PP2C phosphatase Pic1 negatively regulates phosphorylation status of Pti1b kinase, a regulator of flagellin-triggered immunity in tomato.

PP2C phosphatase Pic1 negatively regulates phosphorylation status of Pti1b kinase, a regulator of flagellin-triggered immunity in tomato. Biochem J. 2019 May 16;: Authors: Giska F, Martin GB Abstract Plant immune responses, including the production of reactive oxygen species (ROS), are triggered when pattern recognition receptors (PRR) become activated upon detection of microbe-associated molecular patterns (MAMPs). Receptor-like cytoplasmic kinases are key components of PRR-dependent signaling pathways. In tomato two such kinases, Pti1a and Pti1b, are important positive regulators of the plant immune response. However, it is unknown how these kinases control plant immunity at the molecular level, and how their activity is regulated. To investigate these issues, we used mass spectrometry to search for interactors of Pti1b in Nicotiana benthamiana leaves and identified a PP2C protein phosphatase, referred to as Pic1. An in vitro pull-down assay and in vivo split luciferase complementation assay verified this interaction. Pti1b was found to autophosphorylate on threonine-233 and this phosphorylation was abolished in the presence of Pic1. An arginine-to-cysteine substitution at position 240 in the Arabidopsis MARIS kinase was previously reported to convert it into a constitutive-active form. The analogous substitution in Pti1b made it resistant to Pic1 phosphatase activity, although it still interacted with Pic1. Treatment of N. bentham...
Source: The Biochemical Journal - Category: Biochemistry Authors: Tags: Biochem J Source Type: research