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Microscopy of Fission Yeast Sexual Lifecycle
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A Unique DNA Recombination Mechanism of the Mating/Cell-type Switching of Fission Yeasts: a Review

Amar J S Klar1, Ken Ishikawa1, Sharon Moore1

  • 1National Cancer Institute at Frederick, Gene Regulation and Chromosome Biology Laboratory, National Cancer Institute at Frederick, P.O. Box B, Frederick, MD 21702-1201.

Microbiology Spectrum
|June 25, 2015
PubMed

Insights

Schizosaccharomyces fission yeasts switch mating types via a DNA recombination mechanism. This involves a cell-cycle-dependent epigenetic imprint on DNA strands, ensuring asymmetric cell division and cellular differentiation.

Area of Science:

  • Cell Biology
  • Genetics
  • Epigenetics

Background:

  • Fission yeasts Schizosaccharomyces pombe and S. japonicus possess two mating types (P and M) determined by the mat1 locus.
  • Mating type switching occurs through programmed DNA recombination with silent mating-type genes.
  • This process is linked to cell-cycle progression, with switching occurring in specific cell generations.

Purpose of the Study:

  • To review recent advancements in understanding mating-type switching in fission yeasts.
  • To explore the role of DNA strand chirality and epigenetic imprinting in asymmetric cell division.
  • To propose potential mechanisms for similar DNA strand-based epigenetic cellular differentiation in diploid organisms.

Main Methods:

  • Review of existing literature on fission yeast mating-type switching.
  • Analysis of cell-cycle and generation-dependent DNA recombination events.
  • Examination of epigenetic imprinting at the mat1 locus.

Main Results:

  • Established DNA strand chirality at mat1 as the basis for asymmetric cell division.
  • Identified a unique site- and strand-specific epigenetic imprint at mat1.
  • Demonstrated imprint inheritance for one cell cycle to initiate subsequent recombination.

Conclusions:

  • The DNA strand-based epigenetic mechanism is crucial for mating-type switching and cellular differentiation in Schizosaccharomyces.
  • This mechanism, while seemingly unique, may offer insights into cellular differentiation in diploid organisms.
  • Further research is needed to determine the broader applicability of this epigenetic switching mechanism.

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