| Autor: |
Ley, Ronald D., Applegate, Lee A., de Riel, Jon K., Henderson, Ear E. |
| Zdroj: |
Mutation Research/DNA Repair; March 1989, Vol. 217 Issue: 2 p101-107, 7p |
| Abstrakt: |
Introduction of the denV gene if phage T4, encoding the pyrimidine dimer-specific endonuclease V, into xeroderma pigmentosum cells XP12RO(M1) was reported to result in partial restoration of colony-forming ability and excision repair synthesis. We have further characterized 3 denV-transformed XP clones in terms of rates of excision of pyrimidine dimers and size of the resulting resynthesized regions following exposure to 100 J/M2from an FS-40 sunlamp. In the denV-transformed XP cells were observed 50% dimer removal within 3–6 h after UV exposure as compared to no measurable removal in the XP12RO(M1) line and 50% dimer excision after 18 h in the GM637A human, control cells. Dimer removal was assayed with Micrococcus luteusUV-endonucleasse in conjunction with sedimentation of treated DNA in alkaline sucrose gradients. The size of the resulting repaired regions was determined by the bromouracil photolysis technique. Based on the photolytic sensitivity of DNA repaired in the presence of bromodeoxyuridine, we calculated that the excision of a dimer in the GM637A cells to be accompanied by the resynthesis of a region ∼ 95 nucleotides in length. Conversely, the resynthesized regions in the denV-transformed clones were considerably smaller and were estimated to be between 13 and 18 nucleotides in length. These results may indicate that either the endonuclease that initiated dimer repair dictated the size of the resynthesized region or that the long-patch repair observed in the normal cells resulted from the repair of non-dimer DNA lesions. |
| Databáze: |
Supplemental Index |
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