Diversification of the “EDVID” packing motif underpins structural and functional variation in plant NLR coiled-coil domains

Nucleotide-binding leucine-rich repeat receptors (NLRs) are critical in plant immunity and display remarkable allelic diversity. Coiled-coiled NLRs (CC-NLRs) are the most widespread group of these receptors found across flowering and non-flowering plants.

Here we investigate the sequence conservation and functional variation of the conserved EDVID motif found in the α3-helix of the cell death inducing CC domain of plant NLRs. We analyse our findings in context of published protein structures and structure prediction.

We find that the conserved EDVID motif can serve as a predictor of canonical CC-NLR function and oligomeric assembly.

We also find that the EDVID motif is accompanied by preceding acidic residues in certain CC-NLRs with homology to the Arabidopsis CC-NLR RPP8. The appearance of this so-called preEDVID motif across the phylogeny of flowering plants and its contribution to the CC-NLR function underpins the structural diversity across NLRs with EDVID motif.

We further show that CC-NLRs exist that have lost the EDVID motif sequence and function suggesting that this subgroup, previously referred to as CC_G10-NLRs, functions in a different manner from the canonical mechanism.

We find that acidic residues located to the α3-helix of the helper NLR NRG1.1 are linked to NRG1.1 cell death inducing activity.