Membrane Curvature Sensing by Amphipathic Helices A SINGLE LIPOSOME STUDY USING α-SYNUCLEIN AND ANNEXIN B12
Membrane Curvature Sensing by Amphipathic Helices A SINGLE LIPOSOME STUDY USING α-SYNUCLEIN AND ANNEXIN B12
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DOI：
10.1074/jbc.m111.271130
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发表时间：
2011-12-09
影响因子：
4.8
通讯作者：
Stamou, Dimitrios
中科院分区：
文献类型：
--
作者：
Jensen, Martin Borch;Bhatia, Vikram Kjoller;Stamou, Dimitrios
蛋白质在弯曲膜上的优先结合（膜曲率传感）日益成为细胞影响蛋白质定位和运输的一般机制。在这里，我们使用一种新颖的单脂质体荧光显微镜检测常见的传感基元，两亲螺旋（AH），并提供定量测量描述和区分膜结合和传感行为。通过研究两种含AH的蛋白，α -突触核蛋白和膜联蛋白B12，以及一系列AH肽突变体，我们发现螺旋的疏水性和亲水性都极大地影响了结合和传感。尽管与膜的疏水和静电相互作用增加都会导致结合蛋白的密度增加，但前者产生膜曲率敏感结合，而后者不依赖于曲率。然而，这两种成分的相对贡献决定了AHs的感知。相比之下，脂质膜上的电荷密度似乎主要是在吸引AHs到膜上，但对传感没有显著影响。这些观察结果是由于我们的分析能够区分样品中有和没有结合蛋白的脂质体以及结合蛋白的密度。我们的研究结果表明，膜曲率传感的描述需要考虑几个因素，如短程和长距离静电相互作用，氢键，以及插入的疏水残基的体积和结构。
Preferential binding of proteins on curved membranes (membrane curvature sensing) is increasingly emerging as a general mechanism whereby cells may effect protein localization and trafficking. Here we use a novel single liposome fluorescence microscopy assay to examine a common sensing motif, the amphipathic helix (AH), and provide quantitative measures describing and distinguishing membrane binding and sensing behavior. By studying two AH-containing proteins, alpha-synuclein and annexin B12, as well as a range of AH peptide mutants, we reveal that both the hydrophobic and hydrophilic faces of the helix greatly influence binding and sensing. Although increased hydrophobic and electrostatic interactions with the membrane both lead to greater densities of bound protein, the former yields membrane curvature-sensitive binding, whereas the latter is not curvature-dependent. However, the relative contributions of both components determine the sensing of AHs. In contrast, charge density in the lipid membrane seems important primarily in attracting AHs to the membrane but does not significantly influence sensing. These observations were made possible by the ability of our assay to distinguish within our samples liposomes with and without bound protein as well as the density of bound protein. Our findings suggest that the description of membrane curvature-sensing requires consideration of several factors such as short and long range electrostatic interactions, hydrogen bonding, and the volume and structure of inserted hydrophobic residues.