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Updated: Oct 11, 2025
Use of Time-Lapse Microscopy and Stage-Specific Nuclear Depletion of Proteins to Study Meiosis in S. cerevisiae
Published on: October 11, 2022
Regulation of Msh4-Msh5 association with meiotic chromosomes in budding yeast
Krishnaprasad G Nandanan1, Sagar Salim1, Ajith V Pankajam1
1School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Trivandrum 695016, India.
Abstract:
In the baker's yeast Saccharomyces cerevisiae, most of the meiotic crossovers are generated through a pathway involving the highly conserved mismatch repair related Msh4-Msh5 complex. To understand the role of Msh4-Msh5 in meiotic crossing over, we determined its genome wide in vivo binding sites in meiotic cells. We show that Msh5 specifically associates with DSB hotspots, chromosome axes, and centromeres on chromosomes. A basal level of Msh5 association with these chromosomal features is observed even in the absence of DSB formation (spo11Δ mutant) at the early stages of meiosis. But efficient binding to DSB hotspots and chromosome axes requires DSB formation and resection and is enhanced by double Holliday junction structures. Msh5 binding is also correlated to DSB frequency and enhanced on small chromosomes with higher DSB and crossover density. The axis protein Red1 is required for Msh5 association with the chromosome axes and DSB hotspots but not centromeres. Although binding sites of Msh5 and other pro-crossover factors like Zip3 show extensive overlap, Msh5 associates with centromeres independent of Zip3. These results on Msh5 localization in wild type and meiotic mutants have implications for how Msh4-Msh5 works with other pro-crossover factors to ensure crossover formation.
Insights
The Msh4-Msh5 complex is crucial for generating meiotic crossovers in yeast. This study maps Msh5 binding sites, revealing its association with double-strand break hotspots and chromosome axes, essential for crossover formation.
Area of Science:
- Genetics
- Molecular Biology
- Cell Biology
Background:
- Meiotic recombination is essential for accurate chromosome segregation.
- The Msh4-Msh5 complex is a key factor in promoting meiotic crossovers.
- Understanding Msh4-Msh5 localization is vital for elucidating crossover formation mechanisms.
Purpose of the Study:
- To determine the genome-wide in vivo binding sites of the Msh4-Msh5 complex during meiosis in Saccharomyces cerevisiae.
- To investigate the factors influencing Msh5 association with chromosomal features.
- To clarify the relationship between Msh5 and other pro-crossover factors.
Main Methods:
- Genome-wide chromatin immunoprecipitation (ChIP) followed by sequencing (ChIP-seq) to map Msh5 binding sites.
- Analysis of Msh5 localization in wild-type and various meiotic mutants (e.g., spo11Δ, red1Δ).
- Correlation analysis of Msh5 binding with double-strand break (DSB) hotspots, chromosome axes, centromeres, and crossover density.
Main Results:
- Msh5 specifically binds to DSB hotspots, chromosome axes, and centromeres.
- Msh5 association with DSB hotspots and axes requires DSB formation, resection, and is enhanced by double Holliday junctions.
- Msh5 binding is dependent on the axis protein Red1 for association with axes and hotspots, but not centromeres.
- Msh5 shows extensive overlap with the pro-crossover factor Zip3 but binds centromeres independently of Zip3.
Conclusions:
- Msh4-Msh5 localization is tightly regulated during meiosis, influenced by DSB formation and processing.
- Msh5's distinct binding patterns suggest roles in both DSB-dependent and DSB-independent crossover pathways.
- These findings provide insights into the coordinated action of Msh4-Msh5 with other factors to ensure proper crossover formation and genome stability.
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