The Role of Natural Polymorphic Variants of DNA Polymerase beta in DNA Repair

DNA polymerase beta (Pol beta) is considered the main repair DNA polymerase involved in the base excision repair (BER) pathway, which plays an important part in the repair of damaged DNA bases usually resulting from alkylation or oxidation. In general, BER involves consecutive actions of DNA glycosylases, AP endonucleases, DNA polymerases, and DNA ligases. It is known that protein-protein interactions of Pol beta with enzymes from the BER pathway increase the efficiency of damaged base repair in DNA. However natural single-nucleotide polymorphisms can lead to a substitution of functionally significant amino acid residues and therefore affect the catalytic activity of the enzyme and the accuracy of Pol beta action. Up-to-date databases contain information about more than 8000 SNPs in the gene of Pol beta. This review summarizes data on the in silico prediction of the effects of Pol beta SNPs on DNA repair efficacy; available data on cancers associated with SNPs of Pol beta; and experimentally tested variants of Pol beta. Analysis of the literature indicates that amino acid substitutions could be important for the maintenance of the native structure of Pol beta and contacts with DNA; others affect the catalytic activity of the enzyme or play a part in the precise and correct attachment of the required nucleotide triphosphate. Moreover, the amino acid substitutions in Pol beta can disturb interactions with enzymes involved in BER, while the enzymatic activity of the polymorphic variant may not differ significantly from that of the wild-type enzyme. Therefore, investigation regarding the effect of Pol beta natural variants occurring in the human population on enzymatic activity and protein-protein interactions is an urgent scientific task.