Connecting molecular structure with cellular function is fundamental to understanding the mechanism of action of water-soluble enzymes acting on cell membranes (PNAS 2015, 112, E516-E525). Cytosolic (cPLA2), calcium-independent (iPLA2) and lipoprotein-associated (Lp-PLA2) provide an ideal system for studying protein-lipid molecular recognition and membrane functioning. cPLA2 is the main arachidonic acid provider for the eicosanoid pathway, iPLA2 is involved in membrane phospholipid remodeling and Lp-PLA2 was found to associate with LDL and HDL in human plasma to hydrolyze phospholipids containing short-chain and oxidized fatty acids. A lipidomics mass spectrometric assay allowed us to define unique specificity of PLA2s towards a wide variety of phospholipids that was not feasible with existing assays. Computational techniques such as molecular dynamics simulations and docking guided by hydrogen/deuterium (H/D) exchange experimental data showed that membrane phospholipids bind to allosteric sites located on the interfacial surface of PLA2s, shifting their conformation from the “closed” to the “open” state. This process enables PLA2s to extract and bind a phospholipid molecule in the active site where the hydrolysis occurs. This is a novel study addressing recognition between water-soluble enzymes and membranes as well as substrate specificity, binding and interactions using computational techniques guided by experimental data. PLA2s are implicated in chronic inflammatory diseases and understanding their association with membranes as well as their interactions with substrates will allow us to identify potent and selective inhibitors that can be further developed as anti-inflammatory agents.

Connecting molecular structure with cellular function: Membranes allosterically regulate phospholipases A2

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.