Evolving DNA Repair Polymerases: From Double—Strand Break Repair to Base Excision Repair and VDJ Recombination

Currently five polymerases have been identified in Escherichia coli, at least eight in Saccharo‐ myces cerevisiae, nine in Schizosaccharomyces pombe, and fourteen in humans [1-4]. Based on the primary structure of the catalytic subunits, DNA polymerases have been classified into different families. Eukaryotic organisms have four families: A family (Polγ, Polθ and Polν), B family (Polα, Polδ, Polε and Polζ), X family (Polß, Polλ, Polμ and TdT) and Y family (Polη, Polι, Polκ and Rev1), whose members were discovered in the last decade [5], and are involved in replication through DNA lesions. Another significant development was the discovery of Polλ [6] and Polμ [7], which doubled the number of known enzymes of the X family of DNA polymerases, whose members are involved in DNA repair and generation of variability.