| Autor: |
Pegg, Anthony E., Kanugula, Sreenivas, Edara, Suvarchala, Pauly, Gary T., Moschel, Robert C., Goodtzova, Karina |
| Zdroj: |
Journal of Biological Chemistry; May 1998, Vol. 273 Issue: 18 p10863-10867, 5p |
| Abstrakt: |
Inactivation of the human DNA repair protein,O6-alkylguanine-DNA alkyltransferase (AGT), byO6-benzylguanine renders tumor cells susceptible to killing by alkylating agents. AGT mutants resistant toO6-benzylguanine can be made by converting Pro140to an alanine (P140A) or Gly156to an alanine (G156A). These mutations had a much smaller effect on the reaction with O6-benzylguanine when it was incorporated into a short single-stranded oligodeoxyribonucleotide. Such oligodeoxyribonucleotides could form the basis for the design of improved AGT inhibitors. AGT and mutants P140A and G156A preferentially reacted with O6-benzylguanine when incubated with a mixture of two 16-mer oligodeoxyribonucleotides, one containingO6-benzylguanine and the other,O6-methylguanine. When the 6 amino acids located in positions 159–164 in AGT were replaced by the equivalent sequence from the Escherichia coliAda-C protein (mutant AGT/6ada) the preference for benzyl repair was eliminated. Further mutation incorporating the P140A change into AGT/6ada giving mutant P140A/6ada led to a protein that resembled Ada-C in preference for the repair of methyl groups, but P140A/6ada did not differ from P140A in reaction with the free base O6-benzylguanine. Changes in the AGT active site pocket can therefore affect the preference for repair of O6-benzyl or -methyl groups when present in an oligodeoxyribonucleotide without altering the reaction with free O6-benzylguanine. |
| Databáze: |
Supplemental Index |
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