1sfe
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ADA O6-METHYLGUANINE-DNA METHYLTRANSFERASE FROM ESCHERICHIA COLI
OverviewOverview
The mutagenic and carcinogenic effects of simple alkylating agents are mainly due to methylation at the O6 position of guanine in DNA. O6-methylguanine directs the incorporation of either thymine or cytosine without blocking DNA replication, resulting in GC to AT transition mutations. In prokaryotic and eukaryotic cells antimutagenic repair is effected by direct reversal of this DNA damage. A suicidal methyltransferase repair protein removes the methyl group from DNA to one of its own cysteine residues. The resulting self-methylation of the active site cysteine renders the protein inactive. Here we report the X-ray structure of the 19 kDa C-terminal domain of the Escherichia coli ada gene product, the prototype of these suicidal methyltransferases. In the crystal structure the active site cysteine is buried. We propose a model for the significant conformational change that the protein must undergo in order to bind DNA and effect methyl transfer.
About this StructureAbout this Structure
1SFE is a Single protein structure of sequence from Escherichia coli. Active as [protein-cysteine_S-methyltransferase Methylated-DNA--[protein]-cysteine S-methyltransferase], with EC number 2.1.1.63 Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of a suicidal DNA repair protein: the Ada O6-methylguanine-DNA methyltransferase from E. coli., Moore MH, Gulbis JM, Dodson EJ, Demple B, Moody PC, EMBO J. 1994 Apr 1;13(7):1495-501. PMID:8156986 [[Category: Methylated-DNA--[protein]-cysteine S-methyltransferase]]
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