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XPG-related nucleases are hierarchically recruited for double-stranded rDNA break resection.
- Source :
-
The Journal of biological chemistry [J Biol Chem] 2019 May 10; Vol. 294 (19), pp. 7632-7643. Date of Electronic Publication: 2019 Mar 18. - Publication Year :
- 2019
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Abstract
- dsDNA breaks (DSBs) are resected in a 5'→3' direction, generating single-stranded DNA (ssDNA). This promotes DNA repair by homologous recombination and also assembly of signaling complexes that activate the DNA damage checkpoint effector kinase Chk1. In fission yeast ( Schizosaccharomyces pombe ), genetic screens have previously uncovered a family of three xeroderma pigmentosum G (XPG)-related nucleases (XRNs), known as Ast1, Exo1, and Rad2. Collectively, these XRNs are recruited to a euchromatic DSB and are required for ssDNA production and end resection across the genome. Here, we studied why there are three related but distinct XRN enzymes that are all conserved across a range of species, including humans, whereas all other DSB response proteins are present as single species. Using S. pombe as a model, ChIP and DSB resection analysis assays, and highly efficient I-PpoI-induced DSBs in the 28S rDNA gene, we observed a hierarchy of recruitment for each XRN, with a progressive compensatory recruitment of the other XRNs as the responding enzymes are deleted. Importantly, we found that this hierarchy reflects the requirement for different XRNs to effect efficient DSB resection in the rDNA, demonstrating that the presence of three XRN enzymes is not a simple division of labor. Furthermore, we uncovered a specificity of XRN function with regard to the direction of transcription. We conclude that the DSB-resection machinery is complex, is nonuniform across the genome, and has built-in fail-safe mechanisms, features that are in keeping with the highly pathological nature of DSB lesions.<br /> (© 2019 Barnum et al.)
- Subjects :
- DNA, Fungal genetics
DNA, Ribosomal genetics
DNA, Ribosomal metabolism
Deoxyribonucleases genetics
Endodeoxyribonucleases genetics
Humans
RNA, Fungal genetics
RNA, Fungal metabolism
RNA, Ribosomal, 28S genetics
RNA, Ribosomal, 28S metabolism
Schizosaccharomyces genetics
Schizosaccharomyces pombe Proteins genetics
DNA Breaks, Double-Stranded
DNA, Fungal metabolism
Deoxyribonucleases metabolism
Endodeoxyribonucleases metabolism
Schizosaccharomyces metabolism
Schizosaccharomyces pombe Proteins metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1083-351X
- Volume :
- 294
- Issue :
- 19
- Database :
- MEDLINE
- Journal :
- The Journal of biological chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 30885940
- Full Text :
- https://doi.org/10.1074/jbc.RA118.005415