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Genome-wide high-resolution mapping of UV-induced mitotic recombination events in Saccharomyces cerevisiae.

Yin Y, Petes TD - PLoS Genet. (2013)

Bottom Line: Mitotic recombination between homologous chromosomes can result in loss of heterozygosity (LOH).UV doses that have little effect on the viability of diploid cells stimulate crossovers more than 1000-fold in wild-type cells.Genome-wide mapping of about 380 unselected crossovers, break-induced replication (BIR) events, and gene conversions shows that UV-induced recombination events occur throughout the genome without pronounced hotspots, although the ribosomal RNA gene cluster has a significantly lower frequency of crossovers.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Genetics and Microbiology and University Program in Genetics and Genomics, Duke University Medical Center, Durham, North Carolina, United States of America.

ABSTRACT
In the yeast Saccharomyces cerevisiae and most other eukaryotes, mitotic recombination is important for the repair of double-stranded DNA breaks (DSBs). Mitotic recombination between homologous chromosomes can result in loss of heterozygosity (LOH). In this study, LOH events induced by ultraviolet (UV) light are mapped throughout the genome to a resolution of about 1 kb using single-nucleotide polymorphism (SNP) microarrays. UV doses that have little effect on the viability of diploid cells stimulate crossovers more than 1000-fold in wild-type cells. In addition, UV stimulates recombination in G1-synchronized cells about 10-fold more efficiently than in G2-synchronized cells. Importantly, at high doses of UV, most conversion events reflect the repair of two sister chromatids that are broken at approximately the same position whereas at low doses, most conversion events reflect the repair of a single broken chromatid. Genome-wide mapping of about 380 unselected crossovers, break-induced replication (BIR) events, and gene conversions shows that UV-induced recombination events occur throughout the genome without pronounced hotspots, although the ribosomal RNA gene cluster has a significantly lower frequency of crossovers.

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Related in: MedlinePlus

Selected SCB and DSCB conversions in strains treated with 1/m2 and 15 J/m2.SCB and DSCB events are indicated in gray and red, respectively.
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pgen-1003894-g008: Selected SCB and DSCB conversions in strains treated with 1/m2 and 15 J/m2.SCB and DSCB events are indicated in gray and red, respectively.

Mentions: A striking difference was observed in the distributions of events diagnostic of SCBs and DSCBs in cells irradiated with 1 and 15 J/m2 of UV. Of selected events on chromosome V in cells irradiated with 1 J/m2, we observed 5 crossovers unassociated with conversion, 31 SCB events, and 10 DSCB events. In contrast, in cells irradiated with 15 J/m2, most of the selected events on chromosome V were DSCB events (Figure 8). By the Fisher exact test, the difference in the numbers of SCB and DSCB events induced by the two different UV treatments is very significant (p<0.0001). The conclusion that G1-synchronized cells have different recombinogenic DNA lesions induced by different UV doses will be discussed further below.


Genome-wide high-resolution mapping of UV-induced mitotic recombination events in Saccharomyces cerevisiae.

Yin Y, Petes TD - PLoS Genet. (2013)

Selected SCB and DSCB conversions in strains treated with 1/m2 and 15 J/m2.SCB and DSCB events are indicated in gray and red, respectively.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3814309&req=5

pgen-1003894-g008: Selected SCB and DSCB conversions in strains treated with 1/m2 and 15 J/m2.SCB and DSCB events are indicated in gray and red, respectively.
Mentions: A striking difference was observed in the distributions of events diagnostic of SCBs and DSCBs in cells irradiated with 1 and 15 J/m2 of UV. Of selected events on chromosome V in cells irradiated with 1 J/m2, we observed 5 crossovers unassociated with conversion, 31 SCB events, and 10 DSCB events. In contrast, in cells irradiated with 15 J/m2, most of the selected events on chromosome V were DSCB events (Figure 8). By the Fisher exact test, the difference in the numbers of SCB and DSCB events induced by the two different UV treatments is very significant (p<0.0001). The conclusion that G1-synchronized cells have different recombinogenic DNA lesions induced by different UV doses will be discussed further below.

Bottom Line: Mitotic recombination between homologous chromosomes can result in loss of heterozygosity (LOH).UV doses that have little effect on the viability of diploid cells stimulate crossovers more than 1000-fold in wild-type cells.Genome-wide mapping of about 380 unselected crossovers, break-induced replication (BIR) events, and gene conversions shows that UV-induced recombination events occur throughout the genome without pronounced hotspots, although the ribosomal RNA gene cluster has a significantly lower frequency of crossovers.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Genetics and Microbiology and University Program in Genetics and Genomics, Duke University Medical Center, Durham, North Carolina, United States of America.

ABSTRACT
In the yeast Saccharomyces cerevisiae and most other eukaryotes, mitotic recombination is important for the repair of double-stranded DNA breaks (DSBs). Mitotic recombination between homologous chromosomes can result in loss of heterozygosity (LOH). In this study, LOH events induced by ultraviolet (UV) light are mapped throughout the genome to a resolution of about 1 kb using single-nucleotide polymorphism (SNP) microarrays. UV doses that have little effect on the viability of diploid cells stimulate crossovers more than 1000-fold in wild-type cells. In addition, UV stimulates recombination in G1-synchronized cells about 10-fold more efficiently than in G2-synchronized cells. Importantly, at high doses of UV, most conversion events reflect the repair of two sister chromatids that are broken at approximately the same position whereas at low doses, most conversion events reflect the repair of a single broken chromatid. Genome-wide mapping of about 380 unselected crossovers, break-induced replication (BIR) events, and gene conversions shows that UV-induced recombination events occur throughout the genome without pronounced hotspots, although the ribosomal RNA gene cluster has a significantly lower frequency of crossovers.

Show MeSH
Related in: MedlinePlus