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: The data of Table S2 can be used to calculate gene conversion tract lengths for the UV-treated strains. For interstitial LOH events, the tract length was calculated as the average of the maximum tract length (the distance between the heterozygous SNPs flanking the LOH region) and the minimum tract length (the distance between the first and last homozygous SNP in the conversion tract). For conversions associated with crossovers, the length was the average between the maximum tract length (the distance between the last heterozygous SNP before the conversion tract and the SNP that has the reciprocal LOH pattern indicative of the crossover) and the minimum length (the distance between the first and last homozygous SNPs of the tract). For crossovers with no detectable conversion, we estimated the length of the conversion tract as half the distance between the heterozygous and homozygous SNPs most closely flanking the crossover transition. The median lengths of the crossover-associated conversions for the wild-type and exo1 strains were 7.6 kb [95% confidence limits of 6.4–9.6 kb (Yin and Petes 2013)] and 3.2 kb (1.3–6 kb), respectively; the P-value for the comparison of these lengths is 8 × 10−5 (Mann–Whitney test). Figure 3A is a histogram of these data.
Affiliation: Department of Molecular Genetics and Microbiology and University Program in Genetics and Genomics, Duke University Medical Center, Durham, North Carolina 27710.