A single unbranched S-phase DNA damage and replication fork blockage checkpoint pathway

doi:10.1073/pnas.112702399

A single unbranched S-phase DNA damage and replication fork blockage checkpoint pathway

^*Department of Cancer Genetics, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263-0001; ^†Genome Damage and Stability Centre, School of Biological Sciences, Sussex University, Falmer, Brighton BN1 9RR, United Kingdom; and ^‡Department of Environmental Health Sciences, School of Public Health, Columbia University, New York, NY 10032

Edited by Bruce W. Stillman, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, and approved March 27, 2002 (received for review December 26, 2001)

Abstract

The eukaryotic intra-S-phase checkpoint, which slows DNA synthesis in response to DNA damage, is poorly understood. Is DNA damage recognized directly, or indirectly through its effects on replication forks? Is the slowing of S phase in part because of competition between DNA synthesis and recombination/repair processes? The results of our genetic analyses of the intra-S-phase checkpoint in the fission yeast, Schizosaccharomyces pombe, suggest that the slowing of S phase depends weakly on the helicases Rqh1 and Srs2 but not on other recombination/repair pathways. The slowing of S phase depends strongly on the six checkpoint-Rad proteins, on Cds1, and on Rad4/Cut5 (similar to budding yeast Dpb11, which interacts with DNA polymerase ɛ) but not on Rhp9 (similar to budding yeast Rad9, necessary for direct damage recognition). These results suggest that, in fission yeast, the signal activating the intra-S-phase checkpoint is generated only when replication forks encounter DNA damage.

Footnotes

↵ § To whom reprint requests should be addressed. E-mail: joel.huberman{at}roswellpark.org.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations:

MMS,

methyl methanesulfonate;

BRCT,

Brca1 carboxyl terminal