Pyrimidine Dimer Formation and Oxidative Damage in M13 Bacteriophage Inactivation by Ultraviolet C Irradiation

Abstract The mechanism by which UV-C irradiation inactivates M13 bacteriophage was studied by analyzing the M13 genome using agarose gel electrophoresis and South-Western blotting for pyrimidine dimers. The involvement of singlet oxygen (1O2) was also investigated using azide and deuterium oxide and under deoxygenated conditions. With a decrease in M13 infectivity on irradiation, single-stranded circular genomic DNA (sc-DNA) was converted to Form I and Form II, which had an electrophoretic mobility between that of sc-DNA and linear-form DNA. However, the amount of sc-DNA remaining was not correlated with the survival of M13. The formation of cyclobutane pyrimidine dimers (CPD) and pyrimidine (6–4) pyrimidone photoproducts ((6–4)PP) increased as a function of irradiation dose. The decrease in M13 infectivity was highly correlated with the increase in CPD and (6–4)PP, whereas no change was seen in M13 coat protein on sodium dodecyl sulfate–polyacrylamide gel electrophoresis. 8-Oxo-7,8-dihydro-2′-deoxyguanos...