial differences in RGI motif distribution within individual cell walls of potato tubers and carrot roots. These observations raise questions about the biosynthesis and assembly of pectin structural domains and their integration and remodeling in cell walls.
authors.affiliation: INRA, UR1268 Biopolymères Interactions Assemblages, 44300 Nantes, France Present address: Institute for Wine Biotechnology, Department of Viticulture and Oenology, Faculty of AgriSciences, Stellenbosch University, Matieland 7602, South Africa.
authors.forename: Fanny
authors.initials: F
authors.lastname: Buffetto
authors.affiliation: Centre for Plant Sciences, Faculty of Biological Sciences University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Valérie
authors.initials: V
authors.lastname: Cornuault
authors.affiliation: Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Frederiksberg, Denmark.
authors.forename: Maja Gro
authors.initials: MG
authors.lastname: Rydahl
authors.affiliation: INRA, UR1268 Biopolymères Interactions Assemblages, 44300 Nantes, France.
authors.forename: David
authors.initials: D
authors.lastname: Ropartz
authors.affiliation: INRA, UR1268 Biopolymères Interactions Assemblages, 44300 Nantes, France.
authors.forename: Camille
authors.initials: C
authors.lastname: Alvarado
authors.affiliation: INRA, UR1268 Biopolymères Interactions Assemblages, 44300 Nantes, France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Echasserieau
authors.affiliation: INRA, UR1268 Biopolymères Interactions Assemblages, 44300 Nantes, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Le Gall
authors.affiliation: INRA, UR1268 Biopolymères Interactions Assemblages, 44300 Nantes, France.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Bouchet
authors.affiliation: INRA, UR1268 Biopolymères Interactions Assemblages, 44300 Nantes, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Tranquet
authors.affiliation: INRA, UR1268 Biopolymères Interactions Assemblages, 44300 Nantes, France.
authors.forename: Yves
authors.initials: Y
authors.lastname: Verhertbruggen
authors.affiliation: Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Frederiksberg, Denmark.
authors.forename: William G T
authors.initials: WG
authors.lastname: Willats
authors.affiliation: Centre for Plant Sciences, Faculty of Biological Sciences University of Leeds, Leeds LS2 9JT, UK.
authors.forename: J Paul
authors.initials: JP
authors.lastname: Knox
authors.affiliation: INRA, UR1268 Biopolymères Interactions Assemblages, 44300 Nantes, France.
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Ralet
authors.affiliation: INRA, UR1268 Biopolymères Interactions Assemblages, 44300 Nantes, France fabienne.guillon@nantes.inra.fr.
authors.forename: Fabienne
authors.initials: F
authors.lastname: Guillon
mesh_terms: D000818:Animals; D002473:Cell Wall / Q000737:chemistry*; D018552:Daucus carota / Q000737:chemistry; D000939:Epitopes; D005685:Galactans / Q000032:analysis / Q000276:immunology*; D051379:Mice; D010368:Pectins / Q000737:chemistry*; D018517:Plant Roots / Q000737:chemistry / Q000166:cytology; D011134:Polysaccharides / Q000032:analysis; D011198:Solanum tuberosum / Q000737:chemistry
chemical_list: D000939:Epitopes; D005685:Galactans; D011134:Polysaccharides; C042491:rhamnogalacturonan I; C030080:araban; D010368:Pectins; C005653:arabinogalactan
keywords: AGI; INRA-AGI-1; Plant cell wall; Rhamnogalacturonan I; Solanum tuberosum