The RNA-DNA world and the emergence of DNA-encoded heritable traits

Abstract

AbstractThe RNA world hypothesis of origin of life confers a central role to RNA molecules in information encoding and catalysis. Nevertheless, 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. 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 replicaseencoded DNA in low copy numbers and replicases in high copy numbers can dominate the population. Our work suggests a plausible pathway for the transition from an RNA world to a mixed RNA-DNA world characterized by Darwinian evolution, where DNA sequences encode heritable phenotypes.