scholarly journals Role of Hexose Transport in Control of Glycolytic Flux in Saccharomyces cerevisiae

2004 ◽  
Vol 70 (9) ◽  
pp. 5323-5330 ◽  
Author(s):  
Karin Elbing ◽  
Christer Larsson ◽  
Roslyn M. Bill ◽  
Eva Albers ◽  
Jacky L. Snoep ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Glucose Uptake ◽  
Ethanol Production ◽  
Glycolytic Flux ◽  
Glucose Levels ◽  
High Degree ◽  
First Time ◽  
Proportional Decrease ◽  
External Glucose

ABSTRACT The yeast Saccharomyces cerevisiae predominantly ferments glucose to ethanol at high external glucose concentrations, irrespective of the presence of oxygen. In contrast, at low external glucose concentrations and in the presence of oxygen, as in a glucose-limited chemostat, no ethanol is produced. The importance of the external glucose concentration suggests a central role for the affinity and maximal transport rates of yeast's glucose transporters in the control of ethanol production. Here we present a series of strains producing functional chimeras between the hexose transporters Hxt1 and Hxt7, each of which has distinct glucose transport characteristics. The strains display a range of decreasing glycolytic rates resulting in a proportional decrease in ethanol production. Using these strains, we show for the first time that at high glucose levels, the glucose uptake capacity of wild-type S. cerevisiae does not control glycolytic flux during exponential batch growth. In contrast, our chimeric Hxt transporters control the rate of glycolysis to a high degree. Strains whose glucose uptake is mediated by these chimeric transporters will undoubtedly provide a powerful tool with which to examine in detail the mechanism underlying the switch between fermentation and respiration in S. cerevisiae and will provide new tools for the control of industrial fermentations.

scholarly journals Effects of Ultrasound on Fermentation of Glucose to Ethanol by Saccharomyces cerevisiae

Fermentation ◽  
2019 ◽  
Vol 5 (1) ◽  
pp. 16 ◽  
Author(s):  
Luis Huezo ◽  
Ajay Shah ◽  
Frederick Michel
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mass Transfer ◽  
Glucose Uptake ◽  
Ethanol Production ◽  
Ethanol Yield ◽  
Biofuel Production ◽  
Inhibitory Effects ◽  
Negative Effects ◽  
Intraparticle Mass Transfer ◽  
Improve Mass Transfer

Previous studies have shown that pretreatment of corn slurries using ultrasound improves starch release and ethanol yield during biofuel production. However, studies on its effects on the mass transfer of substrates and products during fermentation have shown that it can have both beneficial and inhibitory effects. In this study, the effects of ultrasound on mass transfer limitations during fermentation were examined. Calculation of the external and intraparticle observable moduli under a range of conditions indicate that no external or intraparticle mass transfer limitations should exist for the mass transfer of glucose, ethanol, or carbon dioxide. Fermentations of glucose to ethanol using Saccharomyces cerevisiae were conducted at different ultrasound intensities to examine its effects on glucose uptake, ethanol production, and yeast population and viability. Four treatments were compared: direct ultrasound at intensities of 23 and 32 W/L, indirect ultrasound (1.4 W/L), and no-ultrasound. Direct and indirect ultrasound had negative effects on yeast performance and viability, and reduced the rates of glucose uptake and ethanol production. These results indicate that ultrasound during fermentation, at the levels applied, is inhibitory and not expected to improve mass transfer limitations.

scholarly journals Blocking mitophagy does not improve fuel ethanol production in Saccharomyces cerevisiae

2021 ◽  
Author(s):  
Kevy Pontes Eliodório ◽  
Gabriel Caetano de Gois e Cunha ◽  
Brianna A White ◽  
Demisha HM Patel ◽  
Fangyi Zhang ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Viability ◽  
Ethanol Production ◽  
Ethanol Fermentation ◽  
Synthetic Medium ◽  
Fuel Ethanol ◽  
Specific Gene ◽  
Fermentation Performance ◽  
Cell Recycling

Ethanol fermentation is frequently performed under conditions of low nitrogen. In Saccharomyces cerevisiae, nitrogen limitation induces macroautophagy, including the selective removal of mitochondria, also called mitophagy. Shiroma and co-workers (2014) showed that blocking mitophagy by deletion of the mitophagy specific gene ATG32 increased the fermentation performance during the brewing of Ginjo sake. In this study, we tested if a similar strategy could enhance alcoholic fermentation in the context of fuel ethanol production from sugarcane in Brazilian biorefineries. Conditions that mimic the industrial fermentation process indeed induce Atg32-dependent mitophagy in cells of S. cerevisiae PE-2, a strain frequently used in the industry. However, after blocking mitophagy, no differences in CO2production, final ethanol titres or cell viability were observed after five rounds of ethanol fermentation, cell recycling and acid treatment, as commonly performed in sugarcane biorefineries. To test if S. cerevisiae's strain background influences this outcome, cultivations were carried out in a synthetic medium with strains PE-2, Ethanol Red (industrial) and BY (laboratory), with and without a functional ATG32 gene, under oxic and oxygen restricted conditions. Despite the clear differences in sugar consumption, cell viability and ethanol titres, among the three strains, we could not observe any improvement in fermentation performance related to the blocking of mitophagy. We conclude with caution that results obtained with Ginjo sake yeast is an exception and cannot be extrapolated to other yeast strains and that more research is needed to ascertain the role of autophagic processes during fermentation.

scholarly journals Both E6 and E7 in HPV16 Promote the Glucose Uptake of GLUT1 in Lung Cancer Cells By Repressing NDRG2 Expression and Further Nuclear Translocation of β-Catenin

2021 ◽  
Author(s):  
Xin Wang ◽  
Ming-Zhe Wu ◽  
Na-Jin Gu ◽  
Shi-Yu Wang ◽  
Hong-Tao Xu ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Glucose Uptake ◽  
Nuclear Translocation ◽  
Molecular Signaling ◽  
Genetic Manipulations ◽  
Ndrg2 Expression ◽  
E6 And E7 ◽  
E7 Proteins ◽  
First Time

Abstract Background: HPV16 is the most common infection subtype, among which E6 and E7 proteins are the most common carcinogenic proteins. Our previous studies found that E6 and E7 proteins regulated the expression of GLUT1 through multiple molecular signaling pathways in lung cancer. However, whether they can regulate the glucose uptake of GLUT1 and the underlying molecular mechanism has not been identified. Methods: The modulating effects of E6 or E7, NDRG2, β-catenin, and GLUT1 were detected by double directional genetic manipulations in lung cancer cell lines; The immunofluorescence was used to detect the effect of NDRG2 on the nuclear translocation of β-catenin; The glucose uptake level of GLUT1 was observed under the confocal microscope.Results: We demonstrated for the first time that E6 and E7 had inhibitory effects of NDRG2 which further resulted in increased β-catenin expression and promoted β-catenin nuclear translocation, furthermore promoted the expression and glucose uptake of GLUT1. Therefore, we hypothesized both E6 and E7 in HPV16 promoted the expression and glucose uptake of GLUT1 through HPV-NDRG2- β-catenin-GLUT1 axis. Conclusion: Our findings confirmed the regulatory role of tumor suppressor NDRG2 in the pathogenesis of lung cancer, and we further demonstrate the detail relationships among E6 and E7, NDRG2, β-catenin, and GLUT1; which provided a novel therapeutic target for tumor treatment.

scholarly journals Gcn5p and Ubp8p Affect Protein Ubiquitylation and Cell Proliferation by Altering the Fermentative/Respiratory Flux Balance in Saccharomyces cerevisiae

mBio ◽  
2020 ◽  
Vol 11 (4) ◽  
Author(s):  
Antonella De Palma ◽  
Giulia Fanelli ◽  
Elisabetta Cretella ◽  
Veronica De Luca ◽  
Raffaele Antonio Palladino ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Glucose Consumption ◽  
Redox Balance ◽  
Glycolytic Enzymes ◽  
Glycolytic Flux ◽  
Direct Role ◽  
Content Type ◽  
Proteomic Approach ◽  
Altered Glucose

ABSTRACT Protein ubiquitylation regulates not only endocellular trafficking and proteasomal degradation but also the catalytic activity of enzymes. In Saccharomyces cerevisiae, we analyzed the composition of the ubiquitylated proteomes in strains lacking acetyltransferase Gcn5p, Ub-protease Ubp8p, or both to understand their involvement in the regulation of protein ubiquitylation. We analyzed His6Ub proteins with a proteomic approach coupling micro-liquid chromatography and tandem mass spectrometry (μLC-MS/MS) in gcn5Δ, ubp8Δ and ubp8Δ gcn5Δ strains. The Ub-proteome altered in the absence of Gcn5p, Ubp8p, or both was characterized, showing that 43% of the proteins was shared in all strains, suggesting their functional relationship. Remarkably, all major glycolytic enzymes showed increased ubiquitylation. Phosphofructokinase 1, the key enzyme of glycolytic flux, showed a higher and altered pattern of ubiquitylation in gcn5Δ and ubp8Δ strains. Severe defects of growth in poor sugar and altered glucose consumption confirmed a direct role of Gcn5p and Ubp8p in affecting the REDOX balance of the cell. IMPORTANCE We propose a study showing a novel role of Gcn5p and Ubp8p in the process of ubiquitylation of the yeast proteome which includes main glycolytic enzymes. Interestingly, in the absence of Gcn5p and Ubp8p glucose consumption and redox balance were altered in yeast. We believe that these results and the role of Gcn5p and Ubp8p in sugar metabolism might open new perspectives of research leading to novel protocols for counteracting the enhanced glycolysis in tumors.

scholarly journals Saccharomyces cerevisiae exhibiting a modified route for uptake and catabolism of glycerol forms significant amounts of ethanol from this carbon source considered as ‘non-fermentable’

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Maximilian R. Aßkamp ◽  
Mathias Klein ◽  
Elke Nevoigt
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Carbon Source ◽  
Ethanol Production ◽  
Shake Flask ◽  
Biodiesel Production ◽  
Catabolic Pathway ◽  
Metabolic Switch ◽  
In The Wild ◽  
Glycerol Uptake ◽  
High Degree

Abstract Background Due to its inevitable formation during biodiesel production and its relatively high degree of reduction, glycerol is an attractive carbon source for microbial fermentation processes. However, glycerol is catabolized in a fully respiratory manner by the eukaryotic platform organism Saccharomyces cerevisiae. We previously engineered S. cerevisiae strains to favor fermentative metabolism of glycerol by replacing the native FAD-dependent glycerol catabolic pathway with the NAD-dependent ‘DHA pathway’. In addition, a heterologous aquaglyceroporin (Fps1 homolog) was expressed to facilitate glycerol uptake. The current study was launched to scrutinize the formation of S. cerevisiae’s natural fermentation product ethanol from glycerol caused by the conducted genetic modifications. This understanding is supposed to facilitate future engineering of this yeast for fermenting glycerol into valuable products more reduced than ethanol. Results A strain solely exhibiting the glycerol catabolic pathway replacement produced ethanol at concentrations close to the detection limit. The expression of the heterologous aquaglyceroporin caused significant ethanol production (8.5 g L−1 from 51.5 g L−1 glycerol consumed) in a strain catabolizing glycerol via the DHA pathway but not in the wild-type background. A reduction of oxygen availability in the shake flask cultures further increased the ethanol titer up to 15.7 g L−1 (from 45 g L−1 glycerol consumed). Conclusion The increased yield of cytosolic NADH caused by the glycerol catabolic pathway replacement seems to be a minimal requirement for the occurrence of alcoholic fermentation in S. cerevisiae growing in synthetic glycerol medium. The remarkable metabolic switch to ethanol formation in the DHA pathway strain with the heterologous aquaglyceroporin supports the assumption of a much stronger influx of glycerol accompanied by an increased rate of cytosolic NADH production via the DHA pathway. The fact that a reduction of oxygen supply increases ethanol production in DHA pathway strains is in line with the hypothesis that a major part of glycerol in normal shake flask cultures still enters the catabolism in a respiratory manner.

scholarly journals Catestatin Induces Glucose Uptake and GLUT4 Trafficking in Adult Rat Cardiomyocytes

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Maria Pia Gallo ◽  
Saveria Femminò ◽  
Susanna Antoniotti ◽  
Giulia Querio ◽  
Giuseppe Alloatti ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Glucose Uptake ◽  
Cardiac Metabolism ◽  
Glut4 Translocation ◽  
Rat Cardiomyocytes ◽  
Adult Rat ◽  
Hydrophobic Peptide ◽  
First Time ◽  
Intracellular Pathway

Catestatin is a cationic and hydrophobic peptide derived from the enzymatic cleavage of the prohormone Chromogranin A. Initially identified as a potent endogenous nicotinic–cholinergic antagonist, Catestatin has recently been shown to act as a novel regulator of cardiac function and blood pressure and as a cardioprotective agent in both pre- and postconditioning through AKT-dependent mechanisms. The aim of this study is to investigate the potential role of Catestatin also on cardiac metabolism modulation, particularly on cardiomyocytes glucose uptake. Experiments were performed on isolated adult rat cardiomyocytes. Glucose uptake was assessed by fluorescent glucose incubation and confocal microscope analysis. Glut4 plasma membrane translocation was studied by immunofluorescence experiments and evaluation of the ratio peripheral vs internal Glut4 staining. Furthermore, we performed immunoblot experiments to investigate the involvement of the intracellular pathway AKT/AS160 in the Catestatin dependent Glut4 trafficking. Our results show that 10 nM Catestatin induces a significant increase in the fluorescent glucose uptake, comparable to that exerted by 100 nM Insulin. Moreover, Catestatin stimulates Glut4 translocation to plasma membrane and both AKT and AS160 phosphorylation. All these effects were inhibited by Wortmannin. On the whole, we show for the first time that Catestatin is able to modulate cardiac glucose metabolism, by inducing an increase in glucose uptake through Glut4 translocation to the plasma membrane and that this mechanism is mediated by the AKT/AS160 intracellular pathway.

scholarly journals The screening and management of newborns at risk for low blood glucose

2019 ◽  
Vol 24 (8) ◽  
pp. 536-544 ◽  
Author(s):  
Michael R Narvey ◽  
Seth D Marks
Keyword(s):  
At Risk ◽  
Blood Glucose ◽  
Severe Hypoglycemia ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
Group Experiences ◽  
Key Issues ◽  
Definition Of ◽  
First Time

Abstract Hypoglycemia in the first hours to days after birth remains one of the most common conditions facing practitioners across Canada who care for newborns. Many cases represent normal physiologic transition to extrauterine life, but another group experiences hypoglycemia of longer duration. This statement addresses key issues for providers of neonatal care, including the definition of hypoglycemia, risk factors, screening protocols, blood glucose levels requiring intervention, and managing care for this condition. Screening, monitoring, and intervention protocols have been revised to better identify, manage, and treat infants who are at risk for persistent, recurrent, or severe hypoglycemia. The role of dextrose gels in raising glucose levels or preventing more persistent hypoglycemia, and precautions to reduce risk for recurrence after leaving hospital, are also addressed. This statement differentiates between approaches to care for hypoglycemia during the ‘transitional’ phase—the first 72 hours post-birth—and persistent hypoglycemia, which occurs or presents for the first time past that point.

scholarly journals Inhibition of alternative respiration system of Scheffersomyces stipitis and effect on glucose or xylose fermentation

2021 ◽  
Author(s):  
J A Granados-Arvizu ◽  
M Canizal-Garcia ◽  
L A Madrigal-Perez ◽  
J C González-Hernández ◽  
C Regalado-González
Keyword(s):  
Ethanol Production ◽  
Xylose Fermentation ◽  
Carbon Sources ◽  
Active Role ◽  
Glycolytic Flux ◽  
Alternative Respiration ◽  
Scheffersomyces Stipitis ◽  
Salicylhydroxamic Acid ◽  
Mild Reduction

Abstract Scheffersomyces stipitis is a Crabtree-negative pentose fermenting yeast, which shows a complex respiratory system involving a cytochrome and an alternative salicylhydroxamic acid (SHAM)-sensitive respiration mechanism that is poorly understood. This work aimed to investigate the role of the antimycin A (AA) sensitive respiration and SHAM-sensitive respiration in the metabolism of xylose and glucose by S. stipitis, upon different agitation conditions. Inhibition of the SHAM-sensitive respiration caused a significant (p < 0.05) decrease in glycolytic flux and oxygen consumption when using glucose and xylose under agitation conditions, but without agitation, only a mild reduction was observed. The combination of SHAM and AA abolished respiration, depleting the glycolytic flux using both carbon sources tested, leading to increased ethanol production of 21.05 g/L at 250 rpm for 0.5 M glucose, and 8.3 g/L ethanol using xylose. In contrast, inhibition of only the AA-sensitive respiration, caused increased ethanol production to 30 g/L using 0.5 M glucose at 250 rpm, and 11.3 g/L from 0.5 M xylose without agitation. Results showed that ethanol production can be induced by respiration inhibition, but the active role of SHAM-sensitive respiration should be considered to investigate better conditions to increase and optimize yields.

scholarly journals Produksi Etanol Berbahan Baku Molasses Melalui Proses Fermentasi Menggunakan Ragi Roti

2021 ◽  
Vol 1 (1) ◽  
pp. 1
Author(s):  
Yustia Wulandari Mirzayanti ◽  
Sugiono . ◽  
Reta Kurniayati
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Renewable Energy ◽  
Ethanol Production ◽  
Incubation Time ◽  
Baker’S Yeast ◽  
Baker's Yeast ◽  
Alcohol Content ◽  
Glucose Content ◽  
Alcohol Production ◽  
Glucose Levels

<table class="NormalTable"><tbody><tr><td width="200"><span class="fontstyle0">One of the alternatives and renewable energy that is being developed is ethanol.<br />Ethanol is better known as Gasohol. Molasses can make Gasohol through the<br />synthesis of molasses fermentation using a yeast starter. This study aims to<br />analyze how the effect of the addition of baker's yeast, the length of fermentation<br />incubation time on the resulting alcohol content. In addition, the yield obtained<br />from the highest amount of ethanol production in the molasses fermentation<br />process. Ethanol production through fermentation synthesis using the help of<br />microorganisms Saccharomyces cerevisiae. Based on the objective review, the<br />variation used is the amount of baker's yeast, namely 0.1; 0.2; 0.3; 0.4; and 0.5%<br />glucose levels. The fermentation times were 24, 48, 72, 96, and 120 hours (T =<br />30?C and pH = 5). Based on these variations, the highest alcohol production<br />was 11%, obtained by adding 0.2% of yeast to the glucose content in the solution.<br />The incubation time is 72 hours. The yield obtained for the highest alcohol<br />content is 4.48%</span></td></tr></tbody></table>

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