In vivo repair of UV-irradiation damage of single stranded DNA phage phi-X 174

Summary When E. coli C cells, infected with UV irradiated X 174, were allowed to grow in liquid tris-glucose medium at 37° C with aeration, the UV damage of the single stranded (ss) DNA could be repaired to some extent. Such repair was not possible if the irradiated phage were plated immediately on E. coli C in the usual double layer agar method, or if the infected complexes were initially exposed to 0.02 M KCN for 15 min before they were allowed to grow in tris-glucose medium as before. Our results indicate that in order to be repaired, ss DNA containing UV damage must be able to convert itself to a closed circular double stranded replicative form (RF) within the host cells escaping prior scission. The whole process of repair was found to be dependent on protein synthesis in the infected complexes.