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Redundant control of rereplication in fission yeast.
- Source :
-
Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2001 Nov 06; Vol. 98 (23), pp. 13114-9. Date of Electronic Publication: 2001 Oct 23. - Publication Year :
- 2001
-
Abstract
- The initiation of DNA replication at replication origins in eukaryotic cells is tightly controlled to ensure that the genome is duplicated only once each cell cycle. We present evidence that in fission yeast, independent regulation of two essential components of the initiation complex, Cdc18 and Cdt1, contributes to the prevention of reinitiation of DNA replication. Cdc18 is negatively controlled by cyclin-dependent kinase (CDK) phosphorylation, but low level expression of a mutant form of Cdc18 lacking CDK phosphorylation sites (Cdc18(CDK)) is not sufficient to induce rereplication. Similar to Cdc18, Cdt1 is expressed periodically in the cell cycle, accumulating in the nucleus in G(1) and declining in G(2). When Cdt1 is expressed constitutively from an ectopic promoter, it accumulates in the nucleus throughout the cell cycle but does not promote reinitiation. However, constitutive expression of Cdt1, together with Cdc18(CDK), is sufficient to induce extra rounds of DNA replication in the absence of mitosis. Significantly greater levels of rereplication can be induced by coexpression of Cdc18(CDK) and a Cdt1 mutant lacking a conserved C-terminal motif. In contrast, uncontrolled DNA replication does not occur when either mutant protein is expressed in the absence of the other. Constitutive expression of wild-type or mutant Cdt1 also leads to an increase in the levels of Cdc18(CDK), possibly as a result of increased protein stability. Our data are consistent with the hypothesis that control of rereplication depends on a redundant mechanism in which negative regulation of Cdt1 functions in parallel with the negative regulation of Cdc18.
- Subjects :
- Cell Cycle Proteins metabolism
DNA-Binding Proteins metabolism
Fluorescent Antibody Technique
Fungal Proteins metabolism
Phosphorylation
Precipitin Tests
Schizosaccharomyces pombe Proteins
Subcellular Fractions metabolism
Cell Cycle Proteins physiology
DNA Replication
DNA, Fungal biosynthesis
DNA-Binding Proteins physiology
Fungal Proteins physiology
Schizosaccharomyces genetics
Subjects
Details
- Language :
- English
- ISSN :
- 0027-8424
- Volume :
- 98
- Issue :
- 23
- Database :
- MEDLINE
- Journal :
- Proceedings of the National Academy of Sciences of the United States of America
- Publication Type :
- Academic Journal
- Accession number :
- 11606752
- Full Text :
- https://doi.org/10.1073/pnas.221467598