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Human replicative DNA polymerase δ can bypass T‐T (6‐4) ultraviolet photoproducts on template strands
Author(s) -
Narita Takeo,
Tsurimoto Toshiki,
Yamamoto Junpei,
Nishihara Kana,
Ogawa Kaori,
Ohashi Eiji,
Evans Terry,
Iwai Shigenori,
Takeda Shunichi,
Hirota Kouji
Publication year - 2010
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1111/j.1365-2443.2010.01457.x
Subject(s) - dna polymerase , biology , dna replication , dna polymerase ii , exonuclease , polymerase , pyrimidine dimer , processivity , dna clamp , dna , base excision repair , dna polymerase delta , dna synthesis , microbiology and biotechnology , biochemistry , dna repair , polymerase chain reaction , gene , reverse transcriptase
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.