Deoxyribonucleic Acid Repair Replication after Ultraviolet Light or X-Ray Exposure of Bacteria

Billen, Daniel; Hewitt, Roger R.; Lapthisophon, T.; Achey, Phillip M.

doi:10.1128/jb.94.5.1538-1545.1967

Cited by 35 publications

(4 citation statements)

References 18 publications

(16 reference statements)

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“…Exposure to ultraviolet light (UV) was usually carried out just before addition of the freeze-treated cells to the assay mixture. Details of UV exposure were as described elsewhere (4).…”

Section: Methodsmentioning

confidence: 99%

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Evidence Suggestive of Compartmentalization of Deoxyribonucleic Acid-Synthesizing Systems in Freeze-Treated Bacillus subtilis

et al. 1971

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Freezing of Bacillus subtilis in liquid nitrogen results, upon thawing of the cells, in an enhanced deoxyribonucleoside triphosphate and reduced thymidine (Tdr) incorporation into cellular deoxyribonucleic acid (DNA). The DNA synthesized from thymidine triphosphate (TTP) was made by a "repair"-type system as determined by density transfer experiments. The mono-and diphosphate precursors were also incorporated by a "repair"-type synthesis. When Tdr was used as the radioactive precursor in the assay mixture, the product was only that expected from a semiconservative synthesis. Superlethal ultraviolet light exposure of the freeze-treated cells stimulated incorporation of phosphorylated precursors into DNA. Tdr uptake was greatly reduced by ultraviolet exposure, and only repair synthesis was observed. TTP and Tdr do not compete with one another in this system. The possibility that two DNA synthesizing systems exist in separate, nonmixing cellular compartments is considered.

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“…Exposure to ultraviolet light (UV) was usually carried out just before addition of the freeze-treated cells to the assay mixture. Details of UV exposure were as described elsewhere (4).…”

Section: Methodsmentioning

confidence: 99%

“…A superlethal dose of UV stops Tdr incorporation by the semiconservative mode and induces repair synthesis. The relationship between UVinduced repair synthesis (4) and "repair"-type synthesis in these freeze-treated cells is not currently known. They may be identical, or two independent systems.…”

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confidence: 99%

Evidence Suggestive of Compartmentalization of Deoxyribonucleic Acid-Synthesizing Systems in Freeze-Treated Bacillus subtilis

et al. 1971

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“…One of the mechanisms used by bacterial cells for repair of damage done to DNA by UV light is known as the excision-repair system. In this system pyrimidine dimers (32) formed in the DNA by UV are removed (5,29), and the nucleotides are replaced during repair synthesis (3,22). A mutant of Escherichia coli that is unable to excise pyrimidine dimers is also unable to carry out repair synthesis (9).…”

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confidence: 99%

Gap-filling repair synthesis induced by ultraviolet light in a Bacillus subtilis Uvr- mutant

Hadden¹

1979

J Bacteriol

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Deoxyribonucleic acid repair synthesis was studied in one wild-type and two mutant strains of Bacillus subtilis that are defective in excision of pyrimidine dimers. The cells were irradiated with ultraviolet light, and 6-(p-hydroxyphenylazo)-uracil was used to block replicative synthesis, allowing only repair synthesis. One of the mutations (uvs-42) resulted in a severe inhibition of incision, diiner excision, and repair synthesis. In contrast, the other mutant (uvr-1 ) slowly incised and excised dimers and did repair synthesis in patches which appear to be severalfold longer than those in the wild-type strain, apparently because large gaps are produced at excision sites. The results indicate that the primary defect in uvs-42 cells is in initiation of dimer excision, whereas the uvr-1 mutation appears to be a defect in the exonuclease normally used to complete dimer excision.

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“…An alteration in the expected sequence of chromosome replication in Escherichia coli occurs after exposure to ultraviolet light (UV; reference 13) or X-rays (7). The reorientation of the replication sequence is not an artifact of the methodology (14) or a consequence of repair synthesis (8), but results from a semiconservative synthesis starting at a region differing from that occupied by the growth point at the time of irradiation.…”

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confidence: 99%

Replication of the Bacterial Chromosome: Location of New Initiation Sites After Irradiation

Billen

1969

J Bacteriol

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New loci of replication along the bacterial chromosome are observed after irradiation of Escherichia coli. It was conjectured that, after X-irradiation, the new initiation site was random with respect to the fixed-origin, whereas, after ultraviolet light exposure, it was selective and appeared to be from the fixed-origin. Evidence presented here shows that, after X-irradiation of E. coli, the new initiation site(s) for the onset of deoxyribonucleic acid replication is induced at chromosomal regions not restricted to the fixed-origin. After ultraviolet light exposure, the new initiation site is preferentially from the fixed-origin. In these studies amino acid starvation was used to synchronize chromosome replication and to allow for differential radioisotopic labeling of the chromosomal origin and terminus. To facilitate interpretation, growing cells actively replicating their chromosome were compared with cells lacking growth points at the time of irradiation. The role of these new replication sites in the observed kinetics of deoxyribonucleic acid replication following X-ray or ultraviolet light exposure is discussed.An alteration in the expected sequence of chromosome replication in Escherichia coli occurs after exposure to ultraviolet light (UV; reference 13) or X-rays (7). The reorientation of the replication sequence is not an artifact of the methodology (14) or a consequence of repair synthesis (8), but results from a semiconservative synthesis starting at a region differing from that occupied by the growth point at the time of irradiation.The present studies were designed to determine whether the new initiation sites were at the fixedorigin of cycles of replication or elsewhere on the chromosome. Advantage was taken of the amino acid deprivation method which allows synchronization of replication starting from the vegetative origin (fixed-origin) of the bacterial chromosome (1,9,21,23). The sequence of replication of radioisotopically marked origin and terminus was then followed by density-transfer.The resulting data show that, in the immediate round of replication following X-irradiation, the new initiation sites are non-origin in location, whereas, after UV they are predominantly from the origin.MATERIALS AND METHODS Bacterial growth. The multiauxotrophic E. coli 15T-(555-7) requiring thymine, arginine, methionine, and tryptophan was used. The cells were grown with forced aeration at 37 C in a minimal salts medium (3) supplemented with 20 ,ug of arginine, 30 /g of methionine, 14 Mug of tryptophan, and 20 MAg of thymine per ml.Harvesting of cells. Cells were harvested and washed on membrane filters (Millipore Filter Corp., Bedford, Mass.) at ambient temperature to reduce trauma. Care was exercised to avoid drying the cells on the filter. The washing consisted of adding an equal volume of minimal salts solution followed by filtration. The sequence was repeated three times. The total time required for washing was less than 5 min.There was no observable deleterious effect on cell growth or macromolecular synt...

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Deoxyribonucleic Acid Repair Replication after Ultraviolet Light or X-Ray Exposure of Bacteria

Cited by 35 publications

References 18 publications

Evidence Suggestive of Compartmentalization of Deoxyribonucleic Acid-Synthesizing Systems in Freeze-Treated Bacillus subtilis

Evidence Suggestive of Compartmentalization of Deoxyribonucleic Acid-Synthesizing Systems in Freeze-Treated Bacillus subtilis

Gap-filling repair synthesis induced by ultraviolet light in a Bacillus subtilis Uvr- mutant

Replication of the Bacterial Chromosome: Location of New Initiation Sites After Irradiation

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