The leucine-rich repeat receptor kinase BIR2 is a negative regulator of BAK1 in plant immunity

Thierry Halter, Julia Imkampe, Sara Mazzotta, Michael Wierzba, Sandra Postel, Christoph Bücherl, Christian Kiefer, Mark Stahl, Delphine Chinchilla, Xiaofeng Wang, Thorsten Nürnberger, Cyril Zipfel, Steven Clouse, Jan Willem Borst, Sjef Boeren, Sacco C. De Vries, Frans Tax, Birgit Kemmerling

Research output: Contribution to journalArticle

129 Scopus citations

Abstract

Background Transmembrane leucine-rich repeat (LRR) receptors are commonly used innate immune receptors in plants and animals but can also sense endogenous signals to regulate development. BAK1 is a plant LRR-receptor-like kinase (RLK) that interacts with several ligand-binding LRR-RLKs to positively regulate their functions. BAK1 is involved in brassinosteroid-dependent growth and development, innate immunity, and cell-death control by interacting with the brassinosteroid receptor BRI1, immune receptors, such as FLS2 and EFR, and the small receptor kinase BIR1, respectively. Results Identification of in vivo BAK1 complex partners by LC/ESI-MS/MS uncovered two novel BAK1-interacting RLKs, BIR2 and BIR3. Phosphorylation studies revealed that BIR2 is unidirectionally phosphorylated by BAK1 and that the interaction between BAK1 and BIR2 is kinase-activity dependent. Functional analyses of bir2 mutants show differential impact on BAK1-regulated processes, such as hyperresponsiveness to pathogen-associated molecular patterns (PAMP), enhanced cell death, and resistance to bacterial pathogens, but have no effect on brassinosteroid- regulated growth. BIR2 interacts constitutively with BAK1, thereby preventing interaction with the ligand-binding LRR-RLK FLS2. PAMP perception leads to BIR2 release from the BAK1 complex and enables the recruitment of BAK1 into the FLS2 complex. Conclusions Our results provide evidence for a new regulatory mechanism for innate immune receptors with BIR2 acting as a negative regulator of PAMP-triggered immunity by limiting BAK1-receptor complex formation in the absence of ligands.

Original languageEnglish (US)
Pages (from-to)134-143
Number of pages10
JournalCurrent Biology
Volume24
Issue number2
DOIs
StatePublished - Jan 20 2014

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)

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    Halter, T., Imkampe, J., Mazzotta, S., Wierzba, M., Postel, S., Bücherl, C., Kiefer, C., Stahl, M., Chinchilla, D., Wang, X., Nürnberger, T., Zipfel, C., Clouse, S., Borst, J. W., Boeren, S., De Vries, S. C., Tax, F., & Kemmerling, B. (2014). The leucine-rich repeat receptor kinase BIR2 is a negative regulator of BAK1 in plant immunity. Current Biology, 24(2), 134-143. https://doi.org/10.1016/j.cub.2013.11.047