Detection of Primary DNA Lesions by Transient Changes in Mating Behavior in Yeast Saccharomyces cerevisiae Using the
Anna S Zhuk1,2,3, Anna A Shiriaeva4, Yulia V Andreychuk3
1Institute of Applied Computer Science, ITMO University, 191002 St. Petersburg, Russia.
Abstract:
Spontaneous or induced DNA lesions can result in stable gene mutations and chromosomal aberrations due to their inaccurate repair, ultimately resulting in phenotype changes. Some DNA lesions per se may interfere with transcription, leading to temporary phenocopies of mutations. The direct impact of primary DNA lesions on phenotype before their removal by repair is not well understood. To address this question, we used the alpha-test, which allows for detecting various genetic events leading to temporary or hereditary changes in mating type α→a in heterothallic strains of yeast Saccharomyces cerevisiae. Here, we compared yeast strains carrying mutations in DNA repair genes, mismatch repair (pms1), base excision repair (ogg1), and homologous recombination repair (rad52), as well as mutagens causing specific DNA lesions (UV light and camptothecin). We found that double-strand breaks and UV-induced lesions have a stronger effect on the phenotype than mismatches and 8-oxoguanine. Moreover, the loss of the entire chromosome III leads to an immediate mating type switch α→a and does not prevent hybridization. We also evaluated the ability of primary DNA lesions to persist through the cell cycle by assessing the frequency of UV-induced inherited and non-inherited genetic changes in asynchronous cultures of a wild-type (wt) strain and in a cdc28-4 mutant arrested in the G1 phase. Our findings suggest that the phenotypic manifestation of primary DNA lesions depends on their type and the stage of the cell cycle in which it occurred.
Insights
DNA lesions can alter phenotypes before repair. Double-strand breaks and UV damage significantly impact yeast cell mating type, unlike mismatches or 8-oxoguanine, with effects varying by cell cycle stage.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- DNA lesions can cause mutations and affect phenotypes, but their immediate impact before repair is unclear.
- Understanding primary DNA lesion effects is crucial for comprehending mutation origins and cellular responses.
Purpose of the Study:
- To investigate the direct phenotypic impact of various DNA lesions before repair.
- To determine how DNA repair gene mutations influence the manifestation of DNA damage.
- To assess the cell cycle-dependent persistence and phenotypic effects of DNA lesions.
Main Methods:
- Utilized the alpha-test in *Saccharomyces cerevisiae* to detect mating type changes (α→a).
- Compared wild-type and DNA repair mutant yeast strains (pms1, ogg1, rad52) exposed to UV light and camptothecin.
- Analyzed UV-induced genetic changes in asynchronous and G1-arrested (cdc28-4) cells.
Main Results:
- Double-strand breaks and UV lesions had a more pronounced phenotypic effect than mismatches and 8-oxoguanine.
- Loss of chromosome III induced an immediate mating type switch without hindering hybridization.
- Phenotypic manifestation of primary DNA lesions varied based on lesion type and cell cycle stage.
Conclusions:
- The type of DNA lesion and the cell cycle stage significantly influence its immediate phenotypic impact.
- Primary DNA lesions can exert phenotypic effects prior to repair or removal.
- This study provides insights into the transient effects of DNA damage on cellular phenotypes.
