title: Binding properties of the N-acetylglucosamine and high-mannose N-glycan PP2-A1 phloem lectin in Arabidopsis.
abstract: Phloem Protein2 (PP2) is a component of the phloem protein bodies found in sieve elements. We describe here the lectin properties of the Arabidopsis (Arabidopsis thaliana) PP2-A1. Using a recombinant protein produced in Escherichia coli, we demonstrated binding to N-acetylglucosamine oligomers. Glycan array screening showed that PP2-A1 also bound to high-mannose N-glycans and 9-acyl-N-acetylneuraminic sialic acid. Fluorescence spectroscopy-based titration experiments revealed that PP2-A1 had two classes of binding site for N,N',N''-triacetylchitotriose, a low-affinity site and a high-affinity site, promoting the formation of protein dimers. A search for structural similarities revealed that PP2-A1 aligned with the Cbm4 and Cbm22-2 carbohydrate-binding modules, leading to the prediction of a beta-strand structure for its conserved domain. We investigated whether PP2-A1 interacted with phloem sap glycoproteins by first characterizing abundant Arabidopsis phloem sap proteins by liquid chromatography-tandem mass spectrometry. Then we demonstrated that PP2-A1 bound to several phloem sap proteins and that this binding was not completely abolished by glycosidase treatment. As many plant lectins have insecticidal activity, we also assessed the effect of PP2-A1 on weight gain and survival in aphids. Unlike other mannose-binding lectins, when added to an artificial diet, recombinant PP2-A1 had no insecticidal properties against Acyrthosiphon pisum and Myzus persicae. However, at mid-range concentrations, the protein affected weight gain in insect nymphs. These results indicate the presence in PP2-A1 of several carbohydrate-binding sites, with potentially different functions in the trafficking of endogenous proteins or in interactions with phloem-feeding insects.
authors.affiliation: UR1268 Unité de Recherches Biopolymères Interactions Assemblages, INRA, F-44300 Nantes, France.
authors.forename: Julie
authors.initials: J
authors.lastname: Beneteau
authors.forename: Denis
authors.initials: D
authors.lastname: Renard
authors.forename: Laurent
authors.initials: L
authors.lastname: Marché
authors.forename: Elise
authors.initials: E
authors.lastname: Douville
authors.forename: Laurence
authors.initials: L
authors.lastname: Lavenant
authors.forename: Yvan
authors.initials: Y
authors.lastname: Rahbé
authors.forename: Didier
authors.initials: D
authors.lastname: Dupont
authors.forename: Françoise
authors.initials: F
authors.lastname: Vilaine
authors.forename: Sylvie
authors.initials: S
authors.lastname: Dinant
mesh_terms: D000117:Acetylglucosamine / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001042:Aphids / Q000254:growth & development; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D002240:Carbohydrate Sequence; D002686:Chitin / Q000378:metabolism; D002846:Chromatography, Affinity; D006639:Histidine / Q000378:metabolism; D008358:Mannose / Q000378:metabolism*; D008969:Molecular Sequence Data; D019158:N-Acetylneuraminic Acid / Q000378:metabolism; D009842:Oligopeptides / Q000378:metabolism; D053147:Plant Exudates / Q000378:metabolism; D037121:Plant Lectins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D013050:Spectrometry, Fluorescence; D020349:Surface Plasmon Resonance
chemical_list: D029681:Arabidopsis Proteins; C471213:His-His-His-His-His-His; D009842:Oligopeptides; C552547:PP2-A1 protein, Arabidopsis; D053147:Plant Exudates; D037121:Plant Lectins; D011134:Polysaccharides; D011993:Recombinant Fusion Proteins; D002686:Chitin; C091028:phloem lectin; D006639:Histidine; D019158:N-Acetylneuraminic Acid; D008358:Mannose; D000117:Acetylglucosamine