Coarse grained protein-lipid model with application to lipoprotein particles

Area of Science:

• Biophysics
• Computational Biology
• Structural Biology

Background:

• Coarse-grained models simplify molecular dynamics simulations by representing groups of atoms as single beads.
• Existing models primarily focused on lipids, limiting their application to complex protein-lipid systems.

Purpose of the Study:

• To extend a coarse-grained lipid model to accurately represent proteins for molecular dynamics simulations.
• To validate the extended model using discoidal high-density lipoprotein (HDL) particles.

Main Methods:

• Developed a coarse-grained model where each amino acid is represented by two beads: one for the backbone and one for the side-chain.
• Applied the model to simulate HDL particles, including water, lipids, and helical proteins.
• Performed microsecond simulations to observe lipoprotein assembly dynamics.

Main Results:

• The coarse-graining approach reduced system size approximately 10-fold, enabling longer integration time steps (25-50 fs).
• The model successfully maintained the shape of preassembled HDL particles and reproduced their structural features.
• Simulations revealed the formation of a stable protein-lipid complex with two proteins binding to opposite sides of the discoidal lipid bilayer.

Conclusions:

• The extended coarse-grained model provides a reliable and efficient method for simulating protein-lipid complexes.
• This approach facilitates the study of complex biological systems like high-density lipoproteins at the microsecond timescale.
• The findings contribute to a better understanding of lipoprotein structure and assembly mechanisms.