DNA Turnover and Strand Breaks in Escherichia coli
The extent of DNA turnover has been measured in a dnaB mutant of Escherichia coli, temperature sensitive for semiconservative DNA replication. At the nonpermissive temperature about 0.02% of the deoxynucleotides in DNA are exchanged per generation period. This turnover rate is markedly depressed in the presence of rifampicin. During thymine starvation strand breaks accumulate in the DNA of E. coli strains that are susceptible to thymineless death. Rifampicin suppresses the appearance of these breaks, consistent with our hypothesis that transcription may be accompanied by repairable single-strand breaks in DNA.
DNA turnover is enhanced severalfold in strands containing 5-bromodeoxy-uridine in place of thymidine, possibly because the analog (or the deoxyuridine, following debromination) is sometimes recognized and excised.
KeywordsStrand Break Micrococcus Luteus Nonpermissive Temperature Repair Synthesis Thymine Starvation
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- Bendigkeit, H. and Hanawalt, P. C., (1968). Bacteriol. Proc. Abstr. G103.Google Scholar
- Carrier, W. L. and Setlow, R. B. (1974). Fed. Proc. 33, 5 (abstr.).Google Scholar
- Grivell, A. R. and Hanawalt, P. C. (1972). Biophys. Soc. Abstr. 37a, Biophys. J. 12.Google Scholar
- Grivell, A. R., Grivell, M. and Hanawalt, P. C. (1975). J. Mol. Biol. (in press).Google Scholar
- Worcha, M. G. and Warner, H. R. (1973). J. Biol. Chem. 248, 1746–1750.Google Scholar