Uracil-DNA glycosylases are widespread enzymes that are found in all living organisms. EC 3.2.2.27 and double-stranded uracil-DNA glycosylase (EC 3.2.2.28) form a central part of the DNA-repair machinery since they initiate the DNA base-excision repair pathway by hydrolysing the N-glycosidic bond between uracil and the deoxyribose sugar thereby catalysing the removal of mis-incorporated uracil from DNA.
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
Hydrolyses single-stranded DNA or mismatched double-stranded DNA and polynucleotides, releasing free uracil
catalytic reaction mechanism, the active side comprises the GEGPG motif, residues 40-44, the side-chain of Arg161 in family 4 TthUDG might play a role in binding AP-DNA after catalysis
Hydrolyses single-stranded DNA or mismatched double-stranded DNA and polynucleotides, releasing free uracil
a conserved asparagine residue acts as a ligand to the catalytic water molecule, and another water molecule acts as a barrier during substrate recognition, slide-in mechanism for initial damage recognition, catalytic reaction mechanism, overview
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SYSTEMATIC NAME
IUBMB Comments
uracil-DNA deoxyribohydrolase (uracil-releasing)
Uracil-DNA glycosylases are widespread enzymes that are found in all living organisms. EC 3.2.2.27 and double-stranded uracil-DNA glycosylase (EC 3.2.2.28) form a central part of the DNA-repair machinery since they initiate the DNA base-excision repair pathway by hydrolysing the N-glycosidic bond between uracil and the deoxyribose sugar thereby catalysing the removal of mis-incorporated uracil from DNA.
UDG removes uracil from DNA to initiate DNA base excision repair, Thermus thermophilus UDG processes both single-stranded and double-stranded DNA containing uracil, regardless of opposing base, but does not process G-T mismatched DNA, nor does it possess AP endonuclease activity, uracil bases in U-A mismatches are excised less efficiently, due to the stability of that particular base-pair. The UDG possesses a [4Fe-4S] cluster, distant from the active site, which interacts with loop structures and is unessential to the activity but necessary for stabilizing the loop structures. Uracil recognition mechanism, overview
UDG removes uracil from DNA to initiate DNA base excision repair, Thermus thermophilus UDG processes both single-stranded and double-stranded DNA containing uracil, regardless of opposing base, but does not process G-T mismatched DNA, nor does it possess AP endonuclease activity, uracil bases in U-A mismatches are excised less efficiently, due to the stability of that particular base-pair. The UDG possesses a [4Fe-4S] cluster, distant from the active site, which interacts with loop structures and is unessential to the activity but necessary for stabilizing the loop structures. Uracil recognition mechanism, overview
UDG is an essential enzyme for maintaining the integrity of genomic information, it is the first enzyme of a base excision repair, BER, pathway that corrects uracil lesions. TthUDG specifically recognizes uracil that is flipped out from double-stranded DNA, in a manner similar to that of the family 1 human UDG, rather than binding to the guanine base of the complementary strand in mismatched DNA, as does the family 2 Escherichia coli MUG
UDG removes uracil generated by the deamination of cytosine or misincorporation of deoxyuridine monophosphate. The fifth UDG family lacks a polar residue in the active-site motif, which mediates the hydrolysis of the glycosidic bond by activation of a water molecule in UDG families 1 to 4
UDG is an essential enzyme for maintaining the integrity of genomic information, it is the first enzyme of a base excision repair, BER, pathway that corrects uracil lesions. TthUDG specifically recognizes uracil that is flipped out from double-stranded DNA, in a manner similar to that of the family 1 human UDG, rather than binding to the guanine base of the complementary strand in mismatched DNA, as does the family 2 Escherichia coli MUG
UDG removes uracil generated by the deamination of cytosine or misincorporation of deoxyuridine monophosphate. The fifth UDG family lacks a polar residue in the active-site motif, which mediates the hydrolysis of the glycosidic bond by activation of a water molecule in UDG families 1 to 4
the UDG possesses a [4Fe-4S] cluster, distant from the active site, which interacts with loop structures and is unessential to the activity but necessary for stabilizing the loop structures
the UDG possesses a [4Fe-4S] cluster, distant from the active site, which interacts with loop structures and is unessential to the activity but necessary for stabilizing the loop structures, salt-bridges and ion pairs on the molecular surface and the presence of proline on loops and turns contribute to the enzyme's thermostability
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CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
family 4 UDG in complex with uracil, hanging drop vapor diffusion method, mixing of 0.002 ml of 13 mg/ml of selenomethionyl protein solution with 0.002 ml of 1.2-1.5 M ammonium sulfate, 25% v/v glycerol, and 75 mM Tris-HCl, pH 8.5, and equilibration against 0.3 ml of the reservoir solution at 4°C, X-ray diffraction structure determination and analysis at 1.5 A resolution
recombinant family 5 UDGB, as free protein or selenomethionine-labeled protein, or in complex with rAP-G DNA and rAP-A DNA, hanging drop vapor diffusion method, 0.001 ml drops of 11 mg/ml TtUDGB are mixed with 0.001 ml of 9-13% v/v PEG 3350, 0.2 M ammonium acetate, 5% v/v glycerol and 0.1 M MES, pH 6.5, and equilibrated against 0.5 ml of the reservoir solution at 20°C. X-ray diffraction structure determination and analysis at 1.45-2.1 A resolution, molecular replacement
the D75A mutant shows low enzymatic activity for the removal of uracil from U-G or thymine from T-G. However, the mutant can distinguish between the C5-hydrogen and the C5-methyl group
recombinant wild-type and selenomethionine-labeled enzymes from Escherichia coli strain BL21(DE3) by hydrophobic interaction and anion exchange chromatography, followed by hydroxyapatite adsorption chromatography and gel filtration