Related Experiment Video

Updated: Jul 31, 2026

Preparation of the Mgm101 Recombination Protein by MBP-based Tagging Strategy
11:40

Preparation of the Mgm101 Recombination Protein by MBP-based Tagging Strategy

Published on: June 25, 2013

Mrc1 and Srs2 are major actors in the regulation of spontaneous crossover

Thomas Robert1, Delphine Dervins, Francis Fabre

  • 1Commissariat à l'Energie Atomique, UMR217 CNRS-CEA/DSV/DRR/SRMC/LERA, Fontenay-aux-roses, France.

The EMBO Journal
|May 26, 2006
PubMed

Insights

This study reveals key proteins like Srs2, Mrc1, and PCNA that prevent unwanted DNA crossovers during cell division. Understanding these mechanisms is crucial for maintaining genome stability and preventing mutations.

Area of Science:

  • Molecular Biology
  • Genetics
  • Cell Biology

Background:

  • Most DNA recombination intermediates are processed without forming crossovers (COs) to maintain genome stability.
  • Avoiding ectopic recombination prevents potentially harmful genomic rearrangements.

Purpose of the Study:

  • To investigate the outcome of spontaneous intragenic recombination events in Saccharomyces cerevisiae.
  • To analyze the role of specific proteins, including helicases and checkpoint proteins, in regulating crossover formation.

Main Methods:

  • Developed a system to screen spontaneous intragenic recombination in yeast.
  • Analyzed crossover outcomes in mutants lacking Srs2 and Sgs1 helicases, checkpoint proteins, and a mutant proliferating cell nuclear antigen (PCNA).

Main Results:

  • Srs2, Sgs1, Mrc1, and PCNA are essential for genome stability.
  • Absence of Srs2 (srs2Δ), Mrc1 (mrc1Δ), and a specific PCNA mutation (pol30-RR) significantly increased crossover events.
  • Mrc1 promotes Srs2 recruitment to PCNA, independent of checkpoint signaling, to prevent double Holliday junction formation.

Conclusions:

  • Srs2 acts to prevent double Holliday junction formation and thus crossover outcomes.
  • Sgs1 resolves double Holliday junctions into non-crossover products, also regulating crossover frequency.
  • Mrc1 plays a critical role in DNA replication, influencing Srs2 activity and genome stability.

More Related Videos

Frequency and Distribution of Crossovers in Caenorhabditis elegans Meiosis by SNP Genotyping using Real-time PCR06:18

Frequency and Distribution of Crossovers in Caenorhabditis elegans Meiosis by SNP Genotyping using Real-time PCR

Published on: July 11, 2025

Preparation of Meiotic Chromosome Spreads from Mouse Oocytes for Assessment of Synapsis and Recombination09:24

Preparation of Meiotic Chromosome Spreads from Mouse Oocytes for Assessment of Synapsis and Recombination

Published on: July 18, 2025

Related Concept Videos

Crossing Over01:34

Crossing Over

Unlike mitosis, meiosis aims for genetic diversity in its creation of haploid gametes. Dividing germ cells first begin this process in prophase I, where each chromosome—replicated in S phase—is now composed of two sister chromatids (identical copies) joined centrally.
The homologous pairs of sister chromosomes—one from the maternal and one from the paternal genome—then begin to align alongside each other lengthwise, matching corresponding DNA positions in a process called synapsis.
In order to...
Gene Conversion02:08

Gene Conversion

Other than maintaining genome stability via DNA repair, homologous recombination plays an important role in diversifying the genome. In fact, the recombination of sequences forms the molecular basis of genomic evolution. Random and non-random permutations of genomic sequences create a library of new amalgamated sequences. These newly formed genomes can determine the fitness and survival of cells. In bacteria, homologous and non-homologous types of recombination lead to the evolution of new...
Conservative Site-specific Recombination and Phase Variation02:53

Conservative Site-specific Recombination and Phase Variation

Because the DNA segments are cut and reorganized in a direction-specific manner, site-specific recombination has emerged as an efficient genetic engineering technique. Flippase and Cyclization recombinases or Flp and Cre, respectively, are two members of the tyrosine recombinase family derived from bacteriophages, that are used to mediate site-specific DNA insertions, deletions, and targeted expression of proteins in mammalian cell lines.
The recognition sites for Cre recombinase called LoxP...
Master Transcription Regulators02:23

Master Transcription Regulators

Master transcription regulators are regulatory proteins that are predominantly responsible for regulating the expression of multiple genes. Often these genes work in concert to drive a  complex process. Activation of a master transcription regulator can lead to a cascade of transcriptional activation necessary for that outcome. These regulators can directly bind to the regulatory sequences of the various genes involved, or they can indirectly regulate transcription by binding to regulatory...
Master Transcription Regulators02:23

Master Transcription Regulators

Master transcription regulators are regulatory proteins that are predominantly responsible for regulating the expression of multiple genes. Often these genes work in concert to drive a  complex process. Activation of a master transcription regulator can lead to a cascade of transcriptional activation necessary for that outcome. These regulators can directly bind to the regulatory sequences of the various genes involved, or they can indirectly regulate transcription by binding to regulatory...
Crossing Over01:30

Crossing Over

Crossing over is the exchange of genetic information between homologous chromosomes during prophase I of meiosis I. Genetic recombination gives rise to allelic diversity in the newly formed daughter cells. In humans, crossing over produces genetically distinct haploid egg and sperm cells that undergo fertilization to produce unique offspring. Before cell division starts, the germ cell’s chromosome(s) undergo duplication in the S phase of the cell cycle. As the cells enter prophase I, duplicated...