Conversion-type and restoration-type repair of DNA mismatches formed during meiotic recombination in Saccharomyces cerevisiae |
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Authors: | DT Kirkpatrick M Dominska TD Petes |
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Affiliation: | Department of Biology, Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, North Carolina 27599-3280, USA. |
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Abstract: | Meiotic recombination in yeast is associated with heteroduplex formation. Heteroduplexes formed between nonidentical DNA strands contain DNA mismatches, and most DNA mismatches in wild-type strains are efficiently corrected. Although some patterns of mismatch correction result in non-Mendelian segregation of the heterozygous marker (gene conversion), one predicted pattern of correction (restoration-type repair) results in normal Mendelian segregation. Using a yeast strain in which a marker leading to a well-repaired mismatch is flanked by markers that lead to poorly repaired mismatches, we present direct evidence for restoration-type repair in yeast. In addition, we find that the frequency of tetrads with conversion-type repair is higher for a marker at the 5' end of the HIS4 gene than for a marker in the middle of the gene. These results suggest that the ratio of conversion-type to restoration-type repair may be important in generating gradients of gene conversion (polarity gradients). |
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