DNA lesion and mutagenesis induced in phageM13mp2 by UVA, UVB and UVC irradiation.

Sunlight is carcinogenic and mutagenic and its genotoxic effects are believed to be the result of UV light-induced lesions in DNA. These lesions include pyrimidine dimers and (6-4) photoproducts, but it is uncertain whether the pyrimidine modifications are the sole pre-mutagenic lesions induced by UV light. Previous studies indicate that some sunlight-induced mutations in the single-stranded DNA phage M13mp2 may not be caused by these photoproducts. In this work, purified single-stranded phage DNA was exposed to UVA, UVB and UVC and the induced mutations were analyzed. All 3 types of UV light increase the mutation frequency. The mutants were sequenced and the results suggest that UVA exposure may induce formation of a non-dipyrimidine lesion in DNA.