Early life is thought to have required the self-replication of RNA by RNA replicases. However, how such replicases evolved and subsequently enabled gene expression remains largely unexplored. We engineered and selected a holopolymerase ribozyme that uses a sigma factor–like specificity primer to first recognize an RNA promoter sequence and then, in a second step, rearrange to a processive elongation form. Using its own sequence, the polymerase can also program itself to polymerize from certain RNA promoters and not others. This selective promoter–based polymerization could allow an RNA replicase ribozyme to define “self” from “nonself,” an important development for the avoidance of replicative parasites. Moreover, the clamp-like mechanism of this polymerase could eventually enable strand invasion, a critical requirement for replication in the early evolution of life.

人们认为，早期生活需要通过RNA复制来自我复制RNA。但是，这种复制体如何进化以及随后的基因表达如何在很大程度上尚待探索。我们设计并选择了一种全聚合酶核酶，该酶​​使用一种类似于sigma因子的特异性引物来识别RNA启动子序列，然后在第二步中将其重新排列为连续的延伸形式。利用其自身的序列，聚合酶还可以编程使其自身从某些RNA启动子而非其他RNA启动子聚合。这种基于选择性启动子的聚合反应可以使RNA复制酶核酶从“非自身”定义为“自身”，这是避免复制性寄生虫的重要进展。而且，这种聚合酶的钳样机制最终可能使链入侵，