Lipopolysaccharide membrane building and simulation

Abstract

While membrane simulations are widely employed to study the structure and dynamics of various lipid bilayers and membrane proteins in the bilayers, simulations of lipopolysaccharides (LPS) in membrane environments have been limited due to their structural complexity, diffi culties in building LPS-membrane systems, and lack of the appropriate molecular force fi elds. In this work, as a fi rst step to extend CHARMMGUI Membrane Builder to incorporate LPS molecules and to explore their structures and dynamics in membrane environments using molecular dynamics simulations, we describe step-by-step procedures to build LPS bilayer systems using CHARMM and the recently developed CHARMM carbohydrate and lipid force fi elds. Such procedures are illustrated by building various bilayers of Escherichia coli R1.O6 LPS and the presentation of preliminary simulation results in terms of per-LPS area and density distributions of various components along the membrane normal.