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Updated: Aug 4, 2026
Targeted in Situ Mutagenesis of Histone Genes in Budding Yeast
Published on: January 26, 2017
Budding yeast Hed1 down-regulates the mitotic recombination machinery when meiotic recombination is impaired
Hideo Tsubouchi1, G Shirleen Roeder
1Department of Molecular, Cellular, and Developmental Biology, Howard Hughes Medical Institute, Yale University, New Haven, Connecticut 06520, USA.
Abstract:
In budding yeast, there are two RecA homologs: Rad51 and Dmc1. While Rad51 is involved in both mitotic and meiotic recombination, Dmc1 participates specifically in meiotic recombination. Here, we describe a meiosis-specific protein (Hed1) with a novel Rad51 regulatory function. Several observations indicate that Hed1 attenuates Rad51 activity when Dmc1 is absent. First, although double-strand breaks are normally poorly repaired in the dmc1 mutant, repair becomes efficient when Hed1 is absent, and this effect depends on Rad51. Second, Rad51 and Hed1 colocalize as foci on meiotic chromosomes, and chromosomal localization of Hed1 depends on Rad51. Third, production of Hed1 in vegetative cells inhibits Rad51-dependent recombination events. Fourth, the Hed1 protein shows an interaction with Rad51 in the yeast two-hybrid protein system. We propose that Hed1 provides a mechanism to ensure the coordinated action of Rad51 and Dmc1 during meiosis, by down-regulating Rad51 activity when Dmc1 is unavailable.
Insights
Hed1, a meiosis-specific protein in budding yeast, regulates Rad51 activity. Hed1 attenuates Rad51 when Dmc1 is absent, ensuring coordinated meiotic recombination.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- Budding yeast possesses two RecA homologs: Rad51 (mitotic and meiotic recombination) and Dmc1 (meiotic recombination).
- Understanding the regulation of meiotic recombination is crucial for comprehending genome stability and inheritance.
Purpose of the Study:
- To characterize the function of Hed1, a meiosis-specific protein, in regulating Rad51 activity during meiosis.
- To elucidate the mechanism by which Hed1 coordinates the actions of Rad51 and Dmc1.
Main Methods:
- Yeast two-hybrid system to assess protein interactions.
- Analysis of meiotic recombination repair in yeast mutants (dmc1, hed1).
- Microscopic observation of protein localization (foci) on meiotic chromosomes.
Main Results:
- Hed1 attenuates Rad51 activity when Dmc1 is absent, enhancing double-strand break repair efficiency in dmc1 mutants.
- Hed1 and Rad51 colocalize on meiotic chromosomes, with Hed1 localization dependent on Rad51.
- Hed1 production in vegetative cells inhibits Rad51-dependent recombination.
- Direct interaction between Hed1 and Rad51 confirmed via yeast two-hybrid assay.
Conclusions:
- Hed1 acts as a negative regulator of Rad51 during meiosis, particularly when Dmc1 is unavailable.
- Hed1 ensures the coordinated function of Rad51 and Dmc1, preventing inappropriate Rad51 activity during meiosis.
- This regulatory mechanism is vital for accurate meiotic recombination and genome integrity.
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