title: Molecular basis of lipo-chitooligosaccharide recognition by the lysin motif receptor-like kinase LYR3 in legumes.
abstract: LYR3 [LysM (lysin motif) receptor-like kinase 3] of Medicago truncatula is a high-affinity binding protein for symbiotic LCO (lipo-chitooligosaccharide) signals, produced by rhizobia bacteria and arbuscular mycorrhizal fungi. The present study shows that LYR3 from several other legumes, but not from two Lupinus species which are incapable of forming the mycorrhizal symbiosis, bind LCOs with high affinity and discriminate them from COs (chitooligosaccharides). The biodiversity of these proteins and the lack of binding to the Lupinus proteins were used to identify features required for high-affinity LCO binding. Swapping experiments between each of the three LysMs of the extracellular domain of the M. truncatula and Lupinus angustifolius LYR3 proteins revealed the crucial role of the third LysM in LCO binding. Site-directed mutagenesis identified a tyrosine residue, highly conserved in all LYR3 LCO-binding proteins, which is essential for high-affinity binding. Molecular modelling suggests that it may be part of a hydrophobic tunnel able to accommodate the LCO acyl chain. The lack of conservation of these features in the binding site of plant LysM proteins binding COs provides a mechanistic explanation of how LCO recognition might differ from CO perception by structurally related LysM receptors.
authors.affiliation: LIPM, Université de Toulouse, INRA, CNRS, Castanet-Tolosan, France.
authors.forename: Nikita
authors.initials: N
authors.lastname: Malkov
authors.affiliation: LIPM, Université de Toulouse, INRA, CNRS, Castanet-Tolosan, France.
authors.forename: Judith
authors.initials: J
authors.lastname: Fliegmann
authors.affiliation: LIPM, Université de Toulouse, INRA, CNRS, Castanet-Tolosan, France.
authors.forename: Charles
authors.initials: C
authors.lastname: Rosenberg
authors.affiliation: LIPM, Université de Toulouse, INRA, CNRS, Castanet-Tolosan, France.
authors.forename: Virginie
authors.initials: V
authors.lastname: Gasciolli
authors.affiliation: LIPM, Université de Toulouse, INRA, CNRS, Castanet-Tolosan, France.
authors.forename: Antonius C J
authors.initials: AC
authors.lastname: Timmers
authors.affiliation: School of Pharmaceutical Sciences, UNIGE, Quai Ernest Ansermet 30, 1205 Geneva, Switzerland.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Nurisso
authors.affiliation: LIPM, Université de Toulouse, INRA, CNRS, Castanet-Tolosan, France.
authors.forename: Julie
authors.initials: J
authors.lastname: Cullimore
authors.affiliation: LIPM, Université de Toulouse, INRA, CNRS, Castanet-Tolosan, France Jean-Jacques.Bono@toulouse.inra.fr.
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Bono
mesh_terms: D002686:Chitin / Q000031:analogs & derivatives* / Q000378:metabolism; D048271:Chitosan; D031297:Lupinus / Q000378:metabolism; D046913:Medicago truncatula / Q000378:metabolism*; D009844:Oligosaccharides; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D015398:Signal Transduction; D013559:Symbiosis / Q000235:genetics / Q000502:physiology
chemical_list: D009844:Oligosaccharides; D010940:Plant Proteins; C493484:oligochitosan; D002686:Chitin; D048271:Chitosan
keywords: LysM; ligand-binding protein; lipo-chitooligosaccharides; receptor structure–function; symbiosis