Poster
Ryan Toth
PhD student
Institute of Plant and Microbial Biology, University of Zurich
Zurich, Zurich, Switzerland
Florian Schwanke
Institute of Plant and Microbial Biology, University of Zurich
Zurich, Zurich, Switzerland
Jared Johnson
Meyer Cancer Center, Weill Cornell Medicine
New York, New York, United States
Tomer Yaron-Barir
Englander Institute for Precision Medicine, Institute for Computational Biomedicine, Weill Cornell Medicine
New York, New York, United States
Philipp Köster
Institute of Plant and Microbial Biology, University of Zurich
Zurich, Zurich, Switzerland
Kyle W. Bender
Institute of Plant and Microbial Biology, University of Zurich
Zurich, Zurich, Switzerland
Paul Derbyshire
The Sainsbury Laboratory
Norwich, England, United Kingdom
Frank L.H. Menke
The Sainsbury Laboratory
Norwich, England, United Kingdom
Lewis Cantley
Meyer Cancer Center, Weill Cornell Medicine
Zurich, Zurich, Switzerland
Thomas A. DeFalco
Assistant professor
Department of Biology, Western University
London, Ontario, Canada
Cyril Zipfel
Institute of Plant and Microbial Biology, University of Zurich / The Sainsbury Laboratory
Zurich, Zurich, Switzerland
The Arabidopsis receptor-like cytoplasmic kinase BOTRYTIS-INDUCED KINASE1 (BIK1) is activated by numerous cell surface immune receptor complexes upon elicitor perception. Once activated, BIK1 trans-phosphorylates downstream substrate proteins to mediate pattern-triggered immunity (PTI). However, a comprehensive understanding of how BIK1 targets specific substrates and a full repertoire of BIK1 substrates remains unknown. Using a positional scanning peptide array, we identified BIK1 as a highly selective kinase with distinct amino acid preferences proximal to Ser/Thr phosphosites, and applied this target motif to systematically screen the Arabidopsis proteome for potential BIK1 substrates. Integrating transcriptomic and proteomic data, we filtered for candidate substrates with potential PTI functions and screened them based on pathogen susceptibility and BIK1-mediated trans-phosphorylation. Several novel immune signaling components identified belong to a poorly characterized protein kinase family, termed cyclin-dependent kinase-like (CDKL) proteins. We confirmed that BIK1 interacts with and trans-phosphorylates multiple CDKLs in vitro and in vivo. Furthermore, cdkl mutant lines exhibited enhanced immune responses, e.g., reactive oxygen species production, callose deposition, and resistance to Pseudomonas syringae, indicating that CDKLs act as negative regulators of immunity. These findings highlight the power of our motif-based approach in deciphering signaling pathways.