| 1. |
- Aranda, A., et al.
(författare)
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Yeast Life Span and its Impact on Food Fermentations
- 2019
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Ingår i: Fermentation-Basel. - : MDPI AG. ; 5:2
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Tidskriftsartikel (refereegranskat)abstract
- Yeasts are very important microorganisms for food production. The high fermentative capacity, mainly of the species of the genus Saccharomyces, is a key factor for their biotechnological use, particularly to produce alcoholic beverages. As viability and vitality are essential to ensure their correct performance in industry, this review addresses the main aspects related to the cellular aging of these fungi as their senescence impacts their proper functioning. Laboratory strains of S. cerevisiae have proven a very successful model for elucidating the molecular mechanisms that control life span. Those mechanisms are shared by all eukaryotic cells. S. cerevisiae has two models of aging, replicative and chronological. Replicative life span is measured by the number of daughter cells a mother can produce. This kind of aging is relevant when the yeast biomass is reused, as in the case of beer fermentations. Chronological life span is measured by the time cells are viable in the stationary phase, and this is relevant for batch fermentations when cells are most of the time in a non-dividing state, such as wine fermentations. The molecular causes and pathways regulating both types of aging are explained in this review.
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| 2. |
- Garrigós, Víctor, et al.
(författare)
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Wine yeast peroxiredoxin tsa1 plays a role in growth, stress response and trehalose metabolism in biomass propagation
- 2020
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Ingår i: Microorganisms. - : MDPI AG. - 2076-2607. ; 8:10, s. 1-18
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Tidskriftsartikel (refereegranskat)abstract
- Peroxiredoxins are a family of peroxide-degrading enzymes for challenging oxidative stress. They receive their reducing power from redox-controlling proteins called thioredoxins, and these, in turn, from thioredoxin reductase. The main cytosolic peroxiredoxin is Tsa1, a moonlighting protein that also acts as protein chaperone a redox switch controlling some metabolic events. Gene deletion of peroxiredoxins in wine yeasts indicate that TSA1, thioredoxins and thioredoxin reductase TRR1 are required for normal growth in medium with glucose and sucrose as carbon sources. TSA1 gene deletion also diminishes growth in molasses, both in flasks and bioreactors. The TSA1 mutation brings about an expected change in redox parameters but, interestingly, it also triggers a variety of metabolic changes. It influences trehalose accumulation, lowering it in first molasses growth stages, but increasing it at the end of batch growth, when respiratory metabolism is set up. Glycogen accumulation at the entry of the stationary phase also increases in the tsa1∆ mutant. The mutation reduces fermentative capacity in grape juice, but the vinification profile does not significantly change. However, acetic acid and acetaldehyde production decrease when TSA1 is absent. Hence, TSA1 plays a role in the regulation of metabolic reactions leading to the production of such relevant enological molecules.
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| 3. |
- Gast, Veronica, 1992, et al.
(författare)
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The Yeast eIF2 Kinase Gcn2 Facilitates H 2 O 2 -Mediated Feedback Inhibition of Both Protein Synthesis and Endoplasmic Reticulum Oxidative Folding during Recombinant Protein Production
- 2021
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Ingår i: Applied and Environmental Microbiology. - 1098-5336 .- 0099-2240. ; 87:15, s. e0030121-16
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Tidskriftsartikel (refereegranskat)abstract
- Recombinant protein production is a known source of oxidative stress. However, knowledge of which reactive oxygen species are involved or the specific growth phase in which stress occurs remains lacking. Using modern, hypersensitive genetic H2O2-specific probes, microcultivation, and continuous measurements in batch culture, we observed H2O2 accumulation during and following the diauxic shift in engineered Saccharomyces cerevisiae, correlating with peak α-amylase production. In agreement with previous studies supporting a role of the translation initiation factor kinase Gcn2 in the response to H2O2, we find that Gcn2-dependent phosphorylation of eIF2α increases alongside translational attenuation in strains engineered to produce large amounts of α-amylase. Gcn2 removal significantly improved α-amylase production in two previously optimized high-producing strains but not in the wild type. Gcn2 deficiency furthermore reduced intracellular H2O2 levels and the Hac1 splicing ratio, while expression of antioxidants and the endoplasmic reticulum (ER) disulfide isomerase PDI1 increased. These results suggest protein synthesis and ER oxidative folding are coupled and subject to feedback inhibition by H2O2. IMPORTANCE Recombinant protein production is a multibillion dollar industry. Optimizing the productivity of host cells is, therefore, of great interest. In several hosts, oxidants are produced as an unwanted side product of recombinant protein production. The buildup of oxidants can result in intracellular stress responses that could compromise the productivity of the host cell. Here, we document a novel protein synthesis inhibitory mechanism that is activated by the buildup of a specific oxidant (H2O2) in the cytosol of yeast cells upon the production of recombinant proteins. At the center of this inhibitory mechanism lies the protein kinase Gcn2. By removing Gcn2, we observed a doubling of recombinant protein productivity in addition to reduced H2O2 levels in the cytosol. In this study, we want to raise awareness of this inhibitory mechanism in eukaryotic cells to further improve protein production and contribute to the development of novel protein-based therapeutic strategies.
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| 4. |
- Picazo Campos, Cecilia, 1987, et al.
(författare)
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Impact of hydrogen peroxide on protein synthesis in yeast
- 2021
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Ingår i: Antioxidants. - : MDPI AG. - 2076-3921. ; 10:6
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Forskningsöversikt (refereegranskat)abstract
- Cells must be able to respond and adapt to different stress conditions to maintain normal function. A common response to stress is the global inhibition of protein synthesis. Protein synthesis is an expensive process consuming much of the cell’s energy. Consequently, it must be tightly regulated to conserve resources. One of these stress conditions is oxidative stress, resulting from the accumulation of reactive oxygen species (ROS) mainly produced by the mitochondria but also by other intracellular sources. Cells utilize a variety of antioxidant systems to protect against ROS, directing signaling and adaptation responses at lower levels and/or detoxification as levels increase to preclude the accumulation of damage. In this review, we focus on the role of hydrogen peroxide, H2O2, as a signaling molecule regulating protein synthesis at different levels, including transcription and various parts of the translation process, e.g., initiation, elongation, termination and ribosome recycling.
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| 5. |
- Roger, Friederike, et al.
(författare)
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Peroxiredoxin promotes longevity and H2O2-resistance in yeast through redox-modulation of protein kinase A
- 2020
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Ingår i: eLife. - 2050-084X. ; 9, s. 1-32
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Tidskriftsartikel (refereegranskat)abstract
- Peroxiredoxins are H2O2 scavenging enzymes that also carry out 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.
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| 6. |
- Sjölander, Johanna J, 1980, et al.
(författare)
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A redox-sensitive thiol in Wis1 modulates the fission yeast MAPK response to H2O2 and is the target of a small molecule.
- 2020
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Ingår i: Molecular and Cellular Biology. - 0270-7306 .- 1098-5549. ; 40:7
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Tidskriftsartikel (refereegranskat)abstract
- Oxidation of a highly-conserved cysteine (Cys) residue located in the kinase-activation loop of mitogen-activated protein kinase kinases (MAPKK) inactivates mammalian MKK6. This residue is conserved in the fission yeast MAPKK Wis1, which belongs to the H2O2-responsive MAPK Sty1 pathway. Here, we show that H2O2 reversibly inactivates Wis1 through this residue (C458) in vitro. We found that C458 is oxidized in vivo and that serine substitution of this residue significantly enhances Wis1 activation upon addition of H2O2 The allosteric MAPKK inhibitor, INR119, which binds in a pocket next to the activation loop and C458 prevented the inhibition of Wis1 by H2O2in vitro, and significantly increased Wis1 activation by low levels of H2O2in vivo We propose that oxidation of C458 inhibits Wis1 and that INR119 cancels out this inhibitory effect by binding close to this residue. Kinase inhibition through the oxidation of a conserved Cys residue in MKK6 (C196) is thus conserved in the S. pombe MAPKK Wis1.
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| 7. |
- Sjölander, Johanna J., et al.
(författare)
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A Redox-Sensitive Thiol in Wis1 Modulates the Fission Yeast Mitogen-Activated Protein Kinase Response to H2O2 and Is the Target of a Small Molecule
- 2020
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Ingår i: Molecular and cellular biology. - 1098-5549 .- 0270-7306. ; 40:7
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Tidskriftsartikel (refereegranskat)abstract
- Oxidation of a highly conserved cysteine (Cys) residue located in the kinase activation loop of mitogen-activated protein kinase kinases (MAPKK) inactivates mammalian MKK6. This residue is conserved in the fission yeast Schizosaccharomyces pombe MAPKK Wis1, which belongs to the H2O2-responsive MAPK Sty1 pathway. Here, we show that H2O2 reversibly inactivates Wis1 through this residue (C458) in vitro We found that C458 is oxidized in vivo and that serine replacement of this residue significantly enhances Wis1 activation upon addition of H2O2 The allosteric MAPKK inhibitor INR119, which binds in a pocket next to the activation loop and C458, prevented the inhibition of Wis1 by H2O2in vitro and significantly increased Wis1 activation by low levels of H2O2in vivo We propose that oxidation of C458 inhibits Wis1 and that INR119 cancels out this inhibitory effect by binding close to this residue. Kinase inhibition through the oxidation of a conserved Cys residue in MKK6 (C196) is thus conserved in the S. pombe MAPKK Wis1.
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