scholarly journals DNA polymerases required for repair of UV-induced damage in Saccharomyces cerevisiae.

1995 ◽  
Vol 15 (4) ◽  
pp. 2173-2179 ◽  
Author(s):  
M E Budd ◽  
J L Campbell
Keyword(s):  
Dna Polymerase ◽  
Dna Polymerases ◽  
Dna Polymerase Delta ◽  
Weight Changes ◽  
Repair Synthesis ◽  
Strand Breaks ◽  
Single Strand Breaks ◽  
Quadruple Mutant ◽  
Cellular Dna ◽  
Repair Defect

The ability of yeast DNA polymerase mutant strains to carry out repair synthesis after UV irradiation was studied by analysis of postirradiation molecular weight changes in cellular DNA. Neither DNA polymerase alpha, delta, epsilon, nor Rev3 single mutants evidenced a defect in repair. A mutant defective in all four of these DNA polymerases, however, showed accumulation of single-strand breaks, indicating defective repair. Pairwise combination of polymerase mutations revealed a repair defect only in DNA polymerase delta and epsilon double mutants. The extent of repair in the double mutant was no greater than that in the quadruple mutant, suggesting that DNA polymerases alpha and Rev3p play very minor, if any, roles. Taken together, the data suggest that DNA polymerases delta and epsilon are both potentially able to perform repair synthesis and that in the absence of one, the other can efficiently substitute. Thus, two of the DNA polymerases involved in DNA replication are also involved in DNA repair, adding to the accumulating evidence that the two processes are coupled.

scholarly journals The essential DNA polymerases delta and epsilon are involved in repair of UV-damaged DNA in the yeast Saccharomyces cerevisiae.

1999 ◽  
Vol 46 (2) ◽  
pp. 289-298 ◽  
Author(s):  
A Hałas ◽  
Z Policińska ◽  
H Baranowska ◽  
W J Jachymczyk
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Repair ◽  
Uv Irradiation ◽  
Dna Polymerases ◽  
Relative Molecular Mass ◽  
Yeast Saccharomyces Cerevisiae ◽  
Strand Breaks ◽  
Single Strand Breaks ◽  
Mutant Strains ◽  
Cellular Dna

We have studied the ability of yeast DNA polymerases to carry out repair of lesions caused by UV irradiation in Saccharomyces cerevisiae. By the analysis of postirradiation relative molecular mass changes in cellular DNA of different DNA polymerases mutant strains, it was established that mutations in DNA polymerases delta and epsilon showed accumulation of single-strand breaks indicating defective repair. Mutations in other DNA polymerase genes exhibited no defects in DNA repair. Thus, the data obtained suggest that DNA polymerases delta and epsilon are both necessary for DNA replication and for repair of lesions caused by UV irradiation. The results are discussed in the light of current concepts concerning the specificity of DNA polymerases in DNA repair.

KGF facilitates repair of radiation-induced DNA damage in alveolar epithelial cells

1997 ◽  
Vol 272 (6) ◽  
pp. L1174-L1180 ◽  
Author(s):  
M. Takeoka ◽  
W. F. Ward ◽  
H. Pollack ◽  
D. W. Kamp ◽  
R. J. Panos
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Epithelial Cells ◽  
Dna Polymerase ◽  
Dna Polymerases ◽  
Dna Strand Breaks ◽  
Strand Breaks ◽  
Alveolar Epithelial ◽  
Radiation Induced ◽  
Dna Strand

Administration of exogenous keratinocyte growth factor (KGF) prevents or attenuates several forms of oxidant-mediated lung injury. Because DNA damage in epithelial cells is a component of radiation pneumotoxicity, we determined whether KGF ameliorated DNA strand breaks in irradiated A549 cells. Cells were exposed to 137Cs gamma rays, and DNA damage was measured by alkaline unwinding and ethidium bromide fluorescence after a 30-min recovery period. Radiation induced a dose-dependent increase in DNA strand breaks. The percentage of double-stranded DNA after exposure to 30 Gy increased from 44.6 +/- 3.5% in untreated control cells to 61.6 +/- 5.0% in cells cultured with 100 ng/ml KGF for 24 h (P < 0.05). No reduction in DNA damage occurred when the cells were cultured with KGF but maintained at 0 degree C during and after irradiation. The sparing effect of KGF on radiation-induced DNA damage was blocked by aphidicolin, an inhibitor of DNA polymerases-alpha, -delta, and -epsilon and by butylphenyl dGTP, which blocks DNA polymerase-alpha strongly and polymerases-delta and -epsilon less effectively. However, dideoxythymidine triphosphate, a specific inhibitor of DNA polymerase-beta, did not abrogate the KGF effect. Thus KGF increases DNA repair capacity in irradiated pulmonary epithelial cells, an effect mediated at least in part by DNA polymerases-alpha, -delta, and -epsilon. Enhancement of DNA repair capability after cell damage may be one mechanism by which KGF is able to ameliorate oxidant-mediated alveolar epithelial injury.

Primary structure of the catalytic subunit of calf thymus DNA polymerase .delta.: sequence similarities with other DNA polymerases

Biochemistry ◽  
1991 ◽  
Vol 30 (51) ◽  
pp. 11742-11750 ◽  
Author(s):  
Jian Zhang ◽  
Dominic W. Chung ◽  
Cheng Keat Tan ◽  
Kathleen M. Downey ◽  
Earl W. Davie ◽  
...  
Keyword(s):  
Dna Polymerase ◽  
Primary Structure ◽  
Dna Polymerases ◽  
Catalytic Subunit ◽  
Calf Thymus Dna ◽  
Dna Polymerase Delta ◽  
Calf Thymus ◽  
Delta Sequence ◽  
Sequence Similarities

scholarly journals DNA polymerases δ and λ cooperate in repairing double-strand breaks by microhomology-mediated end-joining in Saccharomyces cerevisiae

2015 ◽  
Vol 112 (50) ◽  
pp. E6907-E6916 ◽  
Author(s):  
Damon Meyer ◽  
Becky Xu Hua Fu ◽  
Wolf-Dietrich Heyer
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Polymerase ◽  
Genome Stability ◽  
Double Strand Breaks ◽  
Dna Polymerase Delta ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Strand Breaks ◽  
Repair Efficiency ◽  
Repair Pathways

Maintenance of genome stability is carried out by a suite of DNA repair pathways that ensure the repair of damaged DNA and faithful replication of the genome. Of particular importance are the repair pathways, which respond to DNA double-strand breaks (DSBs), and how the efficiency of repair is influenced by sequence homology. In this study, we developed a genetic assay in diploid Saccharomyces cerevisiae cells to analyze DSBs requiring microhomologies for repair, known as microhomology-mediated end-joining (MMEJ). MMEJ repair efficiency increased concomitant with microhomology length and decreased upon introduction of mismatches. The central proteins in homologous recombination (HR), Rad52 and Rad51, suppressed MMEJ in this system, suggesting a competition between HR and MMEJ for the repair of a DSB. Importantly, we found that DNA polymerase delta (Pol δ) is critical for MMEJ, independent of microhomology length and base-pairing continuity. MMEJ recombinants showed evidence that Pol δ proofreading function is active during MMEJ-mediated DSB repair. Furthermore, mutations in Pol δ and DNA polymerase 4 (Pol λ), the DNA polymerase previously implicated in MMEJ, cause a synergistic decrease in MMEJ repair. Pol λ showed faster kinetics associating with MMEJ substrates following DSB induction than Pol δ. The association of Pol δ depended on RAD1, which encodes the flap endonuclease needed to cleave MMEJ intermediates before DNA synthesis. Moreover, Pol δ recruitment was diminished in cells lacking Pol λ. These data suggest cooperative involvement of both polymerases in MMEJ.

scholarly journals DNA-metabolizing enzymes in normal human lymphoid cells. VI. Induction of DNA polymerases alpha, beta, and gamma following stimulation with phytohemagglutinin

Blood ◽  
1975 ◽  
Vol 46 (4) ◽  
pp. 509-518
Author(s):  
RJ Mayer ◽  
RG Smith ◽  
RC Gallo
Keyword(s):  
Dna Polymerase ◽  
Mammalian Cells ◽  
Dna Polymerases ◽  
Polymerase Activity ◽  
Lymphoid Cells ◽  
Blood Lymphocytes ◽  
Polymerase Beta ◽  
Normal Human ◽  
Alpha Beta ◽  
Cellular Dna

At least three distinct DNA polymerases, named alpha, beta, and gamma, have been isolated from normal mammalian cells. The function of these enzymes in regard to DNA replication and repair remains unclear. Stimulation of blood lymphocytes with the plant mitogen phytohemagglutinin (PHA), is known to increase total DNA polymerase activity. In this study, we measured the change of each of these activities as lymphocytes intered a mitotic cycle. Aliquots of a pool of normal human blood lymphocytes were incubated with PHA for 0, 24, 48, and 72 hr, respectively, and the various DNA polymerase activities quantitated at each point. No significant DNA polymerase activity was detected in unstimulated cells. Low levels of polymerase beta were found at 24 hr. The average DNA content per cell doubled between 24 and 48 hr, and during this interval all three DNA polymerases increased to easily detectable levels. By far the greatest fractional increase in activity of all three polymerases was seen between 48 and 72 hr, after the average doubling of cellular DNA. In summary, these blood lymphocytes lack significant levels of DNA polymerases; stimulation with PHA induces all three of the major DNA polymerase species. In both these respects, these cells differ from other proliferating mammalian cell systems. The possible significance of this difference is discussed.

scholarly journals Manipulating chromosome structure and metaphase status with ultraviolet light and repair synthesis inhibitors

1985 ◽  
Vol 73 (1) ◽  
pp. 159-186
Author(s):  
A.M. Mullinger ◽  
R.T. Johnson
Keyword(s):  
Simian Virus 40 ◽  
Human Cells ◽  
Single Strand ◽  
Dna Breaks ◽  
Intact Cells ◽  
Repair Synthesis ◽  
Single Strand Break ◽  
Strand Breaks ◽  
Single Strand Breaks ◽  
Chromosome Decondensation

DNA repair occurs in metaphase-arrested cells in response to ultraviolet irradiation. In the presence of the repair synthesis inhibitors hydroxyurea and 1-beta-D-arabinofuranosylcytosine the chromosomes of such cells, as seen in Carnoy-fixed preparations, are decondensed. The extent of decondensation is related to both the u.v. dose and the duration of incubation in the presence of inhibitors. For any particular cell type there is a reasonable correlation between the amount of decondensation and the number of single-strand DNA breaks generated by the repair process under the same inhibitory conditions, though the chromosome changes continue after the number of single-strand breaks has reached a plateau. The dose response of chromosome decondensation varies between different cell types but is in general correlated with differences in levels of single-strand breaks accumulated under comparable inhibitory conditions. Decondensation can be detected after 0.5 Jm-2 in repair-competent human cells. In human cells defective in excision repair there is much less chromosome decondensation in response to the same u.v. dose and time of repair inhibition. However, a simian virus 40-transformed muntjac cell displays pronounced chromosome decondensation but has limited incision ability. Both chromosome decondensation and single-strand break accumulation in the presence of inhibitors are reversed when DNA precursors are provided, but reversal after higher u.v. doses and longer periods of incubation leads to recondensed chromosomes that are fragmented. Elution of the DNA from such cells through polycarbonate filters under non-denaturing conditions reveals that double-strand DNA breaks are generated during the period of incubation with inhibitors. Although the chromosomes of repair-inhibited metaphase cells are decondensed in fixed preparations, their morphology appears normal in intact cells. The cells also retain a capacity to induce prematurely condensed chromosomes (PCC) when fused with interphase cells: compared with control mitotic cells, the speed of induction is sometimes reduced but the final amount of PCC produced is similar.

scholarly journals DNA-metabolizing enzymes in normal human lymphoid cells. VI. Induction of DNA polymerases alpha, beta, and gamma following stimulation with phytohemagglutinin

Blood ◽  
1975 ◽  
Vol 46 (4) ◽  
pp. 509-518 ◽  
Author(s):  
RJ Mayer ◽  
RG Smith ◽  
RC Gallo
Keyword(s):  
Dna Polymerase ◽  
Mammalian Cells ◽  
Dna Polymerases ◽  
Polymerase Activity ◽  
Lymphoid Cells ◽  
Blood Lymphocytes ◽  
Polymerase Beta ◽  
Normal Human ◽  
Alpha Beta ◽  
Cellular Dna

Abstract At least three distinct DNA polymerases, named alpha, beta, and gamma, have been isolated from normal mammalian cells. The function of these enzymes in regard to DNA replication and repair remains unclear. Stimulation of blood lymphocytes with the plant mitogen phytohemagglutinin (PHA), is known to increase total DNA polymerase activity. In this study, we measured the change of each of these activities as lymphocytes intered a mitotic cycle. Aliquots of a pool of normal human blood lymphocytes were incubated with PHA for 0, 24, 48, and 72 hr, respectively, and the various DNA polymerase activities quantitated at each point. No significant DNA polymerase activity was detected in unstimulated cells. Low levels of polymerase beta were found at 24 hr. The average DNA content per cell doubled between 24 and 48 hr, and during this interval all three DNA polymerases increased to easily detectable levels. By far the greatest fractional increase in activity of all three polymerases was seen between 48 and 72 hr, after the average doubling of cellular DNA. In summary, these blood lymphocytes lack significant levels of DNA polymerases; stimulation with PHA induces all three of the major DNA polymerase species. In both these respects, these cells differ from other proliferating mammalian cell systems. The possible significance of this difference is discussed.

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