title: How plant lysin motif receptors get activated: lessons learned from structural biology.
abstract: Lysin motif (LysM) receptor kinases are unique to plants and serve important functions in plant-microbe interactions. These proteins recognize microbe-derived N-acetylglucosamine (NAG)-containing ligands, but the molecular mode of ligand perception and of receptor activation has remained unknown. The three-dimensional structure of the LysM receptor kinase CERK1 (chitin elicitor receptor kinase 1) from Arabidopsis thaliana has been reported. CERK1 binds NAG oligomers derived from chitin-the major constituent of fungal cell walls-and mediates immunity to fungal infection. The crystal structure of CERK1 complexed with a NAG pentamer revealed that three NAG moieties attach tightly to one of three lysin motifs within the CERK1 ectodomain. Receptor activation and immune signaling requires, however, ligand-induced CERK1 homodimerization. By acting as bivalent ligands, NAG octamers stabilize CERK1 dimers, providing a structural explanation for why the immunogenic activity of NAG oligomers is restricted to fragments larger than those required for receptor binding. Because CERK1 might serve as a paradigm for the functionality of a whole class of plant LysM proteins, insight into its mode of action will direct future research on these receptors.
authors: University of Tübingen, Center for Plant Molecular Biology-Plant Biochemistry, Germany. roland.willmann@uni-tuebingen.de
authors: Roland
authors: R
authors: Willmann
authors: Thorsten
authors: T
authors: Nürnberger
mesh_terms: D000117:Acetylglucosamine / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D020816:Amino Acid Motifs; D017360:Arabidopsis / Q000196:embryology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002473:Cell Wall / Q000235:genetics / Q000378:metabolism; D005658:Fungi / Q000235:genetics / Q000378:metabolism; D009088:Mucoproteins; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D055503:Protein Multimerization; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D013329:Structure-Activity Relationship
chemical_list: D029681:Arabidopsis Proteins; D009088:Mucoproteins; C010393:lysin, gastropoda; C525882:CERK1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases; D000117:Acetylglucosamine