Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

The malectin-like receptor-like kinase LETUM1 modulates NLR protein SUMM2 activation via MEKK2 scaffolding

Abstract

The innate immune system detects pathogen-derived molecules via specialized immune receptors to prevent infections1,2,3. Plant immune receptors include cell surface-resident pattern recognition receptors (PRRs, including receptor-like kinases (RLKs)), and intracellular nucleotide-binding domain leucine-rich repeat proteins (NLRs). It remains enigmatic how RLK- and NLR-mediated signalling are connected. Disruption of an immune-activated MEKK1–MKK1/2–MPK4 MAPK cascade activates the NLR SUMM2 via the MAPK kinase kinase MEKK2, leading to autoimmunity4,5,6,7,8,9. To gain insights into the mechanisms underlying SUMM2 activation, we used an RNA interference-based genetic screen for mekk1 autoimmune suppressors and identified an uncharacterized malectin-like RLK, named LETUM1 (LET1), as a specific regulator of mekk1–mkk1/2mpk4 autoimmunity via complexing with both SUMM2 and MEKK2. MEKK2 scaffolds LET1 and SUMM2 for protein stability and association, and counter-regulates the F-box protein CPR1-mediated SUMM2 ubiquitination and degradation, thereby regulating SUMM2 accumulation and activation. Our study indicates that malectin-like RLK LET1 senses the perturbance of cellular homoeostasis caused by the deficiency in immune-activated signalling and activates the NLR SUMM2-mediated autoimmunity via MEKK2 scaffolding.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Fig. 1: The let1 mutants suppress autoimmunity triggered by silencing MEKK1.
Fig. 2: LET1 functions genetically downstream of MEKK2 and upstream of SUMM2 in cell death control.
Fig. 3: MEKK2 stabilizes LET1 and SUMM2 and promotes cell death.
Fig. 4: MEKK2 counter-regulates CPR1-mediated SUMM2 ubiquitination and degradation.

Data availability

Original data that support the findings of this study are available from the corresponding author upon request. Source data are provided with this paper.

References

  1. 1.

    Jones, J. D. G. & Dangl, J. L. The plant immune system. Nature 444, 323–329 (2006).

    CAS  PubMed  Google Scholar 

  2. 2.

    Chisholm, S. T., Coaker, G., Day, B. & Staskawicz, B. J. Host–microbe interactions: shaping the evolution of the plant immune response. Cell 124, 803–814 (2006).

    CAS  PubMed  Google Scholar 

  3. 3.

    Spoel, S. H. & Dong, X. How do plants achieve immunity? Defence without specialized immune cells. Nat. Rev. Immunol. 12, 89–100 (2012).

    CAS  PubMed  Google Scholar 

  4. 4.

    Zhang, Z. et al. Disruption of PAMP-induced MAP kinase cascade by a Pseudomonas syringae effector activates plant immunity mediated by the NB-LRR protein SUMM2. Cell Host Microbe 11, 253–263 (2012).

    CAS  PubMed  Google Scholar 

  5. 5.

    Gao, M. et al. MEKK1, MKK1/MKK2 and MPK4 function together in a mitogen-activated protein kinase cascade to regulate innate immunity in plants. Cell Res. 18, 1190–1198 (2008).

    CAS  PubMed  Google Scholar 

  6. 6.

    Ichimura, K., Casais, C., Peck, S. C., Shinozaki, K. & Shirasu, K. MEKK1 is required for MPK4 activation and regulates tissue-specific and temperature-dependent cell death in Arabidopsis. J. Biol. Chem. 281, 36969–36976 (2006).

    CAS  PubMed  Google Scholar 

  7. 7.

    Suarez-Rodriguez, M. C. et al. MEKK1 is required for flg22-induced MPK4 activation in Arabidopsis plants. Plant Physiol. 143, 661–669 (2007).

    CAS  PubMed  PubMed Central  Google Scholar 

  8. 8.

    Nakagami, H., Soukupova, H., Schikora, A., Zarsky, V. & Hirt, H. A mitogen-activated protein kinase kinase kinase mediates reactive oxygen species homeostasis in Arabidopsis. J. Biol. Chem. 281, 38697–38704 (2006).

    CAS  PubMed  Google Scholar 

  9. 9.

    Petersen, M. et al. Arabidopsis map kinase 4 negatively regulates systemic acquired resistance. Cell 103, 1111–1120 (2000).

    CAS  PubMed  Google Scholar 

  10. 10.

    Couto, D. & Zipfel, C. Regulation of pattern recognition receptor signalling in plants. Nat. Rev. Immunol. 16, 537–552 (2016).

    CAS  PubMed  Google Scholar 

  11. 11.

    Yu, X., Feng, B., He, P. & Shan, L. From chaos to harmony: responses and signaling upon microbial pattern recognition. Annu. Rev. Phytopathol. 55, 109–137 (2017).

    CAS  PubMed  PubMed Central  Google Scholar 

  12. 12.

    Gust, A. A., Pruitt, R. & Nurnberger, T. Sensing danger: key to activating plant immunity. Trends Plant Sci. 22, 779–791 (2017).

    CAS  PubMed  Google Scholar 

  13. 13.

    Cui, H., Tsuda, K. & Parker, J. E. Effector-triggered immunity: from pathogen perception to robust defense. Annu. Rev. Plant Biol. 66, 487–511 (2015).

    CAS  PubMed  Google Scholar 

  14. 14.

    Elmore, J. M., Lin, Z. J. & Coaker, G. Plant NB-LRR signaling: upstreams and downstreams. Curr. Opin. Plant Biol. 14, 365–371 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  15. 15.

    DeYoung, B. J. & Innes, R. W. Plant NBS-LRR proteins in pathogen sensing and host defense. Nat. Immunol. 7, 1243–1249 (2006).

    CAS  PubMed  PubMed Central  Google Scholar 

  16. 16.

    Rodriguez, M. C., Petersen, M. & Mundy, J. Mitogen-activated protein kinase signaling in plants. Annu. Rev. Plant Biol. 61, 621–649 (2010).

    CAS  PubMed  Google Scholar 

  17. 17.

    Meng, X. & Zhang, S. MAPK cascades in plant disease resistance signaling. Annu. Rev. Phytopathol. 51, 245–266 (2013).

    CAS  PubMed  Google Scholar 

  18. 18.

    Tena, G., Boudsocq, M. & Sheen, J. Protein kinase signaling networks in plant innate immunity. Curr. Opin. Plant Biol. 14, 519–529 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  19. 19.

    Sun, T. et al. Antagonistic interactions between two MAP kinase cascades in plant development and immune signaling. EMBO Rep. 19, e45324 (2018).

    PubMed  PubMed Central  Google Scholar 

  20. 20.

    Bi, G. et al. Receptor-like cytoplasmic kinases directly link diverse pattern recognition receptors to the activation of mitogen-activated protein kinase cascades in Arabidopsis. Plant Cell 30, 1543–1561 (2018).

    CAS  PubMed  PubMed Central  Google Scholar 

  21. 21.

    Asai, T. et al. MAP kinase signalling cascade in Arabidopsis innate immunity. Nature 415, 977–983 (2002).

    CAS  PubMed  Google Scholar 

  22. 22.

    de Oliveira, M. V. V. et al. Specific control of Arabidopsis BAK1/SERK4-regulated cell death by protein glycosylation. Nat. Plants 2, 15218 (2016).

    PubMed  PubMed Central  Google Scholar 

  23. 23.

    Yu, X. et al. The receptor kinases BAK1/SERK4 regulate Ca2+ channel-mediated cellular homeostasis for cell death containment. Curr. Biol. 29, 3778–3790 (2019).

    CAS  PubMed  PubMed Central  Google Scholar 

  24. 24.

    Yang, Y. et al. RNA interference-based screen reveals concerted functions of MEKK2 and CRCK3 in plant cell death regulation. Plant Physiol. 183, 331–344 (2020).

    PubMed  PubMed Central  Google Scholar 

  25. 25.

    Kong, Q. et al. The MEKK1-MKK1/MKK2-MPK4 kinase cascade negatively regulates immunity mediated by a mitogen-activated protein kinase kinase kinase in Arabidopsis. Plant Cell 24, 2225–2236 (2012).

    CAS  PubMed  PubMed Central  Google Scholar 

  26. 26.

    Su, S. H. et al. Deletion of a tandem gene family in Arabidopsis: increased MEKK2 abundance triggers autoimmunity when the MEKK1-MKK1/2-MPK4 signaling cascade is disrupted. Plant Cell 25, 1895–1910 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  27. 27.

    Zhang, Z. et al. The NLR protein SUMM2 senses the disruption of an immune signaling MAP kinase cascade via CRCK3. EMBO Rep. 18, 292–302 (2017).

    CAS  PubMed  Google Scholar 

  28. 28.

    Nissen, K. S., Willats, W. G. & Malinovsky, F. G. Understanding CrRLK1L function: cell walls and growth control. Trends Plant Sci. 21, 516–527 (2016).

    CAS  PubMed  Google Scholar 

  29. 29.

    Li, C., Wu, H. M. & Cheung, A. Y. FERONIA and her pals: functions and mechanisms. Plant Physiol. 171, 2379–2392 (2016).

    CAS  PubMed  PubMed Central  Google Scholar 

  30. 30.

    Lindner, H., Muller, L. M., Boisson-Dernier, A. & Grossniklaus, U. CrRLK1L receptor-like kinases: not just another brick in the wall. Curr. Opin. Plant Biol. 15, 659–669 (2012).

    CAS  PubMed  Google Scholar 

  31. 31.

    Franck, C. M., Westermann, J. & Boisson-Dernier, A. Plant malectin-like receptor kinases: from cell wall integrity to immunity and beyond. Annu. Rev. Plant Biol. 69, 301–328 (2018).

    CAS  PubMed  Google Scholar 

  32. 32.

    Huck, N., Moore, J. M., Federer, M. & Grossniklaus, U. The Arabidopsis mutant feronia disrupts the female gametophytic control of pollen tube reception. Development 130, 2149–2159 (2003).

    CAS  PubMed  Google Scholar 

  33. 33.

    Boisson-Dernier, A. et al. Disruption of the pollen-expressed FERONIA homologs ANXUR1 and ANXUR2 triggers pollen tube discharge. Development 136, 3279–3288 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  34. 34.

    Miyazaki, S. et al. ANXUR1 and 2, sister genes to FERONIA/SIRENE, are male factors for coordinated fertilization. Curr. Biol. 19, 1327–1331 (2009).

    CAS  PubMed  Google Scholar 

  35. 35.

    Guo, H. et al. Three related receptor-like kinases are required for optimal cell elongation in Arabidopsis thaliana. Proc. Natl Acad. Sci. USA 106, 7648–7653 (2009).

    CAS  PubMed  Google Scholar 

  36. 36.

    Ge, Z. et al. Arabidopsis pollen tube integrity and sperm release are regulated by RALF-mediated signaling. Science 358, 1596–1600 (2017).

    CAS  PubMed  PubMed Central  Google Scholar 

  37. 37.

    Stegmann, M. et al. The receptor kinase FER is a RALF-regulated scaffold controlling plant immune signaling. Science 355, 287–289 (2017).

    CAS  PubMed  Google Scholar 

  38. 38.

    Mang, H. et al. Differential regulation of two-tiered plant immunity and sexual reproduction by ANXUR receptor-like kinases. Plant Cell 29, 3140–3156 (2017).

    CAS  PubMed  PubMed Central  Google Scholar 

  39. 39.

    Guo, H. et al. FERONIA receptor kinase contributes to plant immunity by suppressing jasmonic acid signaling in Arabidopsis thaliana. Curr. Biol. 28, 3316–3324 (2018).

    CAS  PubMed  Google Scholar 

  40. 40.

    Kessler, S. A. et al. Conserved molecular components for pollen tube reception and fungal invasion. Science 330, 968–971 (2010).

    CAS  PubMed  Google Scholar 

  41. 41.

    Nitta, Y. et al. MEKK2 inhibits activation of MAP kinases in Arabidopsis. Plant J. 103, 705–714 (2020).

    CAS  PubMed  Google Scholar 

  42. 42.

    Cheng, Y. T. et al. Stability of plant immune-receptor resistance proteins is controlled by SKP1-CULLIN1-F-box (SCF)-mediated protein degradation. Proc Natl Acad. Sci. USA 108, 14694–14699 (2011).

    CAS  PubMed  Google Scholar 

  43. 43.

    Gou, M. et al. The F-box protein CPR1/CPR30 negatively regulates R protein SNC1 accumulation. Plant J. 69, 411–420 (2012).

    CAS  PubMed  Google Scholar 

  44. 44.

    Lu, D. et al. Direct ubiquitination of pattern recognition receptor FLS2 attenuates plant innate immunity. Science 332, 1439–1442 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  45. 45.

    Zhang, J. et al. A Pseudomonas syringae effector inactivates MAPKs to suppress PAMP-induced immunity in plants. Cell Host Microbe 1, 175–185 (2007).

    CAS  PubMed  Google Scholar 

  46. 46.

    Haruta, M., Sabat, G., Stecker, K., Minkoff, B. B. & Sussman, M. R. A peptide hormone and its receptor protein kinase regulate plant cell expansion. Science 343, 408–411 (2014).

    CAS  PubMed  PubMed Central  Google Scholar 

  47. 47.

    Xiao, Y. et al. Mechanisms of RALF peptide perception by a heterotypic receptor complex. Nature 572, 270–274 (2019).

    CAS  PubMed  Google Scholar 

  48. 48.

    Li, F. et al. Modulation of RNA polymerase II phosphorylation downstream of pathogen perception orchestrates plant immunity. Cell Host Microbe 16, 748–758 (2014).

    CAS  PubMed  PubMed Central  Google Scholar 

  49. 49.

    Bajar, B. T., Wang, E. S., Zhang, S., Lin, M. Z. & Chu, J. A guide to fluorescent protein FRET pairs. Sensors 16, 1488 (2016).

  50. 50.

    He, P., Shan, L. & Sheen, J. in Plant–Pathogen Interactions (ed. Ronald, P.C.) 1–9 (Springer, 2007).

  51. 51.

    Shu, C. et al. Structural insights into the functions of TBK1 in innate antimicrobial immunity. Structure 21, 1137–1148 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  52. 52.

    Bucherl, C., Aker, J., de Vries, S. & Borst, J. W. Probing protein–protein Interactions with FRET–FLIM. Methods Mol. Biol. 655, 389–399 (2010).

    PubMed  Google Scholar 

  53. 53.

    Halter, T. et al. The leucine-rich repeat receptor kinase BIR2 Is a negative regulator of BAK1 in plant immunity. Curr. Biol. 24, 134–143 (2014).

    CAS  PubMed  Google Scholar 

Download references

Acknowledgements

We thank the ABRC for Arabidopsis T-DNA insertion library and various mutant seeds. We thank P. Krysan (University of Wisconsin, United States), Y. Zhang (University of British Columbia, Canada) and J. Hua (Cornell University, United States) for Arabidopsis seeds. We thank C. Franck and C. Zipfel for the critical reading of the manuscript and members of the laboratories of L.S. and P.H. for discussions and comments on the experiments. The work was supported by National Institutes of Health (NIH) grant no. R01GM092893 and National Science Foundation (NSF) grant no. MCB-1906060 to P.H. and NIH grant no. R01GM097247 and the Robert A. Welch Foundation grant no. A-1795 to L.S. Y.H. and D.G. were partially supported by China Scholarship Council (CSC) and G.C.M was partially supported by INCT/CNPq Fellowship, Brazil.

Author information

Affiliations

Authors

Contributions

Y.H., J.L., L.S. and P.H. conceived the project, designed experiments and analysed data. J.L., Y.H., L.K., X.Y., B.F., D.L., B.Z., G.C.M., P.Y. and D.G. performed experiments and analysed data. W.M.W, E.P.B.F. and P.L. analysed data and provided critical feedback. L.S. and P.H. wrote the manuscript with inputs from all authors.

Corresponding author

Correspondence to Ping He.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Figs. 1–10 and Table 1.

Reporting Summary

Supplementary Data 1

Statistical source data.

Supplementary Data 2

Statistical source data.

Supplementary Data 3

Statistical source data.

Supplementary Data 4

Unprocessed western blots.

Supplementary Data 5

Statistical source data.

Supplementary Data 6

Unprocessed western blots.

Supplementary Data 7

Unprocessed western blots.

Supplementary Data 8

Unprocessed western blots.

Supplementary Data 9

Unprocessed western blots.

Source data

Source Data Fig. 1

Statistical source data.

Source Data Fig. 1

Unprocessed western blots.

Source Data Fig. 2

Statistical source data.

Source Data Fig. 2

Unprocessed western blots.

Source Data Fig. 3

Statistical source data.

Source Data Fig. 3

Unprocessed western blots.

Source Data Fig. 4

Statistical source data.

Source Data Fig. 4

Unprocessed western blots.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Liu, J., Huang, Y., Kong, L. et al. The malectin-like receptor-like kinase LETUM1 modulates NLR protein SUMM2 activation via MEKK2 scaffolding. Nat. Plants 6, 1106–1115 (2020). https://doi.org/10.1038/s41477-020-0748-6

Download citation

Further reading

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing