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Catalytic Site Atlas

CSA LITERATURE entry for 1c3j

E.C. nameDNA beta-glucosyltransferase
SpeciesBacteriophage t4 (Virus)
E.C. Number (IntEnz) 2.4.1.27
CSA Homologues of 1c3jThere are 19 Homologs
CSA Entries With UniProtID P04547
CSA Entries With EC Number 2.4.1.27
PDBe Entry 1c3j
PDBSum Entry 1c3j
MACiE Entry M0339

Literature Report

IntroductionDNA beta-glucosyltransferase (BGT) is an enzyme encoded by a number of bacteriophage belonging to the T-even group. It catalyses the transfer of glucose from uridine diphosphoglucose (UDP-glucose) to 5-hydroxymethylcytosine (5-HMC) bases in double stranded DNA. Such glucosylation protects the infecting viral DNA from host restrictive enzymes. It may, in addition, be involved in phage specific gene expression by influencing transcription. Glucosylation also occurs in Trypanosoma bruceii where it is thought to be involved in regulating the expression of variant surface glycoproteins used by the parasite for protection against immune recognition. BGT is one of two enzymes involved in the glucosylation. In contrast to its counterpart which catalyses the formation of alpha-, it forms beta-glycosidic linkages
MechansimAlthough previous proposals for a mechanism involve a general acid catalysis requiring two critical residues, a proton donor and a nucleophile/base current models suggest an alternative. BGT binds two substrates, UDP-glucose and 5-HMC. Glucose transfer occurs by a direct nucleophilic attack by the hydroxyl group of 5-HMC to form a beta-glucosidic bond followed by inversion of configuration. A catalytic base, thought to be Asp100 or Glu22, is provided by the enzyme to abstract a proton from the hydroxyl group activating the attack. Multiple contacts are thought to be made by the enzyme on the substrates but as yet are all speculative.

Catalytic Sites for 1c3j

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
GluA2222macie:sideChain
AspA100100macie:sideChain

Literature References

Notes:
Moréra S
T4 phage beta-glucosyltransferase: substrate binding and proposed catalytic mechanism.
J Mol Biol 1999 292 717-730
PubMed: 10497034
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