[Attenuation of type I restriction in Escherichia coli: effect of the ard gene in UV-irradiated cells].

The effect of conjugative plasmids ColIb-P9 (incI1) and pKM 101 (incN), containing the active ard gene, on the efficiency of EcoK restriction of nonmodified phage lambda .0 in UV-irradiated Escherichia coli cells was studied. ard-Dependent antirestriction enzyme activity was shown to decrease in UV-irradiated cells. The efficiency of action of the ard plasmid gene on lambda .0 was also shown not to depend on cell helicases RecBCD and UvrD, in contrast to the UV-induced alleviation of EcoK restriction (SOS alleviation).