DNA polymerase beta

DNA polymerase beta is a DNA polymerase encoded by the POLB gene, which is located on chromosome 8p11.21. DNA polymerase beta is involved in base excision and repair, a process also known as gap-filling DNA synthesis. DNA polymerase beta, which acts as a monomer, is normally located in the cytoplasm, but migrates to the nucleus when DNA is damaged.

DNA polymerase beta is a type of repair polymerase that plays a key role in base cut repair (Bennett RA et al. 1997; Matsumoto Y et al. 1998). During this process, the damaged base is excised by specific DNA glycosylases, the DNA backbone is nicked at the abasic site by an apurinic/apyrimidic (AP) endonuclease, and POLB removes 5'-deoxyribose phosphate from the pre-incised AP site by acting as a 5'-deoxyribose phosphate lyase (5'-dRP lyase); Through its DNA polymerase activity, it adds a nucleotide to the 3' end of the resulting single nucleotide gap (Kokkinakis DM et al. 2006). Performs "gap-filling" DNA synthesis in a stepwise distributive manner and not processively like other DNA polymerases. It is also able to cleave sugar-phosphate bonds 3' upstream of an intact AP site and thus acts as an AP lyase (Prasad R et al. 1998).

1. Bennett RA et al. (1997) Interaction of human apurinic endonuclease and DNA polymerase beta in the base excision repair pathway. Proc Natl Acad Sci U S A. 94:7166-7169.
2. Lang T et al. (2007) The E295K DNA polymerase beta gastric cancer-associated variant interferes with base excision repair and induces cellular transformation. Mol Cell Biol 27:5587-5596.
3. Kokkinakis DM et al. (2006) Mitotic arrest, apoptosis, and sensitization to chemotherapy of melanomas by methionine deprivation stress. Mol Cancer Res 4:575-589.
4. Matsumoto Y et al. (1998) Catalytic center of DNA polymerase beta for excision of deoxyribose phosphate groups. Biochemistry 37:6456-6464.
5. Prasad R et al. (1998) Human DNA polymerase beta deoxyribose phosphate lyase. Substrate specificity and catalytic mechanism. J Biol Chem 273:15263-15270