Membrane Binding of HIV-1 Matrix Protein: Dependence on Bilayer Composition and Protein Lipidation
Membrane Binding of HIV-1 Matrix Protein: Dependence on Bilayer Composition and Protein Lipidation
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DOI：
10.1128/jvi.02820-15
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发表时间：
2016-05-01
影响因子：
5.4
通讯作者：
Loesche, Mathias
中科院分区：
文献类型：
--
作者：
Barros, Marilia;Heinrich, Frank;Loesche, Mathias
通过在宿主质膜上的蛋白质晶格中组装，逆转录病毒Gag多蛋白触发病毒蛋白/膜壳的形成。Gag的MA结构域采用多种信号-静电、疏水和脂质特异性-将蛋白质带到质膜，从而补充位于全长Gag中的晶格形成中的蛋白质-蛋白质相互作用。我们报告的肉豆蔻酰化和unmyristoylated HIV-1 Gag MA结构域与由纯化的脂质成分组成的双层的相互作用，以解剖这些复杂的膜信号，并量化它们对整体相互作用的贡献。在明确定义的平面膜模型上的表面等离子体共振用于量化蛋白质的结合亲和力和量，并产生各种信号的自由结合能贡献Δ G。在磷脂酰肌醇PI（4，5）P-2不存在的情况下，电荷-电荷相互作用将蛋白质吸引到酸性膜表面，并且肉豆蔻酰化使亲和力增加10倍;因此，我们的数据没有提供PI（4，5）P-2触发肉豆蔻酸酯暴露的证据。与PI（4，5）P-2（内质膜中的主要信号脂质）的脂质特异性相互作用以类似于蛋白质脂质化的水平增加膜吸引力。虽然胆固醇不直接参与相互作用，但它通过促进有效的肉豆蔻酸酯插入和PI（4，5）P-2结合而强烈增强蛋白质亲和力。因此，我们观察到，分离的MA蛋白，在蛋白质-蛋白质相互作用的情况下赋予的全长Gag，与亚微摩尔亲和力的膜结合。
By assembling in a protein lattice on the host's plasma membrane, the retroviral Gag polyprotein triggers formation of the viral protein/membrane shell. The MA domain of Gag employs multiple signals-electrostatic, hydrophobic, and lipid-specific-to bring the protein to the plasma membrane, thereby complementing protein-protein interactions, located in full-length Gag, in lattice formation. We report the interaction of myristoylated and unmyristoylated HIV-1 Gag MA domains with bilayers composed of purified lipid components to dissect these complex membrane signals and quantify their contributions to the overall interaction. Surface plasmon resonance on well-defined planar membrane models is used to quantify binding affinities and amounts of protein and yields free binding energy contributions, Delta G, of the various signals. Charge-charge interactions in the absence of the phosphatidylinositide PI(4,5)P-2 attract the protein to acidic membrane surfaces, and myristoylation increases the affinity by a factor of 10; thus, our data do not provide evidence for a PI(4,5)P-2 trigger of myristate exposure. Lipid-specific interactions with PI(4,5)P-2, the major signal lipid in the inner plasma membrane, increase membrane attraction at a level similar to that of protein lipidation. While cholesterol does not directly engage in interactions, it augments protein affinity strongly by facilitating efficient myristate insertion and PI(4,5)P-2 binding. We thus observe that the isolated MA protein, in the absence of protein-protein interaction conferred by the full-length Gag, binds the membrane with submicromolar affinities.