9v72
Structural basis of signal activation and transduction by chitin elicitor receptor kinase 1 in Oryza sativa
Structural highlights
FunctionCERK1_ORYSJ Lysin motif (LysM) receptor kinase required as a cell surface receptor for chitin elicitor (chitooligosaccharides) signaling leading to innate immunity in response to biotic stresses. Involved in the resistance to pathogenic fungi, probably by sensing microbe-associated molecular patterns (MAMP) and pathogen-associated molecular patterns (PAMP) (PubMed:21070404, PubMed:22891159, PubMed:24964058). Involved in the detection of microbial peptidoglycans (PGNs) and mediates PGN response (PubMed:24964058). Plays dual roles in PGN and chitin signaling during innate immunity. Acts as an adapter for LYP4 and LYP6 and mediates signal transduction from the extracellular to intracellular spaces. Participates in the activation of defense genes during response to PGN and chitin (PubMed:25335639). Phosphorylates the downstream partner RLCK185 in response to chitin elicitation (PubMed:23498959).[1] [2] [3] [4] [5] Publication Abstract from PubMedChitin elicitor receptor kinase 1 (OsCERK1) from Oryza sativa plays a central role in coordinating symbiotic and immune responses by recognizing fungal chitin fragments of different lengths. Although the extracellular domain of OsCERK1 has been well characterized with respect to chitin recognition, the structural basis underlying intracellular activation and downstream signal transduction remains poorly understood. In this study, we determined nine crystal structures of truncated OsCERK1 cytoplasmic kinase domains in either phosphorylated or dephosphorylated states, resolved in the absence of nucleotide or in complex with ADP, ATP, or the ATP analog AMP-PNP. Structural analyses reveal that OsCERK1 consistently adopts an intermediate kinase conformation characterized by an alphaC helix-out and DFG-in configuration, regardless of phosphorylation status or nucleotide binding. Functional assays further demonstrate that both the symbiotic receptor OsMYR1 and the receptor-like cytoplasmic kinase OsRLCK185 act as substrates that allosterically enhance OsCERK1 activity, with OsMYR1 exerting a stronger activation effect. This enhancement correlates with substrate-binding affinity, whereas phosphorylation does not uniformly increase substrate association. Notably, intermolecular autophosphorylation of OsCERK1 markedly elevates its catalytic activity. In addition, T479, T484, and Y492 within the activation segment are identified as critical residues required for OsCERK1 catalytic activity and substrate phosphorylation. Collectively, these findings support a dual regulatory model in which autophosphorylation enhances catalytic capacity, while substrate binding promotes allosteric activation. This study provides structural insight into OsCERK1 activation and establishes a mechanistic framework for receptor-like kinase-mediated signaling in plant immunity and symbiosis. Structural basis of OsCERK1-mediated signal activation and transduction in rice immunity and symbiosis.,Su Z, Zhou S, Yu S, Ning X, Fu Q, Fu Q, Zhao Q, Ma J, Niu C, Kong Y, Peng Y, Ming Z Plant Commun. 2025 Dec 16:101677. doi: 10.1016/j.xplc.2025.101677. PMID:41403133[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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