Figure 4.

Survival of chromosomal and plasmid-borne replication-blocking lesions in WT and recA strains. (A) Relative integration efficiency (survival) and TLS events of a damage-containing construct relative to the corresponding damage-free construct, is measured in WT and recA strains. Three lesions, namely G-AAF, TT-CPD and TT(6-4), are introduced in the leading strand at position 17 min in the chromosome by site-specific recombination. The data represent the average value and standard deviation of at least three independent experiments. (B) Relative transformation efficiency (survival) of a ColE1-based plasmid containing a single G-AAF adduct in the leading or lagging strand. In both orientations, for a G-AAF adduct located in a plasmid there is no loss of survival in a recA versus rec+ strain. In contrast to plasmid-borne lesions, tolerance of chromosomal DNA lesions by DA is partially dependent on a functional recA gene.