ABSTRACT
We report the identification of a novel nucleolar protein from fission yeast, p17(nhp2), which is homologous to the recently identified Nhp2p core component of H+ACA snoRNPs in Saccharomyces cerevisiae. We show that the fission yeast p17(nhp2) localizes to the nucleolus in live S. cerevisiae or Schizosaccharomyces pombe cells and is functionally conserved since the fission yeast gene can complement a deletion of the NHP2 gene in budding yeast. Analysis of p17(nhp2) during the mitotic cell cycles of living fission and budding yeast cells shows that this protein, and by implication H+ACA snoRNPs, remains localized with nucleolar material during mitosis, although the gross organization of partitioning of p17(nhp2) during anaphase is different in a comparison of the two yeasts. During anaphase in S. pombe p17(nhp2) trails segregating chromatin, while in S. cerevisiae the protein segregates alongside bulk chromatin. The pattern of segregation comparing haploid and diploid S. cerevisiae cells suggests that p17(nhp2) is closely associated with the rDNA during nuclear division.
Subject(s)
Fungal Proteins/metabolism , Nuclear Proteins/metabolism , Ribonucleoproteins, Small Nuclear , Ribonucleoproteins, Small Nucleolar/metabolism , Saccharomyces cerevisiae Proteins , Saccharomyces cerevisiae/metabolism , Schizosaccharomyces/metabolism , Amino Acid Sequence , Base Sequence , Cell Cycle , Cell Nucleolus/metabolism , DNA Primers/genetics , DNA, Complementary/genetics , DNA, Fungal/genetics , Fungal Proteins/chemistry , Fungal Proteins/genetics , Gene Deletion , Genes, Fungal , Genetic Complementation Test , Molecular Sequence Data , Nuclear Proteins/chemistry , Nuclear Proteins/genetics , Phylogeny , Ribonucleoproteins, Small Nucleolar/chemistry , Ribonucleoproteins, Small Nucleolar/genetics , Saccharomyces cerevisiae/cytology , Saccharomyces cerevisiae/genetics , Schizosaccharomyces/cytology , Schizosaccharomyces/genetics , Sequence Homology, Amino Acid , Species SpecificityABSTRACT
The role of oxidative damage in determining the replicative lifespan of Saccharomyces cerevisiae was investigated using a wild-type haploid laboratory yeast and a Cu,Zn superoxide dismutase (sod1) mutant derivative on glucose, ethanol, glycerol and galactose media. SOD1 expression was necessary to ensure longevity on all carbon sources tested. Whilst carbon source and SOD1 gene expression do influence yeast lifespan, the relationship between the two factors is complex.
