Exonuclease III recognizes urea residues in oxidized DNA.
AUTOR(ES)
Kow, Y W
RESUMO
Escherichia coli exonuclease III was found to be associated with an activity that recognizes urea residues in DNA but not thymine glycol residues from which the urea residues were prepared. This activity was not due to a contaminating activity such as endonuclease III since urea-containing DNA was a competitive inhibitor of exonuclease III when apurinic DNA was used as a substrate and vice versa. The apparent kinetic constants for both the substrate and inhibitor were determined. Like its apurinic activity, exonuclease III activity against urea residues was endonucleolytic, nicking on the 5' side of the damage and having an optimal Mg2+ concentration between 2 and 10 mM. Also, the enzyme recognized alkali-stable damages produced in DNA by H2O2 in vitro. We suggest that it may be this activity of exonuclease III that accounts for its biological role in vivo.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=390914Documentos Relacionados
- Apurinic endonucleases from Saccharomyces cerevisiae also recognize urea residues in oxidized DNA.
- Role of exonuclease III in the base excision repair of uracil-containing DNA.
- SRY, like HMG1, recognizes sharp angles in DNA.
- A peptide motif that recognizes A.T tracts in DNA.
- A plant DNA-binding protein that recognizes 5-methylcytosine residues.
