Near-freezing effects on the proteome of industrial yeast strains of Saccharomyces cerevisiae

• Proteomic data have been analyzed for two baker's yeast strains exposed to 4 °C.
• Glycolytic proteins were predominant among those upregulated under this condition.
• Proteins involved in translation and redox homeostasis were also identified.
• Glycerol protects yeast cells against freeze damage.
• Certain cold-induced proteins provide specifically protection against cold damage.

At near-freezing temperatures (0–4 °C), the growth of the yeast Saccharomyces cerevisiae stops or is severely limited, and viability decreases. Under these conditions, yeast cells trigger a biochemical response, in which trehalose and glycerol accumulate and protect them against severe cold and freeze injury. However, the mechanisms that allow yeast cells to sustain this response have been not clarified. The effects of severe cold on the proteome of S. cerevisiae have been not investigated and its importance in providing cell survival at near-freezing temperatures and upon freezing remains unknown. Here, we have compared the protein profile of two industrial baker’s yeast strains at 30 °C and 4 °C. Overall, a total of 16 proteins involved in energy-metabolism, translation and redox homeostasis were identified as showing increased abundance at 4 °C. The predominant presence of glycolytic proteins among those upregulated at 4 °C, likely represents a mechanism to maintain a constant supply of ATP for the synthesis of glycerol and other protective molecules. Accumulation of these molecules is by far the most important component in enhancing viability of baker’s yeast strains upon freezing. Overexpression of genes encoding certain proteins associated with translation or redox homeostasis provided specifically protection against extreme cold damage, underlying the importance of these functions in the near-freezing response.