Effects of Rapamycin on Dia2 in S. cerevisiae

Abstract

The SCF ubiquitin ligase is a protein complex which selectively ubiquitinates various proteins in order to mark them for degradation. Dia2 is an example of an F-box protein, one of the components of the SCF complex. Dia2 is known to operate at the rDNA locus within the cell’s nucleus; this localization may be related to Dia2’s role in regulating the cell’s progress through the S-phase checkpoint. In this way, it has some similarities to Tor1, which has been shown to associate with the rDNA promoter except when the cell is under stress from starvation or the chemical rapamycin. We therefore hypothesized that treatment with rapamycin would result in a loss of Dia2’s nuclear localization. We demonstrate via indirect immunofluorescence that this nuclear localization is partially lost after exposure to rapamycin. Current efforts focus on quantifying the amount of Dia2 present in rapamycin-exposed and rapamycin-free cells, both within the cell as a whole and within the nuclear and cytoplasmic cell fractions.