Cleavage Factor I Links Transcription Termination to DNA Damage Response and Genome Integrity Maintenance in Saccharomyces cerevisiae

Hélène Gaillard,Andrés Aguilera,Sue Jinks-Robertson

doi:10.1371/journal.pgen.1004203

Abstract

During transcription, the nascent pre-mRNA undergoes a series of processing steps before being exported to the cytoplasm. The 3′-end processing machinery involves different proteins, this function being crucial to cell growth and viability in eukaryotes. Here, we found that the rna14-1, rna15-1, and hrp1-5 alleles of the cleavage factor I (CFI) cause sensitivity to UV-light in the absence of global genome repair in Saccharomyces cerevisiae. Unexpectedly, CFI mutants were proficient in UV-lesion repair in a transcribed gene. DNA damage checkpoint activation and RNA polymerase II (RNAPII) degradation in response to UV were delayed in CFI-deficient cells, indicating that CFI participates in the DNA damage response (DDR). This is further sustained by the synthetic growth defects observed between rna14-1 and mutants of different repair pathways. Additionally, we found that rna14-1 suffers severe replication progression defects and that a functional G1/S checkpoint becomes essential in avoiding genetic instability in those cells. Thus, CFI function is required to maintain genome integrity and to prevent replication hindrance. These findings reveal a new function for CFI in the DDR and underscore the importance of coordinating transcription termination with replication in the maintenance of genomic stability.

Highlights

All cells are continuously exposed to DNA damaging agents, which can arise from exogenous sources or from endogenous metabolic processes
DNA repair is relevant for lesions occurring in actively transcribed DNA strands because the RNA polymerase cannot proceed through a damaged site
Our findings emphasize the importance of coordinating transcription termination, DNA damage response and replication in the maintenance of genomic stability suggesting that cleavage factor I (CFI) plays a fundamental function in the coupling of these processes

Summary

Introduction

All cells are continuously exposed to DNA damaging agents, which can arise from exogenous sources or from endogenous metabolic processes. The DNA damage response (DDR) includes the activation of checkpoints and induction of DNA repair pathways. DNA lesions can generate structural distortions that interfere with basic cellular functions like transcription and replication. Such helix-distorting DNA lesions are generally handled by nucleotide excision repair (NER), which can be divided into global genome repair (GG-NER) and transcriptioncoupled repair (TC-NER) sub-pathways, depending on whether the DNA lesion is located anywhere in the genome or on the transcribed strand (TS) of an active gene, respectively. TC-NER acts when elongating RNA polymerase (RNAP) stalls at bulky DNA lesions such as UV-induced cyclobutane pyrimidine dimers (CPDs) (reviewed in [1,2]).

Results

Discussion

Conclusion