and editing functions are encoded by separate genes, in the bacterial species Buchnera aphidicola the DNA polymerase encoded by the DNA III (polC) gene contains both DNA polymerase and 3' to 5' exonuclease domains. An evolutionary divergence (about 0.25 to 1.2 billion years ago), appears to have been associated with the separation of the DNA polymerase gene function from the 3' to 5' exonuclease editing gene function in the lineage that led to E. coli and S. typhimurium.

Discoveries in humans