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Searching for a functional analogy between yeast Pso4 and bacterial RecA proteins in induced mitotic recombination
V Vlcková1, M Slaninová, M A Morais
1Department of Genetics, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia.
Abstract:
The pso4-1 mutant of S. cerevisiae is phenotypically similar to the recA mutant of E. coli; it is sensitive to DNA cross-linking agents and defective in both recombination and mutagenesis. In this paper we have measured the effect of the recA gene expression on the frequency of mitotic crossing-over and mitotic gene conversion in response to DNA damage induced by photoactivated 8-methoxypsoralen (8-MOP + UVA), ultraviolet radiation (UV) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). The diploid pso4-1 mutant and the repair wild type strain were transformed with the multicopy plasmid carrying the recA gene placed under the control of the ADH1 promoter. The results showed that RecA is not able to restore block in induced mitotic recombination in pso4-1 cells after DNA damaging agents used. Thus RecA protein is not able to substitute Pso4 protein in homologous mitotic recombination indicating that they have probably different functions in this process.
Insights
The yeast pso4-1 mutant, like E. coli recA, is sensitive to DNA damage and impaired in recombination. RecA expression did not restore DNA damage-induced mitotic recombination in pso4-1 cells, suggesting distinct functions.
Area of Science:
- Molecular Biology
- Genetics
- Yeast Genetics
Background:
- The pso4-1 mutant in Saccharomyces cerevisiae exhibits sensitivity to DNA cross-linking agents and defects in recombination and mutagenesis, similar to the recA mutant in E. coli.
- Understanding the roles of specific genes in DNA repair and recombination pathways is crucial for comprehending genome stability.
Purpose of the Study:
- To investigate the effect of RecA gene expression on DNA damage-induced mitotic recombination in the pso4-1 mutant.
- To determine if RecA can functionally substitute for Pso4 in homologous mitotic recombination processes.
Main Methods:
- Utilizing Saccharomyces cerevisiae strains, including the pso4-1 mutant and a repair wild-type strain.
- Introducing a multicopy plasmid with the recA gene under the ADH1 promoter into these strains.
- Inducing DNA damage using 8-methoxypsoralen (8-MOP) plus UVA, ultraviolet radiation (UV), and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG).
- Measuring the frequency of mitotic crossing-over and mitotic gene conversion.
Main Results:
- RecA expression did not restore the block in induced mitotic recombination in pso4-1 cells following exposure to DNA damaging agents.
- The presence of the recA gene did not rescue the recombination deficiency phenotype of the pso4-1 mutant.
Conclusions:
- RecA protein cannot substitute for Pso4 protein in homologous mitotic recombination in yeast.
- Pso4 and RecA likely possess distinct functions in the process of homologous mitotic recombination and DNA repair.