NB-LRRs work a “bait and switch” on pathogens

Plant genomes encode large numbers of highly variable nucleotide binding leucine-rich repeat (NB-LRR) disease resistance proteins. These proteins have been studied extensively to understand their evolution and the molecular basis of their function. Multiple studies indicate that the C-terminal LRR domain plays a pivotal role in defining pathogen recognition specificity. However, a growing body of evidence suggests that the N-termini of NB-LRR proteins also function in pathogen recognition. To formulate a framework that can explain the underlying principles governing NB-LRR function while accommodating findings from different experimental systems, we present a “bait and switch” model. This model proposes a two-step recognition process involving interactions with both cellular cofactors (bait) and the LRR domain, which in turn activates the molecular switch leading to disease resistance.