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Pachytene exit controlled by reversal of Mek1-dependent phosphorylation

J M Bailis1, G S Roeder

  • 1Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520, USA.

Cell
|April 29, 2000
PubMed

Insights

A yeast meiosis checkpoint uses Red1 and Mek1 proteins to halt cell cycle progression when recombination is faulty. Protein phosphatase type 1 (Glc7) deactivates this checkpoint by dephosphorylating Red1.

Area of Science:

  • Cell Biology
  • Genetics
  • Molecular Biology

Background:

  • Meiosis involves complex chromosome pairing and recombination.
  • A pachytene checkpoint ensures proper meiotic progression, preventing exit if recombination or synapsis is defective.
  • Key proteins Red1 and Mek1 are essential for this checkpoint in yeast.

Purpose of the Study:

  • To investigate the regulatory mechanism of the pachytene checkpoint during yeast meiosis.
  • To elucidate the roles of Red1, Mek1, and Glc7 in controlling meiotic progression.

Main Methods:

  • Utilized yeast genetics to study mutants with defects in meiotic recombination and synapsis.
  • Employed co-immunoprecipitation and in vitro dephosphorylation assays.
  • Investigated protein localization and phosphorylation status.

Main Results:

  • Mek1 kinase activity and Red1 phosphorylation are maintained during checkpoint-induced pachytene arrest.
  • Mek1 activation depends on meiotic recombination initiation and DNA damage checkpoint proteins.
  • Protein phosphatase type 1 (Glc7) counteracts Mek1 activity and pachytene arrest.
  • Glc7 interacts with Red1, dephosphorylates it in vitro, and colocalizes with it on chromosomes.

Conclusions:

  • Phosphorylated Red1 likely maintains the pachytene arrest.
  • Completion of meiotic recombination may trigger Glc7-mediated dephosphorylation of Red1, allowing checkpoint release.
  • This study reveals a regulatory pathway involving phosphorylation and dephosphorylation in meiotic checkpoint control.

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