Coupling between vesicle shape and lateral distribution of mobile membrane inclusions
Coupling between vesicle shape and lateral distribution of mobile membrane inclusions
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DOI：
10.1103/physreve.73.041915
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发表时间：
2006-04-01
影响因子：
2.4
通讯作者：
Svetina, S
中科院分区：
文献类型：
--
作者：
Bozic, B;Kralj-Iglic, V;Svetina, S
膜内含物，如膜内嵌入的肽或蛋白质，由于其固有曲率与局部膜曲率之间的不匹配，与周围脂质基质表现出曲率依赖的相互作用。这种相互作用导致包裹体的横向分布不均匀，并导致囊泡形状的相应调整。考虑到膜自由能包括脂质双分子层的弹性能和包体-膜相互作用的贡献，我们从理论上研究了具有可移动包体的脂质囊泡的轴对称平衡形状。通过最小化固定膜面积下的总自由能、封闭体积和夹杂物数量，推导出描述形状的方程，然后进行数值求解。结果表明，囊泡的形状可能与没有内含物的囊泡具有不同的对称性。如果包体与膜的相互作用超过一定值，则在整个囊泡区域内，包体横向密度连续且可导的方程不存在轴对称解。当接近临界囊泡形状时，得到的形状与脂质膜弹性特性的面积差弹性模型所描述的形状有质的不同。一般来说，囊泡的形状通过增加有利曲率的区域和减少不利曲率的区域来适应内含物的存在，从而使内含物的横向分布变得不均匀。
Membrane inclusions such as membrane-embedded peptides or proteins exhibit a curvature-dependent interaction with the surrounding lipid matrix due to the mismatch between their intrinsic curvature and the local membrane curvature. This interaction causes an inhomogeneous lateral distribution of the inclusions and a corresponding adjustment of the vesicle shape. We have studied theoretically the axisymmetric equilibrium shapes of lipid vesicles with mobile inclusions, taking into account that the membrane free energy includes the elastic energy of the lipid bilayer and a contribution due to an inclusion-membrane interaction. Equations describing the shape are derived by minimizing the total free energy at fixed membrane area, enclosed volume, and number of inclusions and are then solved numerically. It is shown that vesicle shape may assume a symmetry that differs from that of the vesicle with no inclusions. If the inclusion-membrane interaction exceeds a certain value, there is no axisymmetric solution of the equations with a continuous and derivable lateral density of inclusions over the whole area of the vesicle. When approaching the critical vesicle shape, the shapes obtained differ qualitatively from those described by the area difference elasticity model of the elastic properties of lipid membranes. In general, vesicle shapes adjust to the presence of inclusions by increasing regions with favorable curvature and decreasing regions of unfavorable curvature in a way such that the lateral distribution of inclusions becomes inhomogeneous.