Exploring the Elastic Properties of Bilayer Membranes using Molecular Dynamics Simulations

Local membrane deformation has been implicated in regulating a variety of cellular processes, such as ion channel function and vesicle fusion. In this work, we show how molecular dynamic simulations can be used alone or in conjunction with the continuum elastic model to estimate membrane elastic properties. Detail analysis allowed us to divide the energetic cost associated with the partial or complete extraction of a DOPE lipid from a POPC bilayer into two main contributions: a) the elastic deformation of the membrane, involving displacement of neighboring lipids, and b) the solvation energy associated to the exposure of the acyl chains to the water phase. Membrane elastic deformation was observed in molecular detail, and structural information from the simulations was used with the continuum elastic model to estimate an effective membrane spring constant independently from the energy parameters of the simulations. The membrane spring constant was also calculated from the potential of mean force and a good agreement was found between the two methods. Additionally, we confirmed that the calculated solvation energy matches that estimated by critical micelle formation constants. This methodology provides a computational tool for determining membrane elastic properties as a function of composition and in the presence of membrane modifiers.