DNA strand-exchange patterns associated with double-strand break-induced and spontaneous mitotic crossovers in Saccharomyces cerevisiae
| Autor: | Sue Jinks-Robertson, Yee Fang Hum |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
0301 basic medicine
Cancer Research Yeast and Fungal Models Biochemistry Chromosomal crossover 0302 clinical medicine Medicine and Health Sciences DNA Breaks Double-Stranded Crossing Over Genetic DNA Fungal Homologous Recombination Genetics (clinical) biology Organic Compounds Chromosome Biology Monosaccharides Fungal genetics Nucleic Acid Heteroduplexes Eukaryota Cell biology Nucleic acids Chemistry Experimental Organism Systems Physical Sciences Chromosomes Fungal Heteroduplex Research Article Mitotic crossover lcsh:QH426-470 DNA repair DNA recombination Saccharomyces cerevisiae Gene Conversion Carbohydrates Mitosis Surgical and Invasive Medical Procedures Chromatids Research and Analysis Methods Chromosomes 03 medical and health sciences Saccharomyces Model Organisms Genetics Gene conversion Molecular Biology Ecology Evolution Behavior and Systematics Biology and life sciences Surgical Resection Organic Chemistry Organisms Fungi Chemical Compounds Galactose DNA Cell Biology biology.organism_classification Yeast lcsh:Genetics 030104 developmental biology Homologous recombination 030217 neurology & neurosurgery |
| Zdroj: | PLoS Genetics, Vol 14, Iss 3, p e1007302 (2018) PLoS Genetics |
| ISSN: | 1553-7404 1553-7390 |
| Popis: | Mitotic recombination can result in loss of heterozygosity and chromosomal rearrangements that shape genome structure and initiate human disease. Engineered double-strand breaks (DSBs) are a potent initiator of recombination, but whether spontaneous events initiate with the breakage of one or both DNA strands remains unclear. In the current study, a crossover (CO)-specific assay was used to compare heteroduplex DNA (hetDNA) profiles, which reflect strand exchange intermediates, associated with DSB-induced versus spontaneous events in yeast. Most DSB-induced CO products had the two-sided hetDNA predicted by the canonical DSB repair model, with a switch in hetDNA position from one product to the other at the position of the break. Approximately 40% of COs, however, had hetDNA on only one side of the initiating break. This anomaly can be explained by a modified model in which there is frequent processing of an early invasion (D-loop) intermediate prior to extension of the invading end. Finally, hetDNA tracts exhibited complexities consistent with frequent expansion of the DSB into a gap, migration of strand-exchange junctions, and template switching during gap-filling reactions. hetDNA patterns in spontaneous COs isolated in either a wild-type background or in a background with elevated levels of reactive oxygen species (tsa1Δ mutant) were similar to those associated with the DSB-induced events, suggesting that DSBs are the major instigator of spontaneous mitotic recombination in yeast. Author summary Chromosome breakage during mitosis is a threat to genome stability, and duplex integrity can be restored through the process of homologous recombination. Although double-strand breaks (DSBs) are a potent initiator of mitotic recombination, their role in the initiation of spontaneous events is less clear. During recombination, single strands of the broken molecule pair with the complementary strands of an intact repair template to form heteroduplex (het) DNA, which is a key intermediate in the repair process. The canonical DSB repair model makes specific predictions about where hetDNA forms relative to an initiating break, and these predictions were tested using a budding yeast system that detects crossing over between different chromosomes. Following the introduction of a defined DSB, only ~60% of crossovers had the two-sided hetDNA pattern predicted by the model and additional complexities consistent with metastable intermediates were frequent. To determine whether DSBs are the major initiator of spontaneous recombination events, hetDNA patterns associated with spontaneous events were analyzed. These were very similar to those observed following the repair of a defined DSB, suggesting that most spontaneous recombination is initiated by the breakage of both DNA strands. |
| Databáze: | OpenAIRE |
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