Conical Lipids in Flat Bilayers Induce Packing Defects Similar to that Induced by Positive Curvature
Conical Lipids in Flat Bilayers Induce Packing Defects Similar to that Induced by Positive Curvature
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DOI：
10.1016/j.bpj.2012.11.3836
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发表时间：
2013-02-05
影响因子：
3.4
通讯作者：
Fuchs, Patrick F. J.
中科院分区：
文献类型：
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作者：
Vamparys, Lydie;Gautier, Romain;Fuchs, Patrick F. J.
在生物膜中，脂质成分的变化或机械变形会产生脂质几何排列的缺陷，从而允许吸附某些外围蛋白质。在这里，我们对包含圆柱形脂质（PC）和圆锥形脂质（DOG）的双层进行分子动力学模拟。由于与 PC 相比，DOG 的划分更深，因此双层的原子密度和侧压力分布显示酰基链区域存在差异。然而，此类分析对于外围蛋白质吸附的界面区域的信息较少。为了规避这一限制，据我们所知，我们开发了一种新的膜表面分析方法。该方法可以识别化学缺陷（其中烃链可接触到溶剂）和几何缺陷（即比甘油主链更深的空隙）。两种类型的缺陷的大小和数量随着PC中单不饱和酰基链的数量和DOG的引入而增加，尽管这些缺陷不与锥形脂质共定位。有趣的是，DOG 引起的缺陷的大小和概率类似于正曲率引起的缺陷，从而解释了为什么圆锥形脂质和正曲率都可以驱动使用疏水残基作为膜锚定的外围蛋白质的吸附。
In biological membranes, changes in lipid composition or mechanical deformations produce defects in the geometrical arrangement of lipids, thus allowing the adsorption of certain peripheral proteins. Here, we perform molecular dynamics simulations on bilayers containing a cylindrical lipid (PC) and a conical lipid (DOG). Profiles of atomic density and lateral pressure across the bilayer show differences in the acyl chain region due to deeper partitioning of DOG compared to PC. However, such analyses are less informative for the interfacial region where peripheral proteins adsorb. To circumvent this limitation, we develop, to our knowledge, a new method of membrane surface analysis. This method allows the identification of chemical defects, where hydrocarbon chains are accessible to the solvent, and geometrical defects, i.e., voids deeper than the glycerol backbone. The size and number of both types of defects increase with the number of monounsaturated acyl chains in PC and with the introduction of DOG, although the defects do not colocalize with the conical lipid. Interestingly, the size and probability of the defects promoted by DOG resemble those induced by positive curvature, thus explaining why conical lipids and positive curvature can both drive the adsorption of peripheral proteins that use hydrophobic residues as membrane anchors.