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Functionally homologous DNA replication genes in fission and budding yeast
M Sánchez1, A Calzada, A Bueno
1Instituto de Microbiología-Bioquímica/Centro de Investigación del Cáncer, Departamento de Microbiología y Genética, Edificio Departamental, Campus Miguel de Unamuno, CSIC/Universidad de Salamanca, Spain.
Journal of Cell Science
|June 25, 1999
Summary
The Saccharomyces cerevisiae CDC6 gene functionally complements fission yeast cdc18 mutants, indicating CDC6 and cdc18(+) are homologous. This suggests distinct genome duplication controls between budding and fission yeast.
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- The cdc18(+) gene in Schizosaccharomyces pombe is crucial for DNA replication initiation and S phase-mitosis coupling.
- Understanding the functional conservation of cell cycle regulatory genes across different yeast species provides insights into fundamental biological processes.
Purpose of the Study:
- To investigate the functional homology between the Saccharomyces cerevisiae CDC6 gene and the fission yeast cdc18(+) gene.
- To determine if CDC6 can rescue defects in S. pombe lacking functional cdc18(+) and explore its role in cell cycle regulation.
Main Methods:
- Complementation assays using S. pombe strains with cdc18 mutations (ts and deletion).
- In vivo and in vitro interaction studies of Cdc6 protein with Cdc2 kinase complexes.
- Analysis of phenotypes resulting from Cdc6 overexpression in S. pombe, including DNA synthesis and cell division.
Main Results:
- Saccharomyces cerevisiae CDC6 successfully complemented both initiation and checkpoint defects in cdc18 mutant S. pombe strains.
- Cdc6 protein was found to interact with Cdc2 kinase complexes in vivo and serve as a substrate for specific Cdc/Cdc2 kinases.
- Overexpression of Cdc6 in S. pombe led to multiple rounds of S-phase without cell division, dependent on Cig2/Cdc2 activity and independent of cdc18(+).
Conclusions:
- CDC6 and cdc18(+) are functional homologs, highlighting conserved roles in DNA replication initiation.
- The study suggests that mechanisms controlling genome duplication diverge between budding and fission yeast.
- Cdc6 activity, particularly its regulation by specific kinases, plays a significant role in controlling S-phase progression and preventing over-replication.