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Löw, Christian ; Weininger, Ulrich ; Lee, Hwankyu ; Schweimer, Kristian ; Neundorf, Ines ; Beck-Sickinger, Annette G. ; Pastor, Richard W. ; Balbach, Jochen:
Structure and dynamics of Helix-0 of the N-BAR domain in Lipid Micelles and Bilayers.
In: Biophysical Journal.
Bd. 95
(2008)
Heft 9
.
- S. 4315-4323.
ISSN 1542-0086
DOI: https://doi.org/10.1529/biophysj.108.134155
Abstract
Bin/Amphiphysin/Rvs-homology (BAR) domains 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 sodium dodecyl sulfate and dodecylphosphocholine micelles. Molecular dynamics simulations of this 34-amino acid peptide revealed electrostatic and hydrophobic interactions with the detergent molecules that induce helical structure formation from residues 8-10 toward the C-terminus. The orientation in the micelles was experimentally confirmed by backbone amide proton exchange. The simulation and the experiment indicated that the N-terminal region is disordered, and the peptide curves to adopted the micelle shape. Deletion of helix-0 reduced 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 in which helix-0 increases the binding affinity to the membrane and enhances curvature generation.