Structural basis for broad-spectrum recognition and activation of an Arabidopsis TIR-NLR

The Arabidopsis TIR-NLR WRR4A recognizes at least eight CCG effectors from white rust (Albugo candida, an oomycete), providing broad-spectrum resistance.Despite low sequence identity, the N-terminal ~100 amino acids of CCGs share conserved ferredoxin-like folds.Cryo-EM structures of WRR4A bound to distinct CCGs reveal a conserved network of backbone interactions mediated by Asn and Gln residues in WRR4A, likely enabling WRR4A's broad specificity.Notably, AlphaFold accurately predicted these complexes, closely matching experimental structures.Guided by Cryo-EM and AlphaFold models, we engineered WRR4A to recognize an unrecognized effector CCG47 by modifying its LRR and C-JID domains without relying on natural polymorph information, demonstrating the power of structure-informed NLR engineering for expanding pathogen recognition.