Taking the lead: NLR immune receptor N‐terminal domains execute plant immune responses

Abstract

SummaryNucleotide‐binding domain and leucine‐rich repeat (NLR) proteins are important intracellular immune receptors that activate robust plant immune responses upon detecting pathogens. Canonical NLRs consist of a conserved tripartite architecture that includes a central regulatory nucleotide‐binding domain, C‐terminal leucine‐rich repeats, and variable N‐terminal domains that directly participate in immune execution. In flowering plants, the vast majority of NLR N‐terminal domains belong to the coiled‐coil, Resistance to Powdery Mildew 8, or Toll/interleukin‐1 receptor subfamilies, with recent structural and biochemical studies providing detailed mechanistic insights into their functions. In this insight review, we focus on the immune‐related biochemistries of known plant NLR N‐terminal domains and discuss the evolutionary diversity of atypical NLR domains in nonflowering plants. We further contrast these observations against the known diversity of NLR‐related receptors from microbes to metazoans across the tree of life.