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Fission yeast mfr1 activates APC and coordinates meiotic nuclear division with sporulation
M A Blanco1, L Pelloquin, S Moreno
1Instituto de Microbiología Bioquímica, CSIC/Universidad de Salamanca, Edificio Departamental, Campus Miguel de Unamuno, 37007 Salamanca, Spain.
Abstract:
Meiosis is the developmental program by which sexually reproducing diploid organisms generate haploid gametes. In yeast, meiosis is followed by spore morphogenesis. These two events are normally coordinated in such a way that spore formation is dependent upon completion of the meiotic nuclear divisions. Here we describe a meiosis-specific protein, mfr1, that is involved in this coordination. mfr1 is an activator of the anaphase-promoting complex (APC), which is necessary for the rapid degradation of the cdc13 cyclin at the end of meiosis II, prior to the formation of spores. An mfr1 null mutant completes meiosis II but remains with high levels of cdc13 and cdc2 kinase activity and has considerably delayed spore formation. By analogy with the mitotic cell cycle, where proteolysis and inactivation of cdc2 kinase are necessary to trigger mitotic exit and cytokinesis, we propose that at the end of meiosis rapid and timely proteolysis of cyclins is required to switch on the differentiation program that eventually leads to the formation of haploid gametes.
Insights
A newly identified meiosis-specific protein, mfr1, coordinates spore formation with meiotic nuclear divisions. Mfr1 activates the anaphase-promoting complex (APC), ensuring timely cyclin degradation for gamete differentiation.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Meiosis generates haploid gametes in sexually reproducing organisms.
- Spore morphogenesis in yeast follows meiosis and is tightly coordinated with nuclear divisions.
Purpose of the Study:
- To identify and characterize a protein involved in coordinating meiosis and spore formation in yeast.
- To elucidate the molecular mechanism by which spore formation is regulated post-meiosis.
Main Methods:
- Yeast genetics
- Protein analysis
- Cell cycle studies
- Anaphase-promoting complex (APC) activity assays
Main Results:
- A novel meiosis-specific protein, mfr1, was identified.
- Mfr1 acts as an activator of the anaphase-promoting complex (APC).
- Mfr1 is essential for the degradation of the cdc13 cyclin at the end of meiosis II, enabling timely spore formation.
Conclusions:
- Mfr1 plays a critical role in coordinating meiotic progression with spore morphogenesis.
- Rapid cyclin proteolysis, regulated by mfr1 and APC, is essential for initiating the differentiation program leading to haploid gametes.