The fission yeast Cdc1 protein, a homologue of the small subunit of DNA polymerase delta, binds to Pol3 and Cdc27.
cdc1+ is required for cell cycle progression in Schizosaccharomyces pombe. Cells carrying temperature-sensitive cdc1 mutants undergo cell cycle arrest when shifted to the restrictive temperature, becoming highly elongated. Here we describe the cloning and sequencing of cdc1+, which is shown to encode a 462 residue protein that displays significant sequence similarity to the small subunit of mammalian DNA polymerase delta. cdc1+ interacts genetically with pol3+, which encodes the large subunit of DNA polymerase delta in fission yeast, and the Cdc1 protein binds to Pol3 in vitro, strongly suggesting that Cdc1 is likely to be the small subunit of Pol delta. In addition, we show that cdc1+ overexpression is sufficient to rescue cells carrying temperature-sensitive cdc27 alleles and that the Cdc1 and Cdc27 proteins interact in vivo and in vitro. Deletion of either cdc1+ or cdc27+ results in cell cycle arrest with the arrested cells having a single nucleus with 2C DNA content. No evidence was obtained for a cut phenotype, indicating that neither cdc1+ nor cdc27+ is required for checkpoint function. cdc1 mutant cells are supersensitive to the DNA synthesis inhibitor hydroxyurea and to the DNA damaging agent MMS, display increased frequency of mini-chromosome loss and have an extended S phase.
Institute of Cell and Molecular Biology, University of Edinburgh, UK.
S A
SA
MacNeill
S
S
Moreno
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N
Reynolds
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P
Nurse
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Fantes
D000483:Alleles; D000595:Amino Acid Sequence; D064191:Apc3 Subunit, Anaphase-Promoting Complex-Cyclosome; D018797:Cell Cycle Proteins / Q000378:metabolism*; D015825:Chromosomes, Fungal; D003001:Cloning, Molecular; D004258:DNA Polymerase III; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D017353:Gene Deletion; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D029701:Saccharomyces cerevisiae Proteins; D012568:Schizosaccharomyces / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins; D017386:Sequence Homology, Amino Acid; D044767:Ubiquitin-Protein Ligases
D064191:Apc3 Subunit, Anaphase-Promoting Complex-Cyclosome; C090459:CDC1 protein, S cerevisiae; C577355:CDC27 protein, S cerevisiae; D018797:Cell Cycle Proteins; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; C513024:cdc27 protein, S pombe; D044767:Ubiquitin-Protein Ligases; D004258:DNA Polymerase III; D004259:DNA-Directed DNA Polymerase