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

Area of Science:

• Molecular Biology
• Genetics
• Cellular Biology

Background:

• The DNA damage and replication checkpoint pathways are crucial for maintaining genomic stability.
• Understanding the regulatory mechanisms of these pathways is essential for comprehending cellular responses to stress.

Purpose of the Study:

• To identify key effectors in the yeast DNA damage and replication checkpoint pathway.
• To elucidate the function of the CRT1 gene in regulating damage-inducible genes and cell viability.

Main Methods:

• Gene identification and characterization of the yeast CRT1 gene.
• Analysis of protein interactions, including DNA binding and recruitment of repressors Ssn6 and Tup1.
• Assessment of gene expression changes in response to DNA damage and replication stress.
• Evaluation of cell viability under various stress conditions, including mec1 and rad53 null mutations.

Main Results:

• CRT1 encodes a DNA-binding protein that acts as a repressor of damage-inducible genes by recruiting Ssn6 and Tup1.
• Derepression of the CRT1 regulon is vital for cell survival during replicative stress and suppresses lethality in mec1 and rad53 mutants.
• CRT1 undergoes hyperphosphorylation upon DNA damage, leading to its dissociation from DNA and transcriptional induction.
• CRT1 is autoregulated and induced by DNA damage, establishing a negative feedback loop.

Conclusions:

• CRT1 is a critical effector in the DNA damage and replication checkpoint pathway, essential for cell viability under stress.
• The autoregulatory negative feedback mechanism involving CRT1 facilitates the timely repression of damage-induced genes after stress elimination.
• The identified mechanism of inhibiting an autoregulatory repressor in response to DNA damage is evolutionarily conserved across prokaryotes and eukaryotes.