title: Cell cycle expression of two replicative DNA polymerases alpha and delta from Schizosaccharomyces pombe.
abstract: We have investigated the expression of two Schizosaccharomyces pombe replicative DNA polymerases alpha and delta during the cell cycle. The pol alpha+ and pol delta+ genes encoding DNA polymerases alpha and delta were isolated from S. pombe. Both pol alpha+ and pol delta+ genes are single copy genes in haploid cells and are essential for cell viability. In contrast to Saccharomyces cerevisiae homologs, the steady-state transcripts of both S. pombe pol alpha+ and pol delta+ genes were present throughout the cell cycle. Sequence analysis of the pol alpha+ and pol delta+ genes did not reveal the Mlu I motifs in their upstream sequences that are involved in cell cycle-dependent transcription of S. cerevisiae DNA synthesis genes as well as the S. pombe cdc22+ gene at the G1/S boundary. However, five near-match Mlu I motifs were found in the upstream region of the pol alpha+ gene. S. pombe DNA polymerases alpha and delta proteins were also expressed constantly throughout the cell cycle. In addition, the enzymatic activity of the S. pombe DNA polymerase alpha measured by in vitro assay was detected at all stages of the cell cycle. Thus, these S. pombe replicative DNA polymerases, like that of S. pombe cdc17+ gene, are expressed throughout the cell cycle at the transcriptional and protein level. These results indicate that S. pombe has at least two regulatory modes for the expression of genes involved in DNA replication and DNA precursor synthesis.
authors.affiliation: Department of Pathology, Stanford University School of Medicine, California 94305-5324.
authors.forename: H
authors.initials: H
authors.lastname: Park
authors.forename: S
authors.initials: S
authors.lastname: Francesconi
authors.forename: T S
authors.initials: TS
authors.lastname: Wang
mesh_terms: D001483:Base Sequence; D002453:Cell Cycle; D004257:DNA Polymerase II / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D004258:DNA Polymerase III; D004261:DNA Replication; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D016133:Polymerase Chain Reaction; D012331:RNA, Fungal / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D015183:Restriction Mapping; D012568:Schizosaccharomyces / Q000166:cytology / Q000201:enzymology* / Q000235:genetics
chemical_list: D009838:Oligodeoxyribonucleotides; D012331:RNA, Fungal; D012333:RNA, Messenger; D004257:DNA Polymerase II; D004258:DNA Polymerase III; D004259:DNA-Directed DNA Polymerase