The electrostatic basis of diacylglycerol pyrophosphate-protein interaction.

Abstract

Phosphatidic acid (PA) is an anionic lipid with a simple phosphate headgroup that recruits multiple proteins for its diverse functional roles in all eukaryotes. Its charge, shape and Electrostatic Hydrogen bond switch mechanism forms the basis of its interaction with membrane components. PA is phosphorylated to Diacylglycerol pyrophosphate (DGPP) in many signaling events in plants, yeast, and some parasites. DGPP has a pyrophosphate headgroup with similar ionization properties to PA, except that its charge at any given physiological pH is higher. The synthesis of DGPP in the signaling cascade potentially alters membrane dynamics and properties due to the differences in the physicochemical parameters between the two lipids. Thus, DGPP is expected to differ from PA in its interaction with membrane components. However, the overall effect on the biophysical properties of DGPP's interactions with proteins and ions are unexplored. In this study, we investigated the effect of the interactions of DGPP with model peptides KALP23 and WALP23 by 31P MAS NMR spectroscopy. In addition, we also analyzed the effect of DGPP with two positively charged lipids, dioleoyl trimethylammonium propane (DOTAP) and ethyl -phosphatidylcholine (EtPC) as well as with Magnesium and Calcium cations. Results from this study highlight a unique model for DGPP-protein interactions and has important implications in how DGPP interacts with membrane components in the signaling pathway.