title: Role of N-glycosylation sites and CXC motifs in trafficking of medicago truncatula Nod factor perception protein to plasma membrane.
abstract: The lysin motif receptor-like kinase, NFP (Nod factor perception), is a key protein in the legume Medicago truncatula for the perception of lipochitooligosaccharidic Nod factors, which are secreted bacterial signals essential for establishing the nitrogen-fixing legume-rhizobia symbiosis. Predicted structural and genetic analyses strongly suggest that NFP is at least part of a Nod factor receptor, but few data are available about this protein. Characterization of a variant encoded by the mutant allele nfp-2 revealed the sensitivity of this protein to the endoplasmic reticulum quality control mechanisms, affecting its trafficking to the plasma membrane. Further analysis revealed that the extensive N-glycosylation of the protein is not essential for biological activity. In the NFP extracellular region, two CXC motifs and two other Cys residues were found to be involved in disulfide bridges, and these are necessary for correct folding and localization of the protein. Analysis of the intracellular region revealed its importance for biological activity but suggests that it does not rely on kinase activity. This work shows that NFP trafficking to the plasma membrane is highly sensitive to regulation in the endoplasmic reticulum and has identified structural features of the protein, particularly disulfide bridges involving CXC motifs in the extracellular region that are required for its biological function.
authors.affiliation: INRA, Laboratoire des Interactions Plantes-Microorganismes, UMR441, F-31326 Castanet-Tolosan, France. benoit.lefebvre@toulouse.inra.fr
authors.forename: Benoit
authors.initials: B
authors.lastname: Lefebvre
authors.forename: Doerte
authors.initials: D
authors.lastname: Klaus-Heisen
authors.forename: Anna
authors.initials: A
authors.lastname: Pietraszewska-Bogiel
authors.forename: Christine
authors.initials: C
authors.lastname: Hervé
authors.forename: Sylvie
authors.initials: S
authors.lastname: Camut
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Auriac
authors.forename: Virginie
authors.initials: V
authors.lastname: Gasciolli
authors.forename: Alessandra
authors.initials: A
authors.lastname: Nurisso
authors.forename: Theodorus W J
authors.initials: TW
authors.lastname: Gadella
authors.forename: Julie
authors.initials: J
authors.lastname: Cullimore
mesh_terms: D020816:Amino Acid Motifs; D001665:Binding Sites; D002462:Cell Membrane / Q000378:metabolism*; D017124:Conserved Sequence; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006031:Glycosylation; D008239:Lysine; D046913:Medicago truncatula / Q000166:cytology* / Q000378:metabolism* / Q000502:physiology; D008958:Models, Molecular; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism*; D055170:Plant Root Nodulation; D011487:Protein Conformation; D011499:Protein Processing, Post-Translational; D021381:Protein Transport; D015398:Signal Transduction
chemical_list: D010940:Plant Proteins; D008239:Lysine