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Thymineless death

About: Thymineless death is a research topic. Over the lifetime, 188 publications have been published within this topic receiving 6333 citations.


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TL;DR: It is proposed that protein and/or RNA synthesis is necessary to initiate but not to sustain DNA replication, and that during renewed growth the acquired immunity to thymineless death is gradually lost and, in parallel, DNA synthesis is resumed.

571 citations

Journal ArticleDOI
TL;DR: It is shown that the capacity of E. coli 15TAU to synthesize DNA in a medium containing thymine, arginine, and uracil may be restored by a simple filtration and washing process, indicating that the drug is not firmly bound.
Abstract: Goss, William A. (Sterling-Winthrop Research Institute, Rensselaer, N.Y.), William H. Deitz, and Thomas M. Cook. Mechanism of action of nalidixic acid on Escherichia coli. II. Inhibition of deoxyribonucleic acid synthesis. J. Bacteriol. 89:1068-1074. 1965.-Nalidixic acid was shown to inhibit specifically the synthesis of deoxyribonucleic acid (DNA) in Escherichia coli. Slight effects on protein and ribonucleic acid (RNA) synthesis were observed only at higher levels of drug or after prolonged incubation. The inhibition of DNA synthesis in E. coli 15TAU, as measured by incorporation of C(14)-labeled thymine, was observed after exposure to nalidixic acid for 10 min. Inhibition of the incorporation of C(14)-labeled uracil into RNA and C(14)-labeled l-arginine into protein (21 and 28% inhibition, respectively) was observed only after 60 min of exposure. When cultures of E. coli 15TAU were exposed to 3.0 mug/ml of nalidixic acid (slightly greater than the minimal growth inhibitory concentration), the incorporation of C(14)-labeled thymidine was inhibited 30 to 40% after 90 min. Nalidixic acid at 10 mug/ml, a lethal concentration, inhibited thymidine incorporation 72% during this period. Nalidixic acid at 1.0 mug/ml had no apparent effect on the incorporation of C(14)-labeled adenine or C(14)-labeled uracil into RNA of cultures of E. coli 198, a wild-type strain. However, incorporation of both bases into DNA was strongly inhibited after 60 min of exposure (66 and 69%, respectively). Nalidixic acid inhibited DNA replication during a single round of synthesis. In contrast with "thymineless death," nalidixic acid was not lethal to E. coli 15TAU during restricted RNA and protein synthesis (i.e., in a medium containing thymine but lacking arginine and uracil). We have shown also that this chemotherapeutic agent has little effect on the synthesis of protein or RNA required to initiate DNA replication. After 75 min of inhibition, the capacity of E. coli 15TAU to synthesize DNA in a medium containing thymine, arginine, and uracil may be restored by a simple filtration and washing process, indicating that the drug is not firmly bound. These studies leave little doubt that a primary action of nalidixic acid is the inhibition of the synthesis of DNA in E. coli.

323 citations

Journal ArticleDOI
TL;DR: An active lesion of DNA in cells in which thymidylate synthetase is inhibited is suggested, and this consequence of the normal excision-repair process, which occurs when intracellular levels of dUTP approach those of dTTP, may have effects related to the cytotoxicity of drug inhibitors of thymidine, clinical deficiencies of folate and vitamin B-12, and thymineless death, in general.
Abstract: A line of human lymphoid cells was tested for the presence of dUMP in DNA with or without treatment with the dihydrofolate reductase inhibitor, methotrexate. Cells treated with methotrexate and labeled with [3H]dUrd contained dUMP in DNA in readily detectable amounts (≈0.8 pmol of dUMP per μmol of total DNA nucleotide), and this was increased ≈3-fold if the cells were also treated with Ura at the same time. No dUMP (<1 fmol/μmol of DNA) could be detected by these methods in DNA from cells not treated with methotrexate, regardless of whether Ura was present or absent. The presence of dUMP in DNA from cells treated with methotrexate is a result of the great increase in intracellular concentration of dUTP and the fall in dTTP that accompany inhibition of thymidylate synthetase (5,10-methylenetetrahydrofolate:dUMP C-methyltransferase; EC 2.1.1.45) by the drug. These changes are apparently sufficient to overcome the normal mechanisms that exclude dUMP from DNA, and the enhancement by Ura reflects suppression of one of the mechanisms, Ura removal from DNA by the enzyme Ura-DNA glycosylase. The results suggest an active lesion of DNA in cells in which thymidylate synthetase is inhibited. Under these conditions there appears to be a cyclic incorporation and removal of dUMP resulting from reinsertion of dUMP during gap repair at sites of Ura removal. This consequence of the normal excision-repair process, which occurs when intracellular levels of dUTP approach those of dTTP, may have effects related to the cytotoxicity of drug inhibitors of thymidylate synthetase, clinical deficiencies of folate and vitamin B-12, and thymineless death, in general.

264 citations

Journal ArticleDOI
TL;DR: A new mutation (recQ1) located between corA and metE on the standard linkage map was found to result in increased sensitivity to ultraviolet light and deficiency in conjugational recombination when placed in the recBC sbcB background, indicating that it blocked the RecF pathway of recobbination.
Abstract: An Escherichia coli K12 mutant resistant to thymineless death (TLD) was isolated, and its genetic analysis led us to identify a new mutation (recQ1) located between corA and metE on the standard linkage map. The mutation was found to result in increased sensitivity to ultraviolet light and deficiency in conjugational recombination when placed in the recBC sbcB background, indicating that it blocked the RecF pathway of recobbination. It seemed likely that this mutation is also capable of causing partial resistance to TLD, but we reserve the possibility of a separate mutation closely linked to recQ1 giving rise to this phenotype. The original mutant was shown to carry an additional mutation probably in the vicinity of the uhp locus, which was also required for the full TLD resistance of the mutant to be expressed.

242 citations

Journal ArticleDOI
TL;DR: A model is presented for a molecular basis of TLD and suggests that the RecF repair pathway may be critical to cell death, perhaps because it increases the occurrence of double-strand DNA breaks with unique DNA configurations at lesion sites.
Abstract: ▪ Abstract For many years it has been known that thymine auxotrophic microorganisms undergo cell death in response to thymine starvation [thymineless death (TLD)]. This effect is unusual in that deprivation of many other nutritional requirements has a biostatic, but not lethal, effect. Studies of numerous microbes have indicated that thymine starvation has both direct and indirect effects. The direct effects involve both single- and double-strand DNA breaks. The former may be repaired effectively, but the latter lead to cell death. DNA damaged by thymine starvation is a substrate for DNA repair processes, in particular recombinational repair. Mutations in recBCD recombinational repair genes increase sensitivity to thymineless death, whereas mutations in RecF repair protein genes enhance the recovery process. This suggests that the RecF repair pathway may be critical to cell death, perhaps because it increases the occurrence of double-strand DNA breaks with unique DNA configurations at lesion sites. Indire...

226 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20214
20202
20195
20182
20175
20163