Signaling via reversible phosphorylation in organelles

During germination, and biotic and abiotic stresses

The eukaryotic organelle known as the peroxisome, once overlooked and undervalued, has now ascended to a pivotal role in numerous crucial cellular mechanisms. Peroxisomes play a vital role in lipid catabolism and anabolism, detoxifying reactive species, responding to both biotic and abiotic stresses, as well as engaging in the synthesis of essential vitamins and hormones. In plants, peroxisomes are exclusively dedicated to fatty acid beta-oxidation, while in mammals, this responsibility is shared with mitochondria. Despite significant progress in unraveling peroxisome biogenesis and operations, the intricate regulation of these functions via post-translational modifications (PTM) continues to be a realm ripe for further investigation.

We initially delved into investigating the role of the earliest identified peroxisomal phosphatase in any living being (protein phosphatase 2A) in peroxisomal β-oxidation. Subsequently, we unveiled numerous new peroxisomal protein phosphatases within Arabidopsis. Our continuous exploration has not only broadened the understanding of the peroxisomal phosphoproteome but has also established a comprehensive framework of essential regulators overseeing protein phosphorylation events within the plant peroxisome. This framework encompasses the protein kinases and phosphatases, along with documenting an expanded array of (phospho)substrates. Recently, we further identified an additional 12 operational peroxisomal domains attributed to soluble and receptor protein kinases in Arabidopsis.

In our research, we are focusing on utilizing our framework aimed at constructing a peroxisomal phospho-regulation network. This involves delving into the functions of the identified phosphatases and kinases and uncovering their respective substrates through various methodologies including protein:protein interaction techniques and multi-omics approaches. Our efforts extend to creating a peroxisome phospho-proteomics work-flow to enhance this network. Moreover, we are exploring how protein phosphorylation impacts peroxisome biogenesis, fatty acid beta-oxidation, and responses to stress by examining the regulation of phosphosites across different conditions and utilizing phosphomimetic complementations. The insights gained from these endeavors will play a pivotal role in elucidating the as yet unexplored post-translational modification through phosphorylation in peroxisomes.