Symmetry and size of membrane protein polyhedral nanoparticles

TL;DR

This paper presents a model explaining how membrane protein polyhedral nanoparticles self-assemble, predicting their symmetry and size based on lipid-protein interactions, and guiding experimental modifications.

Contribution

The authors develop a predictive model of MPPN self-assembly that accurately matches experimental observations and suggests ways to control nanoparticle properties.

Findings

Model correctly predicts observed symmetry and size of MPPNs.

Key lipid and protein properties influence MPPN morphology.

Model parameters are directly derived from experimental data.

Abstract

In recent experiments [T. Basta et al., Proc. Natl. Acad. Sci. U.S.A. 111, 670 (2014)] lipids and membrane proteins were observed to self-assemble into membrane protein polyhedral nanoparticles (MPPNs) with a well-defined polyhedral protein arrangement and characteristic size. We develop a model of MPPN self-assembly in which the preferred symmetry and size of MPPNs emerge from the interplay of protein-induced lipid bilayer deformations, topological defects in protein packing, and thermal effects. With all model parameters determined directly from experiments, our model correctly predicts the observed symmetry and size of MPPNs. Our model suggests how key lipid and protein properties can be modified to produce a range of MPPN symmetries and sizes in experiments.