Protocells: at the interface of life and non-life.
Protocells: at the interface of life and non-life.
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DOI：
10.3390/life5010447
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发表时间：
2015-02-09
期刊：
影响因子：
--
通讯作者：
Feng Y
中科院分区：
文献类型：
--
作者：
Ma W;Feng Y
细胞形式，表现为膜界系统（包括各种功能分子），是生命所必需的。其最终原因是，通常情况下，一个功能分子只能采用一种“正确”的结构来执行一种特殊功能（例如酶），因此分子合作是不可避免的。虽然这对于具有复杂功能的高级生命来说尤其正确，但对于最初只有有限功能的生命来说，这应该已经是正确的了，这需要某种原始的细胞形式——“原始细胞”。在最开始，原始细胞甚至可能无法干预自身膜的生长，这可以称为“伪原始细胞”。然后，合成膜组分（两亲体）的能力可能在选择压力下出现，导致“真正的原始细胞”。“染色体”（基因连接在一起）的出现——从而避免了原始细胞分裂过程中的“基因丢失”——是原始细胞进化过程中的另一个关键事件。这种含有中心遗传分子的“单一原始细胞”可能是一个里程碑——从原则上讲，从那时起，生命就可以无休止地进化，通过引入新基因“获得”越来越多的功能。在实验室中合成这些处于生命和非生命之间的不同类型的原始细胞，将大大提高我们对生命本质的理解。
The cellular form, manifesting as a membrane-bounded system (comprising various functional molecules), is essential to life. The ultimate reason for this is that, typically, one functional molecule can only adopt one “correct” structure to perform one special function (e.g., an enzyme), and thus molecular cooperation is inevitable. While this is particularly true for advanced life with complex functions, it should have already been true for life at its outset with only limited functions, which entailed some sort of primitive cellular form—“protocells”. At the very beginning, the protocells may have even been unable to intervene in the growth of their own membrane, which can be called “pseudo-protocells”. Then, the ability to synthesize membrane components (amphiphiles) may have emerged under selective pressure, leading to “true-protocells”. The emergence of a “chromosome” (with genes linked together)—thus avoiding “gene-loss” during the protocell division, was another key event in the evolution of protocells. Such “unitary-protocells”, containing a central genetic molecule, may have appeared as a milestone—in principle, since then life could evolve endlessly, “gaining” more and more functions by introducing new genes. To synthesize in laboratory these different types of protocells, which stand at the interface between life and non-life, would greatly enhance our understanding on the essence of life.