Dataset Information

Homology Requirements and Competition between Gene Conversion and Break-Induced Replication during Double-Strand Break Repair.

ABSTRACT: Saccharomyces cerevisiae mating-type switching is initiated by a double-strand break (DSB) at MATa, leaving one cut end perfectly homologous to the HML? donor, while the second end must be processed to remove a non-homologous tail before completing repair by gene conversion (GC). When homology at the matched end is ?150 bp, efficient repair depends on the recombination enhancer, which tethers HML? near the DSB. Thus, homology shorter than an apparent minimum efficient processing segment can be rescued by tethering the donor near the break. When homology at the second end is ?150 bp, second-end capture becomes inefficient and repair shifts from GC to break-induced replication (BIR). But when pol32 or pif1 mutants block BIR, GC increases 3-fold, indicating that the steps blocked by these mutations are reversible. With short second-end homology, absence of the RecQ helicase Sgs1 promotes gene conversion, whereas deletion of the FANCM-related Mph1 helicase promotes BIR.

SUBMITTER: Mehta A

PROVIDER: S-EPMC5291802 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Homology Requirements and Competition between Gene Conversion and Break-Induced Replication during Double-Strand Break Repair.

Mehta Anuja A Beach Annette A Haber James E JE

Molecular cell 20170105 3

Saccharomyces cerevisiae mating-type switching is initiated by a double-strand break (DSB) at MATa, leaving one cut end perfectly homologous to the HMLα donor, while the second end must be processed to remove a non-homologous tail before completing repair by gene conversion (GC). When homology at the matched end is ≤150 bp, efficient repair depends on the recombination enhancer, which tethers HMLα near the DSB. Thus, homology shorter than an apparent minimum efficient processing segment can be r ...[more]

PMID: 28065599

Similar Datasets

Project description:BACKGROUND:The C9ORF72 hexanucleotide repeat expansion is the most common known genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), two fatal age-related neurodegenerative diseases. The C9ORF72 expansion encodes five dipeptide repeat proteins (DPRs) that are produced through a non-canonical translation mechanism. Among the DPRs, proline-arginine (PR), glycine-arginine (GR), and glycine-alanine (GA) are the most neurotoxic and increase the frequency of DNA double strand breaks (DSBs). While the accumulation of these genotoxic lesions is increasingly recognized as a feature of disease, the mechanism(s) of DPR-mediated DNA damage are ill-defined and the effect of DPRs on the efficiency of each DNA DSB repair pathways has not been previously evaluated. METHODS AND RESULTS:Using DNA DSB repair assays, we evaluated the efficiency of specific repair pathways, and found that PR, GR and GA decrease the efficiency of non-homologous end joining (NHEJ), single strand annealing (SSA), and microhomology-mediated end joining (MMEJ), but not homologous recombination (HR). We found that PR inhibits DNA DSB repair, in part, by binding to the nucleolar protein nucleophosmin (NPM1). Depletion of NPM1 inhibited NHEJ and SSA, suggesting that NPM1 loss-of-function in PR expressing cells leads to impediments of both non-homologous and homology-directed DNA DSB repair pathways. By deleting NPM1 sub-cellular localization signals, we found that PR binds NPM1 regardless of the cellular compartment to which NPM1 was directed. Deletion of the NPM1 acidic loop motif, known to engage other arginine-rich proteins, abrogated PR and NPM1 binding. Using confocal and super-resolution immunofluorescence microscopy, we found that levels of RAD52, a component of the SSA repair machinery, were significantly increased iPSC neurons relative to isogenic controls in which the C9ORF72 expansion had been deleted using CRISPR/Cas9 genome editing. Western analysis of post-mortem brain tissues confirmed that RAD52 immunoreactivity is significantly increased in C9ALS/FTD samples as compared to controls. CONCLUSIONS:Collectively, we characterized the inhibitory effects of DPRs on key DNA DSB repair pathways, identified NPM1 as a facilitator of DNA repair that is inhibited by PR, and revealed deficits in homology-directed DNA DSB repair pathways as a novel feature of C9ORF72-related disease.

Dataset Information

Homology Requirements and Competition between Gene Conversion and Break-Induced Replication during Double-Strand Break Repair.

Publications

Homology Requirements and Competition between Gene Conversion and Break-Induced Replication during Double-Strand Break Repair.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets