PDF(Pubmed)
Abstract：
The RNA world hypothesis confers a central role to RNA molecules in information encoding and catalysis. Even though evidence in support of this hypothesis has accumulated from both experiments and computational modelling, the transition from an RNA world to a world where heritable genetic information is encoded in DNA remains an open question. Recent experiments show that both RNA and DNA templates can extend complementary primers using free RNA/DNA nucleotides, either non-enzymatically or in the presence of a replicase ribozyme. Guided by these experiments, we analyse protocellular evolution with an expanded set of reaction pathways made possible through the presence of DNA nucleotides. By encapsulating these reactions inside three different types of protocellular compartments, each subject to distinct modes of selection, we show how protocells containing DNA-encoded replicases in low copy numbers and replicases in high copy numbers can dominate the population. This is facilitated by a reaction that leads to auto-catalytic synthesis of replicase ribozymes from DNA templates encoding the replicase after the chance emergence of a replicase through non-enzymatic reactions. Our work unveils a pathway for the transition from an RNA world to a mixed RNA-DNA world characterized by Darwinian evolution, where DNA sequences encode heritable phenotypes.
摘要：
RNA世界假说赋予RNA分子在信息编码和催化中的核心作用。尽管支持这一假设的证据已经从实验和计算模型中积累起来，从RNA世界到可遗传遗传信息编码在DNA中的世界的转变仍然是一个悬而未决的问题。最近的实验表明，RNA和DNA模板都可以使用游离的RNA/DNA核苷酸延伸互补引物，非酶或在存在复制酶核酶的情况下。在这些实验的指导下，我们通过DNA核苷酸的存在使之成为可能的一系列扩展的反应途径来分析原细胞进化。通过将这些反应封装在三种不同类型的原细胞隔室中，每个人都有不同的选择模式，我们展示了含有低拷贝数的DNA编码复制酶和高拷贝数复制酶的原始细胞如何主导群体。在通过非酶促反应偶然出现复制酶之后,导致从编码复制酶的DNA模板自动催化合成复制酶核酶的反应促进了这一点。我们的工作揭示了从RNA世界过渡到以达尔文进化论为特征的混合RNA-DNA世界的途径，其中DNA序列编码可遗传表型。
