Self-association and an intact NADase active site are required for plant TIR domain immune signaling [Meeting Abstract]

Xiaoxiao Zhang, J Chen, Hayden Burdett, Maxwell X. Rank, T. Ve, John Rathjen, Bostjan Kobe, Peter N Dodds

    Research output: Contribution to journalMeeting Abstractpeer-review


    Plant NLR (nucleotide-binding leucine rich repeat) immune receptors recognise pathogen effectors to trigger plant immunity. The TIR (Toll/interleukin-1 receptor, resistance) domains of many plant NLRs are responsible for signaling. Isolated TIRs can self-associate through two interfaces, which are both required for signaling function. Although TIR domains of some NLRs do not signal autoactively as isolated fragments, we found that mutations in the self-interaction interfaces nevertheless disrupt effector dependent immunity of these full-length proteins, suggesting that this is a general model for TIR function. The TIR domain of the animal protein SARM1 is a functional NADase, and the catalytic glutamic acid (E) residue is highly conserved in plant TIRs. We found that introducing E to A mutants to this position of plant TIRs, abolished cell death signaling of both TIR-alone and full length NLR constructs. In addition, a double mutation of two R residues in the BB loop of the grapevine Run1 TIR resulted in both enhanced enzymatic activity and enhanced cell death signaling activity. Forced oligomerisation of plant TIRs by fusion to the SAM oligomerisation domain of SARM1 resulted in enhanced cell death signaling, while fusion to a non-oligomerising mutant version of SAM did not. Together these results suggest that formation of TIR oligomers is necessary and sufficient to induce TIR domain signaling and that NADase activity is required for this signaling function.
    Original languageEnglish
    Pages (from-to)88-88
    JournalMolecular Plant-Microbe Interactions
    Issue number10
    Publication statusPublished - 2019
    EventIS-MPMI XVIII Congress - Glasgow, Scotland
    Duration: 1 Jan 2019 → …


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