1. CPK28 is a modulator of purinergic signaling in plant growth and defense.
- Author
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Sowders, Joel M., Jewell, Jeremy B., and Tanaka, Kiwamu
- Subjects
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PURINERGIC receptors , *PLANT defenses , *PLANT growth , *PLANT physiology , *PHYSIOLOGY , *TANDEM mass spectrometry - Abstract
SUMMARY: Extracellular ATP (eATP) is a key signaling molecule that plays a pivotal role in plant growth and defense responses. The receptor P2K1 is responsible for perceiving eATP and initiating its signaling cascade. However, the signal transduction mechanisms downstream of P2K1 activation remain incompletely understood. We conducted a comprehensive analysis of the P2K1 interactome using co‐immunoprecipitation‐coupled tandem mass spectrometry, leading to the identification of 121 candidate proteins interacting with P2K1. In silico analysis narrowed down the candidates to 47 proteins, including Ca2+‐binding proteins, ion transport‐related proteins, and receptor kinases. To investigate their involvement in eATP signaling, we employed a screening strategy based on changes in gene expression in response to eATP in mutants of the identified interactors. This screening revealed several Ca2+‐dependent protein kinases (CPKs) that significantly affected the expression of eATP‐responsive genes, suggesting their potential roles in eATP signaling. Notably, CPK28 and CPK6 showed physical interactions with P2K1 both in yeast and plant systems. Calcium influx and gene expression studies demonstrated that CPK28 perturbed eATP‐induced Ca2+ mobilization and some early transcriptional responses. Overexpression of CPK28 resulted in an antagonistic physiological response to P2K1‐mediated eATP signaling during both plant growth and defense responses to the necrotrophic pathogen Botrytis cinerea. Our findings highlight CPK28, among other CPKs, as a modulator of P2K1‐mediated eATP signaling, providing valuable insights into the coordination of eATP signaling in plant growth and immunity. Significance Statement: In the last two decades, extracellular ATP has become a pivotal signaling element in animal physiology and plant biology. Recognized for its role in plant growth and defense, the purinergic signal of eATP is well‐established. Despite some identified interactors of the eATP receptor P2K1, a comprehensive understanding of purinergic signaling has been hindered by the lack of a P2K1 interactome. Our study successfully generated this interactomics dataset, shedding light on eATP‐mediated signaling and revealing a key player, CPK28, a Ca2+‐dependent protein kinase. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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