Amphipathic motifs in BAR domains are essential for membrane curvature sensing
Amphipathic motifs in BAR domains are essential for membrane curvature sensing
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DOI：
10.1038/emboj.2009.261
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发表时间：
2009-11-04
期刊：
影响因子：
11.4
通讯作者：
Stamou, Dimitrios
中科院分区：
文献类型：
--
作者：
Bhatia, Vikram K.;Madsen, Kenneth L.;Stamou, Dimitrios
BAR（Bin/Amphiphysin/Rvs）结构域和两亲性α-螺旋（AH）被认为是膜曲率的传感器，从而促进蛋白质复合物在弯曲膜上的组装。在这里，我们使用定量荧光显微镜来比较不同直径的单个纳米脂质体上的两个基序的结合，因此膜曲率。三个BAR结构域家族成员的表征令人惊讶地显示，具有带正电荷凹面的新月形BAR二聚体不能感知膜曲率。对BAR结构域的诱变表明，膜曲率感测关键取决于N-末端AH，此外，BAR结构域感测膜曲率是通过在脂质包装缺陷中的疏水插入而不是通过静电。因此，通常与BAR结构域相关的两亲性基序，如AH，成为蛋白质感知膜曲率的重要手段。对单个脂质体的测量使我们能够记录系综内的异质结合行为，并量化脂质体多分散性对本体膜曲率传感实验的影响。后者的结果表明，散装脂质体结合实验应非常谨慎地解释。The EMBO Journal（2009）28，3303-3314. doi：10.1038/doj.2009.261; 2009年10月8日在线发布
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. The EMBO Journal (2009) 28, 3303-3314. doi: 10.1038/emboj.2009.261; Published online 8 October 2009