Effects of recB, recF and uvrA mutations on Weigle reactivation of λ phages in Escherichia coli K12 treated with 8-methoxypsoralen or angelicin and 365-nm light

Abstract

The extent of Weigle reactivation (W-R) of λ c + phages treated with bifunctional 8-methoxypsoralen and 365-nm ligh (8-MOP + UVA) and with monofunctional angelicin and 365-nm light (ANG + UVA) were compared in Escherichia coli strains with diffferent excision repair and recombinational capacities. In uvrA6 host cells, irradiation of the cells with 254-nm radiation only decreased the survival of phages treated with 8-MOP + UVA. The extent of W-R of ANG + UVA-treated phages in uvrA6 cells, however, was much larger than that obtained in other host cells. These results indicate that monoadducts produced by ANG + UVA treatment can be repaired effectively by the repair induced without uvrA gene products, but lesions produced by 8-MOP + UVA treatment cannot be repaired by the repair. The small W-R of ANG + UVA-treated phages in wild-type cells may be due to the high repairability of the lesions by constitutive excision repair in the cells. recB21 reduced only a little of the W-R of 8-MOP + UVA- or ANG + UVA-treated phages obtained in wild-type cells. Although recF143 cells have an almost comparable host-cell repair capacity of 8-MOP + UVA- or ANG + UVA-treated phages to that of the wild-type cells, recF143 mutation reduced not onnly the extent of W-R of 8-MOP + UVA-treated phages to 17% of that obtained in wild-type cells but also the extent of W-R of ANG + UVA-treated phages to 12% of that obtained in uvrA6 cells.