A method for functional testing constitutive and ligand-induced interactions of lysin motif receptor proteins.

BACKGROUND

Plant receptors with lysin motifs (LsyM) recognize microbial signals such as fungal chitin and lipo-chitooligosaccharidic Nod factors of nitrogen-fixing rhizobia. It is generally assumed that ligand-induced dimerization of LysM receptors is an essential step in activation of intracellular kinase domains and downstream signaling. Consequently, genes required for plant defense and establishment of symbiosis are expressed. We recently found that three LysM receptor proteins (namely LYK1, LYK4 and LYK5) of form a tripartite receptor complex to perceive chitin. However, constitutive and ligand-induced interactions of LysM receptors generally remain difficult to be characterized.

RESULTS

Interactions between ectodomains of LYK1, LYK4 and LYK5 were investigated by a chimeric receptor approach using hairy roots of the legume . Synthetic receptor pairs consisting of a LYK ectodomain and the intracellular domain of a Nod factor receptor (NFR1 and NFR5, respectively) were tested for their capacity to activate expression of the symbiotic (nodule inception) gene. The results indicated constitutive (LYK4-LYK4, LYK4-LYK5) and chitin-induced interactions (LYK1-LYK1, LYK1-LYK5) of the examined ectodomains.

CONCLUSION

We present a method to functionally analyze constitutive and ligand-induced interactions of LysM-type proteins.