Gram-Negative Bacterial Outer Membrane Molecular Complexity (IMAGE) Lehigh University Caption The image illustrates a typical E. coli outer membrane and the molecular system used to represent the complexity in molecular dynamics simulations. Molecules represent the bilayer composed of (from the top, external leaflet) glycosylated amphipathic molecules known as lipopolysaccharide consisting of an O-antigen polysaccharide, a core oligosaccharide, and lipid A and (the bottom, periplasmic leaflet) consisting of various phospholipid molecules such as phosphatidylethanolamine (PE; green), phosphatidylglycerol (PG; orange), and cardiolipin (CL; magenta) in a ratio of PE : PG : CL = 15 : 4 : 1. The cyan atoms interspersed with the core oligosaccharides are Ca2+ ions, which immobilize the membrane by mediating the cross-linking electrostatic interaction network with phosphate and carboxyl groups attached to the lipid A and core sugars. Magenta and yellow spheres represent K+ and Cl- ions, respectively. Credit Courtesy of Wonpil Im, Lehigh University Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.