Adaptive Evolution and Diversity of an Artificial Rna Self-replication System

Introduction: The adaptive evolutionary ability is one of the remarkable characteristics of living things, which allows them to survive in various environments by changing gene expression and gene function. It also should enable a particular species, even primitive lifeforms, to become extremely diverse, as can be found all over the world. The in vitro reconstitution of these adaptive abilities from biological molecules is a major challenge and certainly provides important insights into the origin of life and early evolution. For years, we have explored the evolutionary ability of an artificial life-like system, translation-coupled RNA replication (TcRR) system, in which the genomic RNA replicates through the translation of the genetic information. The TcRR system contains an artificial genomic RNA encoding Qβ replicase (RNA-dependent RNA polymerase) and a reconstituted Escherichia coli translation system[1]. To date, by repeating TcRR reactions in cell-like compartments, it has been proved that the genomic RNA spontaneously evolved to be highly replicable according to Darwinian principles, due to mutations introduced by replication error[2]. Recently, we have tested the adaptive evolutionary ability of the TcRR system. We continued the evolution experiment with a unique starting genomic RNA clone, an evolved RNA that emerged in the previous study[2], in five different severe translation environments in which different translation proteins were reduced. We already described the results of the evolution in reduced ribosome environment[3]. Here we report on the furher analysis, a combination of the results observed in the five different environments. This is the first attempt of in vitro adaptive evolution experiment in a variety of environments using an artificial self-replication system although some in a particular environment were conducted[3][4][5].