Characterization of G1 checkpoint control in the yeast Saccharomyces cerevisiae following exposure to DNA-damaging agents.
The delay of S-phase following treatment of yeast cells with DNA-damaging agents is an actively regulated response that requires functional RAD9 and RAD24 genes. An analysis of cell cycle arrest indicates the existence of (at least) two checkpoints for damaged DNA prior to S-phase; one at START (a G1 checkpoint characterized by pheromone sensitivity of arrested cells) and one between the CDC4- and CDC7-mediated steps (termed the G1/S checkpoint). When a dna1-1 mutant (that affects early events of replicon initiation) also carries a rad9 deletion mutation, it manifests a failure to arrest in G1/S following incubation at the restrictive temperature. This failure to execute regulated G1/S arrest is correlated with enhanced thermosensitivity of colony-forming ability. In an attempt to characterize the signal for RAD9 gene-dependent G1 and G1/S cell cycle arrest, we examined the influence of the continued presence of unexcised photoproducts. In mutants defective in nucleotide excision repair, cessation of S-phase was observed at much lower doses of UV radiation compared to excision-proficient cells. However, this response was not RAD9-dependent. We suggest that an intermediate of nucleotide excision repair, such as DNA strand breaks or single-stranded DNA tracts, is required to activate RAD9-dependent G1 and G1/S checkpoint controls.
Siede
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Department of Pathology, University of Texas Southwestern Medical Center, Dallas 75235.
Friedberg
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Dianova
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Friedberg
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D002453:Cell Cycle / Q000235:genetics / Q000528:radiation effects*; D018797:Cell Cycle Proteins; D004249:DNA Damage; D004268:DNA-Binding Proteins; D004706:Endodeoxyribonucleases; D005434:Flow Cytometry; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D016193:G1 Phase / Q000235:genetics / Q000528:radiation effects; D017353:Gene Deletion; D005800:Genes, Fungal; D005838:Genotype; D047908:Intracellular Signaling Peptides and Proteins; D000072235:Mating Factor; D010452:Peptide Biosynthesis; D010455:Peptides; D010675:Pheromones / Q000096:biosynthesis; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects*; D029701:Saccharomyces cerevisiae Proteins; D013045:Species Specificity; D014158:Transcription, Genetic
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D047908:Intracellular Signaling Peptides and Proteins; D010455:Peptides; D010675:Pheromones; C088385:RAD24 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C073998:RAD2 protein, S cerevisiae; C069930:rad9 protein; D000072235:Mating Factor; D004706:Endodeoxyribonucleases