title: Abnormality in initiation program of DNA replication is monitored by the highly repetitive rRNA gene array on chromosome XII in budding yeast.
abstract: We have shown previously that perturbation of origin firing in chromosome replication causes DNA lesions and triggers DNA damage checkpoint control, which ensures genomic integrity by stopping cell cycle progression until the lesions are repaired or by inducing cell death if they are not properly repaired. This was based on the observation that the temperature-sensitive phenotype of orc1-4 and orc2-1 mutants required a programmed action of the RAD9-dependent DNA damage checkpoint. Here, we report that DNA lesions in the orc mutants are induced much more quickly and frequently within the rRNA gene (rDNA) locus than at other chromosomal loci upon temperature shift. orc mutant cells with greatly reduced rDNA copy numbers regained the ability to grow at restrictive temperatures, and the checkpoint response after the temperature shift became weak in these cells. In orc2-1 cells, completion of chromosomal duplication was delayed specifically on chromosome XII, where the rDNA array is located, and the delay was partially suppressed when the rDNA copy number was reduced. These results suggest that the rDNA locus primarily signals abnormalities in the initiation program to the DNA damage checkpoint and that the rDNA copy number modulates the sensitivity of this monitoring function.
authors.affiliation: Department of Molecular Biology, Graduate School of Biological Sciences, Nara Institute of Science and Technology, Takayama-cho 8916-5, Ikoma, Nara 630-0192, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Ide
authors.forename: Keiichi
authors.initials: K
authors.lastname: Watanabe
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Watanabe
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Shirahige
authors.forename: Takehiko
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Hisaji
authors.initials: H
authors.lastname: Maki
mesh_terms: D015825:Chromosomes, Fungal / Q000235:genetics / Q000502:physiology*; D004249:DNA Damage; D004261:DNA Replication; D018628:Gene Dosage; D020459:Genes, rRNA; D016681:Genome, Fungal; D009154:Mutation; D051738:Origin Recognition Complex / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D051738:Origin Recognition Complex; D029701:Saccharomyces cerevisiae Proteins