Synthesis-dependent strand annealing in meiosis

PLoS Biol. 2007 Nov 6;5(11):e299. doi: 10.1371/journal.pbio.0050299.

Abstract

Recent studies led to the proposal that meiotic gene conversion can result after transient engagement of the donor chromatid and subsequent DNA synthesis-dependent strand annealing (SDSA). Double Holliday junction (dHJ) intermediates were previously proposed to form both reciprocal crossover recombinants (COs) and noncrossover recombinants (NCOs); however, dHJs are now thought to give rise mainly to COs, with SDSA forming most or all NCOs. To test this model in Saccharomyces cerevisiae, we constructed a random spore system in which it is possible to identify a subset of NCO recombinants that can readily be accounted for by SDSA, but not by dHJ-mediated recombination. The diagnostic class of recombinants is one in which two markers on opposite sides of a double-strand break site are converted, without conversion of an intervening heterologous insertion located on the donor chromatid. This diagnostic class represents 26% of selected NCO recombinants. Tetrad analysis using the same markers provided additional evidence that SDSA is a major pathway for NCO gene conversion in meiosis.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Crossing Over, Genetic
  • DNA Replication*
  • DNA, Cruciform / metabolism
  • Meiosis*
  • Models, Genetic
  • Recombination, Genetic
  • Saccharomyces cerevisiae / genetics

Substances

  • DNA, Cruciform