All photography provided by Amr Kataya
The role of protein phosphorylation in regulating peroxisome-oil body cross-talk during germination
During germination, fatty acids are hydrolyzed from triacylglycerol (TAG) stored in the lipid droplet/oil body by lipases. Fatty acid transport to peroxisomes is facilitated by the direct association of lipid droplets with peroxisomes where fatty acid β-oxidation occurs. Despite the increased knowledge of these processes, the control of these events by post-translational modifications (PTM) by phosphorylation is poorly studied. Lately, our research led to expanding the knowledge of the peroxisomal phosphoproteome and supplied a knowledge of the key players (i.e., the protein kinases and phosphatases), and cataloged a vastly expanded set of peroxisomal (phospho)substrates. We also proposed a model that implicate a phospho-PTM dependent feedback loops between peroxisomes and oil bodies. To validate this model and to further develop a functional phospho-network, we seek to investigate the underlying mechanisms of peroxisome interactions with the subcellular organelles during the energy-source depletion. Therefore, in this study, we blocked the oil body TAGs and we extracted and analyzed quantitatively, using isobaric tagging, the total proteome and the enriched phosophproteome against normal treated Arabidopsis seeds. In addition, we also compared the total transcriptome for treated and untreated samples which have shown a huge up- and down-regulation of genes expression. Overall, by analyzing these results we expect to have insights on cellular and subcellular responses to energy depletion.
What We've Achieved
We have cataloged over 100 polypeptides as peroxisomal phospho-proteins using available phospho-proteomic datasets, fully establishing protein phosphorylation as a regulatory mechanism in peroxisomes (Kataya et al., 2019).
exploring a role for PP2A in peroxisomal beta-oxidation process
Identification of several novel peroxisomal protein phosphatases
Studying the PP4 catalytic and putative regulatory subunits
Investigation of the role of methylation on PP2A function
Validations of multiple novel peroxisomal signals and proteins
Validation of novel peroxisomal proteins implicated in innate immunity
Exploring indications for two novel pathways for importing proteins into peroxisomes
Detection and sequencing of ToCV virus
Identification of two RNA silencing suppressors from two viruses