Single-stranded DNA arising at telomeres in cdc13 mutants may constitute a specific signal for the RAD9 checkpoint.
A cdc13 temperature-sensitive mutant of Saccharomyces cerevisiae arrests in the G2 phase of the cell cycle at the restrictive temperature as a result of DNA damage that activates the RAD9 checkpoint. The DNA lesions present after a failure of Cdc13p function appear to be located almost exclusively in telomere-proximal regions, on the basis of the profile of induced mitotic recombination. cdc13 rad9 cells dividing at the restrictive temperature contain single-stranded DNA corresponding to telomeric and telomere-proximal DNA sequences and eventually lose telomere-associated sequences. These results suggest that the CDC13 product functions in telomere metabolism, either in the replication of telomeric DNA or in protecting telomeres from the double-strand break repair system. Moreover, since cdc13 rad9 cells divide at a wild-type rate for several divisions at the restrictive temperature while cdc13 RAD9 cells arrest in G2, these results also suggest that single-stranded DNA may be a specific signal for the RAD9 checkpoint.
Garvik
B
B
Department of Genetics, University of Washington, Seattle 98195, USA.
Carson
M
M
Hartwell
L
L
D001483:Base Sequence; D018797:Cell Cycle Proteins; D003001:Cloning, Molecular; D019926:Cyclin B; D016213:Cyclins / Q000502:physiology*; D004261:DNA Replication; D004271:DNA, Fungal / Q000096:biosynthesis; D004277:DNA, Single-Stranded / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000235:genetics; D004843:Epistasis, Genetic; D005656:Fungal Proteins / Q000502:physiology*; D017353:Gene Deletion; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D016615:Telomere / Q000648:ultrastructure*
D018797:Cell Cycle Proteins; D019926:Cyclin B; D016213:Cyclins; D004271:DNA, Fungal; D004277:DNA, Single-Stranded; D005656:Fungal Proteins; C069930:rad9 protein; D004259:DNA-Directed DNA Polymerase