The density-threshold affinity: Calculating lipid binding affinities from unbiased coarse-grained molecular dynamics...

Area of Science:

• Biochemistry
• Computational Biology
• Structural Biology

Background:

• Membrane proteins
• are influenced by their surrounding lipid environment.
• Specific lipid-protein interactions are increasingly recognized but difficult to quantify.
• Experimental determination of binding affinities for membrane protein-lipid systems is challenging.

Purpose of the Study:

• To present a novel computational protocol for determining lipid-protein binding affinities.
• To enable quantitative analysis of lipid interactions with membrane proteins.
• To provide a method for comparing affinities across different sites, lipids, or force fields.

Main Methods:

• Utilizing coarse-grained molecular dynamics (CG-MD) simulations.
• Applying the "density threshold affinity" method to quantify lipid binding.
• Analyzing localized lipid densities around membrane proteins.

Main Results:

• The density threshold affinity method provides a robust way to extract binding affinities.
• It overcomes limitations in distinguishing bound vs. bulk lipids.
• The method offers bead-level resolution, suitable for shared binding sites and avoiding reference state ambiguities.

Conclusions:

• Coarse-grained molecular dynamics simulations coupled with the density threshold affinity method offer a powerful approach to study membrane protein-lipid interactions.
• This protocol facilitates comparative analysis of binding affinities in complex membrane environments.
• The method enhances our understanding of how lipids modulate membrane protein structure and function.