Amphipathic motifs in BAR domains are essential for membrane curvature sensing

TY - JOUR

T1 - Amphipathic motifs in BAR domains are essential for membrane curvature sensing

AU - Bhatia, Vikram K

AU - Madsen, Kenneth L

AU - Bolinger, Pierre-Yves

AU - Kunding, Andreas

AU - Hedegård, Per

AU - Gether, Ulrik

AU - Stamou, Dimitrios

N1 - Keywords: Acyltransferases; Animals; Brain Chemistry; Cattle; Gene Expression; Lipid Bilayers; Liposomes; Membrane Proteins; Microscopy, Fluorescence; Models, Biological; Nerve Tissue Proteins; Protein Binding; Protein Structure, Secondary; Protein Structure, Tertiary; Rats

PY - 2009

Y1 - 2009

N2 - BAR (Bin/Amphiphysin/Rvs) domains and amphipathic alpha-helices (AHs) are believed to be sensors of membrane curvature thus facilitating the assembly of protein complexes on curved membranes. Here, we used quantitative fluorescence microscopy to compare the binding of both motifs on single nanosized liposomes of different diameters and therefore membrane curvature. Characterization of members of the three BAR domain families showed surprisingly that the crescent-shaped BAR dimer with its positively charged concave face is not able to sense membrane curvature. Mutagenesis on BAR domains showed that membrane curvature sensing critically depends on the N-terminal AH and furthermore that BAR domains sense membrane curvature through hydrophobic insertion in lipid packing defects and not through electrostatics. Consequently, amphipathic motifs, such as AHs, that are often associated with BAR domains emerge as an important means for a protein to sense membrane curvature. Measurements on single liposomes allowed us to document heterogeneous binding behaviour within the ensemble and quantify the influence of liposome polydispersity on bulk membrane curvature sensing experiments. The latter results suggest that bulk liposome-binding experiments should be interpreted with great caution.

AB - BAR (Bin/Amphiphysin/Rvs) domains and amphipathic alpha-helices (AHs) are believed to be sensors of membrane curvature thus facilitating the assembly of protein complexes on curved membranes. Here, we used quantitative fluorescence microscopy to compare the binding of both motifs on single nanosized liposomes of different diameters and therefore membrane curvature. Characterization of members of the three BAR domain families showed surprisingly that the crescent-shaped BAR dimer with its positively charged concave face is not able to sense membrane curvature. Mutagenesis on BAR domains showed that membrane curvature sensing critically depends on the N-terminal AH and furthermore that BAR domains sense membrane curvature through hydrophobic insertion in lipid packing defects and not through electrostatics. Consequently, amphipathic motifs, such as AHs, that are often associated with BAR domains emerge as an important means for a protein to sense membrane curvature. Measurements on single liposomes allowed us to document heterogeneous binding behaviour within the ensemble and quantify the influence of liposome polydispersity on bulk membrane curvature sensing experiments. The latter results suggest that bulk liposome-binding experiments should be interpreted with great caution.

U2 - 10.1038/emboj.2009.261

DO - 10.1038/emboj.2009.261

M3 - Journal article

C2 - 19816406

SN - 0261-4189

VL - 28

SP - 3303

EP - 3314

JO - EMBO Journal

JF - EMBO Journal

IS - 21

ER -