The lyase activity of the DNA repair protein beta-polymerase protects from DNA-damage-induced cytotoxicity

Nature. 2000 Jun 15;405(6788):807-10. doi: 10.1038/35015598.


Small DNA lesions such as oxidized or alkylated bases are repaired by the base excision repair (BER) pathway. BER includes removal of the damaged base by a lesion-specific DNA glycosylase, strand scission by apurinic/apyrimidinic endonuclease, DNA resynthesis and ligation. BER may be further subdivided into DNA beta-polymerase (beta-pol)-dependent single-nucleotide repair and beta-pol-dependent or -independent long patch repair subpathways. Two important enzymatic steps in mammalian single-nucleotide BER are contributed by beta-pol: DNA resynthesis of the repair patch and lyase removal of 5'-deoxyribose phosphate (dRP). Fibroblasts from beta-pol null mice are hypersensitive to mono-functional DNA-methylating agents, resulting in increases in chromosomal damage, apoptosis and necrotic cell death. Here we show that only the dRP lyase activity of beta-pol is required to reverse methylating agent hypersensitivity in beta-pol null cells. These results indicate that removal of the dRP group is a pivotal step in BER in vivo. Persistence of the dRP moiety in DNA results in the hypersensitivity phenotype of beta-pol null cells and may signal downstream events such as apoptosis and necrotic cell death.

MeSH terms

  • Cell Line
  • Cell Line, Transformed
  • DNA / biosynthesis
  • DNA / drug effects*
  • DNA / metabolism
  • DNA Damage*
  • DNA Methylation
  • DNA Polymerase beta / metabolism*
  • DNA Repair*
  • Deoxyribose / metabolism
  • Lyases / metabolism*
  • Methyl Methanesulfonate / toxicity*
  • Mutagens / toxicity*
  • Transfection


  • Mutagens
  • Deoxyribose
  • DNA
  • Methyl Methanesulfonate
  • DNA Polymerase beta
  • Lyases