Functional characterization of peroxisomal protein kinases in Arabidopsis plants

Abstract

Post-transcriptional modifications of proteins by phosphorylation is one of the most common mechanisms involved in regulating the activity, subcellular location and turnover of proteins. These processes are involved in sensing environmental cues and regulating the cell response to biotic and abiotic factors. Peroxisomes are an important source of signaling molecules such as reactive oxygen species (ROS), NO and hormones, and play a central role in regulating different metabolic pathways and cell response to stress conditions. The presence of kinases and phosphatases in peroxisomes has recently been reported although the protein target of this type of modifications and its role in the peroxisomal metabolism have not been identified so far. In this study, we analyze the role of the peroxisomal protein kinases, CPK1, PK1 and PK4, in the plant response to stress caused by Cd and their role in regulating catalase and glycolate oxidase activities by using Arabidopsis mutants deficient in these kinases (cpk1, pk1 and pk4). The results obtained suggest that CPK1, PK1 and PK4 are not essentially involved in the cell response to Cd, although PK1 and CPK1 may regulate glycolate oxidase activity while CPK1 regulates ROS production under Cd treatment.