Changes in the protein synthesis pattern during a nutritional shift-down transition in Saccharomyces cerevisiae

Area of Science:

• Cellular biology
• Molecular biology
• Yeast genetics

Background:

• Nutrient availability significantly impacts cellular processes.
• Understanding yeast cell responses to environmental changes is crucial for metabolic engineering and fundamental biology.

Purpose of the Study:

• To investigate the impact of a glucose to raffinose nutrient shift-down on Saccharomyces cerevisiae growth and protein synthesis.
• To identify specific proteins whose synthesis is modulated during this transition.

Main Methods:

• Utilized Saccharomyces cerevisiae (strain A364A) for nutrient shift-down experiments.
• Measured RNA and protein accumulation rates.
• Analyzed protein synthesis patterns using [35S]-methionine pulse-labeling and high-resolution two-dimensional gel electrophoresis.

Main Results:

• Observed a rapid decrease in RNA accumulation, with protein accumulation remaining stable for at least 2 hours post-shift.
• Detected alterations in cell cycle distribution, with an increase in unbudded cells and a subpopulation of smaller cells.
• Identified two classes of proteins (I and II) with modulated synthesis, including a significant increase in two 57 kDa polypeptides.
• Noted a positive correlation between heat-shock protein (HSP 256) synthesis and the shift-down transition.

Conclusions:

• The glucose to raffinose shift-down induces distinct changes in RNA and protein synthesis regulation in yeast.
• Specific protein synthesis modulation, including increased 57 kDa polypeptides and HSP 256, is a key response to nutrient limitation.
• These findings provide insights into yeast's adaptive strategies under changing metabolic conditions.