The Base Substitution Fidelity of DNA Polymerase β-dependent Single Nucleotide Base Excision Repair
Damaged DNA bases are removed from mammalian genomes by base excision repair (BER). Single nucleotide BER requires several enzymatic activities, including DNA polymerase and 5â²,2â²-deoxyribose-5-phosphate lyase. Both activities are intrinsic to four human DNA polymerases whose base substitution e...
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Published in | The Journal of biological chemistry Vol. 278; no. 28; p. 25947 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
American Society for Biochemistry and Molecular Biology
11.07.2003
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Online Access | Get full text |
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Summary: | Damaged DNA bases are removed from mammalian genomes by base excision
repair (BER). Single nucleotide BER requires several enzymatic activities,
including DNA polymerase and 5â²,2â²-deoxyribose-5-phosphate lyase.
Both activities are intrinsic to four human DNA polymerases whose base
substitution error rate during gap-filling DNA synthesis varies by more than
10,000-fold. This suggests that BER fidelity could vary over a wide range in
an enzyme dependent manner. To investigate this possibility, here we describe
an assay to measure the fidelity of BER reactions reconstituted with purified
enzymes. When human uracil DNA glycosylase, AP endonuclease, DNA polymerase
β, and DNA ligase 1 replace uracil opposite template A or G, base
substitution error rates are â¤0.3 to â¤2.8 Ã
10 â 4 . BER error rates are higher when excess
incorrect dNTPs are included in the reaction or when wild type DNA polymerase
β is replaced by DNA polymerase β variants that fill single
nucleotide gaps with lower fidelity. Under these conditions, the base
substitution fidelity of polymerase β-dependent BER is 3â8-fold
higher than is single nucleotide gap filling by polymerase β alone. Thus
other proteins in the BER reaction may enhance the base substitution fidelity
of DNA polymerase β during single nucleotide BER. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1074/jbc.C300170200 |