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Cell Host Microbe. 2014 Nov 12;16(5):605-15. doi: 10.1016/j.chom.2014.10.007. Epub 2014 Nov 12.

The calcium-dependent protein kinase CPK28 buffers plant immunity and regulates BIK1 turnover.

Author information

1
The Sainsbury Laboratory, Norwich Research Park, NR4 7UH Norwich, UK.
2
Department of Plant Biochemistry, Dahlem Centre of Plant Sciences, Freie Universität Berlin, 14195 Berlin, Germany.
3
The Sainsbury Laboratory, Norwich Research Park, NR4 7UH Norwich, UK. Electronic address: cyril.zipfel@tsl.ac.uk.

Abstract

Plant perception of pathogen-associated molecular patterns (PAMPs) triggers a phosphorylation relay leading to PAMP-triggered immunity (PTI). Despite increasing knowledge of PTI signaling, how immune homeostasis is maintained remains largely unknown. Here we describe a forward-genetic screen to identify loci involved in PTI and characterize the Arabidopsis calcium-dependent protein kinase CPK28 as a negative regulator of immune signaling. Genetic analyses demonstrate that CPK28 attenuates PAMP-triggered immune responses and antibacterial immunity. CPK28 interacts with and phosphorylates the plasma-membrane-associated cytoplasmic kinase BIK1, an important convergent substrate of multiple pattern recognition receptor (PRR) complexes. We find that BIK1 is rate limiting in PTI signaling and that it is continuously turned over to maintain cellular homeostasis. We further show that CPK28 contributes to BIK1 turnover. Our results suggest a negative regulatory mechanism that continually buffers immune signaling by controlling the turnover of this key signaling kinase.

PMID:
25525792
DOI:
10.1016/j.chom.2014.10.007
[Indexed for MEDLINE]
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