ArticleAĭzenberg OA, Samoĭlenko II, Fradkin GE.
Genetika. 1977;13(11):1988-96.
Thymine requiring mutants of rec+ and recB- Escherichia coli strains have been tested for their response to thymine deprivation. Exonuclease V-deficient mutant is less sensitive to thymine deprivation than the wild type strain, because there is no lag period at thymineless death of recB- thy- cells. However, the mechanism of thymineless death of thy- rec+ and thy- recB- cells may be different. Two types of thymineless death are proposed to exist. The first type is due to DNA primary structure damages (single-strand breaks or gaps), accompanied by DNA degradation. The restoration of the balance disturbed by the thymine deprivation between DNA and protein synthesis rates by their balanced inhibition promotes a complete repair of structural damages in DNA and prevents the death of rec+ cells. The second type of thymineless death is not linked with the formation of DNA damages, and this is observed in recB- thy- mutant, defective in exonuclease V.