模型原核细胞膜的耦合生长和分裂。

Coupled growth and division of model protocell membranes.

机构信息

Howard Hughes Medical Institute, and Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.

出版信息

J Am Chem Soc. 2009 Apr 22;131(15):5705-13. doi: 10.1021/ja900919c.

Abstract

The generation of synthetic forms of cellular life requires solutions to the problem of how biological processes such as cyclic growth and division could emerge from purely physical and chemical systems. Small unilamellar fatty acid vesicles grow when fed with fatty acid micelles and can be forced to divide by extrusion, but this artificial division process results in significant loss of protocell contents during each division cycle. Here we describe a simple and efficient pathway for model protocell membrane growth and division. The growth of large multilamellar fatty acid vesicles fed with fatty acid micelles, in a solution where solute permeation across the membranes is slow, results in the transformation of initially spherical vesicles into long thread-like vesicles, a process driven by the transient imbalance between surface area and volume growth. Modest shear forces are then sufficient to cause the thread-like vesicles to divide into multiple daughter vesicles without loss of internal contents. In an environment of gentle shear, protocell growth and division are thus coupled processes. We show that model protocells can proceed through multiple cycles of reproduction. Encapsulated RNA molecules, representing a primitive genome, are distributed to the daughter vesicles. Our observations bring us closer to the laboratory synthesis of a complete protocell consisting of a self-replicating genome and a self-replicating membrane compartment. In addition, the robustness and simplicity of this pathway suggests that similar processes might have occurred under the prebiotic conditions of the early Earth.

摘要

细胞生命的合成形式的产生需要解决如何从纯粹的物理和化学系统中产生诸如循环生长和分裂等生物过程的问题。当用脂肪酸胶束喂养时,小的单层脂肪酸囊泡会生长,并且可以通过挤压迫使它们分裂,但是这种人工分裂过程会导致在每个分裂周期中大量原生质体内容物的损失。在这里,我们描述了一种用于模型原生质体膜生长和分裂的简单有效的途径。在溶质通过膜渗透缓慢的溶液中,用脂肪酸胶束喂养大的多层脂肪酸囊泡,导致最初的球形囊泡转变成长的线状囊泡,这一过程是由表面积和体积生长之间的瞬时不平衡驱动的。然后,适度的剪切力足以使线状囊泡分裂成多个子囊泡,而不会损失内部内容物。在温和剪切力的环境中,原生质体的生长和分裂是耦合的过程。我们表明,模型原生质体可以经历多次繁殖周期。代表原始基因组的封装 RNA 分子被分配到子囊泡中。我们的观察结果使我们更接近于在含有自我复制基因组和自我复制膜隔室的完整原生质体的实验室合成。此外,这种途径的稳健性和简单性表明,类似的过程可能在早期地球的原始生物条件下发生过。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/3933/2669828/6925a4fe96d7/ja-2009-00919c_0001.jpg

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