The budding yeast transition to quiescence

Area of Science:

• Cellular Biology
• Microbiology
• Genetics

Background:

• Stationary phase Saccharomyces cerevisiae cultures exhibit a quiescent state with enhanced stress tolerance and longevity.
• Trehalose accumulation is crucial but insufficient for this quiescent state, which differs from abrupt starvation responses.

Purpose of the Study:

• To investigate the molecular mechanisms and cellular events underlying the entry into quiescence in yeast.
• To understand the role of glucose metabolism and chromatin dynamics in yeast cell quiescence.

Main Methods:

• Monitoring cell density, stress tolerance, and longevity in stationary phase cultures.
• Analyzing gene expression, protein localization (Rim15 kinase), and histone modifications.
• Investigating chromatin interactions and genome-wide compaction using condensin-dependent assays.

Main Results:

• Quiescence entry is initiated during glucose uptake and involves glycogen storage and G1 cell cycle arrest.
• Post-diauxic shift (DS), growth genes are repressed via histone deacetylase Rpd3 recruitment.
• Significant morphological, protein, and organelle changes occur, alongside global histone modification and chromatin compaction.

Conclusions:

• Yeast quiescence is tightly linked to external glucose levels and culture biomass.
• Genome-wide chromatin compaction, mediated by long-range interactions, is essential for transcriptional repression in quiescent yeast.
• These chromatin dynamics are conserved between yeast and human cells, highlighting fundamental biological processes.