State-dependent Lipid Interactions with the A2a Receptor Revealed by MD Simulations Using In Vivo-Mimetic Membranes
State-dependent Lipid Interactions with the A2a Receptor Revealed by MD Simulations Using In Vivo-Mimetic Membranes
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DOI：
10.1101/362970
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发表时间：
2018-07
期刊：
影响因子：
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通讯作者：
Wanling Song;Hsin-Yung Yen;C. Robinson;M. Sansom
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作者：
Wanling Song;Hsin-Yung Yen;C. Robinson;M. Sansom
G蛋白偶联受体（GPCR）是最大的完整膜蛋白家族，也是一类主要的药物靶点。已知膜通过特异性脂质相互作用对GPCR具有调节作用。然而，细胞膜中这种调节的机制以及它们如何影响GPCR功能仍不清楚。在这里，我们报告了粗粒度的MD模拟腺苷A2 a受体嵌入在体内模拟膜模型，包括10个不同的脂质物种。模拟受体的三种构象状态，即非活性状态、活性状态和与mini-GS蛋白结合的活性状态，以研究蛋白-脂质相互作用对受体活化的影响。模拟揭示了三种特定的脂质（GM 3，胆固醇和PIP 2）与受体形成稳定和优先的相互作用，将它们与PS，PE和PC等散装脂质区分开来。总共发现了9个特异性的脂质结合位点。与这些网站的脂质相互作用的强度取决于受体的构象状态，这表明这些脂质可以调节受体的构象动力学。特别地，我们揭示了PIP 2在促进A2 aR活化中的双重作用，其涉及稳定受体内螺旋TM 6的特征性向外倾斜以及当活化的复合物形成时A2 aR和mini-Gs的缔合。结构比较表明PIP 2可能促进Gα激活。我们的研究结果揭示了结合脂质在调节GPCR功能行为中可能的变构效应，为设计这些生物医学上重要的受体的变构调节剂提供了跳板。
G protein-coupled receptors (GPCRs) are the largest family of integral membrane proteins and a major class of drug targets. Membranes are known to have modulatory effects on GPCRs via specific lipid interactions. However, the mechanisms of such modulations in cell membranes and how they influence GPCR functions remain unclear. Here we report coarse-grained MD simulations on the Adenosine A2a receptor embedded in an in vivo mimetic membrane model comprised of 10 different lipid species. Three conformational states of the receptor, i.e. the inactive state, the active state, and the active state with a mini-GS protein bound were simulated to study the impact of protein-lipid interactions on the receptor activation. The simulations revealed three specific lipids (GM3, cholesterol and PIP2) that form stable and preferential interactions with the receptor, differentiating these from bulk lipids such as PS, PE and PC. In total, nine specific lipid-binding sites were revealed. The strength of lipid interaction with these sites depends on the conformational state of the receptor, suggesting that these lipids may regulate the conformational dynamics of the receptor. In particular, we revealed a dual role of PIP2 in promoting A2aR activation, which involves stabilization of both the characteristic outward tilt of helix TM6 within receptor and also the association of A2aR and mini-Gs when the activated complex forms. Structural comparisons suggested that PIP2 may facilitate Gα activation. Our results reveal likely allosteric effects of bound lipids in regulating the functional behaviour of GPCRs, providing a springboard for design of allosteric modulators of these biomedically important receptors.