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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.

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