Mismatch-specific thymine DNA glycosylase and DNA polymerase beta mediate the correction of G.T mispairs in nuclear extracts from human cells.
AUTOR(ES)
Wiebauer, K
RESUMO
To avoid the mutagenic effect of spontaneous hydrolytic deamination of 5-methylcytosine, G.T mispairs, arising in DNA as a result of this process, should always be corrected to G.C pairs. We describe here the identification of a DNA glycosylase activity present in nuclear extracts from HeLa cells, which removes the mispaired thymine to generate an apyrimidinic (AP) site opposite the guanine. We further show, using a specific antibody and inhibitors, that the single nucleotide gap, created upon processing of the AP site, is filled in by DNA polymerase beta. This finding substantiates the proposed role of this enzyme in short-patch DNA repair.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=54424Documentos Relacionados
- Efficient removal of uracil from G.U mispairs by the mismatch-specific thymine DNA glycosylase from HeLa cells.
- Base mismatch-specific endonuclease activity in extracts from Saccharomyces cerevisiae.
- 3,N4-ethenocytosine, a highly mutagenic adduct, is a primary substrate for Escherichia coli double-stranded uracil-DNA glycosylase and human mismatch-specific thymine-DNA glycosylase
- Mismatch-specific 3'----5' exonuclease associated with the mitochondrial DNA polymerase from Drosophila embryos.
- A 55-kDa protein isolated from human cells shows DNA glycosylase activity toward 3,N4-ethenocytosine and the G/T mismatch