Proteomic response to physiological fermentation stresses in a wild-type wine strain of Saccharomyces cerevisiae

Abstract

We report a study on the adaptive response of a wild-type wine Saccharomyces cerevisiae strain, isolated from natural spontaneous grape must, to mild and progressive physiological stresses due to fermentation. We observed by two-dimensional electrophoresis how the yeast proteome changes during glucose exhaustion, before the cell enters its complete stationary phase. On the basis of their identification, the proteins representing the S. cerevisiae proteomic response to fermentation stresses were divided into three classes: repressed proteins, induced proteins and autoproteolysed proteins. In an overall view, the proteome adaptation of S. cerevisiae at the time of glucose exhaustion seems to be directed mainly against the effects of ethanol, causing both hyperosmolarity and oxidative responses. Stress-induced autoproteolysis is directed mainly towards specific isoforms of glycolytic enzymes. Through the use of a wild-type S. cerevisiae strain and PMSF, a specific inhibitor of vacuolar proteinase B, we could also distinguish the specific contributions of the vacuole and the proteasome to the autoproteolytic process.

Transcriptomic and Proteomic Approach for Understanding the Molecular Basis of Adaptation of Saccharomyces cerevisiae to Wine Fermentation

“…As described above, at 6 days, this strain continues metabolizing glucose actively, while in the case of strain ICV 27 the rate of glucose consumption decreases at this time point. In the case of Pdc1p, the relevance of this finding is not clear, as the isoform detected corresponds to a minor form of this protein, probably due to vacuolar degradation (50). In the case of Qcr2p, the higher levels found in strain ICV 27 could be indicative of a more active respiratory metabolism in this strain.…”

“…For this reason this time point of the vinification was considered. Up to now, only one proteomic analysis with wine yeast cells under conditions that try to mimic vinification has been carried out (50). Although some transcriptomic studies with different purposes have been published (4,31,42,51), our study is the first one in which strains that do not behave in the same way during vinification are considered in an integrated transcriptomic-proteomic analysis.…”

“…Recent data indicate that the expression of Hsp26p is probably important for maintaining the viability of cells during fermentative conditions. In this sense, proteomic analysis of a wildtype wine yeast strain has revealed an important increase in the level of this protein when glucose is exhausted and yeast cells enter into stationary phase (50). Moreover, the levels of this and other stress proteins are up-regulated during the first generation in fermentations carried out by brewing yeast strains, and these levels are maintained during subsequent generations (28).…”

“…For this purpose, analyses of particular subsets of genes (mainly related to stress response and carbohydrate metabolism) have been carried out (33,36,37,39). The development of global analysis methodologies (DNA microarrays and two-dimensional electrophoresis combined with subsequent identification and characterization by mass spectrometry) has allowed a detailed analysis of changes in gene expression and protein levels at various time points during vinification (4,31,42,50,51). These studies have been carried out with a particular industrial strain adapted to vinification conditions, able to complete the process without any defect.…”

Development and application of proteomics technologies in Saccharomyces cerevisiae

“…Also, subproteome reference maps of, for example, yeast mitochondria, have been generated [30]. Moreover, 2D reference maps have been constructed for important industrial yeast strains, such as an ale-fermenting strain [31], a wine strain [32] and a lager-brewing strain [33,34]. These annotated reference maps are useful tools for yeast researchers because they can be used for 2D gel comparisons; however, because of poor gel-to-gel reproducibility and strain variation, protein spot identities should always be confirmed using MS.…”