TY - JOUR

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

A1 - Bhatia,Vikram K.

A1 - Madsen,Kenneth L.

A1 - Bolinger,Pierre-Yves

A1 - Kunding,Andreas Hjarne

A1 - Hedegård,Per

A1 - Gether,Ulrik

A1 - Stamou,Dimitrios

AU - Bhatia,Vikram K.

AU - Madsen,Kenneth L.

AU - Bolinger,Pierre-Yves

AU - Kunding,Andreas Hjarne

AU - Hedegård,Per

AU - Gether,Ulrik

AU - Stamou,Dimitrios

PB - Nature Publishing Group

PY - 2009

Y1 - 2009

N2 - BAR (Bin/Amphiphysin/Rvs) domains and amphipathic a-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.<br /> Keyword: Single liposomes,BAR domain,Amphipathic a-helix,Membrane insertion,Membrane curvature sensing

AB - BAR (Bin/Amphiphysin/Rvs) domains and amphipathic a-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.<br /> Keyword: Single liposomes,BAR domain,Amphipathic a-helix,Membrane insertion,Membrane curvature sensing

U2 - 10.1038/emboj.2009.261

DO - 10.1038/emboj.2009.261

JO - E M B O Journal

JF - E M B O Journal

SN - 0261-4189

VL - 28

SP - 3303

EP - 3314

ER -