Abstract
A prior genetic study indicated that activity of Sir silencing proteins at a hypothetical AGE locus is essential for long life span. In this model, the SIR4-42 mutation would direct the Sir protein complex to the AGE locus, giving rise to a long life span. We show by indirect immunofluorescence that Sir3p and Sir4p are redirected to the nucleolus in the SIR4-42 mutant. Furthermore, this relocalization is dependent on both UTH4 a novel yeast gene that extends life span, and its homologue YGL023. Strikingly, the Sir complex is relocalized from telomeres to the nucleolus in old wild-type cells. We propose that the rDNA is the AGE locus and that nucleolar function is compromised in old yeast cells in a way that may be mitigated by targeting of Sir proteins to the nucleolus.
Publication types
-
Research Support, Non-U.S. Gov't
-
Research Support, U.S. Gov't, P.H.S.
MeSH terms
-
Cell Cycle Proteins*
-
Cell Nucleolus / chemistry
-
Cell Nucleolus / metabolism*
-
Cellular Senescence / physiology
-
Fungal Proteins / genetics*
-
Fungal Proteins / metabolism*
-
Gene Expression Regulation, Fungal / physiology
-
Genes, Fungal / physiology
-
Molecular Sequence Data
-
Mutagenesis / physiology
-
RNA-Binding Proteins
-
Repressor Proteins*
-
Saccharomyces cerevisiae / chemistry
-
Saccharomyces cerevisiae / cytology*
-
Saccharomyces cerevisiae / ultrastructure
-
Saccharomyces cerevisiae Proteins*
-
Sequence Homology, Amino Acid
-
Silent Information Regulator Proteins, Saccharomyces cerevisiae*
-
Telomere / chemistry
-
Telomere / metabolism*
-
Trans-Activators / metabolism
Substances
-
Cell Cycle Proteins
-
Fungal Proteins
-
MPT5 protein, S cerevisiae
-
RNA-Binding Proteins
-
Repressor Proteins
-
SIR3 protein, S cerevisiae
-
SIR4 protein, S cerevisiae
-
Saccharomyces cerevisiae Proteins
-
Silent Information Regulator Proteins, Saccharomyces cerevisiae
-
Trans-Activators