Folding Peptides into Lipid Bilayer Membranes

Area of Science:

• Biophysics
• Computational Biology
• Membrane Protein Studies

Background:

• Understanding peptide-lipid interactions is crucial for membrane biophysics.
• Previous simulations with implicit models suggested unfolded insertion is unlikely.

Purpose of the Study:

• To investigate the adsorption, insertion, and folding of a synthetic WALP peptide in a lipid bilayer.
• To explore peptide behavior at physiological timescales using atomic detail molecular dynamics.

Main Methods:

• Atomic detail molecular dynamics simulations.
• Explicit DPPC/DMPC lipid bilayer model.
• Elevated temperatures (80°C/44°C) for enhanced sampling.
• Simulations conducted at physiological timescales (>μs).

Main Results:

• Peptides spontaneously adsorb and insert into the hydrophobic core before folding.
• Dominant configurations observed were inserted beta-hairpins.
• A transient transmembrane helix formed in DPPC, but was unstable.
• Results contradict simulations using implicit membrane models.

Conclusions:

• Explicit membrane simulations reveal unexpected unfolded peptide insertion.
• Current simulation methods and force fields require validation against experimental data.
• Atomic detail simulations offer insights into complex biophysical phenomena at relevant timescales.