The DNA replication and damage checkpoint pathways induce transcription by inhibition of the Crt1 repressor

We have identified the yeast CRT1 gene as an effector of the DNA damage and replication checkpoint pathway. CRT1 encodes a DNA-binding protein that recruits the general repressors Ssn6 and Tupl to the promoters of damage-inducible genes. Derepression of the Crt1 regulon suppresses the lethality of mec1 and rad53 null alleles and is essential for cell viability during replicative stress. In response to DNA damage and replication blocks, Crt1 becomes hyperphosphorylated and no longer binds DNA, resulting in transcriptional induction. CRT1 is autoregulated and is itself induced by DNA damage, indicating the existence of a negative feedback pathway that facilitates return to the repressed state after elimination of damage. The inhibition of an autoregulatory repressor in response to DNA damage is a strategy conserved throughout prokaryotic and eukaryotic evolution.