Constitutive increase of RecA protein: its influence on pyrimidine dimer excision and survival of UV-irradiated Escherichia coli

Abstract Transformation of E. coli with the plasmid pRA containing recA gene increased the constitutive level of RecA protein 50–67 fold. This slightly inhibited pyrimidine dimer excision and reduced cell survival in three investigated, UV-irradiated E. coli strains. Our data support the view that RecA protein prematurely present at a high level may mask the dimers. The masking subsequently reduces the dimer excision and switches off the inducing signal.