What makes the simple and crucial lipids lysophosphatidic acid and phoshatidic acid so special?

Abstract

Fatty molecules, so-called lipids, form the basis of the biological membrane that surrounds and protects our cells. Moreover, our cells contain diverse intracellular compartments, each housing a distinct function, and these compartments are also surrounded by a lipid-based biomembrane. The intracellular compartments and the cells limiting membrane communicate with each other via the exchange of membrane enclosed transport carriers (TCs). The process of TC formation from a donor membrane and TC fusion with an acceptor membrane is regulated by both proteins and lipids. Unlike many previous reports, this dissertation concentrates on the role of the lipid component in these processes with a special focus on some of the simplest phospholipids present in a cell, namely phosphatidic acid (PA) and lysophosphatidic acid (LPA). PA in particular has been implicated in the regulation of membrane dynamics, fusion and fission, but the underlying molecular mechanism has not been resolved. PA's role may be to deform the membrane by virtue of its molecular shape or PA may bind or activate (through its negative charge) proteins that do the actual work. In order to understand the role of PA and LPA in a cell insight into their physico-chemical properties is required. This dissertation describes both the packing and charge properties of these lipids and shows what makes these simple lipids so special!