Mechanisms that enabled primitive cell membranes to self-reproduce have been discussed based on the physicochemical properties of fatty acids; however, there must be a transition to modern cell membranes composed of phospholipids [Budin I, Szostak JW (2011) Proc Natl Acad Sci USA 108:5249–5254]. Thus, a growth-division mechanism of membranes that does not depend on the chemical nature of amphiphilic molecules must have existed. Here, we show that giant unilamellar vesicles composed of phospholipids can undergo the coupled process of fusion and budding transformation, which mimics cell growth and division. After gaining excess membrane by electrofusion, giant vesicles spontaneously transform into the budded shape only when they contain macromolecules (polymers) inside their aqueous core. This process is a result of the vesicle maximizing the translational entropy of the encapsulated polymers (depletion volume effect). Because the cell is a lipid membrane bag containing highly concentrated biopolymers, this coupling process that is induced by physical and nonspecific interactions may have a general importance in the self-reproduction of the early cellular compartments.
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机译:基于脂肪酸的理化性质,已经讨论了使原始细胞膜能够自我繁殖的机制。但是,必须过渡到由磷脂组成的现代细胞膜[Budin I,Szostak JW(2011)Proc Natl Acad Sci USA 108:5249-5254]。因此,必须存在不依赖于两亲分子的化学性质的膜的生长-分裂机制。在这里,我们表明,由磷脂组成的巨大单层囊泡可以经历融合和萌芽转化的耦合过程,从而模仿细胞的生长和分裂。通过电融合获得过量的膜后,仅当大泡囊在其含水核心中包含大分子(聚合物)时,它们才会自发转变为芽形。该过程是囊泡使包封的聚合物的平移熵最大化(耗尽体积效应)的结果。因为细胞是包含高度浓缩的生物聚合物的脂质膜袋,所以这种由物理和非特异性相互作用诱导的偶联过程在早期细胞区室的自我繁殖中可能具有普遍的重要性。
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