Project description:The yeast Sup35 protein is a subunit of the translation termination factor, and its conversion to the [PSI+] prion state leads to more translational read-through. Although extensive studies have been done on [PSI+], changes at the proteomic level have not been performed exhaustively. We therefore used a SILAC-based quantitative mass spectrometry approach and identified 4187 proteins from both [psi-] and [PSI+] strains. Surprisingly, there was very little difference between the two proteomes under standard growth conditions.
Project description:We subjected yeast to two stresses, oxidative stress, which under current settings induces a fast and transient response in mRNA abundance, and DNA damage, which triggers a slow enduring response. Using microarrays, we performed a transcriptional arrest experiment to measure genome-wide mRNA decay profiles under each condition. Genome-wide decay kinetics in each condition were compared to decay experiments that were performed in a reference condition (only transcription inhibition without an additional stress) to quantify changes in mRNA stability in each condition. We found condition-specific changes in mRNA decay rates and coordination between mRNA production and degradation. In the transient response, most induced genes were surprisingly destabilized, while repressed genes were somewhat stabilized, exhibiting counteraction between production and degradation. This strategy can reconcile high steady-state level with short response time among induced genes. In contrast, the stress that induces the slow response displays the more expected behavior, whereby most induced genes are stabilized, and repressed genes destabilized. Our results show genome-wide interplay between mRNA production and degradation, and that alternative modes of such interplay determine the kinetics of the transcriptome in response to stress. Keywords: Four separate time courses
Project description:Proteotoxic stress triggers adaptive cellular responses, including changes in gene expression on the levels of transcription and translation. In this study, we analyzed the translational response of yeast cells to impaired protein import into mitochondria, a condition under which mitochondrial precursor proteins accumulate in the cytosol and impose proteotoxic stress. We analyzed changes in translational efficiency as well as more subtle changes in the distribution of ribosomes along transcripts, with a special focus on translation initiation sites.
