Phosphorylation-mediated regulation of integrin-linked kinase 5 by purinoreceptor P2K2

ABSTRACT

Extracellular ATP (eATP) in plants plays a crucial role as a ligand for purinoreceptors, mediating purinergic signaling and regulating diverse biological functions, including responses to abiotic and biotic stresses. DORN1/P2K1 (LecRK I.9) was the first identified plant purinoreceptor. P2K2 (LecRK I.5) was subsequently identified as an additional plant purinoreceptor and shown to directly interact with P2K1. Recently, we reported that P2K1 interacts with Integrin-linked kinase 5 (ILK5), a Raf-like MAPKKK protein, and phosphorylates ILK5 to regulate purinergic signaling in relation to plant innate immunity. Here, we report that P2K2 also interacts with the ILK5 protein in planta. Furthermore, we demonstrate that P2K2 phosphorylates ILK5 in the presence of [γ-32P] ATP, similar to P2K1. However, unlike P2K1, P2K2 exhibits strong phosphorylation even when the Serine 192 residue of ILK5 is mutated to Alanine (ILK5^S192A), suggesting the possibility of phosphorylation of other residues to fully regulate ILK5 protein function.

KEYWORDS:

• Extracellular ATP
• purinergic signaling
• P2K2
• purinoreceptor
• Integrin-linked kinase 5 (ILK5)
• danger-associated molecular patterns (DAMPs)

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The authors declare that all other data supporting the findings of this study are available within the manuscript and its supplementary files or are available from the corresponding author on request.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15592324.2023.2261743

Additional information

Funding

This work was supported by the National Institute of General Medical Sciences of the National Institutes of Health (grant no. R01GM121445), the Next-Generation BioGreen 21 Program Systems and Synthetic Agrobiotech Center, Rural Development Administration, Republic of Korea (grant no. PJ01325403), through the 3^rd call of the ERA-NET for Coordinating Action in Plant Sciences, with funding from the US National Science Foundation (NSF, grant no. 1826803) and funding from the NSF Plant Genome Research Program (grant no. 2048410).