Ganesan Sai J, Xu Hongcheng, Matysiak Silvina
Fischell Department of Bioengineering and ‡Biophysics Program, Institute of Physical Science and Technology, University of Maryland , College Park, Maryland 20742, United States.
J Phys Chem B. 2017 Feb 2;121(4):787-799. doi: 10.1021/acs.jpcb.6b10099. Epub 2017 Jan 18.
Phosphatidylserine (PS) and phosphatidylcholine (PC) are two of the major anionic and zwitterionic phospholipids in mammalian cell membranes. Ion-PS interaction is hypothesized to play a crucial role in a range of biological events including membrane fusion, lipid phase modulation, membrane protein insertion and translocation. In this study, we characterize lipid nanodomain formation in PC/PS mixed bilayers using coarse-grained simulations. We investigate the role of monovalent cation sizes in modulating lipid-ion binding modes and lipid demixing. Our simulations suggest that certain lipid-ion binding modes lead to growth of ion-mediated PS lipid clusters. The existing literature reveals the polymorphism in binding and partitioning patterns in monovalent cations (Na, K, and Li) with anionic lipids. Our work provides a microscopic view on the ion-size-dependent PS lipid packing pattern observed experimentally. A coupled relationship between lipid curvature and asymmetry is observed in highly demixed PC/PS mixed bilayers.
磷脂酰丝氨酸（PS）和磷脂酰胆碱（PC）是哺乳动物细胞膜中两种主要的阴离子和两性离子磷脂。离子与PS的相互作用被认为在一系列生物事件中起着关键作用，包括膜融合、脂质相调制、膜蛋白插入和转运。在本研究中，我们使用粗粒度模拟来表征PC/PS混合双层膜中脂质纳米域的形成。我们研究了单价阳离子大小在调节脂质-离子结合模式和脂质分离中的作用。我们的模拟表明，某些脂质-离子结合模式会导致离子介导的PS脂质簇的生长。现有文献揭示了单价阳离子（Na、K和Li）与阴离子脂质结合和分配模式的多态性。我们的工作为实验观察到的离子大小依赖性PS脂质堆积模式提供了微观视角。在高度分离的PC/PS混合双层膜中观察到脂质曲率和不对称性之间的耦合关系。
