BAR Domains as Sensors of Membrane Curvature: The Amphiphysin BAR Structure

TLDR

The BAR domain is a highly conserved feature in amphiphysins across species and also present in endophilins and nadrins. Amphiphysin, via its N‑terminal amphipathic helix and BAR domain, drives membrane curvature both in vitro and in vivo. The Drosophila amphiphysin BAR domain is a crescent‑shaped dimer that preferentially binds highly curved, negatively charged membranes, and its structure—similar to that of arfaptin2—supports the view that the universal minimal BAR domain functions as a dimerization, membrane‑binding, curvature‑sensing module found in many protein families.

Abstract

The BAR (Bin/amphiphysin/Rvs) domain is the most conserved feature in amphiphysins from yeast to human and is also found in endophilins and nadrins. We solved the structure of the Drosophila amphiphysin BAR domain. It is a crescent-shaped dimer that binds preferentially to highly curved negatively charged membranes. With its N-terminal amphipathic helix and BAR domain (N-BAR), amphiphysin can drive membrane curvature in vitro and in vivo. The structure is similar to that of arfaptin2, which we find also binds and tubulates membranes. From this, we predict that BAR domains are in many protein families, including sorting nexins, centaurins, and oligophrenins. The universal and minimal BAR domain is a dimerization, membrane-binding, and curvature-sensing module.