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  • 1
    ISSN: 1432-0983
    Keywords: Platinum compounds ; Yeast ; Repair mutants ; Interstrand cross-links ; DNA degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Four haploid yeast strains differing in proficiency for DNA repair were treated with cis- or transDDP. The wild type was least sensitive while the excision-deficient mutants rad1, rad2 and snm1exhibited higher sensitivities to either platinum compound. In all four strains tested cisDDP showed a two- to five-fold higher cytotoxicity than equimolar concentrations of transDDP. DNA interstrand cross-linking was caused by both agents in all strains. However, transDDP introduced more DNA cross-links at exposure times up to 6 h while cisDDP was the more active cross-linking agent at longer times. There was no clear-cut correlation of the number of DNA interstrand cross-links with survival. Formaldehyde-treated cells showed DNA with lower buoyant density due to proteinase K sensitive DNA-protein cross-linking; this effect was not observed after treatment with either platinum compound. Post-treatment incubation of wild-type cells exposed to cisDDP led to degradation of DNA by single and double-strand breaks, parallel with further increase of DNA interstrand cross-linking. DNA from transDDP-treated cells did not show extensive degradation although interstrand cross-links were lost during liquid holding.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0983
    Keywords: Formaldehyde ; DNA-protein cross-links ; Repair ; Saccharomyces cerevisiae ; Hyperresistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The formation and removal of formaldehyde-mediated DNA protein cross-linking was measured by CsCI density gradient analysis in yeast strains of differing resistance to formaldehyde. Wild-type cells and transformants made hyperresistant to formaldehyde by a multi-copy vector containing the yeast SFA gene were specifically labeled in their DNA and incubated in the presence of formaldehyde. Treatment with formaldehyde lead to the formation of equal amounts of DNA protein cross-links; subsequent liquid holding of cells for 24 h resulted in the removal of nearly all DNA protein crosslinks regardless of the original formaldehyde resistance status of the strains.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Current genetics 29 (1996), S. 437-440 
    ISSN: 1432-0983
    Keywords: Yeast ; Formaldehyde ; Hyper-resistance ; Alcohol dehydrogenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In an attempt to clone genes involved in resistance to formaldehyde we have screened a genomic library based on the episomal plasmid YEp24 for the ability to increase resistance to formaldehyde in a wild-type strain. In addition toSFA, the gene encoding the formaldehyde dehydrogenase Adh5, an enzyme most potent in formaldehyde de-toxification, we isolated a second plasmid that conferred a less pronounced but significant hyper-resistance to formaldehyde. Its passenger DNA contained the geneADH1, encoding alcohol dehydrogenase 1 (EC 1.1.1.1), which could be shown to be responsible for the observed hyper-resistance phenotype. Construction of anadh1-0 mutant revealed that yeast lacking a functionalADH1 gene is sensitive to formaldehyde. While glutathione is essential for Adh5-mediated formaldehyde de-toxification, Adh1 reduced formaldehyde best in the absence of this thiol compound. Evidence is presented that formaldehyde is a substrate for Adh1 in vivo and in vitro and that its cellular de-toxification employs a reductive step that may yield methanol.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1617-4623
    Keywords: Mutagen resistance ; Yeast ; Formaldehyde ; 4-Nitroquinoline-N-oxide ; Multi-copy plasmids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The hyperresistance to 4-nitroquinoline-N-oxide (4-NQO) and formaldehyde (FA) of yeast strains transformed with the multi-copy plasmids pAR172 and pAR184, respectively, is due to the two genes, SNQ and SFA, which are present on these plasmids. Restriction analysis revealed the maximal size of SFA as 2.7 kb and of SNQ as 2.2 kb, including transcription control elements. The presence of the smallest 2.7 kb subclone carrying SFA increased hyperresistance to formaldehyde fivefold over that of the original pAR184 isolate. No such increase in hyperresistance to 4-NQO was seen with the smaller subclones of the pAR172 isolate. Disruption of the SFA gene led to a threefold increase in sensitivity to FA as compared with the wild type. Expression of gene SNQ introduced on a multi-copy vector into haploid yeast mutants rad2, rad3, and snm1 did not complement these mutations that block excision repair.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Molecular genetics and genomics 231 (1992), S. 194-200 
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; DNA repair ; Nitrogen mustard ; Interstrand cross-links ; Nucleotide sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A 3.2 kb yeast DNA fragment containing the DNA interstrand cross-link-specific repair gene SNM1 has been sequenced. Two genes were identified. SNM1 has an open reading frame of 1983 by and codes for a 661 amino acid protein. Hydrophobic analysis shows that the protein is most probably not directly membrane bound. The second gene, UGX1, has an open reading frame of 573 by coding for a polypeptide of 191 amino acid residues. The two genes are arranged head to head and share a 192 by divergent promoter region that contains three TATAAA motives, two for the SNM1 and one for the UGX1 locus. Gene UGX1 has no apparent influence on the sensitivity of the cell to cross-linking nitrogen mustard, as its disruption in wild type does not increase sensitivity to nitrogen mustard and the presence of multiple copies of the gene fails to complement the nitrogen mustard sensitivity phenotype of snm1 disruption mutants. Northern analysis revealed that the expression of SNM1 yields an average of 0.3 copies/cell of a 2.4 kb transcript, while expression of UGX1 yields higher levels of a 0.8 kb poly(A)+ RNA.
    Type of Medium: Electronic Resource
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