Signaling via reversible phosphorylation in organelles
During germination, and biotic and abiotic stresses
The (previously marginalized) eukaryotic organelle the peroxisome is now established as a key-player in vital cellular processes. For instance, peroxisomes perform roles in lipid catabolism/anabolism, reactive species detoxification, biotic (plant innate immunity) and abiotic stresses, and synthesis of vitamins and hormones. Peroxisomes undertake fatty acid beta-oxidation solely in plants, and jointly with mitochondria in mammals. Despite increased knowledge of peroxisome biogenesis and functions, control of these events by post-translational modifications (PTM) is poorly studied.
We first explored a role for the first known peroxisomal phosphatase in any organism (protein phosphatase 2A) in peroxisomal β-oxidation, and further identified many novel peroxisomal protein phosphatases in Arabidopsis. Importantly, our ongoing research led to expanding the knowledge on the peroxisomal phosphoproteome and supplied a knowledge framework of key players that control protein phosphorylation events in the plant peroxisome (i.e., the protein kinases and phosphatases), and cataloged a vastly expanded set of (phospho)substrates. Lately, we also pinpointed additional 12 functional peroxisomal domains that belong to soluble and receptor protein kinases in Arabidopsis.
Timeline showing the progress in the identification of peroxisomal protein phosphatases, kinases and phosphosubstrates.
In our research, we are employing our framework for building a peroxisomal phospho-regulation network through investigating the identified phosphatases and kinases functions and find their substrates by protein:protein interaction methods and multi-omics approaches. Such network will be complemented by our plan to establish a peroxisome phospho-proteomics work-flow. In the same context, the impact of protein phosphorylation on peroxisome biogenesis, fatty acid beta-oxidation and stresses will be investigated through studying the regulation of phosphosites under different conditions and employing phosphomimetic complementations. Overall, the developed knowledge will be instrumental in underlying the yet uncharacterized PTM by phosphorylation in peroxisomes.