Lipid-protein interaction induced domains: kinetics and conformational changes in multicomponent vesicles

TL;DR

This study uses Monte Carlo simulations to explore how lipid-protein interactions influence membrane domain formation, clustering kinetics, and conformational changes, revealing mechanisms for signal amplification and phase separation in membranes.

Contribution

It demonstrates that lipid-protein affinity accelerates protein aggregation and influences domain morphology, highlighting the effects of protein anisotropy on membrane organization.

Findings

Strong lipid-protein interactions promote large protein clusters.

Protein domains can form buds similar to lipid phase separation.

Anisotropic proteins suppress domain budding and alter clustering kinetics.

Abstract

The spatio-temporal organization of proteins and the associated morphological changes in membranes are of importance in cell signaling. Several mechanisms that promote the aggregation of proteins at low cell surface concentrations have been investigated in the past. We show, using Monte Carlo simulations, that the affinity of proteins for specific lipids can hasten its aggregation kinetics. The lipid membrane is modeled as a dynamically triangulated surface with the proteins defined as in-plane fields at the vertices. We show that, even at low protein concentrations, strong lipid-protein interactions can result in large protein clusters indicating a route to lipid mediated signal amplification. At high protein concentrations the domains form buds similar to that seen in lipid-lipid interaction induced phase separation. Protein interaction induced domain budding is suppressed when proteins act as anisotropic inclusions and exhibit nematic orientational order. The kinetics of protein clustering and resulting conformational changes are shown to be significantly different for the isotropic and anisotropic curvature inducing proteins.