Characterization of α-synuclein N-terminal domain as a novel cellular phosphatidic acid sensor

Tracking the localization and dynamics of the intracellular bioactive lipid phosphatidic acid (PA) is important for understanding diverse biological phenomena. Although several PA sensors have been developed, better ones are still needed for comprehensive PA detection in cells. We recently found that alpha-synuclein (alpha-Syn) selectively and strongly bound to PA in vitro. Here, we revealed that the N-terminal region of alpha-Syn (alpha-Syn-N) specifically bound to PA, with a dissociation constant of 6.6 mu m. alpha-Syn-N colocalized with PA-producing enzymes, diacylglycerol kinase (DGK) beta at the plasma membrane (PM), myristoylated DGK zeta at the Golgi apparatus, phorbol ester-stimulated DGK gamma at the PM, and phospholipase D2 at the PM and Golgi but not with the phosphatidylinositol-4,5-bisphosphate-producing enzyme in COS-7 cells. However, alpha-Syn-N failed to colocalize with them in the presence of their inhibitors and/or their inactive mutants. These results indicate that alpha-Syn-N specifically binds to cellular PA and can be applied as an excellent PA sensor.