Acetylation of human 8-oxoguanine-DNA glycosylase by p300 and its role in 8-oxoguanine repair in vivo.

The human 8-oxoguanine-DNA glycosylase 1 (OGG1) is the major DNA glycosylase responsible for repair of 7,8-dihydro-8-oxoguanine (8-oxoG) and ring-opened fapyguanine, critical mutagenic DNA lesions that are induced by reactive oxygen species. Here we show that OGG1 is acetylated by p300 in vivo predominantly at Lys338/Lys341. About 20% of OGG1 is present in acetylated form in HeLa cells.

Stimulation of DNA glycosylase activity of OGG1 by NEIL1: functional collaboration between two human DNA glycosylases.

The eukaryotic 8-oxoguanine-DNA glycosylase 1 (OGG1) provides the major activity for repairing mutagenic 7,8-dihydro-8-oxoguanine (8-oxoG) induced in the genome due to oxidative stress. Earlier in vitro studies showed that, after excising the base lesion, the human OGG1 remains bound to the resulting abasic (AP) site in DNA and does not turn over efficiently. The human AP-endonuclease (APE1), which cleaves the phosphodiester bond 5' to the AP site, in the next step of repair, displaces the bound OGG1 and thus increases its turnover.

Dideoxynucleoside triphosphate-sensitive DNA polymerase from rice is involved in base excision repair and immunologically similar to mammalian DNA pol beta.

A single polypeptide with ddNTP-sensitive DNA polymerase activity was purified to near homogeneity from the shoot tips of rice seedlings and analysis of the preparations by SDS-PAGE followed by silver staining showed a polypeptide of 67 kDa size. The DNA polymerase activity was found to be inhibitory by ddNTP in both in vitro DNA polymerase activity assay and activity gel analysis. Aphidicolin, an inhibitor of other types of DNA polymerases, had no effect on plant enzyme.

Lack of dependance of transcription-induced cytosine deaminations on protein synthesis.

Transcription-induced mutations (TIM) is a phenomenon in Escherichia coli in which transcription promotes C to T and other mutations in a strand-specific manner. Because the processes of transcription and translation are coupled in prokaryotes and some models regarding creating a hypermutagenic state in E. coli require new protein synthesis, we tested the possibility that TIM was dependent on efficient synthesis of proteins.

Identification and characterization of a novel human DNA glycosylase for repair of cytosine-derived lesions.

Two candidate human orthologs of Escherichia coli MutM/Nei were recently identified in the human genome database, and one of these, NEH1, was characterized earlier (Hazra, T. K., Izumi, T.