[Postreplication DNA repair in Escherichia coli cells. II. The necessity of primase for constitutive repair].

In a thermosensitive mutant of Escherichia coli--PC3 dnaGts (the dnaG gene controls the synthesis of primase, or rifampycin resistant RNA polymerase in initiation of the Okazaki pieces synthesis in vegetative DNA replication), after UV-irradiation, the postreplication repair of DNA is lower by 5-20% at a non-permissive temperature 43 degrees, than at permissive temperature 30 degrees. A short-term inactivation of the dnaG gene activity before irradiation does not exert influence on the survival of bacteria, which remains the same at 30 and 43 degrees. In the presence of chloramphenicol, the efficiency of postreplication repair of DNA does not change at 30 and 43 degrees, but the survival of bacteria is somewhat higher, than without chloramphenicol treatment, being the same at 30 and 43 degrees. The data obtained indicate, that primase is a necessary constitutive component of postreplication repair of DNA, and that the short-term inactivation of the dnaG gene activity before inactivation does not exert influence on the survival of bacteria. In the PC3 dnaGts strain no inducible component of postreplication repair of DNA was detected.