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Meiotic DNA breaks at the S. pombe recombination hot spot M26
Walter W Steiner1, Randall W Schreckhise, Gerald R Smith
1Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, A1-162, Seattle, WA 98109, USA.
Abstract:
The ade6-M26 allele of Schizosaccharomyces pombe creates a well-defined meiotic recombination hot spot that requires a specific sequence, 5'-ATGACGT-3', and the Atf1*Pcr1 transcription factor for activity. We find that M26 stimulates the formation of meiosis-specific double-strand DNA breaks at multiple sites surrounding M26. Like hot spot activity, breakage requires the M26 heptamer, Pcr1, and the general recombination factor Rec12. When the M26 heptamer is moved to new positions within ade6, new break sites are observed spanning approximately 0.5-2 kb around the moved heptamer. Break frequency is strongly correlated with recombination frequency for these alleles. The occurrence of breaks at M26 suggests mechanistic similarities to hot spots in the distantly related yeast Saccharomyces cerevisiae.
Insights
The ade6-M26 allele in fission yeast triggers DNA breaks at specific sites, requiring a DNA sequence and transcription factors. This hot spot activity is linked to recombination, suggesting conserved mechanisms across yeast species.
Area of Science:
- Molecular Biology
- Genetics
- Yeast Research
Background:
- Meiotic recombination hot spots are crucial for accurate chromosome segregation.
- The ade6-M26 allele in Schizosaccharomyces pombe serves as a model for studying recombination hot spot regulation.
Purpose of the Study:
- To investigate the molecular mechanisms underlying the ade6-M26 meiotic recombination hot spot.
- To determine the sequence and protein requirements for M26-stimulated DNA breakage and recombination.
Main Methods:
- Analysis of ade6-M26 alleles with altered heptamer sequences and positions.
- Assays for meiosis-specific double-strand DNA breaks and recombination frequencies.
- Investigating the roles of the M26 heptamer, Pcr1 transcription factor, and Rec12 recombination factor.
Main Results:
- The M26 heptamer sequence (5'-ATGACGT-3') and the Atf1/Pcr1 transcription factor are essential for hot spot activity.
- M26 stimulates double-strand DNA breaks at multiple sites, dependent on the M26 heptamer, Pcr1, and Rec12.
- Relocating the M26 heptamer creates new break sites, with break frequency correlating strongly with recombination frequency.
Conclusions:
- The ade6-M26 hot spot's activity is directly linked to the induction of programmed DNA breaks.
- These findings highlight conserved mechanisms of meiotic recombination hot spot function between Schizosaccharomyces pombe and Saccharomyces cerevisiae.