The role of phosphorylation in regulating AROGENATE DEHYDRATASE2 subcellular localization in Arabidopsis thaliana

Phenylalanine is an essential amino acid and a building block for many specialized metabolites. AROGENATE DEHYDRATASES (ADTs) are responsible for catalyzing the final step of phenylalanine biosynthesis by decarboxylating and dehydrating arogenate. While all six Arabidopsis ADTs localize to the chloroplast stroma, ADT2 has a unique moonlighting role in chloroplast division forming rings at the chloroplast division plane. Phosphorylation is a regulator of subcellular localization. I hypothesized that phosphorylation regulates ADT2 ring formation during chloroplast division. Here, I demonstrate that ADT2 is a phosphoprotein in vivo as it interacts with a 14-3-3 protein. Further, I determined that an Arabidopsis ADT2-Ypet fusion line can be used to isolate specific ADT isoforms for profiling post-translational modifications using mass spectrometry. The impact of phosphorylation at single sites was analyzed with phosphomimetics and I found that changes within the ACT domain altered subcellular localization of ADT2.