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The role of Exo1p exonuclease in DNA end resection to generate gene conversion tracts in Saccharomyces cerevisiae.

Yin Y, Petes TD - Genetics (2014)

Bottom Line: In accordance with this expectation, gene conversion tract lengths associated with spontaneous crossovers in exo1 strains were reduced about twofold relative to wild type.For UV-induced events, conversion tract lengths associated with crossovers were also shorter for the exo1 strain than for the wild-type strain (3.2 and 7.6 kb, respectively).Unexpectedly, however, the lengths of conversion tracts that were unassociated with crossovers were longer in the exo1 strain than in the wild-type strain (6.2 and 4.8 kb, respectively).

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 27710.

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Related in: MedlinePlus

Patterns of LOH resulting from crossovers, BIR events, and gene conversions. The homologs derived from W303a and YJM789 are shown in red and black, respectively. Ovals and circles indicate centromeres. In A–D, the initiating DSB is on the YJM789-derived homolog. The green, red, and black lines on the right summarize patterns of heterozygosity and homozygosity in the daughter cells after the recombination event. In this depiction, green, red, and black signify heterozygosity, homozygosity for SNPs derived from the W303a homolog, and homozygosity for SNPs derived from the YJM789 homolog, respectively. (A) Crossover initiated with an SCB associated with a 3:1 gene conversion. The blue rectangle outlines the conversion event. (B) Gene conversion (3:1) unassociated with a crossover, initiated by an SCB. (C) Mitotic crossover and an associated 4:0 conversion event. Replication of a chromosome broken in G1 results in two broken sister chromatids. The repair of this DSCB (one repair event associated with a crossover) generates the observed LOH pattern. (D) BIR event initiated by an SCB.
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fig1: Patterns of LOH resulting from crossovers, BIR events, and gene conversions. The homologs derived from W303a and YJM789 are shown in red and black, respectively. Ovals and circles indicate centromeres. In A–D, the initiating DSB is on the YJM789-derived homolog. The green, red, and black lines on the right summarize patterns of heterozygosity and homozygosity in the daughter cells after the recombination event. In this depiction, green, red, and black signify heterozygosity, homozygosity for SNPs derived from the W303a homolog, and homozygosity for SNPs derived from the YJM789 homolog, respectively. (A) Crossover initiated with an SCB associated with a 3:1 gene conversion. The blue rectangle outlines the conversion event. (B) Gene conversion (3:1) unassociated with a crossover, initiated by an SCB. (C) Mitotic crossover and an associated 4:0 conversion event. Replication of a chromosome broken in G1 results in two broken sister chromatids. The repair of this DSCB (one repair event associated with a crossover) generates the observed LOH pattern. (D) BIR event initiated by an SCB.

Mentions: The frequency and map positions of recombination events were examined in a diploid heterozygous for ∼55,000 single-nucleotide polymorphisms (SNPs) distributed throughout the genome (Lee et al. 2009). Crossovers and gene conversion events occurring between homologs can be detected as loss of heterozygosity (LOH), using oligonucleotide-containing microarrays (described further below). Some of the patterns of LOH observed in previous studies (St. Charles et al. 2012; St. Charles and Petes 2013; Yin and Petes 2013) are shown in Figure 1.


The role of Exo1p exonuclease in DNA end resection to generate gene conversion tracts in Saccharomyces cerevisiae.

Yin Y, Petes TD - Genetics (2014)

Patterns of LOH resulting from crossovers, BIR events, and gene conversions. The homologs derived from W303a and YJM789 are shown in red and black, respectively. Ovals and circles indicate centromeres. In A–D, the initiating DSB is on the YJM789-derived homolog. The green, red, and black lines on the right summarize patterns of heterozygosity and homozygosity in the daughter cells after the recombination event. In this depiction, green, red, and black signify heterozygosity, homozygosity for SNPs derived from the W303a homolog, and homozygosity for SNPs derived from the YJM789 homolog, respectively. (A) Crossover initiated with an SCB associated with a 3:1 gene conversion. The blue rectangle outlines the conversion event. (B) Gene conversion (3:1) unassociated with a crossover, initiated by an SCB. (C) Mitotic crossover and an associated 4:0 conversion event. Replication of a chromosome broken in G1 results in two broken sister chromatids. The repair of this DSCB (one repair event associated with a crossover) generates the observed LOH pattern. (D) BIR event initiated by an SCB.
© Copyright Policy - open-access
Related In: Results  -  Collection

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fig1: Patterns of LOH resulting from crossovers, BIR events, and gene conversions. The homologs derived from W303a and YJM789 are shown in red and black, respectively. Ovals and circles indicate centromeres. In A–D, the initiating DSB is on the YJM789-derived homolog. The green, red, and black lines on the right summarize patterns of heterozygosity and homozygosity in the daughter cells after the recombination event. In this depiction, green, red, and black signify heterozygosity, homozygosity for SNPs derived from the W303a homolog, and homozygosity for SNPs derived from the YJM789 homolog, respectively. (A) Crossover initiated with an SCB associated with a 3:1 gene conversion. The blue rectangle outlines the conversion event. (B) Gene conversion (3:1) unassociated with a crossover, initiated by an SCB. (C) Mitotic crossover and an associated 4:0 conversion event. Replication of a chromosome broken in G1 results in two broken sister chromatids. The repair of this DSCB (one repair event associated with a crossover) generates the observed LOH pattern. (D) BIR event initiated by an SCB.
Mentions: The frequency and map positions of recombination events were examined in a diploid heterozygous for ∼55,000 single-nucleotide polymorphisms (SNPs) distributed throughout the genome (Lee et al. 2009). Crossovers and gene conversion events occurring between homologs can be detected as loss of heterozygosity (LOH), using oligonucleotide-containing microarrays (described further below). Some of the patterns of LOH observed in previous studies (St. Charles et al. 2012; St. Charles and Petes 2013; Yin and Petes 2013) are shown in Figure 1.

Bottom Line: In accordance with this expectation, gene conversion tract lengths associated with spontaneous crossovers in exo1 strains were reduced about twofold relative to wild type.For UV-induced events, conversion tract lengths associated with crossovers were also shorter for the exo1 strain than for the wild-type strain (3.2 and 7.6 kb, respectively).Unexpectedly, however, the lengths of conversion tracts that were unassociated with crossovers were longer in the exo1 strain than in the wild-type strain (6.2 and 4.8 kb, respectively).

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 27710.

Show MeSH
Related in: MedlinePlus