Biology subjects

Garrigos, V.

Publications and source records attributed to Garrigos, V..

4 recordsLinked to original sources

bioRxiv2025

Tsa1-Mediated Regulation of PKA Tunes Trehalose Metabolism in Saccharomyces cerevisiae

Cells must continuously adapt their metabolism, growth, and division to fluctuating nutrient availability. In Saccharomyces cerevisiae, this coordination is largely governed by the Ras/cAMP/PKA pathway, which promotes fermentative growth under glucose-rich conditions and is rapidly downregulated upon glucose depletion. This downregulation enables stress responses, global metabolic rewiring, and entry into quiescence. While PKA is known to integrate multiple environmental cues with glucose availability, the crosstalk to other stress-responsive signaling mechanisms remains incompletely understood. Here, we identify the peroxiredoxin Tsa1, a central player in oxidative stress protection and redox signaling, as a key modulator of PKA activity during glucose depletion and stationary phase entry. Combining live-cell imaging of Msn2, analysis of STRE-dependent gene expression, Nth1 phosphorylation assays, and metabolic flux modelling, we show that loss of Tsa1 leads to incomplete downregulation of PKA signaling. Consequently, tsa1{Delta} cells display delayed transition to respiratory growth, reduced gluconeogenic capacity, and impaired accumulation of storage carbohydrates. Failure to properly attenuate PKA activity also disrupts accurate cell cycle control upon glucose depletion, resulting in abnormally small cells that contribute to the reduced chronological lifespan and delayed recovery upon nutrient repletion. Together, our findings establish Tsa1 as a critical link between redox regulation and nutrient signaling, ensuring proper metabolic adaptation and cellular fitness during glucose exhaustion.

molecular biology↗

bioRxiv2024

Cytosolic peroxiredoxin Tsa1 influences acetic acid metabolism and pH homeostasis in wine yeasts

Acetic acid is a key metabolite in yeast fermentation, influencing wine quality through its role in volatile acidity. In Saccharomyces cerevisiae, acetic acid production involves aldehyde dehydrogenases, primarily Ald6 during fermentation and Ald4 under respiration. However, the regulatory mechanisms of these enzymes throughout fermentation and how they differ in commonly used strains remain partially unclear. This study explores the cytosolic peroxiredoxin Tsa1 as a novel regulator of acetic acid metabolism. TSA1 gene deletion revealed strain-dependent effects on acetic acid metabolism and tolerance, showing reduced production and enhanced consumption in laboratory media. Under respiration, Ald4-driven acetic acid production, which raises extracellular pH, was mitigated by the absence of Tsa1. During wine fermentation, TSA1 deletion decreased the initial acetic acid surge by downregulating ALD6 transcription and enzymatic activity. These findings position Tsa1 as a metabolic regulator and a potential target for modulating acetic acid levels to manage volatile acidity and wine quality.

microbiology↗

bioRxiv2023

Up-regulation of Retrograde Response in yeast increases glycerol and reduces ethanol during wine fermentation

Nutrient signaling pathways play a pivotal role in regulating the balance between metabolism, growth and stress response depending on the available food supply. They are key factor for the biotechnological success of the yeast Saccharomyces cerevisiae during food-producing fermentations. One such pathway is the Retrograde Response, which controls the use of carbon backbones for the synthesis of amino acids derived from alpha-ketoglutarate, such as glutamate and lysine. The repressor MKS1 is linked to the TORC1 complex and negatively regulates this pathway. Deletion of MKS1 on a variety of industrial strains causes an increase in glycerol in winemaking, brewing and baking conditions. This increase is accompanied by a reduction in ethanol production in grape juice fermentations in four commercial wine strains. Interestingly, this does not lead to an increase in volatile acidity, as the levels of acetic acid actually decrease. Aeration during winemaking usually increases acetic acid levels, but this effect is reduced in the MKS1 mutant. Although there is an improvement in the metabolites of oenological interest, it comes at a cost, as the mutant showed slower fermentation kinetics when grown in grape juice, malt, and laboratory media using glucose, sucrose, and maltose as carbon sources. The deletion of RTG2, an activator of the Retrograde Response that acts as an antagonist of MKS1, also results in a defect in wine fermentation speed. These findings suggest that the deregulation of this pathway causes a fitness defect. Therefore, manipulating the repressor MKS1 is a promising approach to modulate yeast metabolism and produce low-ethanol drinks.

microbiology↗

bioRxiv2021

Impact of Starmerella bacillaris and Zygosaccharomyces bailii on ethanol reduction and Saccharomyces cerevisiae metabolism during mixed wine fermentations

The bulk of grape juice fermentation is carried out by the yeast Saccharomyces cerevisiae, but non-Saccharomyces yeasts can modulate many sensorial aspects of the final products in ways not well understood. In this study, some of such non-conventional yeasts were screened as mixed starter cultures in a fermentation defined medium in both simultaneous and sequential inoculations. One strain of Starmerella bacillaris and another of Zygosaccharomyces bailii were chosen by their distinct phenotypic footprint and their ability to reduce ethanol levels at the end of fermentation, particularly during simultaneous vinification. S. bacillaris losses viability strongly at the end of mixed fermentation, while Z. bailii remains viable until the end of vinification. Interestingly, for most non-Saccharomyces yeasts, simultaneous inoculation helps for survival at the end of fermentation compared to sequential inoculation. S. cerevisiae viability was unchanged by the presence of the either yeast. Characterization of both strains indicates that S. bacillaris behavior is overall more different from S. cerevisiae than Z. bailii. S. bacillaris has a less strict glucose repression mechanism and molecular markers like catabolite repression kinase Snf1 is quite different in size. Besides, S. cerevisiae transcriptome changes to a bigger degree in the presence of S. bacillaris than when inoculated with Z. bailii. S. bacillaris induces the translation machinery and repress vesicular transport. Both non-Saccharomyces yeast induce S. cerevisiae glycolytic genes, and that may be related to ethanol lowering, but there are specific aspects of carbon-related mechanisms between strains: Z. bailii presence increases the stress-related polysaccharides trehalose and glycogen while S. bacillaris induces gluconeogenesis genes.

microbiology↗