Biology subjects

Gysel, K.

Publications and source records attributed to Gysel, K..

3 recordsLinked to original sources

bioRxiv2025

Structural basis for size-selective perception of chitin in plants

Plants detect microbes through pattern recognition receptors that perceive conserved microbial surface motifs known as microbe-associated molecular patterns (MAMPs). LysM receptors recognize and mediate downstream responses to chitinous MAMPs. Here, we elucidate the mechanism for the specific recognition of long-chain chitin oligomers and identify a hallmark bridge domain characteristic for the CHIP receptor class. Structural analysis of receptor-ligand complexes, biochemistry, and in planta functional studies using inhibitory nanobodies reveal the mechanism of size-selective, high affinity chitin perception in Lotus japonicus and Medicago truncatula. Additionally, we identify CERKs as low-affinity, yet essential co-receptors and propose a mechanistic model for a ligand-induced core signaling heterocomplex. Our findings provide mechanistic insights into plant chitin perception and the formation of receptor complexes critical for immune signaling.

plant biology↗

bioRxiv2024

The Medicago truncatula LYR4 intracellular domain serves as a scaffold in immunity signaling independent of its phosphorylation activity

Plants perceive and respond to chitin derived from fungal cell walls through lysine motif (LysM) receptor kinases. In the model legume Medicago truncatula, CERK1 and LYR4 represent the LysM receptor pair important for chitin-triggered immunity signaling. Here, we show that both the active kinase receptor CERK1 and the pseudokinase receptor LYR4 contribute to immunity signaling, leading to the production of reactive oxygen species (ROS). We determine the crystal structure of the LYR4 core intracellular domain with a bound nucleotide analog in the active site. Biochemical characterization shows that LYR4 binds ATP and has both autophosphorylation as well as transphosphorylation activity towards CERK1. However, in planta experiments demonstrate that the phosphorylation ability is not necessary for the function of LYR4 in chitin-triggered ROS production, but that the presence of its intracellular domain is indispensable. Together, we show that in chitin-triggered immunity the intracellular domain of LYR4 serves as a signaling scaffold independent of its catalytic activity.

plant biology↗

bioRxiv2024

Two residues reprogram immunity receptor kinases to signal in nitrogen-fixing symbiosis

Receptor signalling determines cellular responses and is crucial for defining specific biological outcomes. In legume root cells, highly similar and structurally conserved chitin and Nod factor receptor kinases activate immune or symbiotic pathways, respectively, upon perception of chitinous ligands. Here, we show that specific amino acid residues in the intracellular part of the Nod factor receptor NFR1 determine signalling specificity and enable the distinction between immune and symbiotic responses. Functional investigation of CERK6, NFR1 and receptor variants hereof revealed a conserved motif that we term Symbiosis Determinant 1 in the juxtamembrane region of the kinase domain that is key for symbiotic signalling. We demonstrate that two residues in Symbiosis Determinant 1 are indispensable hallmarks for NFR1-type receptors and are sufficient to convert Lotus CERK6 and barley RLK4 kinase outputs to enable symbiotic signalling in Lotus japonicus.

plant biology↗