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.
Highlights
Simulations[31,32,33,34]
Once the spontaneous curvatures are altered at t = 0, the rods begin to assemble perpendicularly to the rod axis
In addition to the spontaneous curvature along the protein rods Crod, the perpendicular spontaneous curvature Cside significantly influences the protrusion of membrane tubules
Summary
Simulations[31,32,33,34]. For example, Simunovic et al have simulated a linear aggregation of N-BAR domains parallel to the domain axis[33,34]. Tubular formation has been simulated using a dynamically triangulated membrane model[35,36] and, meshless membrane models[37,38]. Despite these numerous advancements, the present understanding of the physics of membrane shape deformation due to anisotropic curvature is still far from complete. Our previous studies showed that parallel and perpendicular assemblies occur separately through membrane-mediated attractive interactions at low protein density[38], and that polyhedral shapes are formed at high protein density[42] for vesicles and membrane tubes
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