N. Rhind et P. Russell, THE SCHIZOSACCHAROMYCES-POMBE S-PHASE CHECKPOINT DIFFERENTIATES BETWEEN DIFFERENT TYPES OF DNA-DAMAGE, Genetics, 149(4), 1998, pp. 1729-1737
We have identified an S-phase DNA damage checkpoint in Schizosaccharom
yces pombe. This checkpoint is dependent on Rad3, the S. pombe homolog
of the mammalian ATM/ATR checkpoint proteins, and Cds1. Cds1 had prev
iously been believed to be involved only in the replication checkpoint
. The requirement of Cds1 in the DNA damage checkpoint suggests that C
ds1 may be a general target of S-phase checkpoints. Unlike other check
points, the S. pombe S-phase DNA damage checkpoint discriminates betwe
en different types of damage. W-irradiation, which causes base modific
ation that can be repaired during G1 and S-phase, invokes the checkpoi
nt, while gamma-irradiation, which causes double-stranded breaks that
cannot be repaired by a haploid cell if induced before replication, do
es not invoke the checkpoint. Because the same genes are required to r
espond to UV- and gamma-irradiation during G2, this discrimination may
represent an active suppression of the gamma response during S-phase.