Binding of anisotropic curvature-inducing proteins onto membrane tubes

Abstract

Bin/Amphiphysin/Rvs superfamily proteins and other curvature-inducing proteins have anisotropic shapes and anisotropically bend biomembranes. Here, we report how the anisotropic proteins bind the membrane tube and are orientationally ordered using mean-field theory including an orientation-dependent excluded volume. The proteins exhibit a second-order or first-order nematic transition with increasing protein density depending on the radius of the membrane tube. The tube curvatures for the maximum protein binding and orientational order are different and varied by the protein density and rigidity. As the external force along the tube axis increases, a first-order transition from a large tube radius with low protein density to a small radius with high density occurs once, and subsequently, the protein orientation tilts to the tube-axis direction. When an isotropic bending energy is used for the proteins with an elliptic shape, the force-dependence curves become symmetric and the first-order transition occurs twice. This theory quantitatively reproduces the results of meshless membrane simulation for short proteins, whereas deviations are seen for long proteins owing to the formation of protein clusters.

This work was supported by JSPS KAKENHI Grant Number JP21K03481, the European Research Council (CoG-81434), the European Commission (Project No. H2020-FETPROACT-01-2016-731957), the Spanish Ministry for Science and Innovation/FEDER (PID2019-110949GBI00, BES-2016-078220 to C.T.), and the Generalitat de Catalunya (ICREA Academia award). This research was also supported in part by the National Science Foundation under Grant No. NSF PHY-1748958, through KITP program: The Physics of Elastic Films: from Biological Membranes to Extreme Mechanics (FILMS21).

Peer Reviewed

Postprint (author's final draft)