DNA polymerase zeta introduces multiple mutations when bypassing spontaneous DNA damage in Saccharomyces cerevisiae
1Department of Biology, Emory University, Atlanta, GA 30322, USA.
Abstract:
Spontaneous DNA damage can be dealt with by multiple repair/bypass pathways that have overlapping specificities. We have used a frameshift reversion assay to examine spontaneous mutations that accumulate in yeast strains defective for the high-fidelity nucleotide excision repair or recombination pathways. In contrast to the simple frameshift mutations that occur in wild-type strains, the reversion events in mutant strains are often complex in nature, with the selected frameshift mutation being accompanied by one or more base substitutions. Genetic analyses demonstrate that the complex events are dependent on the Pol zeta translesion polymerase, thus implicating the DNA damage bypass activity of low-fidelity translesion polymerases in hypermutation phenomena.
Insights
Yeast strains lacking DNA repair pathways accumulate complex mutations. These complex events, involving frameshifts and base substitutions, depend on the Pol zeta translesion polymerase, highlighting its role in DNA damage bypass and hypermutation.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Spontaneous DNA damage is repaired by multiple pathways with overlapping specificities.
- High-fidelity repair pathways like nucleotide excision repair and recombination are crucial for maintaining genomic stability.
Purpose of the Study:
- To investigate spontaneous mutations in yeast strains deficient in high-fidelity DNA repair pathways.
- To elucidate the mechanisms underlying complex mutation events and their relationship with DNA damage tolerance.
Main Methods:
- Utilized a frameshift reversion assay in yeast.
- Analyzed spontaneous mutations accumulating in nucleotide excision repair and recombination-deficient strains.
- Performed genetic analyses to identify key molecular players.
Main Results:
- Mutant strains exhibited complex reversion events, including frameshifts accompanied by base substitutions, unlike wild-type strains.
- These complex mutational events were found to be dependent on the Pol zeta translesion polymerase.
- Implicated the DNA damage bypass activity of low-fidelity translesion polymerases in hypermutation.
Conclusions:
- Deficiencies in high-fidelity DNA repair pathways lead to complex spontaneous mutations in yeast.
- Pol zeta translesion polymerase plays a critical role in generating these complex mutations.
- Low-fidelity translesion polymerases contribute to hypermutation phenomena through DNA damage bypass mechanisms.
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