DNA polymerase epsilon encoded by cdc20+ is required for chromosomal DNA replication in the fission yeast Schizosaccharomyces pombe.
BACKGROUND
DNA polymerase II (PolII), the homologue of mammalian DNA polymerase epsilon, is essential for chromosomal DNA replication in the budding yeast Saccharomyces cerevisiae and also participates in S-phase checkpoint control. An important issue is whether chromosomal DNA replication in other eukaryotes, including the fission yeast Schizosaccharomyces pombe--in which the characteristics of replication origins are poorly defined--also requires DNA polymerase epsilon. It has been shown that DNA polymerase epsilon is not required for the in vitro replication of SV40 DNA by human cell extracts.


RESULTS
We have cloned and sequenced S. pombe pol2+, which is identical to the cell-cycle gene cdc20+, encoding the catalytic polypeptide of DNA polymerase epsilon (Pol epsilon). The predicted amino acid sequence of Pol epsilon is highly homologous to that of S. cerevisiae PolII and human Pol epsilon. Consistent with this, the Pol epsilon polypeptide was recognized by polyclonal antibodies against S. cerevisiae PolII holoenzyme (PolII*). The terminal morphology of cells containing the disrupted pol2 gene was similar to that of DNA replication mutant cells and cdc20 mutant cells. Furthermore, the Pol epsilon activity from temperature-sensitive S. pombe cdc20 mutant cells was temperature-sensitive, and chromosomal DNA replication in the mutant cells was inhibited at the restrictive temperatures.


CONCLUSIONS
These data strongly suggest that Pol epsilon is required for normal chromosomal DNA replication in S. pombe, as is PolII in S. cerevisiae. Thus, eukaryotic chromosomal DNA is replicated differently from that of viral SV40 DNA.
Sugino
A
A
Department of Biochemistry and Molecular Biology, Research Institute for Microbial Diseases, Osaka University, Suita, Japan. asugino@biken.osaka-u.ac.jp
Ohara
T
T
Sebastian
J
J
Nakashima
N
N
Araki
H
H
D000595:Amino Acid Sequence; D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D004257:DNA Polymerase II / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D004261:DNA Replication; D004587:Electrophoresis, Agar Gel; D005800:Genes, Fungal; D006801:Humans; D008969:Molecular Sequence Data; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D012568:Schizosaccharomyces / Q000201:enzymology* / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D014170:Transformation, Genetic
C577495:CDC20 protein, S cerevisiae; D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins; D029701:Saccharomyces cerevisiae Proteins; D004257:DNA Polymerase II