Temperature-dependent modulation of chromosome segregation in msh4 mutants of budding yeast

PLoS One. 2009 Oct 9;4(10):e7284. doi: 10.1371/journal.pone.0007284.


Background: In many organisms, homologous chromosomes rely upon recombination-mediated linkages, termed crossovers, to promote their accurate segregation at meiosis I. In budding yeast, the evolutionarily conserved mismatch-repair paralogues, Msh4 and Msh5, promote crossover formation in conjunction with several other proteins, collectively termed the Synapsis Initiation Complex (SIC) proteins or 'ZMM's (Zip1-Zip2-Zip3-Zip4-Spo16, Msh4-Msh5, Mer3). zmm mutants show decreased levels of crossovers and increased chromosome missegregation, which is thought to cause decreased spore viability.

Principal findings: In contrast to other ZMM mutants, msh4 and msh5 mutants show improved spore viability and chromosome segregation in response to elevated temperature (23 degrees C versus 33 degrees C). Crossover frequencies in the population of viable spores in msh4 and msh5 mutants are similar at both temperatures, suggesting that temperature-mediated chromosome segregation does not occur by increasing crossover frequencies. Furthermore, meiotic progression defects at elevated temperature do not select for a subpopulation of cells with improved segregation. Instead, another ZMM protein, Zip1, is important for the temperature-dependent improvement in spore viability.

Conclusions: Our data demonstrate interactions between genetic (zmm status) and environmental factors in determining chromosome segregation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chromosome Segregation*
  • Chromosomes / ultrastructure*
  • Crossing Over, Genetic
  • DNA-Binding Proteins / genetics*
  • In Situ Hybridization, Fluorescence
  • Meiosis
  • Models, Genetic
  • Mutation*
  • Nuclear Proteins / genetics
  • Saccharomyces cerevisiae Proteins / genetics*
  • Saccharomycetales / genetics*
  • Spores, Fungal / metabolism
  • Temperature


  • DNA-Binding Proteins
  • MSH4 protein, S cerevisiae
  • MSH5 protein, S cerevisiae
  • Nuclear Proteins
  • Saccharomyces cerevisiae Proteins
  • Zip1 protein, S cerevisiae