Inhibition of dimer excision in repeatedly UV-irradiated Escherichia coli: Its requirement for RecA protein and de novo protein synthesis

• Published in: Journal of photochemistry and photobiology. B, Biology Biology, 1993-05, Vol.18 (2), p.205-210
• Main Authors: Fridrichová, I., Kleibl, K., Mašek, F., Sedliaková, M.
• Format: Article
• Language: English
• Subjects: Bacterial Proteins - biosynthesis; Biological and medical sciences; Cell physiology; Dimer excision; DNA Damage; DNA, Bacterial - radiation effects; Effects of physical and chemical agents; Es sites; Escherichia coli; Escherichia coli - metabolism; Escherichia coli - radiation effects; Fundamental and applied biological sciences. Psychology; Kinetics; Molecular and cellular biology; Pyrimidine Dimers - analysis; Rec A Recombinases - metabolism; RecA protein; Time Factors; Ultraviolet Rays; UV irradiation; uvrABC
• ISSN: 1011-1344; 1873-2682
• DOI: 10.1016/1011-1344(93)80064-G

In UV-irradiated Escherichia coli dimer excision was found to be inhibited by predamage (M. Sedliaková, F. Mašek and J. Brozmanová, FEBS Lett., 23 (1972) 325–326) or overproduction of RecA protein, which suggests that the coating of the dimers by this protein may make them inaccessible to the excision nuclease (M. Sedliaková, K. Kleibl and F. Mašek, Mutat. Res., 191 (1987) 13–16). We measured the levels of RecA protein and dimer excision in cells irradiated with (i) a single dose of 50 J m −2; (ii) two separate doses of 30 and 50 J m −2, post-incubated with chloramphenicol; (iii) two separate doses of 30 and 50 J m −2, post-incubated without chloramphenicol. Dimer excision was complete in the first two cases, but in the latter it was inhibited by 40%. At the time of active dimer excision, there were marked differences in RecA protein content between the cells irradiated with a single dose and cells irradiated with two separate doses (both post-incubated without chloramphenicol), which might account for the differences in dimer excision. However, relatively small differences in RecA protein content were found in cells irradiated with two doses and post-incubated with or without chloramphenicol, which could therefore not account for the differences in dimer excision. The data suggest that the inhibition of dimer excision involves some short-lived component(s) other than RecA protein.