Abstract
Diacylglycerol pyrophosphate (DGPP) is an anionic phospholipid formed in plants, yeast, and parasites under multiple stress stimuli. It is synthesized by the phosphorylation action of phosphatidic acid (PA) kinase on phosphatidic acid, a signaling lipid with multifunctional properties. PA functions in the membrane through the interaction of its negatively charged phosphomonoester headgroup with positively charged proteins and ions. DGPP, like PA, can interact electrostatically via the electrostatic-hydrogen bond switch mechanism but differs from PA in its overall charge and shape. The formation of DGPP from PA alters the physicochemical properties as well as the structural dynamics of the membrane. This potentially impacts the molecular and ionic binding of cationic proteins and ions with the DGPP enriched membrane. However, the results of these important interactions in the stress response and in DGPP’s overall intracellular function is unknown. Here, using 31P MAS NMR, we analyze the effect of the interaction of low DGPP concentrations in model membranes with the peptides KALP23 and WALP23, which are flanked by positively charged Lysine and neutral Tryptophan residues, respectively. Our results show a significant effect of KALP23 on the charge of DGPP as compared to WALP23. There was, however, no significant effect on the charge of the phosphomonoester of DGPP due to the interaction with positively charged lipids, dioleoyl trimethylammonium propane (DOTAP) and dioleoyl ethyl-phosphatidylcholine (EtPC). Divalent calcium and magnesium cations induce deprotonation of the DGPP headgroup but showed no noticeable differences on DGPP’s charge. Our results lead to a novel model for DGPP—protein interaction.
Highlights
Introduction iationsAnionic signaling lipids such as phosphatidic acid (PA) and the phosphoinositides (PIPs) play crucial roles in the life of a cell [1–3]
PA is present in small amounts in biomembranes but increases rapidly in plants after a stress stimulus [11,12]. This is followed by a decline in PA concentration and a subsequent increase in diacylglycerol pyrophosphate (DGPP) production as PA is converted to DGPP by phosphatidic acid kinase (PAK) [10]
We showed that the phosphomonoester of DGPP follows the electrostatic hydrogen bond switch model, as PE increases the charge
Summary
Anionic signaling lipids such as phosphatidic acid (PA) and the phosphoinositides (PIPs) play crucial roles in the life of a cell [1–3]. Their diverse functions are mediated directly by interaction with membrane proteins and/or indirectly by modulation of key membrane properties, such as membrane curvature [4–7]. PA is present in small (at most a few percent) amounts in biomembranes but increases rapidly in plants after a stress stimulus [11,12]. This is followed by a decline in PA concentration and a subsequent increase in DGPP production as PA is converted to DGPP by phosphatidic acid kinase (PAK) [10]. PAK phosphorylates the phosphomonoester of PA to a pyrophosphate and has been reported in plants such as Arabidopsis thaliana, Craterostigma
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