The yeast osmostress response is carbon source dependent.

Area of Science:

• Cellular biology
• Microbiology
• Biochemistry

Background:

• Yeast Saccharomyces cerevisiae adapts to osmotic stress by accumulating glycerol, regulated by the High Osmolarity Glycerol (HOG) pathway.
• Previous studies predominantly used glucose as the carbon source, where glycolysis produces glycerol as a byproduct.

Purpose of the Study:

• To investigate yeast osmotic stress response when ethanol is the carbon source, contrasting with glucose metabolism.
• To determine if trehalose plays a role in osmotic adaptation when glycerol accumulation is absent.

Main Methods:

• Comparative analysis of yeast osmotic stress response under glucose and ethanol respiration.
• Monitoring compatible solute accumulation (glycerol, trehalose) and cell volume recovery.
• Investigating High Osmolarity Glycerol (HOG) pathway activation and gene expression profiles.

Main Results:

• Yeast cells respiring ethanol do not accumulate glycerol under osmotic stress; trehalose appears to be a compensatory compatible solute.
• The HOG pathway is activated similarly to glucose-grown cells and is essential for adaptation.
• Ethanol-grown cells exhibit slower volume recovery and show evidence of redox metabolism rearrangement under osmostress.

Conclusions:

• Ethanol metabolism significantly alters yeast osmotic adaptation strategies compared to glucose metabolism.
• Trehalose can partially substitute for glycerol in yeast osmostress adaptation.
• Osmostress in ethanol-respiring yeast involves complex metabolic rearrangements, particularly in redox balance.