Palindromic sequences in heteroduplex DNA inhibit mismatch repair in yeast.
Although single heterozygous markers in yeast usually segregate during meiosis in a 2:2 ratio, abberant 3:1 segregations occur quite frequently as a result of gene-conversion events. A second type of aberrant segregation, post-meiotic segregation, results from the segregation of two genotypes from a single haploid spore; in yeast such events are detected as sectored spore colonies and usually occur rarely. Post-meiotic segregation is thought to result from the replication of heteroduplex DNA formed during meiotic recombination. We report here that if the heteroduplex includes a palindromic insertion sequence, a high frequency of post-meiotic segregation results. This suggests that palindromic insertions are poorly repaired, which may be the result of hairpin-loop formation that affects the efficiency of repair of heteroduplex DNA.
Nag
D K
DK
Department of Biology, University of North Carolina, Chapel Hill 27599-3280.
White
M A
MA
Petes
T D
TD
D001483:Base Sequence; D004260:DNA Repair; D004251:DNA Transposable Elements; D004271:DNA, Fungal / Q000235:genetics*; D005785:Gene Conversion; D008540:Meiosis; D008957:Models, Genetic; D009154:Mutation; D009690:Nucleic Acid Conformation; D011995:Recombination, Genetic; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics*
D004251:DNA Transposable Elements; D004271:DNA, Fungal