Can an arbitrary sequence evolve towards acquiring a biological function?
Can an arbitrary sequence evolve towards acquiring a biological function?
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DOI：
10.1007/s00239-002-2389-y
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发表时间：
2003-02-01
影响因子：
3.9
通讯作者：
Yomo, T
中科院分区：
文献类型：
--
作者：
Hayashi, Y;Sakata, H;Yomo, T
为了探索当与其他预先存在的蛋白质模块融合时任意序列可以朝向获得功能作用进化的可能性，我们用可溶性随机多肽RP 3 -42替换fd-tet噬菌体基因组的D2结构域。替换产生的fd-RP缺陷的噬菌体是六个数量级的感染性比野生型fd-tet噬菌体低。通过迭代突变和选择研究了RP 3 -42的可进化性。每一代由最多10个任意选择的克隆组成，其中具有最高感染性的克隆被选择为下一代的亲本克隆。实验进化证明，从最初的单个随机序列开始，感兴趣的属性将存在可选择的变化，并且所讨论的属性能够在几代人中得到改善。fd-7是在实验进化结束时具有最高感染性的克隆，与其来源fd-RP相比，其感染性增加了240倍。通过使用抗M13抗体和抗T7抗体的噬菌体ELISA分析，发现fd-7的感染性增加了约37倍，这归因于替换差距蛋白的D2结构域的单一多肽的分子性质的变化。因此，这项研究证实了随机多肽在融合一些预先存在的蛋白质模块时在恢复缺陷噬菌体的感染性方面产生功能作用的过程，表明任意序列可以朝着获得功能作用的方向进化。总之，本研究预示着在分子进化领域对原始多肽研究的新视角。
To explore the possibility that an arbitrary sequence can evolve towards acquiring functional role when fused with other pre-existing protein modules, we replaced the D2 domain of the fd-tet phage genome with the soluble random polypeptide RP3-42. The replacement yielded an fd-RP defective phage that is six-order magnitude lower infectivity than the wild-type fd-tet phage. The evolvability of RP3-42 was investigated through iterative mutation and selection. Each generation consists of a maximum of ten arbitrarily chosen clones, whereby the clone with highest infectivity was selected to be the parent clone of the generation that followed. The experimental evolution attested that, from an initial single random sequence, there will be selectable variation in a property of interest and that the property in question was able to improve over several generations. fd-7, the clone with highest infectivity at the end of the experimental evolution, showed a 240-fold increase in infectivity as compared to its origin, fd-RP. Analysis by phage ELISA using anti-M13 antibody and anti-T7 antibody revealed that about 37-fold increase in the infectivity of fd-7 was attributed to the changes in the molecular property of the single polypeptide that replaced the D2 domain of the gap protein. This study therefore exemplifies the process of a random polypeptide generating a functional role in rejuvenating the infectivity of a defective bacteriophage when fused so some preexisting protein modules, indicating that an arbitrary sequence can evolve toward acquiring a functional role. Overall, this study could herald the conception of new perspective regarding primordial polypeptides in the field of molecular evolution.