Atomistic simulation of lipid and DiI dynamics in membrane bilayers under tension.
Atomistic simulation of lipid and DiI dynamics in membrane bilayers under tension.
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DOI：
10.1039/c0cp00430h
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发表时间：
2011-01-28
期刊：
影响因子：
--
通讯作者：
Butler PJ
中科院分区：
文献类型：
--
作者：
Muddana HS;Gullapalli RR;Manias E;Butler PJ
膜张力通过启动其分子组成的动态变化来调节细胞过程。为了定量研究膜的张力、结构性质、脂类和亲脂报告染料的动力学之间的精确关系，我们对DiI标记的二棕榈酰磷脂酰胆碱(DPPC)脂双层进行了原子分子动力学(MD)模拟，模拟结果表明，在−2.6mN−1到15.9mN−1的生理横向张力范围内，双层膜的厚度随着张力与体积不可压缩性一致而线性减小，这种减薄是由于双层中面上酰链交错和酰基链的展开而显著增加。张力导致双分子层的峰值静电势显著下降，这与水和脂偶极子的强烈重新排列有关。在低张力下，DPPC的横向扩散系数随张力的增加而增大，符合自由区理论。对于较大的张力，自由区理论由于张力引起的分子形状和摩擦的变化而崩溃。模拟的DII旋转和侧向扩散系数低于DPPC，但随着张力的增加而增加，其方式与DPPC相似。DPPC头基下方DII发色团附近的膜有序性和粘度的直接相关性表明，测得的DII荧光寿命(据报道随着脂质有序性的降低而减少)很可能是张力引起的脂头组粘度下降的很好报告。总之，这些结果为膜张力相关的机械转导和DiI在表征张力诱导的脂质堆积变化中的应用提供了新的分子水平的见解。
Membrane tension modulates cellular processes by initiating changes in the dynamics of its molecular constituents. To quantify the precise relationship between tension, structural properties of the membrane, and the dynamics of lipids and a lipophilic reporter dye, we performed atomistic molecular dynamics (MD) simulations of DiI-labeled dipalmitoylphosphatidylcholine (DPPC) lipid bilayers under physiological lateral tensions ranging from −2.6 mN m−1 to 15.9 mN m−1. Simulations showed that the bilayer thickness decreased linearly with tension consistent with volume-incompressibility, and this thinning was facilitated by a significant increase in acyl chain interdigitation at the bilayer midplane and spreading of the acyl chains. Tension caused a significant drop in the bilayer's peak electrostatic potential, which correlated with the strong reordering of water and lipid dipoles. For the low tension regime, the DPPC lateral diffusion coefficient increased with increasing tension in accordance with free-area theory. For larger tensions, free area theory broke down due to tension-induced changes in molecular shape and friction. Simulated DiI rotational and lateral diffusion coefficients were lower than those of DPPC but increased with tension in a manner similar to DPPC. Direct correlation of membrane order and viscosity near the DiI chromophore, which was just under the DPPC headgroup, indicated that measured DiI fluorescence lifetime, which is reported to decrease with decreasing lipid order, is likely to be a good reporter of tension-induced decreases in lipid headgroup viscosity. Together, these results offer new molecular-level insights into membrane tension-related mechanotransduction and into the utility of DiI in characterizing tension-induced changes in lipid packing.
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影响因子：
4.8
作者：
Garcia-Saez, Ana J.;Chiantia, Salvatore;Schwille, Petra
通讯作者：
Schwille, Petra
影响因子：
3.3
作者：
Gullapalli, Ramachandra R.;Demirel, Melik C.;Butler, Peter J.
通讯作者：
Butler, Peter J.
影响因子：
3.4
作者：
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通讯作者：
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影响因子：
3.4
作者：
Gudmand, M.;Fidorra, Matthias;Heimburg, T.
通讯作者：
Heimburg, T.
影响因子：
2.4
作者：
GALLA, HJ;HARTMANN, W;SACKMANN, E
通讯作者：
SACKMANN, E