Finding the “Right” Balance for Asymmetric Lipid Bilayers

Lawrence Livermore National Laboratory

Cellular membranes are the barrier protecting the inner cell components from the outside environment. They are composed of proteins and lipids that form lipid bilayers of varying complexity. One approach to understanding the behavior of lipid bilayers uses molecular dynamics simulations of realistic size and complexity. Realistic bilayers are asymmetric, having different concentrations of various lipids in the two leaflets. This asymmetry affects the stability, sometimes approximated as “flatness,” of the simulated bilayer. Many properties have been used to judge whether simulated bilayers are stable and realistic, but a quantitative definition incorporating multiple properties has not been proposed.

For the Lawrence Livermore National Lab Clinic project, we will create and analyze lipid membrane simulations to provide a deeper understanding of how asymmetries of varying complexity within the lipid bilayer leaflets affect membrane properties. These properties may include area per lipid, area compressibility, order parameters, and bilayer thickness, among others. From these properties, we will attempt to create a metric of stability for asymmetric bilayers. We will also develop a streamlined process for simulating and analyzing stable bilayer membranes. The final product will be used to inform and benefit future research in membrane biophysics.

Advisor(s): Peter N. Saeta.

Team: Madison Rae Blumer ’19, Sophia (Sophie) Laurice Harris ’19, Mengzhe Li ’20, Luis Angel Martinez ’19, and Michael Untereiner ’19.