1. Activation and Autoinhibition Mechanisms of NLR Immune Receptor Pi36 in Rice.
- Author
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Yang Y, Tan L, Xu X, Tang Q, Wang J, Xing S, Wang R, Zou T, Wang S, Zhu J, Li S, Liang Y, Deng Q, and Li P
- Subjects
- Cell Death, Mutation, Receptors, Immunologic metabolism, Receptors, Immunologic genetics, Plant Diseases immunology, Plant Diseases genetics, Plant Diseases microbiology, Protein Domains, Disease Resistance genetics, Plant Immunity genetics, Oryza metabolism, Oryza genetics, Oryza immunology, Plant Proteins metabolism, Plant Proteins genetics, Plant Proteins chemistry, NLR Proteins metabolism, NLR Proteins genetics, NLR Proteins chemistry
- Abstract
Nucleotide-binding and leucine-rich repeat receptors (NLRs) are the most important and largest class of immune receptors in plants. The Pi36 gene encodes a canonical CC-NBS-LRR protein that confers resistance to rice blast fungal infections. Here, we show that the CC domain of Pi36 plays a role in cell death induction. Furthermore, self-association is required for the CC domain-mediated cell death, and the self-association ability is correlated with the cell death level. In addition, the NB-ARC domain may suppress the activity of the CC domain through intramolecular interaction. The mutations D440G next to the RNBS-D motif and D503V in the MHD motif autoactivated Pi36, but the mutation K212 in the P-loop motif inhibited this autoactivation, indicating that nucleotide binding of the NB-ARC domain is essential for Pi36 activation. We also found that the LRR domain is required for D503V- and D440G-mediated Pi36 autoactivation. Interestingly, several mutations in the CC domain compromised the CC domain-mediated cell death without affecting the D440G- or D503V-mediated Pi36 autoactivation. The autoactivate Pi36 variants exhibited stronger self-associations than the inactive variants. Taken together, we speculated that the CC domain of Pi36 executes cell death activities, whereas the NB-ARC domain suppressed CC-mediated cell death via intermolecular interaction. The NB-ARC domain releases its suppression of the CC domain and strengthens the self-association of Pi36 to support the CC domain, possibly through nucleotide exchange.
- Published
- 2024
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