G:U mismatches resulting from deamination of cytosine are the most common pro-mutagenic lesions occurring in DNA. Uracil is removed in a base-excision repair pathway by uracil DNA-glycosylase (UDG), which excises uracil from both single- and double-stranded DNA. The uracil DNA glycosylase family 2 consists of thymine DNA glycosylase (TDG) from eukaryotes and mismatch-specific uracil DNA glycosylase (MUG) from prokaryotes. Thymine DNA glycosylases (TDG) in eukaryotic organisms are known for their double-stranded glycosylase activity on guanine/uracil (G/U) base pairs []. In human TDG removes uracil and thymine from G:U and G:T mismatches in double-stranded DNA [, ]. In E. coli MUG is highly specific to G:U mismatches but also repairs G:T mismatches at high enzyme concentration. Structural studies of E. coli MUG reveal its structural homology to UDG despite low sequence identity. It has a specific uracil-binding pocket located in a DNA-binding groove and this specificity is likely the result of a multistep lesion recognition process [].
This entry includes a group of eukaryotic G/U mismatch-specific DNA glycosylases, including the uracil DNA glycosylase from fission yeasts and the thymine DNA glycosylase from animals. They excise the mismatched base from G:X mismatches, where X is uracil, thymine or 5-hydroxymethyluracil (5hmU). The mammalian thymine DNA glycosylase (TDG) may be involved in active DNA demethylation via the base excision repair pathway [, , ]. It can also act as a transcriptional co-activator or co-repressor [].G:U mismatches resulting from deamination of cytosine are the most common pro-mutagenic lesions occurring in DNA. Uracil is removed in a base-excision repair pathway by uracil DNA-glycosylase (UDG), which excises uracil from both single- and double-stranded DNA. The uracil DNA glycosylase family 2 consists of thymine DNA glycosylase (TDG) from eukaryotes and mismatch-specific uracil DNA glycosylase (MUG) from prokaryotes. Thymine DNA glycosylases (TDG) in eukaryotic organisms are known for their double-stranded glycosylase activity on guanine/uracil (G/U) base pairs []. In human TDG removes uracil and thymine from G:U and G:T mismatches in double-stranded DNA [, ]. In E. coli MUG is highly specific to G:U mismatches but also repairs G:T mismatches at high enzyme concentration. Structural studies of E. coli MUG reveal its structural homology to UDG despite low sequence identity. It has a specific uracil-binding pocket located in a DNA-binding groove and this specificity is likely the result of a multistep lesion recognition process [].
G:U mismatches resulting from deamination of cytosine are the most common pro-mutagenic lesions occurring in DNA. Uracil is removed in a base-excision repair pathway by uracil DNA-glycosylase (UDG),which excises uracil from both single- and double-stranded DNA. The uracil DNA glycosylase family 2 consists of thymine DNA glycosylase (TDG) from eukaryotes and mismatch-specific uracil DNA glycosylase (MUG) from prokaryotes. Thymine DNA glycosylases (TDG) in eukaryotic organisms are known for their double-stranded glycosylase activity on guanine/uracil (G/U) base pairs []. In human TDG removes uracil and thymine from G:U and G:T mismatches in double-stranded DNA [, ]. In E. coli MUG is highly specific to G:U mismatches but also repairs G:T mismatches at high enzyme concentration. Structural studies of E. coli MUG reveal its structural homology to UDG despite low sequence identity. It has a specific uracil-binding pocket located in a DNA-binding groove and this specificity is likely the result of a multistep lesion recognition process [].This family represents the bacterial G/U mismatch-specific DNA glycosylase MUG.
