Ogt

O6-alkyl guanine transferase II (O6 AGT II) previously known as O6 Guanine transferase (ogt) is a protein that is involved in DNA repair with Ada.[1]

Like Ada, AGT II is responsible for the removal of alkyl groups from O6-alkyl guanine, O4-alkyl thymine and alkyl phosphotriester in the sugar-phosphate backbone of DNA.[1] AGT II shows a greater preference for O4-alkyl thymine than O6-alkyl guanine and alkyl phosphotriester. [1][2]

Unlike Ada, AGT II is expressed constitutively in cells.[1][3] Therefore, AGT II will repair alkylated DNA adducts even before Ada is fully induced. AGT II is similar to Ada in its suicide inactivation in that AGT II transfers the alkyl group to a cysteine residue in its own structure, thereby inactivating itself.[1] The human equivalent of AGT II is MGMT (O6-methyl guanine methyl transferase). MGMT preferentially removes alkyl groups from O6-alkyl guanine than from O4–alkyl thymine.[1]

References

  1. ^ a b c d e f Friedberg, Errol; Graham C. Walker, Wolfram Siede, Richard D. Wood, Roger A. Schultz, Tom Ellenberger (2006). DNA Repair and Mutagenesis (2 ed.). Washington, DC: ASM Press. ISBN 1-55581-319-4. OCLC 59360087. 
  2. ^ Sassanfar M, Dosanjh MK, Essigmann JM, Samson L. Relative efficiencies of the bacterial, yeast, and human DNA methyltransferases for the repair of O6-methylguanine and O4-methylthymine. Suggestive evidence for O4-methylthymine repair by eukaryotic methyltransferases. J Biol Chem. 1991 Feb 15;266(5):2767-71. PMID 1993655.
  3. ^ Rebeck GW, Samson L. Increased spontaneous mutation and alkylation sensitivity of Escherichia coli strains lacking the ogt O6-methylguanine DNA repair methyltransferase. J Bacteriol. 1991 Mar;173(6):2068-76. PMID 2002008.