Duan Xiaozheng, Zhang Ran, Li Yunqi, Yang Yongbiao, Shi Tongfei, An Lijia, Huang Qingrong
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, People's Republic of China.
Eur Biophys J. 2014 Sep;43(8-9):377-91. doi: 10.1007/s00249-014-0969-6. Epub 2014 Jun 28.
We employ Monte Carlo simulations to investigate the interaction between an adsorbing linear flexible cationic polyelectrolyte and a ternary mixed fluid membrane containing neutral (phosphatidylcholine, PC), monovalent (phosphatidylserine, PS), and multivalent (phosphatidylinositol, PIP2) anionic lipids. We systematically explore the influences of polyelectrolyte chain length, polyelectrolyte charge density, polyelectrolyte total charge amount, and salt solution ionic strength on the static and dynamic properties of different anionic lipid species. Our results show that the multivalent PIP2 lipids dominate the polyelectrolyte-membrane interaction and competitively inhibit polyelectrolyte-PS binding. When the total charge amount of the polyelectrolyte is less than that of the local oppositely charged PIP2 lipids, the polyelectrolyte can drag the bound multivalent lipids to diffuse on the membrane, but cannot interact with the PS lipids. Under this condition, the diffusion behaviors of the polyelectrolyte closely follow the prediction of the Rouse model, and the polyelectrolyte chain properties determine the adsorption amount, concentration gradients, and hierarchical mobility of the bound PIP2 lipids. However, when the total charge amount of the polyelectrolyte is larger than that of the local PIP2 lipids, the polyelectrolyte further binds the PS lipids around the polyelectrolyte-PIP2 complex to achieve local electrical neutrality. In this condition, parts of the polyelectrolyte desorb from the membrane and show faster mobility, and the bound PS presents much faster mobility than the segregated PIP2. This work provides an explanation for heterogeneity formation in different anionic lipids induced by polyelectrolyte adsorption.
我们采用蒙特卡罗模拟来研究吸附性线性柔性阳离子聚电解质与包含中性（磷脂酰胆碱，PC）、单价（磷脂酰丝氨酸，PS）和多价（磷脂酰肌醇，PIP2）阴离子脂质的三元混合流体膜之间的相互作用。我们系统地探讨了聚电解质链长度、聚电解质电荷密度、聚电解质总电荷量和盐溶液离子强度对不同阴离子脂质种类的静态和动态性质的影响。我们的结果表明，多价PIP2脂质主导聚电解质 - 膜相互作用，并竞争性抑制聚电解质与PS的结合。当聚电解质的总电荷量小于局部带相反电荷的PIP2脂质的电荷量时，聚电解质可以拖动结合的多价脂质在膜上扩散，但不能与PS脂质相互作用。在此条件下，聚电解质的扩散行为紧密遵循劳厄模型的预测，并且聚电解质链的性质决定了结合的PIP2脂质的吸附量、浓度梯度和分级迁移率。然而，当聚电解质的总电荷量大于局部PIP2脂质的电荷量时，聚电解质会进一步结合聚电解质 - PIP2复合物周围的PS脂质以实现局部电中性。在这种情况下，部分聚电解质从膜上解吸并表现出更快的迁移率，并且结合的PS的迁移率比分离的PIP2快得多。这项工作为聚电解质吸附诱导的不同阴离子脂质中异质性的形成提供了解释。
