S-acylation of P2K1 mediates extracellular ATP-induced immune signaling in Arabidopsis.

S-acylation is a reversible protein post-translational modification mediated by protein S-acyltransferases (PATs). How S-acylation regulates plant innate immunity is our main concern. Here, we show that the plant immune receptor P2K1 (DORN1, LecRK-I.9; extracellular ATP receptor) directly interacts with and phosphorylates Arabidopsis PAT5 and PAT9 to stimulate their S-acyltransferase activity. This leads, in a time-dependent manner, to greater S-acylation of P2K1, which dampens the immune response. pat5 and pat9 mutants have an elevated extracellular ATP-induced immune response, limited bacterial invasion, increased phosphorylation and decreased degradation of P2K1 during immune signaling. Mutation of S-acylated cysteine residues in P2K1 results in a similar phenotype. Our study reveals that S-acylation effects the temporal dynamics of P2K1 receptor activity, through autophosphorylation and protein degradation, suggesting an important role for this modification in regulating the ability of plants in respond to external stimuli.