Controlling Anomalous Diffusion in Lipid Membranes
Controlling Anomalous Diffusion in Lipid Membranes
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DOI：
10.1016/j.bpj.2018.12.024
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发表时间：
2019-03-19
影响因子：
3.4
通讯作者：
Wallace, Mark, I
中科院分区：
文献类型：
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作者：
Coker, Helena L. E.;Cheetham, Matthew R.;Wallace, Mark, I
细胞膜中的扩散不仅仅是简单的二维布朗运动，而是典型地依赖于观察的时间尺度。这种异常亚扩散的物理起源尚未得到解决，并且能够定量和可重复控制膜扩散的模型系统已被公认为关键的实验瓶颈。在这里，我们使用含有聚乙二醇（PEG）头基衍生的脂质的支撑脂质双层来控制异常扩散。通过控制PEG脂质摩尔分数形成具有特定排除面积分数的双层。这些双层表现出扩散行为的开关，成为异常的双层连续性被破坏。使用单分子荧光和干涉成像的组合，我们测量在这个模型中的异常行为超过四个数量级的时间。在这些双层扩散很好地描述了幂律依赖的均方位移与观察时间。该系统中的异常可以通过简单地控制PEG脂质的摩尔分数来定制，产生具有与在生物膜中观察到的异常扩散相似的扩散参数的双层。
Diffusion in cell membranes is not just simple two-dimensional Brownian motion but typically depends on the time-scale of the observation. The physical origins of this anomalous subdiffusion are unresolved, and model systems capable of quantitative and reproducible control of membrane diffusion have been recognized as a key experimental bottleneck. Here, we control anomalous diffusion using supported lipid bilayers containing lipids derivatized with polyethylene glycol (PEG) head-groups. Bilayers with specific excluded area fractions are formed by control of PEG lipid mole fraction. These bilayers exhibit a switch in diffusive behavior, becoming anomalous as bilayer continuity is disrupted. Using a combination of single-molecule fluorescence and interferometric imaging, we measure the anomalous behavior in this model over four orders of magnitude in time. Diffusion in these bilayers is well described by a power-law dependence of the mean-square displacement with observation time. Anomaleity in this system can be tailored by simply controlling the mole fraction of PEG lipid, producing bilayers with diffusion parameters similar to those observed for anomalous diffusion in biological membranes.