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Use of Time-Lapse Microscopy and Stage-Specific Nuclear Depletion of Proteins to Study Meiosis in S. cerevisiae
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The meiosis-specific protein kinase Ime2 directs phosphorylation of replication protein A

Dawn M Clifford1, Suzanne M Marinco, George S Brush

  • 1Program in Molecular Biology and Genetics, Karmanos Cancer Institute, Wayne State University, Detroit, Michigan 48201, USA.

The Journal of Biological Chemistry
|November 25, 2003
PubMed

Insights

The meiosis-specific kinase Ime2 directly phosphorylates replication protein A (RPA) in yeast, initiating a key step in meiotic progression. This process is crucial for differentiating DNA metabolism between mitotic and meiotic growth.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Genetics

Background:

  • Replication protein A (RPA) is essential for DNA replication, repair, and recombination.
  • RPA undergoes phosphorylation during meiosis in Saccharomyces cerevisiae via two distinct reactions.
  • The timing and regulation of these phosphorylation events are critical for meiotic progression.

Purpose of the Study:

  • To investigate the role of the meiosis-specific protein kinase Ime2 in RPA phosphorylation during meiosis.
  • To determine if Ime2 directly phosphorylates RPA in vivo and in vitro.
  • To elucidate the mechanism by which Ime2 influences both RPA phosphorylation reactions.

Main Methods:

  • Expression of Ime2 in vegetative yeast cells.
  • Immunoprecipitation of Ime2.
  • In vitro phosphorylation assays using purified RPA.
  • Analysis of RPA phosphorylation patterns during meiotic progression.

Main Results:

  • Ime2 expression in vegetative cells induced an unscheduled RPA phosphorylation reaction.
  • Immunoprecipitated Ime2 catalyzed the phosphorylation of purified RPA.
  • Ime2 is essential for the correct timing of both meiotic RPA phosphorylation reactions.
  • Ime2 directly phosphorylates RPA in the primary reaction and indirectly promotes the secondary reaction.

Conclusions:

  • Ime2 acts as a direct RPA kinase in vivo, catalyzing the primary phosphorylation reaction.
  • Ime2 advances meiotic progression, indirectly promoting the Mec1-dependent secondary RPA phosphorylation.
  • This novel meiosis-specific pathway involving Ime2 and RPA is critical for regulating DNA metabolism during meiosis.

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