title: Mutations in PRG1, a yeast proteasome-related gene, cause defects in nuclear division and are suppressed by deletion of a mitotic cyclin gene.
abstract: Proteasomes are ubiquitous complexes exhibiting proteolytic activity in vitro. The function(s) of these enzymes in vivo is not known. To investigate the in vivo role of proteasomes, four temperature-sensitive alleles of the Saccharomyces cerevisiae proteasome-related gene, PRG1, were constructed and analyzed. At both the permissive and restrictive temperatures, many prg1 cells have a large bud, contain replicated DNA, and have their nucleus positioned at the neck with a short spindle. These different phenotypes indicate a defect in nuclear division. Consistent with a nuclear division defect, prg1 mutant strains lose a dispensable chromosome at a higher frequency than wild-type cells. Importantly, deletion of CLB2, a gene encoding a mitotic cyclin, suppresses the temperature-sensitive growth phenotype of prg1 mutant strains. Our results indicate that proteasomes are important for nuclear division and suggest that they participate in degradation of the Clb2 protein (Clb2p).
authors.affiliation: Department of Biology, Yale University, New Haven, CT 06511.
authors.forename: H
authors.initials: H
authors.lastname: Friedman
authors.forename: M
authors.initials: M
authors.lastname: Snyder
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D016213:Cyclins / Q000235:genetics*; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D005800:Genes, Fungal; D008938:Mitosis / Q000235:genetics / Q000502:physiology; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism*; D016296:Mutagenesis; D010641:Phenotype; D046988:Proteasome Endopeptidase Complex; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D013696:Temperature
chemical_list: D016213:Cyclins; D005656:Fungal Proteins; D009097:Multienzyme Complexes; D029701:Saccharomyces cerevisiae Proteins; D003546:Cysteine Endopeptidases; C080044:PRE2 protein, S cerevisiae; D046988:Proteasome Endopeptidase Complex