Origin of DNA replication is an enigma because the replicative DNA polymerases (DNAPs) are not homologous among the three domains of life, Bacteria, Archaea, and Eukarya. The homology between the archaeal replicative DNAP (PolD) and the large subunits of the universal RNA polymerase (RNAP) responsible for transcription suggests a parsimonious evolutionary scenario. Under this model, RNAPs and replicative DNAPs evolved from a common ancestor that functioned as an RNA-dependent RNA polymerase in the RNA-protein world that predated the advent of DNA replication. The replicative DNAP of the Last Universal Cellular Ancestor (LUCA) would be the ancestor of the archaeal PolD.

中文翻译：

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LUCA的复制机制：DNA复制和转录的共同起源。

DNA复制的起源是一个谜，因为复制的DNA聚合酶（DNAP）在生命的三个域（细菌，古细菌和Eukarya）之间不是同源的。古细菌复制性DNAP（PolD）和负责转录的通用RNA聚合酶（RNAP）的大亚基之间的同源性表明了一个简约的进化场景。在此模型下，RNAP和复制性DNAP从共同祖先演变而来，在DNA复制时代来临之前，它在RNA蛋白质世界中起着RNA依赖性RNA聚合酶的作用。最后通用细胞祖先（LUCA）的复制DNAP将成为古细菌PolD的祖先。