Study reveals how plant immune receptor LORE recognizes bacterial fatty acid signals
Scientists have characterized how the plant immune receptor LORE recognizes bacterial medium-chain 3-hydroxy fatty acids (mc-3-OH-FAs) at the molecular level, identifying a hydrophobic pocket in the lectin 2 domain and a flexible loop as key structural elements. The study combined computational methods—including protein structure prediction, molecular dynamics simulations, and ligand-docking modeling—with experimental binding assays and functional receptor analysis. The findings provide a mechanistic framework for how plants detect microbial signals and open potential avenues for engineering enhanced or modified plant immune responses.
A new preprint study on bioRxiv investigates how LORE, an S-domain receptor kinase in Arabidopsis thaliana, senses medium-chain 3-hydroxy fatty acids (mc-3-OH-FAs) produced by bacteria as part of pattern-triggered immunity. Using domain-swap experiments between LORE and its non-binding paralog AtSD1-23, researchers pinpointed the lectin 2 (L2) domain as the primary ligand-binding region. Mutational analysis and reverse-engineering approaches confirmed that a hydrophobic pocket within the L2 core is the main binding site, while multiple walker Supervised Molecular Dynamics (mwSuMD) simulations showed that the fatty acid's acyl tail enters the pocket first, with the polar headgroup subsequently stabilized by a flexible loop. Notably, 3-OH-C10:0 analogues bearing bulky headgroup modifications could dock into the pocket but functioned as antagonists, apparently by preventing the flexible loop from adopting the conformation needed to trigger signaling. The study concludes that this flexible L2 loop serves multiple roles: gating pocket access, anchoring the bound ligand, and contributing to downstream receptor activation, offering a detailed mechanistic model for immunogenic fatty acid sensing in plants.
What's missing
As a preprint, this study has not yet undergone formal peer review, so findings should be interpreted with caution. The study relies heavily on computational modeling (MD simulations, structure prediction); direct structural validation via X-ray crystallography or cryo-EM of the ligand-bound complex is not reported. The in vivo relevance of the identified antagonists and whether the proposed loop mechanism generalizes to LORE orthologs in crop plants remain open questions.
What different sources said
- bioRxivCenter
The plant immune receptor LORE binds agonistic and antagonistic 3-hydroxy fatty acid ligands via a dynamic loop in its G-type lectin domain
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