From RNA to DNA: Insights about the transition of informational molecule in the biological systems based on the structural proximity between the polymerases

Structural relations in an evolutionary context of polymerases is crucial to gain insights into the transition from an RNA world to a Ribonucleoprotein world. Herein, we present a structural proximity tree for the polymerases, from which we observe that the enzymes that have RNA as substrate are more homogeneous than the group with DNA as substrate. The homogeneity observed in enzymes with RNA as a substrate, may be because they performed all steps in information processing. In this sense, the emergence of the DNA molecule posed new challenges to the biological systems, where several parts of the informational flow were individualized by the emergence of enzymes for each step. From the data presented, we propose a polymerase diversification model, in which we have RNA-dependent RNA polymerases as an ancestor and all other polymerases diverged directly from this group by a radiation process.