Model for the switch function of NBS-LRR proteins.
In the absence of a pathogen an NB-LRR protein resides in its resting (ADP) state, in which the LRR stabilizes the closed conformation. The recognition platform forthe AVR protein is provided by the C-terminal part of the LRR together with CC/TIR domain (CC). Perception of the AVR (direct or indirect) changes the interaction surface between the N-terminal part of the LRR and the ARC2subdomain, thereby releasing the autoinhibition conferred by the LRR.Subsequent nucleotide exchange triggersasecondconformational change, altering the interactions of the NB-ARC domain with CC and LRR domains (induced state). In the activated state the NB subdomain is accessible to interact with downstream signalling partners. Hydrolysis of ATP could return the protein to its resting state. (figure adapted from Takken and Tameling (2009) Science,