Membrane mediated aggregation of curvature inducing nematogens and membrane tubulation

TL;DR

This study uses a numerical model to show how curvature-inducing membrane proteins can spontaneously oligomerize and shape membranes into tubes or sheets, revealing key factors for membrane morphology and elastic properties.

Contribution

We introduce a model demonstrating spontaneous oligomerization of curvature-active proteins and analyze their role in membrane tubulation and sheet formation.

Findings

Membrane inclusions can oligomerize at low concentrations due to membrane-mediated interactions.

Tubular and sheet conformations are common equilibrium shapes for certain inclusions.

Elastic properties of membrane tubes, like stiffness and persistence length, are quantified.

Abstract

The shapes of cell membranes are largely regulated by membrane associated, curvature active, proteins. We use a numerical model of the membrane with elongated membrane inclusions, recently developed by us, which posses spontaneous directional curvatures that could be different along and perpendicular to its long axis. We show that, due to membrane mediated interactions these curvature inducing membrane nematogens can oligomerize spontaneously, even at low concentrations, and change the local shape of the membrane. We demonstrate that for a large group of such inclusions, where the two spontaneous curvatures have equal sign, the tubular conformation and sometime the sheet conformation of the membrane are the common equilibrium shapes. We elucidate the factors necessary for the formation of these {\it protein lattices}. Furthermore, the elastic properties of the tubes, like their compressional stiffness and persistence length are calculated. Finally, we discuss the possible role of nematic disclination in capping and branching of the tubular membranes.