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  • Oxidative stress  (2)
  • Transposon mapping  (2)
  • 3-carbethoxypsoralen  (1)
  • 1
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Mutagen hyperresistance ; Southern, Northern analysis ; Gene transplacement ; Transposon mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The genes SNQ and SFA confer hyperresistance to 4-NQO and FA when present on a multi-copy plasmid in yeast. Both are non-essential genes since transplacement of SNQ by a disrupted snq-0::LEU2 yielded stable and viable haploid integrants. Southern analysis revealed that SNQ and SFA are single-loci genes, and OFAGE analysis showed that they are located on chromosome XIII and IV, respectively. Northern blot analysis of SNQ and SFA revealed poly(A)+ RNA transcripts of 2 kb and 1.7 kb, respectively. Nuclease S 1 mapping showed SNQ to have a coding region of 1.6 kb and SFA, one of 1.3 kb. The 5′ coding regions were determined for both genes, while the 3′ end could only be determined for gene SNQ. Both genes do not appear to contain introns. The SFA locus was also mapped by transposon mutagenesis. Tn10-LUK integrants disrupted the SFA gene function at sites that were determined by subcloning to lie within the SFA transcription unit.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0983
    Keywords: pso and rad mutants ; Repair ; S. cerevisiae ; 8-methoxypsoralen ; 3-carbethoxypsoralen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The mutant allele pso3-1 of Saccharomyces cerevisiae confers sensitivity to treatment with UV365nm (UVA) light-activated mono- and bi-functional psoralens. When pso3-1 is combined in double mutants with selected rad and pso mutant alleles and subjected to 8-MOP+UVA treatment, epistatic interaction with regard to survival is observed with pso1, pso2, and rad3. With the same treatment the combination of pso3-1 with rad6 and rad52 leads to synergistic interaction. For the monofunctional agent 3-carbethoxypsoralen (3-CPs) the analysis of double mutants yields the same results as with the bifunctional 8-methoxypsoralen (8-MOP) with the exception of the pso1-1pso3-1 double mutant. Here we find an additive interaction, i.e., the sensitivities of both parental strains are summed in the double mutant, which indicates a different substrate specificity of the repair activity encoded by the PSO1 and PSO3 genes.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0983
    Keywords: Key words Glutathione ; Yap1 ; H2O2 ; t-BOOH ; Glucose repression ; Oxidative stress ; Diauxic shift
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Resistance of haploid yeast to hydrogen peroxide and to tert-butylhydroperoxide strongly increases when 4% glucose is replaced by glycerol or ethanol as the carbon source of the complex medium. Using a GSH1-promoter-lacZ-fusion reporter construct we could demonstrate that GSH1 is one of the genes that are up-regulated during the shift from fermentative to oxidative metabolism. A gsh1 mutant did not exhibit respiratory growth resistance to H2O2, whereas it was only slightly impaired in acquiring resistance against t-BOOH in the same experimental conditions. An isogenic Δyap1 mutant, although more sensitive to oxidative stress than the wild-type (WT), could increase resistance to both peroxides by a similar factor as observed for the WT when shifted from 4% glucose to a non-fermentable carbon source. This indicates that in this case induction of resistance to oxidative stress is independent from Yap1 and from the Yap1-mediated stress response via the STRE motif.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0983
    Keywords: Key words Psoralen sensitivity ; Cytochrome oxidase ; Saccharomyces cerevisiae ; Oxidative stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The yeast gene PSO7 was cloned from a genomic library by complementation of the pso7-1 mutant's sensitivity phenotype to 4-nitroquinoline-1-oxide (4NQO). Sequence analysis revealed that PSO7 is allelic to the 1.1-kb ORF of the yeast gene COX11 which is located on chromosome XVI and encodes a protein of 28-kDa localized in the inner mitochondrial membrane. Allelism of PSO7/COX11 was verified by non-complementation of 4NQO-sensitivity in diploids homo- and hetero-allelic for the pso7-1 and cox11::TRP1 mutant alleles. Sensitivity to 4NQO was the same in exponentially growing cells of the pso7-1 mutant and the cox11::TRP1 disruptant. Allelism of COX11 and PSO7 indicates that the pso7 mutant's sensitivity to photoactivated 3-carbethoxypsoralen and to 4NQO is not caused by defective DNA repair, but rather is due to an altered metabolism of the pro-mutagen 4NQO in the absence of cytochrome oxidase (Cox) in pso7-1/cox11::TRP1 mutants/disruptants. Lack of Cox might also lead to a higher reactivity of the active oxygen species produced by photoactivated 3-carbethoxypsoralen. The metabolic state of the cells is important for their sensitivity phenotype since the largest enhancement of sensitivity to 4NQO between wild-type (WT) and the pso7 mutant occurs in exponentially growing cells, while cells in stationary phase or growing cells in phosphate buffer have the same 4NQO resistance, irrespective of their WT/mutant status. Strains containing the pso7-1 or cox11::TRP1 mutant allele were also sensitive to the oxidative stress-generating agents H2O2 and paraquat. Mutant pso7-1, as well as disruptant cox11::TRP1, harboured mitochondria that in comparison to WT contained less than 5% and no detectable Cox activity, respectively.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; DNA repair ; Cross-link ; Transposon mapping ; Nitrogen mustard
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have isolated yeast gene SNM1 via complementation of sensitivity towards bi- and tri-functional alkylating agents in haploid and diploid yeast DNA repair-deficient snm1-1 mutants. Four independent clones of plasmid DNA containing the SNM1 locus were isolated after transformation with a YEp24-based yeast gene bank. Subcloned SNM1-containing DNA showed (i) complementation of the repair-deficiency phenotype caused by either one of the two different mutant alleles snm1-1 and snm1-2 ts; (ii) complementation in haploid and diploid yeast snm1-1 mutants by either single or multiple copies of the SNM1 locus; and (iii) that the SNM1 gene is at most 2.4 kb in size. Expression of SNM1 on the smallest subclone, however, was under the control of the GAL1 promotor. Gene size and direction of transcription was further verified by mutagenesis of SNM1 by Tn10-LUK transposon insertion. Five plasmids containing Tn10-LUK insertions at different sites of the SNM1-containing DNA were able to disrupt function of genomic SNM1 after gene transplacement. Correct integration of the disrupted SNM1::Tn10-LUK at the genomic site of SNM1 was verified via tetrad analysis of the sporulated diploid obtained after mating of the SNM1::Tn10-LUK transformant to a haploid strain containing the URA3 SNM1 wild-type alleles. The size of the poly(A)+ RNA transcript of the SNM1 gene is 1.1 kb as determined by Northern analysis.
    Type of Medium: Electronic Resource
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