Rigidity of transmembrane proteins determines their cluster shape.

Area of Science:

• Biophysics
• Computational Biology
• Membrane Protein Dynamics

Background:

• Protein aggregation in cell membranes is crucial for biological functions.
• Transmembrane domains (TMDs) of proteins, like alpha-helices and beta-sheets, exhibit varying structural rigidities.
• Previous models proposed hydrophobic mismatch as the primary driver of protein aggregation.

Purpose of the Study:

• Investigate the mechanisms of protein clustering in lipid membranes.
• Determine how the structural rigidity of TMDs influences protein aggregation.
• Explore the role of lipid distribution and dynamics in aggregate formation.

Main Methods:

• Utilized molecular dynamics simulations with a coarse-grained model.
• Simulated protein-embedded lipid membranes under thermal equilibrium.
• Analyzed protein concentrations, structural rigidity, and lipid density.

Main Results:

• Observed stable protein aggregates independent of hydrophobic mismatch.
• Semiflexible proteins formed two-dimensional clusters.
• Rigid proteins formed one-dimensional string-like structures.
• Lipid density and dynamics around aggregates differed based on protein rigidity.

Conclusions:

• Protein TMD rigidity is a key factor in determining aggregation dimensionality (1D vs. 2D).
• Lipid distribution and faster lipid movement around semiflexible proteins contribute to 2D cluster formation.
• The proposed aggregation mechanism is experimentally testable with current technologies.