Mechanisms Employed by Escherichia coli to Prevent Ribonucleotide Incorporation into Genomic DNA by Pol V
Figure 1
Effect of ΔrnhA and ΔrnhB on UV survival of recA730 lexA(Def) ΔumuDC ΔdinB strains expressing pol V variants.
10 µl of 10-fold serial dilutions of overnight cultures were spotted onto the surface of rectangular LB agar plates and exposed to 40 J/m2 254 nM UV-light (panels A and C) and 20 J/m2 254 nM UV-light (panels B and D). Both unirradiated (−) and UV-irradiated (+) plates were incubated overnight at 37°C. In each panel, UV survival is shown for the recA730 lexA(Def) ΔumuDC ΔdinB strains either harboring pGB2 vector, or expressing pol V variants. The main observation of these experiments is that the UV-resistance of cells expressing umuC_Y11A increase dramatically in strains lacking rnhB, whereas survival of cells equipped with wild-type pol V, umuC_F10L, or umuC_Y11F is largely unaffected by the status of rnhB.