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ABSTRACTUracil DNA glycosylases (UDGs) excise uracil from DNA arising from dUMP misincorporation ... more ABSTRACTUracil DNA glycosylases (UDGs) excise uracil from DNA arising from dUMP misincorporation during replication or from cytosine deamination. Besides functioning in canonical uracil repair, UDGs cooperate with DNA base modifying enzymes to effect mutagenesis or DNA demethylation. Mammalian cells express four UDGs, the functional dissection of which represents a challenge. Here, we usedSchizosaccharomyces pombewith only two UDGs, Ung1 and Thp1, as a simpler model to study functional interactions in uracil repair. We show that despite a predominance of Ung1 activity in cell extracts, both UDGs act redundantly against genomic uracil accumulation and mutations from cytosine deamination in cells. Notably, Thp1 but not Ung1-dependent repair is cytotoxic under genomic uracil stress induced by 5-fluorouracil exposure or AID expression. Also, Thp1-but not Ung1-mediated base excision is recombinogenic, accounting for more than 60% of spontaneous mitotic recombination events in a recombina...
Human thymine-DNA glycosylase (TDG) is well known to excise thymine and uracil from G´T and G´U m... more Human thymine-DNA glycosylase (TDG) is well known to excise thymine and uracil from G´T and G´U mismatches, respectively, and was therefore proposed to play a central role in the cellular defense against genetic mutation through spon-taneous deamination of 5-methylcytosine and cyto-sine. In this study, we characterized two newly discovered orthologs of TDG, the Drosophila melanogaster Thd1p and the Schizosaccharomyces pombe Thp1p proteins, with an objective to address the function of this subfamily of uracil-DNA glycosylases from an evolutionary perspective. A systematic biochemical comparison of both enzymes with human TDG revealed a number of biologically signi®cant facts. (i) All eukaryotic TDG orthologs have broad and species-speci®c substrate spectra that include a variety of damaged pyrimidine and purine bases; (ii) the common most ef®ciently processed substrates of all are uracil and 3,N4-ethenocytosine opposite guanine and 5-¯uorouracil in any double-stranded DNA context; (i...
Cardiovascular Revascularization Medicine
Journal of the American College of Cardiology
JACC: Cardiovascular Interventions
Cardiovascular Revascularization Medicine
Nucleic Acids Research, 2003
Human thymine-DNA glycosylase (TDG) is well known to excise thymine and uracil from G´T and G´U m... more Human thymine-DNA glycosylase (TDG) is well known to excise thymine and uracil from G´T and G´U mismatches, respectively, and was therefore proposed to play a central role in the cellular defense against genetic mutation through spontaneous deamination of 5-methylcytosine and cytosine. In this study, we characterized two newly discovered orthologs of TDG, the Drosophila melanogaster Thd1p and the Schizosaccharomyces pombe Thp1p proteins, with an objective to address the function of this subfamily of uracil-DNA glycosylases from an evolutionary perspective. A systematic biochemical comparison of both enzymes with human TDG revealed a number of biologically signi®cant facts. (i) All eukaryotic TDG orthologs have broad and species-speci®c substrate spectra that include a variety of damaged pyrimidine and purine bases; (ii) the common most ef®ciently processed substrates of all are uracil and 3,N4ethenocytosine opposite guanine and 5-¯uorouracil in any double-stranded DNA context; (iii) 5-methylcytosine and thymine derivatives are processed with an appreciable ef®ciency only by the human and the Drosophila enzymes; (iv) none of the proteins is able to hydrolyze a non-damaged 5¢-methylcytosine opposite G; and (v) the double strand and mismatch dependency of the enzymes varies with the substrate and is not a stringent feature of this subfamily of DNA glycosylases. These ®ndings advance our current view on the role of TDG proteins and document that they have evolved with high structural exibility to counter a broad range of DNA base damage in accordance with the speci®c needs of individual species.
Journal of Biological Chemistry, 2000
Journal of Biological Chemistry, 2000
ABSTRACTUracil DNA glycosylases (UDGs) excise uracil from DNA arising from dUMP misincorporation ... more ABSTRACTUracil DNA glycosylases (UDGs) excise uracil from DNA arising from dUMP misincorporation during replication or from cytosine deamination. Besides functioning in canonical uracil repair, UDGs cooperate with DNA base modifying enzymes to effect mutagenesis or DNA demethylation. Mammalian cells express four UDGs, the functional dissection of which represents a challenge. Here, we usedSchizosaccharomyces pombewith only two UDGs, Ung1 and Thp1, as a simpler model to study functional interactions in uracil repair. We show that despite a predominance of Ung1 activity in cell extracts, both UDGs act redundantly against genomic uracil accumulation and mutations from cytosine deamination in cells. Notably, Thp1 but not Ung1-dependent repair is cytotoxic under genomic uracil stress induced by 5-fluorouracil exposure or AID expression. Also, Thp1-but not Ung1-mediated base excision is recombinogenic, accounting for more than 60% of spontaneous mitotic recombination events in a recombina...
Human thymine-DNA glycosylase (TDG) is well known to excise thymine and uracil from G´T and G´U m... more Human thymine-DNA glycosylase (TDG) is well known to excise thymine and uracil from G´T and G´U mismatches, respectively, and was therefore proposed to play a central role in the cellular defense against genetic mutation through spon-taneous deamination of 5-methylcytosine and cyto-sine. In this study, we characterized two newly discovered orthologs of TDG, the Drosophila melanogaster Thd1p and the Schizosaccharomyces pombe Thp1p proteins, with an objective to address the function of this subfamily of uracil-DNA glycosylases from an evolutionary perspective. A systematic biochemical comparison of both enzymes with human TDG revealed a number of biologically signi®cant facts. (i) All eukaryotic TDG orthologs have broad and species-speci®c substrate spectra that include a variety of damaged pyrimidine and purine bases; (ii) the common most ef®ciently processed substrates of all are uracil and 3,N4-ethenocytosine opposite guanine and 5-¯uorouracil in any double-stranded DNA context; (i...
Cardiovascular Revascularization Medicine
Journal of the American College of Cardiology
JACC: Cardiovascular Interventions
Cardiovascular Revascularization Medicine
Nucleic Acids Research, 2003
Human thymine-DNA glycosylase (TDG) is well known to excise thymine and uracil from G´T and G´U m... more Human thymine-DNA glycosylase (TDG) is well known to excise thymine and uracil from G´T and G´U mismatches, respectively, and was therefore proposed to play a central role in the cellular defense against genetic mutation through spontaneous deamination of 5-methylcytosine and cytosine. In this study, we characterized two newly discovered orthologs of TDG, the Drosophila melanogaster Thd1p and the Schizosaccharomyces pombe Thp1p proteins, with an objective to address the function of this subfamily of uracil-DNA glycosylases from an evolutionary perspective. A systematic biochemical comparison of both enzymes with human TDG revealed a number of biologically signi®cant facts. (i) All eukaryotic TDG orthologs have broad and species-speci®c substrate spectra that include a variety of damaged pyrimidine and purine bases; (ii) the common most ef®ciently processed substrates of all are uracil and 3,N4ethenocytosine opposite guanine and 5-¯uorouracil in any double-stranded DNA context; (iii) 5-methylcytosine and thymine derivatives are processed with an appreciable ef®ciency only by the human and the Drosophila enzymes; (iv) none of the proteins is able to hydrolyze a non-damaged 5¢-methylcytosine opposite G; and (v) the double strand and mismatch dependency of the enzymes varies with the substrate and is not a stringent feature of this subfamily of DNA glycosylases. These ®ndings advance our current view on the role of TDG proteins and document that they have evolved with high structural exibility to counter a broad range of DNA base damage in accordance with the speci®c needs of individual species.
Journal of Biological Chemistry, 2000
Journal of Biological Chemistry, 2000