A mutation in SPC42, which encodes a component of the spindle pole body, results in production of two-spored asci in Saccharomyces cerevisiae

Mol Genet Genomics. 2001 Jun;265(4):585-95. doi: 10.1007/s004380000442.


In the yeast Saccharomyces cerevisiae, SPC42 is an essential gene, which encodes one of the major components of the spindle pole body (SPB). We report on a mutation in the SPC42 gene (spc42-102) that results in a sporulation-specific defect. Mitotic growth of haploid and diploid spc42-102 strains is normal and both exhibit the same growth rates as the isogenic wild-type strains. Many diploid spc42-102/spc42-102 cells undergo normal meiotic nuclear divisions, producing four haploid nuclei. However, a significant fraction of meiotic spc42-102/spc42-102 cells contain two immature SPBs and aberrant nuclei that are not surrounded by a prospore membrane. Some 40% of the resultant asci contain only two spores, while wild-type diploid cells almost always produce four-spored asci. Segregation of auxotrophic markers that are tightly linked to the centromere reveals that two-spore asci formed from spc42-102/spc42-102 diploid cells exclusively contain nonsister haploid spores. Western analysis and measurements of the fluorescent signal from an Spc42p-GFP (green fluorescent protein) fusion reveal that the mutant strain fails to accumulate Spc42p at meiosis. Thus, our results suggest that insufficiency of Spc42p during meiosis results in a pair of immature nonsister SPBs that are not enclosed by prospore membrane.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blotting, Western
  • Cytoskeletal Proteins / genetics*
  • Cytoskeletal Proteins / physiology
  • Diploidy
  • Fungal Proteins / genetics*
  • Fungal Proteins / physiology
  • Genes, Fungal*
  • Haploidy
  • Meiosis / physiology*
  • Mutation
  • Phenotype
  • Phosphoproteins / genetics*
  • Phosphoproteins / physiology
  • Recombinant Fusion Proteins / physiology
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / physiology
  • Saccharomyces cerevisiae / ultrastructure
  • Saccharomyces cerevisiae Proteins*
  • Spindle Apparatus / genetics*
  • Spores, Fungal


  • Cytoskeletal Proteins
  • Fungal Proteins
  • Phosphoproteins
  • Recombinant Fusion Proteins
  • SPC42 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins