The surface organization of diacylglycerol pyrophosphate and its interaction with phosphatidic acid at the air-water interface

A. L. VILLASUSO, N. WILKE, B. MAGGIO, E. MACHADO

CHEMISTRY AND PHYSICS OF LIPIDS

ELSEVIER IRELAND LTD

Año: 2010 vol. 163 p. 771 - 777

0009-3084

Diacylglycerol pyrophosphate (DGPP), a phosphorylated form of phosphatidic acid (PA), gained attentionrecently due to its role as signaling lipid. However, little is known about its surface organization andpotential impact on membrane-mediated function. In this work we investigated the interfacial behaviorof Langmuir monolayers formed with pureDGPPand of its mixtures with PA.Wefound that changes of thesubphase pH affect the surface behavior of DGPP. At pH 8, DGPP forms liquid expanded monolayers with acompressibility modulus of about 60mNm−1 at collapse.Onacidic solutions, the compressibility modulusincreases to 90mNm−1 and the average molecular area is smaller. AtpH8, DGPP and its precursor PA formthermodynamically favored topographically homogeneous non-ideal mixtures. The interaction amongthese lipids leads to a non-ideal diminution of the mean molecular area and consequently, to an increaseof the compressibility modulus, with variations of the surface electrostatics. The favorable interactionof PA and DGPP, leading to changes of the film packing suggest that DGPP may act as a structural signaltransducer in membrane-mediated cellular processes.