Molecular Biophysics Unit, Indian Institute of Science Bangalore, Bangalore, Karnataka, India.
Molecular Biophysics Unit, Indian Institute of Science Bangalore, Bangalore, Karnataka, India.
Biophys J. 2018 Jul 3;115(1):117-128. doi: 10.1016/j.bpj.2018.05.021.
Lateral heterogeneities in biomembranes play a crucial role in various physiological functions of the cell. Such heterogeneities lead to demixing of lipid constituents and formation of distinct liquid domains in the membrane. We study lateral heterogeneities in terms of topological rearrangements of lipids to identify the liquid-liquid phase coexistence in model membranes. Using ideas from the physics of amorphous systems and glasses, we calculate the degree of nonaffine deformation associated with individual lipids to characterize the liquid-ordered (L) and liquid-disordered (L) regions in model lipid bilayers. We explore the usage of this method on all-atom and coarse-grained lipid bilayer trajectories. This method is helpful in defining the instantaneous L-L domain boundaries in complex multicomponent bilayer systems. The characterization is also used to highlight the effect of line-active molecules on the phase boundaries and domain mixing. Overall, we propose a framework to explore the molecular origin of spatial and dynamical heterogeneity in biomembrane systems, which can be exploited not only in computer simulations but also in experiments.
生物膜中的侧向非均质性在细胞的各种生理功能中起着至关重要的作用。这种非均质性导致脂质成分的分离和膜中形成不同的液相域。我们从脂质的拓扑重排方面研究侧向非均质性，以确定模型膜中的液-液相共存。我们利用非晶态系统和玻璃物理学的思想，计算与单个脂质相关的非仿射变形程度，以表征模型脂质双层中的液相有序（L）和液相无序（L）区域。我们探索了在全原子和粗粒脂质双层轨迹上使用这种方法的方法。这种方法有助于在复杂的多组分双层系统中定义瞬时 L-L 域边界。该特征还用于突出线活性分子对相边界和域混合的影响。总的来说，我们提出了一个框架来探索生物膜系统中空间和动态非均质性的分子起源，该框架不仅可以在计算机模拟中，也可以在实验中得到利用。
