Membrane tubule formation by banana-shaped proteins with or without transient network structure

TL;DR

This study uses large-scale simulations to explore how banana-shaped BAR proteins induce membrane tubulation, revealing that side curvature and network formation significantly influence tubulation dynamics and stability.

Contribution

It demonstrates the impact of perpendicular side curvature and network formation on membrane tubulation, providing new insights into protein-induced membrane shaping mechanisms.

Findings

Side curvature drastically affects tubulation at high protein density.

Percolated network formation can suppress tubule protrusion.

Surface tension and membrane curvature stabilize network structures.

Abstract

In living cells, membrane morphology is regulated by various proteins. Many membrane reshaping proteins contain a Bin/Amphiphysin/Rvs (BAR) domain, which consists of a banana-shaped rod. The BAR domain bends the biomembrane along the rod axis and the features of this anisotropic bending have recently been studied. Here, we report on the role of the BAR protein rods in inducing membrane tubulation, using large-scale coarse-grained simulations. We reveal that a small spontaneous side curvature perpendicular to the rod can drastically alter the tubulation dynamics at high protein density, whereas no significant difference is obtained at low density. A percolated network is intermediately formed depending on the side curvature. This network suppresses tubule protrusion, leading to the slow formation of fewer tubules. Thus, the side curvature, which is generated by protein--protein and membrane--protein interactions, plays a significant role in tubulation dynamics. We also find that positive surface tensions and the vesicle membrane curvature can stabilize this network structure by suppressing the tubulation.