Mammalian DNA beta-polymerase in base excision repair of alkylation damage.

Abstract

DNA beta-polymerase (beta-pol) carries out two critical enzymatic reactions in mammalian single-nucleotide base excision repair (BER): DNA synthesis to fill the repair patch and lyase removal of the 5'-deoxyribose phosphate (dRP) group following cleavage of the abasic site by apurinic/apyrimidinic (AP) endonuclease (1). The requirement for beta-pol in single-nucleotide BER is exemplified in mouse fibroblasts with a null mutation in the beta-pol gene. These cells are hypersensitive to monofunctional DNA methylating agents such as methyl methane-sulfonate (MMS) (2). This hypersensitivity is associated with an abundance of chromosomal damage and induction of apoptosis and necrotic cell death (3). We have found that beta-pol null cells are defective in repair of MMS-induced DNA lesions, consistent with a cellular BER deficiency as a causative agent in the observed hypersensitivity. Further, the N-terminal 8-kDa domain of beta-pol, which contains the dRP lyase activity in the wild-type enzyme, is sufficient to reverse the methylating agent hypersensitivity in beta-pol null cells. These results indicate that lyase removal of the dRP group is a pivotal step in BER in vivo. Finally, we examined MMS-induced genomic DNA mutagenesis in two isogenic mouse cell lines designed for study of the role of BER. MMS exposure strongly increases mutant frequency in beta-pol null cells, but not in wild-type cells. With MMS treatment, beta-pol null cells have a higher frequency of all six base-pair substitutions, suggesting that BER plays a role in protecting the cell against methylation-induced mutations.

• Authors: R W Sobol, S H Wilson
• Journal: Progress in nucleic acid research and molecular biology (Prog Nucleic Acid Res Mol Biol) Vol. 68 Pg. 57-74 ( 2001) ISSN: 0079-6603 [Print] United States
• PMID: 11554313 (Publication Type: Journal Article, Review)

Chemical References

• Mutagens
• Recombinant Fusion Proteins
• Ribosemonophosphates
• Aspartic Acid
• 5-deoxyribose 1-phosphate
• Methyl Methanesulfonate
• 5'-deoxyribose phosphate lyase
• DNA Polymerase beta
• Deoxyribonuclease IV (Phage T4-Induced)
• Carbon-Oxygen Lyases
• DNA-(Apurinic or Apyrimidinic Site) Lyase
• Phosphorus-Oxygen Lyases
• DNA Ligases

Topics

• Alkylation
• Animals
• Aspartic Acid (chemistry)
• Bacteriophage lambda (genetics)
• Carbon-Oxygen Lyases (physiology)
• DNA Damage
• DNA Ligases (physiology)
• DNA Polymerase beta (chemistry, deficiency, genetics, physiology)
• DNA Repair
• DNA-(Apurinic or Apyrimidinic Site) Lyase
• Deoxyribonuclease IV (Phage T4-Induced)
• Fibroblasts (cytology, drug effects)
• Genotype
• Methyl Methanesulfonate (toxicity)
• Methylation
• Mice
• Mutagenesis
• Mutagenesis, Site-Directed
• Mutagens (toxicity)
• Phosphorus-Oxygen Lyases (physiology)
• Protein Structure, Tertiary
• Recombinant Fusion Proteins (metabolism)
• Ribosemonophosphates (chemistry)