The role of Exo1p exonuclease in DNA end resection to generate gene conversion tracts in Saccharomyces cerevisiae.
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).
Affiliation: Department of Molecular Genetics and Microbiology and University Program in Genetics and Genomics, Duke University Medical Center, Durham, North Carolina 27710.Show MeSH
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Mentions: Figure 4 shows the location of spontaneous recombination events on chromosome IV in the wild-type (Figure 4A, data from St. Charles and Petes 2013) and exo1 (Figure 4B) strains. In Figure 4, the y-axis indicates the number of times SNPs on the right arm of chromosome IV were involved in a recombination event, and the x-axis shows the SGD coordinates of SNPs. The peak marked HS4 (hotspot 4) in the wild-type strain is an inverted pair of 6-kb retrotransposons (Ty elements) located between SGD coordinates 981 and 993 kb that is involved in ∼7% of the crossovers in wild type. Recombination at HS4 is significantly (P = 0.02) reduced in the exo1 strain. In addition, there is less recombination at HS3 (a second pair of closely spaced retrotransposons located between SGD coordinates 872 and 884 kb) in the exo1 strain compared to wild type, although this reduction is not statistically significant. Below, we present models that are relevant to the role of Exo1p in generating recombinogenic DNA lesions at HS3 and HS4.
Affiliation: Department of Molecular Genetics and Microbiology and University Program in Genetics and Genomics, Duke University Medical Center, Durham, North Carolina 27710.