Journal Article

Chitin-induced and CHITIN ELICITOR RECEPTOR KINASE1 (CERK1) phosphorylation-dependent endocytosis of Arabidopsis thaliana LYSIN MOTIF-CONTAINING RECEPTOR-LIKE KINASE5 (LYK5)

Alexandra Matei, Ronja Hacke, Elena Petutschnig, Hassan Ghareeb, Jan Erwig, Michaela Kopischke, Volker Lipka

2017

Overview

To detect potential pathogens, plants perceive the fungal polysaccharide chitin through receptor complexes containing lysin motif receptor-like kinases (LysM-RLKs). To investigate the ligand-induced spatial dynamics of chitin receptor components, we studied the subcellular behaviour of two Arabidopsis thaliana LysM-RLKs involved in chitin signalling, CHITIN ELICITOR RECEPTOR KINASE1 (CERK1) and LYSIN MOTIF-CONTAINING RECEPTOR-LIKE KINASE5. We performed standard and quantitative confocal laser scanning microscopy on stably transformed A. thaliana plants expressing fluorescently tagged CERK1 and LYK5 from their native promoters. Microscopy approaches were complemented by biochemical analyses in plants and in vitro. Both CERK1 and LYK5 localized to the plasma membrane and showed constitutive endomembrane trafficking. After chitin treatment, however, CERK1 remained at the plasma membrane while LYK5 relocalized into mobile intracellular vesicles. Detailed analyses revealed that chitin perception transiently induced the internalization of LYK5 into late endocytic compartments. Plants that lacked CERK1 or expressed an enzymatically inactive CERK1 variant did not exhibit chitin-induced endocytosis of LYK5. CERK1 could phosphorylate LYK5 in vitro and chitin treatment induced CERK1-dependent phosphorylation of LYK5 in planta. Our results suggest that chitin-induced phosphorylation by CERK1 triggers LYK5 internalization. Thus, our work identifies phosphorylation as a key regulatory step in endocytosis of plant RLKs and also provides evidence for receptor complex dissociation after ligand perception.

• Publisher: New Phytologist Trust,Wiley Subscription Services, Inc
• Subject: Arabidopsis / Arabidopsis - cytology / Arabidopsis - metabolism / Arabidopsis Proteins - metabolism / Arabidopsis Proteins - physiology / Arabidopsis thaliana / Chitin / Chitin - metabolism / CHITIN ELICITOR RECEPTOR KINASE1 (CERK1) / confocal laser scanning microscopy / Confocal microscopy / dissociation / elicitors / Endocytosis / Fungi / Internalization / Kinases / Ligands / LYSIN MOTIF‐CONTAINING RECEPTOR‐LIKE KINASE5 (LYK5) / Microscopy / Pathogens / pattern recognition receptor (PRR) / Perception / Phosphorylation / phosphotransferases (kinases) / plasma membrane / Promoters / Protein Kinases - metabolism / Protein-Serine-Threonine Kinases - metabolism / Protein-Serine-Threonine Kinases - physiology / Spatial discrimination