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Search The CSA
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Catalytic Site Atlas

CSA LITERATURE entry for 1mug

E.C. namedouble-stranded uracil-DNA glycosylase
SpeciesEscherichia coli (Bacteria)
E.C. Number (IntEnz) 3.2.2.28
CSA Homologues of 1mugThere are 16 Homologs
CSA Entries With UniProtID P0A9H1
CSA Entries With EC Number 3.2.2.28
PDBe Entry 1mug
PDBSum Entry 1mug
MACiE Entry 1mug

Literature Report

IntroductionMismatched base pairing between G and U or G and T is common in DNA replication and would lead to substitution mutations. Therefore the enzyme G:T/U MISMATCH-SPECIFIC DNA GLYCOSYLASE is vital in preserving the integrity of DNA: it is able to hydrolyse the glycosidic bond to release the uracil or thymine base, thus creating an abasic site which allows the entire nucleotide to be recognised and removed. The enzyme shows significant structural and functional similarity to the well characterised family of Uracil DNA glycosylases which remove uracil wherever it occurs in DNA; however there is very little sequence similarity suggesting that convergent evolution may be responsible for the similarities observed.
MechansimThe mechanism proceeds via the attack of a nucleophilic water molecule on the carbon atom of the glycosidic bond. Activation of the water molecule is achieved by Asn 18's electrostatic interactions with the lone pair and hydrogen atom of the water. The uracil moiety then acts as the leaving group, abstracting a proton from the attacking water molecule. This reaction mechanism therefore is slow compared to the general acid/general base mechanism employed by the UDG family.
Reaction

Catalytic Sites for 1mug

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
AsnA1818macie:sideChainActivates water to allow it to act as a nucleophile and attack the glycosidic bond.

Literature References

Notes:
Barrett TE
Crystal structure of a G:T/U mismatch-specific DNA glycosylase: mismatch recognition by complementary-strand interactions.
Cell 1998 92 117-129
PubMed: 9489705
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