title: Cyclin-dependent kinase inhibits reinitiation of a normal S-phase program during G2 in fission yeast.
abstract: To achieve faithful replication of the genome once in each cell cycle, reinitiation of S phase is prevented in G(2) and origins are restricted from refiring within S phase. We have investigated the block to rereplication during G(2) in fission yeast. The DNA synthesis that occurs when G(2)/M cyclin-dependent kinase (CDK) activity is depleted has been assumed to be repeated rounds of S phase without mitosis, but this has not been demonstrated to be the case. We show here that on G(2)/M CDK depletion in G(2), repeated S phases are induced, which are correlated with normal G(1)/S transcription and attainment of doublings in cell size. Mostly normal mitotic S-phase origins are utilized, although at different efficiencies, and replication is essentially equal across the genome. We conclude that CDK inhibits reinitiation of S phase during G(2), and if G(2)/M CDK is depleted, replication results from induction of a largely normal S-phase program with only small differences in origin usage and efficiency.
authors.affiliation: Laboratory of Yeast Genetics and Cell Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA. lkiang@rockefeller.edu
authors.forename: Lee
authors.initials: L
authors.lastname: Kiang
authors.forename: Christian
authors.initials: C
authors.lastname: Heichinger
authors.forename: Stephen
authors.initials: S
authors.lastname: Watt
authors.forename: Jürg
authors.initials: J
authors.lastname: Bähler
authors.forename: Paul
authors.initials: P
authors.lastname: Nurse
mesh_terms: D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D019926:Cyclin B / Q000235:genetics / Q000378:metabolism; D018844:Cyclin-Dependent Kinases / Q000235:genetics / Q000378:metabolism*; D004261:DNA Replication / Q000235:genetics; D005434:Flow Cytometry; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D016195:G2 Phase / Q000235:genetics / Q000502:physiology*; D015966:Gene Expression Regulation, Fungal; D016681:Genome, Fungal; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D016196:S Phase / Q000235:genetics / Q000502:physiology*; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D020666:ras-GRF1 / Q000235:genetics / Q000378:metabolism
chemical_list: C498823:Cdc13 protein, S pombe; D018797:Cell Cycle Proteins; D019926:Cyclin B; D005656:Fungal Proteins; D029702:Schizosaccharomyces pombe Proteins; D020666:ras-GRF1; D049452:Green Fluorescent Proteins; D018844:Cyclin-Dependent Kinases