Regulation of plant PI4P 5-kinases by phosphorylation
Phosphatidylinositol-4,5-bisphosphate (PtdIns(4,5)P2) is a regulatory phospholipid specifically controlling localization and/or activity of target proteins with housekeeping functions or with roles in stress-adaptation. PtdIns(4,5)P2 is formed by PI4P 5-kinases, which are represented in Arabidopsis as a family of eleven isoenzymes. PI4P 5-kinases from various eukyryotic models are regulated by posttranslational modification, and it has been demonstrated that several Arabidopsis PI4P 5-kinases can be phosphorylated. So far, it has remained unclear under what circumstances phosphorylation occurs, which amino acid residues are phosphorylated, and what consequences of phosphorylation are with regard to localization or functionality of the enzymes. Our current work is aiming to test how reversible phosphorylation controls the function of PI4P 5-kinases in vitro and in vivo.