A New Coarse-Grained Force Field for Membrane-Peptide Simulations.

Area of Science:

• Biophysics
• Computational Chemistry
• Molecular Dynamics

Background:

• Coarse-grained (CG) models simplify complex molecular systems for large-scale simulations.
• The MARTINI force field is widely used for biomolecular simulations, but its water model has limitations.
• Accurate electrostatic interactions at the membrane-water interface are crucial for understanding peptide-membrane interactions.

Purpose of the Study:

• To develop and validate a new coarse-grained force field (BMW-MARTINI) for lipid-peptide systems.
• To improve the representation of water's electrostatic properties in CG simulations.
• To investigate the interactions of charged peptides with lipid membranes and phenomena like electroporation.

Main Methods:

• Development of the BMW-MARTINI force field, integrating the big multipole water (BMW) model with the MARTINI framework.
• Coarse-grained molecular dynamics simulations of lipid bilayers and peptides.
• Comparison of simulation results with experimental data and other force fields (e.g., MARTINI).

Main Results:

• The BMW-MARTINI force field accurately reproduces fundamental membrane properties.
• Improved energetics for charged amino acid-lipid membrane interactions, particularly at the interface.
• Correct prediction of cationic peptide (e.g., Arg8) stable attachment to membranes.
• Accurate prediction of electroporation due to charge imbalance, forming toroidal pores.

Conclusions:

• The BMW-MARTINI force field offers enhanced accuracy for CG simulations of lipid-peptide interactions.
• Accurate electrostatic modeling of water is essential for CG simulations of membrane-related phenomena.
• This model is particularly valuable for studying highly charged peptides interacting with biomembranes.