R genes: Structure, recognition, signaling, & evolution – part 1

1. R genes: Structure, recognition, signaling, & evolution – part 1 • Major classes of R genes • R gene structure • Early signaling events • R gene evolution

2. The zigzag model for plant pathogen interactions Dangl and Jones. 2006. Nature 444:323-329

3. Plant immune system Dangl. 2013. Science. 341:746

4. R protein structure R proteins encompass multiple domains involved in different aspects of activation and signaling, and intramolecular interaction is involved. Domains TIR – Toll/Interleukin-1 receptor CC – Coiled coil NBS – Nucleotide binding site LRR – Leucine-rich repeat R protein classes TIR-NBS-LRR, TNL CC-NBS-LRR, CNL NB-LRR, NBS-LRR, NLR – Nucleotide-binding leucine-rich repeat

5. Cloned disease resistance genes NBS-LRR is largest class Major subclasses of NBS-LRR are: - CC-NBS-LRR - TIR-NBS-LRR R gene class and pathogen are not correlated TIR-NBS-LRR are not found in cereals Liu et al. 2007. J. Genet. Genom. 34:765-776

7. Major classes of R proteins Liu et al. 2007. J. Genet. Genom. 34:765-776

8. Nucleotide binding site (NBS) I-2 Mi-1 P loop sequences kinase 2 4 hydrophobic amino acids followed by D (e.g. LIVLD ) kinase 3a Highly conserved tyrosine or arginine (e.g. FGNGSR) GLPL MHDV Tammeling et al. (2002) Plant Cell 14, 2929–2939

9. Inferred structure of R protein nucleotide binding sites McHale et al. 2006. Genome Biology. 7:212

10. Inferred structure of LRR domain McHale et al. 2006. Genome Biology. 7:212

11. Variation in numbers of LRRs

12. Structural models of domains in NLR proteins Takken. 2012. Curr. Opin. Plant Biol. 15:375-384

13. Model of LRR motif of lettuce downy mildew resistance protein, Dm3 Michelmore. 2013. Annu. Rev. Phytopathol. 51:291-319

14. LRR is least conserved part of R genes Michelmore and Meyers. 1998. Genome Res. 8: 1113-1130

15. NLR proteins are involved in plant & animal innate immunity Bonardi et al. (2012) Curr. Opin. Immunol. 24:41-50

16. Evidence for intramolecular interaction between domains of a CNL protein CP-independent HR when TEX’d Co-expression of full-length GPA2 with either LRR or ARC−LRR of Rx did not lead to a CP-dependent HR. However, co-expression of GPA2 with Rx NBS−LRR resulted in a CP-dependent HR (Figure 2B). This result demonstrates that a CC domain can be provided by full-length CC−NBS−LRR protein. Our observation that Rx NBS−LRR produced a CP-dependent HR when expressed in rx genotype potato leaves can be explained in the same way (Figure 2C). Presumably, a CC domain was provided to NBS−LRR by full-length homologues of Rx and GPA2 that are present in the rx potato genome (Bendahmane et al., 1999). Moffett et al. (2002) EMBO J. 21:4511

17. Intramolecular interactions - continued

18. N protein oligomerizes in response to elicitor Mestre. 2006. Plant Cell. 18:491-501

19. NLR proteins – Mechanisms for activation Bonardi et al. (2012) Curr. Opin. Immunol. 24:41-50

20. NLR folding and signaling Takken. 2012. Curr. Opin. Plant Biol. 15:375-384

21. Signaling by animal NLR proteins Ting et al. 2008. Nat. Rev. Immunol. 8:372-379