The effect of inhibition of protein synthesis on UV-irradiated Escherichia coli uvrE cells.

The uvrE (E. coli KS 114) cells carry a mutation in the gene that codes for helicase II. This is the protein responsible for replicative unwinding of double-helical DNA. The repair mode of such cells may be altered as compared with the wild type. The survival of uvrE cells during postirradiation incubation under inhibition of de novo protein synthesis was increased which indicates that this process of repair in uvrE cells is mediated by constitutive proteins and does not require any inducible products but takes a certain time. This inhibition of de novo protein synthesis causes also an inhibition of dimer excision, an increase of the parental DNA degradation and a decrease of parental and daughter DNA molar mass. On the other hand, it seems that induced proteins are formed in uvrE cells after UV irradiation but their influence is low in inducible repair and they can act only under conditions of complete protein synthesis.