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: In depictions of the double-strand break repair model, the extent of the gene conversion tract is usually shown as equivalent to the extent of end resection (Figure 6A). For a recombination event in a wild-type strand, we indicate the resection length of the invading chromosome end as AWT and the resection length of the other end as BWT, and the simplest assumption is that AWT = BWT. Further, we hypothesize that amount of DNA synthesized by the invading end (CWT) is equivalent to the resection length. With these assumptions, one would expect that the length of gene conversion tracts unassociated with crossovers would be half of that associated with crossovers. In addition, we would expect both types of conversion tracts would be shorter in the exo1 strain because of less resection. If AWT and BWT are not equal, nonetheless, the conversion tracts unassociated with crossovers would be expected to be shorter than those associated with crossovers.
Affiliation: Department of Molecular Genetics and Microbiology and University Program in Genetics and Genomics, Duke University Medical Center, Durham, North Carolina 27710.