Palindromic sequences in heteroduplex DNA inhibit mismatch repair in yeast

Nature. 1989 Jul 27;340(6231):318-20. doi: 10.1038/340318a0.


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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Base Sequence
  • DNA Repair*
  • DNA Transposable Elements
  • DNA, Fungal / genetics*
  • Gene Conversion
  • Meiosis*
  • Models, Genetic
  • Mutation*
  • Nucleic Acid Conformation
  • Recombination, Genetic*
  • Restriction Mapping
  • Saccharomyces cerevisiae / genetics*


  • DNA Transposable Elements
  • DNA, Fungal