Title

The role of MRN in the S-phase DNA damage checkpoint is independent of its Ctp1-dependent roles in double-strand break repair and checkpoint signaling

UMMS Affiliation

Department of Biochemistry and Molecular Pharmacology

Publication Date

2-13-2009

Document Type

Article

Subjects

Chromosomal Proteins, Non-Histone; *DNA Breaks, Double-Stranded; *DNA Repair; DNA-Binding Proteins; Exodeoxyribonucleases; Meiosis; Microbial Viability; Mutation; Phenotype; Recombination, Genetic; *S Phase; Schizosaccharomyces; Schizosaccharomyces pombe Proteins; *Signal Transduction; Spores, Fungal; Telomere

Disciplines

Life Sciences | Medicine and Health Sciences

Abstract

The Mre11-Rad50-Nbs1 (MRN) complex has many biological functions: processing of double-strand breaks in meiosis, homologous recombination, telomere maintenance, S-phase checkpoint, and genome stability during replication. In the S-phase DNA damage checkpoint, MRN acts both in activation of checkpoint signaling and downstream of the checkpoint kinases to slow DNA replication. Mechanistically, MRN, along with its cofactor Ctp1, is involved in 5' resection to create single-stranded DNA that is required for both signaling and homologous recombination. However, it is unclear whether resection is essential for all of the cellular functions of MRN. To dissect the various roles of MRN, we performed a structure-function analysis of nuclease dead alleles and potential separation-of-function alleles analogous to those found in the human disease ataxia telangiectasia-like disorder, which is caused by mutations in Mre11. We find that several alleles of rad32 (the fission yeast homologue of mre11), along with ctp1Delta, are defective in double-strand break repair and most other functions of the complex, but they maintain an intact S phase DNA damage checkpoint. Thus, the MRN S-phase checkpoint role is separate from its Ctp1- and resection-dependent role in double-strand break repair. This observation leads us to conclude that other functions of MRN, possibly its role in replication fork metabolism, are required for S-phase DNA damage checkpoint function.

Rights and Permissions

Citation: Mol Biol Cell. 2009 Apr;20(7):2096-107. Epub 2009 Feb 11. Link to article on publisher's site

DOI of Published Version

10.1091/mbc.E08-09-0986

Related Resources

Link to Article in PubMed

Journal/Book/Conference Title

Molecular biology of the cell

PubMed ID

19211838