Project description:Telomere chromatin structure is pivotal for maintaining genome stability by regulating the binding of telomere-associated proteins and inhibition of a DNA damage response. In yeast, the silent information regulator (Sir) proteins bind to terminal telomeric repeats and to subtelomeric X-elements resulting in histone deacetylation and transcriptional silencing. Herein, we show that sir2 mutant strains display a very specific loss of a nucleosome residing in the X-element. Most yeast telomeres contain an X-element and the nucleosome occupancy defect in sir2 mutants is remarkably consistent between different telomeres.
Project description:Quiescence is a pivotal state for all living organisms and cells. Recent research indicates lack of one type of qui-escent cells. That is, even if the primary feature of quiescence, restarting divisions is maintained, quiescent cells within populations exhibit variation in their cellular architecture and characteristics. While it is known that the process of quiescent enter is influenced by a combination of nutrient starvation and temporal factors; the under-lying mechanisms remain to be fully elucidated. In this study we compare the transcriptomes of known to be homogenous fraction of dense quiescent yeast isolated from populations of different ecological history. These populations have undergone experimental enrichment of certain types of quiescent cells during cycles of growth and starvation for 300 generations. Transcriptome analysis revealed discrepancies in terms of characteristics as-sociated mainly with energy turnover processes, biosynthesis and the cell wall maintenance. The results of this study suggest that quiescent cells possess the capacity to adapt their transcriptome activity in accordance with their evolutionary history.
Project description:Characterization of the riboproteome composition in quiescent cells and post-translational reactivation. To characterize ribosome heterogeneity during the exit from quiescence, the protein composition of ribosomal particles from stationary phase and nutrient-stimulated cells was assessed. A label-free quantitative mass spectrometry strategy was taken to compare quiescent yeast cells with cells that had been nutrient stimulated for 30 and 60 min. To this end, crude extracts from these cells were subjected to sucrose gradient centrifugation and three fractions free (F); monosome (M=80S + 60S + 40S) and polysome (P) were analyzed by nano-HPLC-MS/MS. A total of 528 proteins were identified.