C-terminal jelly roll/Ig-like domain (C-JID) was defined in cryogenic electron microscopy (cryoEM) structures of plant intracellular immune receptors containing Toll/interleukin-1 receptor (TIR, PF01582), nucleotide-binding (NB-ARC, PF00931) and leucine-rich repeat (LRR) domains (TIR-NLRs) [1,2]. Structurally, the C-JID core is represented by a beta-sandwich made up of 8 to 9 beta-strands. C-JID matches the so-called post-LRR or C-terminal non-LRR domain detected earlier via MEME and BLAST searches [3,7]. The domain showed a strong distribution bias towards TIR-NLRs of dicotyledonous plant species despite broader taxonomic distribution of TIR-NLR in plant groups [1-7]. Structure-function analyses of cryoEM structures suggest that C-JID domains play a role in substrate recognition, such as binding to effector proteins from pathogens, and thus are involved in the initiation of signaling by TIR-NLR receptors [1,2]. Presence of C-JID (or post-LRR) and its importance for the function of Arabidopsis TIR-NLR RPS4 that partners with RRS1 for effector recognition suggest that C-JID has additional functions [4-6].

1: Structure of the activated ROQ1 resistosome directly recognizing the pathogen effector XopQ. Martin R, Qi T, Zhang H, Liu F, King M, Toth C, Nogales E, Staskawicz BJ; Science. 2020; [Epub ahead of print] PMID:33273074

2: Direct pathogen-induced assembly of an NLR immune receptor complex to form a holoenzyme. Ma S, Lapin D, Liu L, Sun Y, Song W, Zhang X, Logemann E, Yu D, Wang J, Jirschitzka J, Han Z, Schulze-Lefert P, Parker JE, Chai J; Science. 2020; [Epub ahead of print] PMID:33273071

3: TNL genes in peach: insights into the post-LRR domain. Van Ghelder C, Esmenjaud D; BMC Genomics. 2016;17:317. PMID:27129402

4: Integrity of the post-LRR domain is required for TNLs' function. Saucet SB, Esmenjaud D, Van Ghelder C; Mol Plant Microbe Interact. 2020; [Epub ahead of print] PMID:33197377

5: Structural basis for assembly and function of a heterodimeric plant immune receptor. Williams SJ, Sohn KH, Wan L, Bernoux M, Sarris PF, Segonzac C, Ve T, Ma Y, Saucet SB, Ericsson DJ, Casey LW, Lonhienne T, Winzor DJ, Zhang X, Coerdt A, Parker JE, Dodds PN, Kobe B, Jones JD; Science. 2014;344:299-303. PMID:24744375

6: The nuclear immune receptor RPS4 is required for RRS1SLH1-dependent constitutive defense activation in Arabidopsis thaliana. Sohn KH, Segonzac C, Rallapalli G, Sarris PF, Woo JY, Williams SJ, Newman TE, Paek KH, Kobe B, Jones JD; PLoS Genet. 2014;10:e1004655. PMID:25340333

7: Six amino acid changes confined to the leucine-rich repeat beta-strand/beta-turn motif determine the difference between the P and P2 rust resistance specificities in flax. Dodds PN, Lawrence GJ, Ellis JG; Plant Cell. 2001;13:163-178. PMID:11158537