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Updated: Apr 1, 2026

Frequency and Distribution of Crossovers in Caenorhabditis elegans Meiosis by SNP Genotyping using Real-time PCR
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Mms4 chromosomal association reveals functional relationships between meiotic crossover pathways in budding yeast

Amamah Farzlin Farnaz1, Sameer Joshi1, Praseetha Sarath1

  • 1School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Trivandrum, India.

Plos Genetics
|March 30, 2026
PubMed

Insights

Meiotic crossovers form from DNA breaks. The Mms4-Mus81 complex preferentially binds weaker DNA break sites, unlike Msh4-Msh5, enhancing meiotic recombination robustness.

Area of Science:

  • * Genetics and Molecular Biology
  • * Cell Biology
  • * DNA Repair Mechanisms

Background:

  • * Meiotic crossovers are essential for accurate chromosome segregation during gamete formation.
  • * Crossovers arise from the repair of programmed DNA double-strand breaks (DSBs).
  • * Two main pathways exist: Class I (Msh4-Msh5 dependent) and Class II (Mms4-Mus81 endonuclease).

Purpose of the Study:

  • * To investigate the genome-wide localization of the Mms4 protein during meiosis in Saccharomyces cerevisiae.
  • * To understand the relationship between Mms4 localization and DNA double-strand break sites.
  • * To elucidate the role of Mms4 in the context of other meiotic recombination proteins like Msh5.

Main Methods:

  • * Genome-wide chromatin immunoprecipitation followed by sequencing (ChIP-seq) to map Mms4 localization.
  • * Analysis of Mms4 binding patterns relative to DSB hotspots.
  • * Examination of Mms4 localization in various genetic backgrounds, including msh5 deletion mutants.

Main Results:

  • * Mms4 exhibits a preference for weaker DSB sites, contrasting with Msh5's bias towards strong DSB sites.
  • * Mms4 localization is independent of DSB formation but facilitated by chromosome axis assembly.
  • * Mms4 binding is largely insensitive to heterozygosity, unlike Msh5.

Conclusions:

  • * Mms4-Mus81 enhances meiotic recombination robustness by targeting weaker or divergent DSB hotspots.
  • * Mms4 associates with chromosomal axes near recombination intermediates.
  • * Findings challenge competitive models for Mms4 and Msh5 association on meiotic chromosomes.

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