Loss of thymine dimers from mammalian cell DNA. The kinetics for antibody-binding sites are not the same as that for T4 endonuclease V sites.
Antiserum specific for thymine-containing dimers was used to assay DNA isolated from ultraviolet-irradiated cells following different repair periods. A 50% loss in antibody-binding sites was evident 1 h post-irradiation, and within 4 h 80% of the sites were removed. This result contrasts with data obtained with dimer-specific T4 endonuclease V and does not appear to be due to masking of the dimers by repair enzymes. T4 endonuclease V treatment of ultraviolet-irradiated DNA at 0 degree C resulted in conversion of the thymine dimers to apyrimidinic sites. This did not result in loss of antigenicity in either PM2 or CHO cell DNA. Likewise, treatment of ultraviolet-irradiated CHO cell DNA with T4 endonuclease at 37 degrees C did not change its antigenicity. These results suggest that aglycosylation of the dimers is not responsible for their inability to bind dimer-specific antibody 2-4 h post-irradiation. The possibility that T4 endonuclease V and the antiserum have different specificities for different dimers is discussed.
D000818:Animals; D001080:Apurinic Acid / Q000276:immunology; D002478:Cells, Cultured; D006224:Cricetinae; D004247:DNA / Q000528:radiation effects; D004260:DNA Repair; D004706:Endodeoxyribonucleases; D004720:Endonucleases / Q000378:metabolism*; D000939:Epitopes; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D011740:Pyrimidine Dimers / Q000276:immunology / Q000378:metabolism*; D014466:Ultraviolet Rays
D000939:Epitopes; D011740:Pyrimidine Dimers; D001080:Apurinic Acid; D004247:DNA; D004706:Endodeoxyribonucleases; D004720:Endonucleases; C026044:deoxyribonuclease V