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Ligand-triggered allosteric ADP release primes a plant NLR complex
Structural highlights
FunctionR13L4_ARATH CC-NB-LRR receptor-like protein required for recognition of the Pseudomonas syringae type III effector HopZ1a. Confers allele-specific recognition and virulence attenuation of HopZ1a. Immunity mediated by ZAR1 is independent of several genes required by other resistance protein signaling pathways such as NDR1 and RAR1.[1] Publication Abstract from PubMedPathogen recognition by nucleotide-binding (NB), leucine-rich repeat (LRR) receptors (NLRs) plays roles in plant immunity. The Xanthomonas campestris pv. campestris effector AvrAC uridylylates the Arabidopsis PBL2 kinase, and the latter (PBL2(UMP)) acts as a ligand to activate the NLR ZAR1 precomplexed with the RKS1 pseudokinase. Here we report the cryo-electron microscopy structures of ZAR1-RKS1 and ZAR1-RKS1-PBL2(UMP) in an inactive and intermediate state, respectively. The ZAR1(LRR) domain, compared with animal NLR(LRR) domains, is differently positioned to sequester ZAR1 in an inactive state. Recognition of PBL2(UMP) is exclusively through RKS1, which interacts with ZAR1(LRR) PBL2(UMP) binding stabilizes the RKS1 activation segment, which sterically blocks ZAR1 adenosine diphosphate (ADP) binding. This engenders a more flexible NB domain without conformational changes in the other ZAR1 domains. Our study provides a structural template for understanding plant NLRs. Ligand-triggered allosteric ADP release primes a plant NLR complex.,Wang J, Wang J, Hu M, Wu S, Qi J, Wang G, Han Z, Qi Y, Gao N, Wang HW, Zhou JM, Chai J Science. 2019 Apr 5;364(6435). pii: 364/6435/eaav5868. doi:, 10.1126/science.aav5868. PMID:30948526[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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