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Substrate specificity of Deinococcus radiodurans Fpg protein
S Sentürker1, C Bauche, J Laval
1Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8311, USA.
Biochemistry
|July 22, 1999
Summary
A DNA repair enzyme from Deinococcus radiodurans excises oxidative DNA base damage, preferring formamidopyrimidines over 8-hydroxyguanine. Its excision rates differ significantly from E. coli Fpg protein.
Area of Science:
- Molecular Biology
- Biochemistry
- DNA Repair
Background:
- A DNA repair enzyme homologous to E. coli Fpg protein was isolated from Deinococcus radiodurans.
- Oxidative DNA damage is a significant threat to genomic stability.
Purpose of the Study:
- To investigate the substrate specificity of the D. radiodurans Fpg protein.
- To compare the excision rates and substrate preferences with E. coli Fpg protein and S. cerevisiae Ogg1 protein.
Main Methods:
- Gas chromatography/isotope-dilution mass spectrometry was used to analyze DNA substrates.
- DNA substrates were damaged via gamma irradiation or chemical oxidation (H(2)O(2)/Fe(III)-EDTA/ascorbic acid).
- Excision of 17 lesions, including FapyGua, FapyAde, and 8-OH-Gua, was quantified.
Main Results:
- D. radiodurans Fpg protein excised FapyGua and FapyAde with similar specificities, and 8-OH-Gua less efficiently.
- Excision rates of D. radiodurans Fpg protein were significantly different from E. coli Fpg protein.
- E. coli Fpg protein showed similar efficiencies for all three lesions, while S. cerevisiae Ogg1 protein excised FapyGua and 8-OH-Gua but not FapyAde.
Conclusions:
- D. radiodurans Fpg protein exhibits distinct substrate specificity compared to its E. coli homolog.
- Formamidopyrimidines are preferred substrates for D. radiodurans Fpg protein.
- Comparative analysis reveals differential substrate preferences among Fpg and Ogg1 DNA repair enzymes.