Sensing membrane stresses by protein insertions.

Area of Science:

• Biophysics
• Cell Biology
• Structural Biology

Background:

• Peripheral membrane proteins utilize shallowly inserting domains for membrane shaping and remodeling.
• Current models propose these domains sense membrane curvature via lipid packing defects.

Purpose of the Study:

• To propose and computationally validate an alternative model where shallow protein insertions sense intra-membrane stresses.
• To differentiate stress sensing from curvature sensing mechanisms in protein-membrane interactions.

Main Methods:

• Computational modeling of protein insertions into lipid bilayers.
• Simulations exploring various membrane stress generation pathways, including those with and without curvature changes.
• Quantitative analysis of experimental data for ALPS1 and ALPS2 motifs of ArfGAP1.

Main Results:

• Shallow protein insertion binding is dictated by the resultant membrane stress, irrespective of the stress origin.
• Binding coefficients show variable correlation with membrane curvature, dependent on the causative factors.
• Computational model successfully explains experimental binding data of ArfGAP1 ALPS motifs.

Conclusions:

• Shallow protein insertions act as universal sensors of intra-membrane stress rather than curvature.
• This stress-sensing mechanism provides a unified explanation for protein interactions in membrane remodeling.
• The findings offer new insights into the regulation of membrane-associated cellular processes.