Replication-dependent and selection-induced mutations in respiration-competent and respiration-deficient strains of Saccharomyces cerevisiae |
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Authors: | Erich Heidenreich and Ulrike Wintersberger |
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Institution: | (1) Department of Molecular Genetics Institute of Tumor Biology and Cancer Research Borschkegasse 8a A-1090 Vienna, Austria e-mail: ulrike.wintersberger@univie.ac.at Tel.:+43-1-4277-65210, Fax:+43-1-4277-9651, AT |
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Abstract: | Adaptive or selection-induced mutations are defined as mutations that occur in non-dividing cells as a response to prolonged
non-lethal selective pressure such as starvation for an essential amino acid. In the absence of DNA replication, the processing
of endogenous DNA lesions by repair enzymes probably acts as a source of mutations. We are studying selection-induced reversions
of frameshift alleles in the eukaryote Saccharomyces cerevisiae. Here we show that respiration-deficient strains, totally devoid of mitochondrial DNA, yield selection-induced mutants at
slightly elevated frequencies compared to isonucleic respiration-competent strains. Therefore factors of mitochondrial origin
such as reactive oxygen species or hypothetical recombinogenic DNA fragments are unlikely to be mediators of selection-induced
nuclear frameshift mutation in yeast. Furthermore we compared sequence spectra of reversions of the +1 hom3-10 frameshift allele and found a strong preference for −1 deletions in mononucleotide repeats in selection-induced and replication-dependent
revertants, indicating slippage errors during DNA repair synthesis as well as during DNA replication. Remarkably, a higher
degree of variation in the site of the reverting frameshift and accompanying base substitutions was found among selection-induced
revertants.
Received: 25 May 1998 / Accepted: 20 August 1998 |
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Keywords: | Replication-independent mutation Petite Starvation-associated mutation Hypermutation |
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