Saccharomyces cerevisiae chromatin-assembly factors that act during DNA replication function in the maintenance of genome stability

Some spontaneous gross chromosomal rearrangements (GCRs) seem to result from DNA-replication errors. The chromatin-assembly factor I (CAF-1) and replication-coupling assembly factor (RCAF) complexes function in chromatin assembly during DNA replication and repair and could play a role in maintaining genome stability. Inactivation of CAF-1 or RCAF increased the rate of accumulating different types of GCRs including translocations and deletion of chromosome arms with associated de novo telomere addition. Inactivation of CAR seems to cause damage that activates the DNA-damage checkpoints, whereas inactivation of RCAF seems to cause damage that activates the DNA-damage and replication checkpoints. Both defects result in increased genome instability that is normally suppressed by these checkpoints, RAD52-dependent recombination, and PIF1-dependent inhibition of de novo telomere addition. Treatment of CAF-1- or RCAF-defective cells with methyl methanesulfonate increased the induction of GCRs compared with that seen for a wild-type strain. These results indicate that coupling of chromatin assembly to DNA replication and DNA repair is critical to maintaining genome stability.