Biology subjects

Picazo, C.

Publications and source records attributed to Picazo, C..

5 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

The yeast eIF2 kinase Gcn2 facilitates H2O2-mediated feedback inhibition of both protein synthesis and ER oxidative folding during recombinant protein production

Recombinant protein production is a known source of oxidative stress. Knowledge of which ROS are involved or the specific growth phase in which stress occurs however remains lacking. Using modern, hypersensitive genetic H2O2-specific probes, micro-cultivation and continuous measurements in batch culture, we observed H2O2 accumulation during and following the diauxic shift in engineered Saccharomyces cerevisiae, correlating with peak -amylase production. In agreement with previous studies supporting a role of the translation initiation factor kinase Gcn2 in the response to H2O2, we find Gcn2-dependent phosphorylation of eIF2 to increase alongside translational attenuation in strains engineered to produce large amounts of -amylase. Gcn2 removal significantly improved -amylase production in two previously optimized high-producing strains, but not in the wild-type. Gcn2-deficiency furthermore reduced intracellular H2O2 levels and the unfolded protein response whilst expression of antioxidants and the ER disulfide isomerase PDI1 increased. These results suggest protein synthesis and ER oxidative folding to be coupled and subject to feedback inhibition by H2O2. ImportanceReactive oxygen species (ROS) accumulate during recombinant protein production both in yeast and Chinese hamster ovary cells, two of the most popular organisms used in the multi-million dollar protein production industry. Here we document increased H2O2 in the cytosol of yeast cells producing -amylase. Since H2O2 predominantly targets the protein synthesis machinery and activates the translation initiation factor kinase Gcn2, we removed Gcn2, resulting in increased recombinant -amylase production in two different previously engineered high-producing protein production strains. Removal of this negative feed-back loop thus represents a complementary strategy for improving recombinant protein production efforts currently used in yeast. Gcn2-deficiency also increased the expression of antioxidant genes and the ER-foldase PDI1, suggesting that protein synthesis and ER oxidative folding are linked and feed-back regulated via H2O2. Identification of additional components in this complex regulation may further improve protein production and contribute to the development of novel protein-based therapeutic strategies.

bioengineering↗

bioRxiv2019

Peroxiredoxin promotes longevity and H2O2-resistance in yeast through redox-modification of PKA

Peroxiredoxins are H2O2 scavenging enzymes that also carry H2O2 signaling and chaperone functions. In yeast, the major cytosolic peroxiredoxin, Tsa1 is required for both promoting resistance to H2O2 and extending lifespan upon caloric restriction. We show here that Tsa1 effects both these functions not by scavenging H2O2, but by repressing the nutrient signaling Ras-cAMP-PKA pathway at the level of the protein kinase A (PKA) enzyme. Tsa1 stimulates sulfenylation of cysteines in the PKA catalytic subunit by H2O2 and a significant proportion of the catalytic subunits are glutathionylated on two cysteine residues. Redox modification of the conserved Cys243 inhibits the phosphorylation of a conserved Thr241 in the kinase activation loop and enzyme activity, and preventing Thr241 phosphorylation can overcome the H2O2 sensitivity of Tsa1-deficient cells. Results support a model of aging where nutrient signaling pathways constitute hubs integrating information from multiple aging-related conduits, including a peroxiredoxin-dependent response to H2O2.

biochemistry↗