Membrane structure formation induced by two types of banana-shaped proteins

Abstract

The assembly of banana-shaped rodlike proteins on membranes, and the associated membrane shape transformations, are investigated by analytical theory and coarse-grained simulations. The membrane-mediated interactions between two banana-shaped inclusions are derived theoretically using a point-like formalism based on fixed anisotropic curvatures, both for zero surface tension and for finite surface tension. On a larger scale, the interactions between assemblies of such rodlike inclusions are determined analytically. Meshless membrane simulations are performed in the presence of a large number of inclusions of two types, corresponding to curved rods of opposite curvatures, both for flat membranes and vesicles. Rods of the same type aggregate into linear assemblies perpendicular to the rod axis, leading to membrane tubulation. However, rods of the other type, those of opposite curvature, are attracted to the lateral sides of these assemblies, and stabilize a straight bump structure that prevents tubulation. When the two types of rods have almost opposite curvatures, the bumps attract one another, forming a stripe structure. Positive surface tension is found to stabilize the stripe formation. The simulation results agree well with the theoretical predictions provided the point-like curvatures of the model are scaled-down to account for the effective flexibility of the simulated rods.

Membrane morphologies induced by mixtures of arc-shaped particles with opposite curvature

“…Attractive membrane-mediated side-to-side pair interactions of arc-shaped particles have been obtained from energy minimization 66 . Side-to-side alignment has also been observed in simulations with arc-shaped inclusions in membranes 28,44,45 . In molecular dynamics (MD) simulations with a coarse-grained molecular model of N-BAR domains proteins on DLPC lipid vesicles, in contrast, a tip-to-tip alignment of proteins has been observed 48,67 , which may be affected by the direct, coarse-grained protein-protein interactions of the model.…”

Acceleration and suppression of banana-shaped-protein-induced tubulation by addition of small membrane inclusions of isotropic spontaneous curvatures

“…The interactions between different curvature-generating proteins have been investigated only in a few studies. Two studies have reported the interactions of two types of protein rods including our previous study [46,52]. The coexistence of two types of rods induces phase separation [52] and straight and striped bump structures [46].…”

“…The protein assembly produces polygonal membrane tubes and polyhedral vesicles at a high protein density [58]. A positive surface tension destabilizes the rod assembly [59] and tubulation [54] whereas it stabilizes the striped structure formed by the two types of rods [46].…”

“…Recently, this anisotropic nature of curvature has received increasing theoretical attention [42][43][44][45][46][47]. To simplify the analytical calculations, the protein and membrane underneath it have often been modeled together as an undeformable object with a fixed curved shape such as a point-like object with an anisotropic curvature [44][45][46] and a bent elliptical surface [47].…”

“…Two studies have reported the interactions of two types of protein rods including our previous study [46,52]. The coexistence of two types of rods induces phase separation [52] and straight and striped bump structures [46]. The rods assembly to surround a large isotropic inclusion (clathrin coat) was studied using a point-like approximation [60].…”