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Redirecting meiotic DNA break hotspot determinant proteins alters localized spatial control of DNA break formation

Randy W Hyppa1, Joshua D Cho1, Mridula Nambiar1

  • 1Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.

Nucleic Acids Research
|December 30, 2021
PubMed

Insights

Linear element proteins are sufficient to create DNA double-strand break (DSB) hotspots in meiosis. However, endogenous factors are crucial for proper hotspot function, including partner choice and competition during recombination.

Area of Science:

  • Molecular Biology
  • Genetics
  • Cell Biology

Background:

  • Meiosis involves programmed DNA double-strand breaks (DSBs) at specific hotspots to ensure proper chromosome segregation.
  • Linear element proteins (Rec25, Rec27, Mug20) in S. pombe are known determinants of DSB hotspot formation, binding with high specificity.

Purpose of the Study:

  • To investigate if linear element proteins are sufficient to determine DSB hotspot formation.
  • To analyze the characteristics of artificially induced DSB hotspots.

Main Methods:

  • Fusing linear element proteins to the Escherichia coli LacI repressor to localize them to a novel chromosomal site (ade6 with lacO substitutions).
  • Analyzing DSB formation, recombinant frequency, and DSB hotspot competition at the engineered site.

Main Results:

  • The Mug20-LacI fusion protein, combined with lacO, successfully created a strong DSB hotspot at the ade6 locus.
  • This induced hotspot exhibited low recombinant frequency and negligible hotspot competition, despite showing DSB interference similar to endogenous hotspots.
  • Individual lac elements or other combinations did not produce a significant hotspot.

Conclusions:

  • Linear element proteins are sufficient to initiate DSB formation at a specific site.
  • Proper placement by endogenous factors is essential for linear element proteins to regulate hotspot competition and partner choice in DSB repair.
  • Findings support and extend the DSB hotspot-clustering model for controlling meiotic recombination.

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