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

ABSTRACT: 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.

SUBMITTER: Chan AC 

PROVIDER: S-EPMC2757900 | biostudies-literature | 2009 Oct

REPOSITORIES: biostudies-literature