Efficient calculation of the free energy for protein partitioning using restraining potentials

Area of Science:

• Biophysics
• Computational Biology
• Membrane Biophysics

Background:

• Lipid bilayers are crucial for cell membrane structure and function.
• Understanding transmembrane protein behavior in heterogeneous membranes is vital.
• Accurate calculation of partitioning free energies is computationally challenging.

Purpose of the Study:

• To develop an efficient simulation approach for phase-separated lipid bilayers.
• To enable precise calculation of equilibrium free energies for lipid-protein partitioning.
• To provide insights into the thermodynamic forces governing protein behavior in complex membranes.

Main Methods:

• Exploitation of restraint potentials and rectangular aspect ratios to enforce lipid phase separation.
• Simulation of smaller systems that approximate bulk lipid bilayer behavior.
• Calculation of potentials of mean force for transmembrane protein translation between lipid domains.

Main Results:

• Demonstrated utility of the approach in calculating protein translation free energies.
• Explored the impact of restraints on lipid tail ordering and packing.
• Provided insights into optimizing restraints for accurate free-energy surface computation.

Conclusions:

• The proposed method offers an efficient way to simulate phase-separated lipid bilayers.
• This approach facilitates accurate computation of partition coefficients for transmembrane proteins.
• The findings contribute to understanding the biophysical drivers of protein partitioning in heterogeneous membranes.