Toward a reciprocal evolution system between RNA and peptides as an artificial model for the early RNP world.

In the early stages of the evolution of life, RNA-polypeptide complexes (RNPs) have been suggested to play crucial roles. At a certain developmental stage of ancient RNPs, their RNA and polypeptide components could evolve in an interdependent manner to develop complex structures and functions. To mimic this possible process, we have designed an RNA molecule that can act as a template for chemical peptide ligation. This designed RNA possesses two peptide-binding sites that capture the two basic peptides. The designed RNA actually facilitated the peptide ligation. The resulting ligated peptide, which has two RNA binding sites, can in turn function as a trans-activator that enhances the intrinsic ribozymatic activity of the designed RNA.