PMID: 18658220

Authors:

Low C, Weininger U, Lee H, Schweimer K, Neundorf I, Beck-Sickinger AG, Pastor RW, Balbach J

Title:

Structure and dynamics of Helix-0 of the N-BAR domain in Lipid Micelles and Bilayers.

Journal:

Biophys J. 2008 Jul 25.

Abstract:

BAR domains (Bin/Amphiphysin/Rvs-homology) generate and sense membrane curvature by binding the negatively charged membrane to their positively charged concave surfaces. N-BAR domains contain an N-terminal extension (helix-0) predicted to form an amphipathic helix upon membrane binding. We determined the NMR structure and nano-to-picosecond dynamics of helix-0 of the human Bin1/Amphiphysin II BAR domain in SDS and DPC micelles. Molecular dynamic simulations of this 34 amino acid peptide revealed electrostatic and hydrophobic interactions with the detergent molecules, which induce helical structure formation from residues 8-10 towards the C-terminus. The orientation in the micelles was experimentally confirmed by backbone amide proton exchange. Both simulation and experiment indicate that the N-terminal region is disordered, and the peptide curves to adopt the micelle shape. Deletion of helix-0 reduces tubulation of liposomes by the BAR domain, whereas the helix-0 peptide itself was fusogenic. These findings support models for membrane curving by BAR domains, where helix-0 increases the binding affinity to the membrane and enhances curvature generation.