Human replicative DNA polymerase δ can bypass T-T (6-4) ultraviolet photoproducts on template strands

Takeo Narita, Toshiki Tsurimoto, Junpei Yamamoto, Kana Nishihara, Kaori Ogawa, Eiji Ohashi, Terry Evans, Shigenori Iwai, Shunichi Takeda, Kouji Hirota

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)


DNA polymerase δ (Polδ) carries out DNA replication with extremely high accuracy. This great fidelity primarily depends on the efficient exclusion of incorrect base pairs from the active site of the polymerase domain. In addition, the 3'-5' exonuclease activity of Polδ further enhances its accuracy by eliminating misincorporated nucleotides. It is believed that these enzymatic properties also inhibit Polδ from inserting nucleotides opposite damaged templates. To test this widely accepted idea, we examined in vitro DNA synthesis by human Polδ enzymes proficient and deficient in the exonuclease activity. We chose the UV-induced lesions cyclobutyl pyrimidine dimer (CPD) and 6-4 pyrimidone photoproduct (6-4 PP) as damaged templates. 6-4 PP represents the most formidable challenge to DNA replication, and no single eukaryotic DNA polymerase has been shown to bypass 6-4 PP in vitro. Unexpectedly, we found that Polδ can perform DNA synthesis across both 6-4 PP and CPD even with a physiological concentration of deoxyribonucleotide triphosphates (dNTPs). DNA synthesis across 6-4 PP was often accompanied by a nucleotide deletion and was highly mutagenic. This unexpected enzymatic property of Polδ in the bypass of UV photoproducts challenges the received notion that the accuracy of Polδ prevents bypassing damaged templates.

Original languageEnglish
Pages (from-to)1228-1239
Number of pages12
JournalGenes to Cells
Issue number12
Publication statusPublished - Dec 2010

All Science Journal Classification (ASJC) codes

  • Genetics
  • Cell Biology


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