Mechanical Properties of Pseudomonas Aeruginosa Outer Membrane

Pseudomonas aeruginosa is a major pathogen for many infectious diseases such as Pneumonia. The outer membrane of these gram-negative bacteria acts as an external shield against environmental threats, which also makes them resistant to antibiotics. This work aims to develop an accurate in silico model of P. aeruginosa outer membrane using all-atom molecular dynamics and characterize its mechanical properties. The outer leaflet of this asymmetric membrane contains PA14 Lipid A, and the inner leaflet is composed of a mixture of POPE and POPG phospholipids. A major challenge in modeling asymmetric membranes is determining the numbers of distinct lipids in each leaflet, which would affect the mechanical properties of bilayers. The most widely used method matches the equilibrium areas of two leaflets, which are obtained from corresponding symmetric bilayers. However, this method may render non-zero tension within each leaflet, and the bilayer would be subject to differential stress. Recently, a new method has been proposed to construct asymmetric membranes with zero leaflet tension. We compare the mechanical properties of PA14 outer membranes made with two methods to understand the effects of membrane building protocols to provide important guidelines for future simulation studies.