scholarly journals Effects of overexpression of STB5 in Saccharomyces cerevisiae on fatty acid biosynthesis, physiology and transcriptome

2019 ◽  
Vol 19 (3) ◽  
Author(s):  
Alexandra Bergman ◽  
Dóra Vitay ◽  
John Hellgren ◽  
Yun Chen ◽  
Jens Nielsen ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Fatty Acid ◽  
Target Genes ◽  
Fatty Acid Biosynthesis ◽  
Pentose Phosphate ◽  
Attractive Alternative ◽  
Microbial Conversion ◽  
Glucose Limitation ◽  
Production Route ◽  
Genes Encoding

ABSTRACTMicrobial conversion of biomass to fatty acids (FA) and products derived thereof is an attractive alternative to the traditional oleochemical production route from animal and plant lipids. This study examined if NADPH-costly FA biosynthesis could be enhanced by overexpressing the transcription factor Stb5 in Saccharomyces cerevisiae. Stb5 activates expression of multiple genes encoding enzymes within the pentose phosphate pathway (PPP) and other NADPH-producing reactions. Overexpression of STB5 led to a decreased growth rate and an increased free fatty acid (FFA) production during growth on glucose. The improved FFA synthetic ability in the glucose phase was shown to be independent of flux through the oxidative PPP. RNAseq analysis revealed that STB5 overexpression had wide-ranging effects on the transcriptome in the batch phase, and appeared to cause a counterintuitive phenotype with reduced flux through the oxidative PPP. During glucose limitation, when an increased NADPH supply is likely less harmful, an overall induction of the proposed target genes of Stb5 (eg. GND1/2, TAL1, ALD6, YEF1) was observed. Taken together, the strategy of utilizing STB5 overexpression to increase NADPH supply for reductive biosynthesis is suggested to have potential in strains engineered to have strong ability to consume excess NADPH, alleviating a potential redox imbalance.

scholarly journals Adjustment of Trehalose Metabolism in Wine Saccharomyces cerevisiae Strains To Modify Ethanol Yields

2013 ◽  
Vol 79 (17) ◽  
pp. 5197-5207 ◽  
Author(s):  
D. Rossouw ◽  
E. H. Heyns ◽  
M. E. Setati ◽  
S. Bosch ◽  
F. F. Bauer
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Genetic Modification ◽  
Target Genes ◽  
Tca Cycle ◽  
Pentose Phosphate ◽  
Systematic Screening ◽  
Content Type ◽  
Genes Encoding ◽  
Ethanol Yields ◽  
Trehalose Biosynthesis

ABSTRACTThe ability ofSaccharomyces cerevisiaeto efficiently produce high levels of ethanol through glycolysis has been the focus of much scientific and industrial activity. Despite the accumulated knowledge regarding glycolysis, the modification of flux through this pathway to modify ethanol yields has proved difficult. Here, we report on the systematic screening of 66 strains with deletion mutations of genes encoding enzymes involved in central carbohydrate metabolism for altered ethanol yields. Five of these strains showing the most prominent changes in carbon flux were selected for further investigation. The genes were representative of trehalose biosynthesis (TPS1, encoding trehalose-6-phosphate synthase), central glycolysis (TDH3, encoding glyceraldehyde-3-phosphate dehydrogenase), the oxidative pentose phosphate pathway (ZWF1, encoding glucose-6-phosphate dehydrogenase), and the tricarboxylic acid (TCA) cycle (ACO1andACO2, encoding aconitase isoforms 1 and 2). Two strains exhibited lower ethanol yields than the wild type (tps1Δ andtdh3Δ), while the remaining three showed higher ethanol yields. To validate these findings in an industrial yeast strain, theTPS1gene was selected as a good candidate for genetic modification to alter flux to ethanol during alcoholic fermentation in wine. Using low-strength promoters active at different stages of fermentation, the expression of theTPS1gene was slightly upregulated, resulting in a decrease in ethanol production and an increase in trehalose biosynthesis during fermentation. Thus, the mutant screening approach was successful in terms of identifying target genes for genetic modification in commercial yeast strains with the aim of producing lower-ethanol wines.

Regulation of the SREBP transcription factors by mTORC1

2011 ◽  
Vol 39 (2) ◽  
pp. 495-499 ◽  
Author(s):  
Caroline A. Lewis ◽  
Beatrice Griffiths ◽  
Claudio R. Santos ◽  
Mario Pende ◽  
Almut Schulze
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Synthase ◽  
Target Genes ◽  
De Novo ◽  
Regulatory Element ◽  
Cholesterol Biosynthesis ◽  
Mammalian Target Of Rapamycin ◽  
Lipid Biosynthesis ◽  
De Novo Lipogenesis ◽  
Genes Encoding

In recent years several reports have linked mTORC1 (mammalian target of rapamycin complex 1) to lipogenesis via the SREBPs (sterol-regulatory-element-binding proteins). SREBPs regulate the expression of genes encoding enzymes required for fatty acid and cholesterol biosynthesis. Lipid metabolism is perturbed in some diseases and SREBP target genes, such as FASN (fatty acid synthase), have been shown to be up-regulated in some cancers. We have previously shown that mTORC1 plays a role in SREBP activation and Akt/PKB (protein kinase B)-dependent de novo lipogenesis. Our findings suggest that mTORC1 plays a crucial role in the activation of SREBP and that the activation of lipid biosynthesis through the induction of SREBP could be part of a regulatory pathway that co-ordinates protein and lipid biosynthesis during cell growth. In the present paper, we discuss the increasing amount of data supporting the potential mechanisms of mTORC1-dependent activation of SREBP as well as the implications of this signalling pathway in cancer.

scholarly journals Regulatory Network Connecting Two Glucose Signal Transduction Pathways in Saccharomyces cerevisiae

2004 ◽  
Vol 3 (1) ◽  
pp. 221-231 ◽  
Author(s):  
Aneta Kaniak ◽  
Zhixiong Xue ◽  
Daniel Macool ◽  
Jeong-Ho Kim ◽  
Mark Johnston
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Signal Transduction ◽  
Transcription Factor ◽  
Regulatory Network ◽  
Target Genes ◽  
Glucose Repression ◽  
Signal Transduction Pathways ◽  
Glucose Signaling ◽  
Genes Encoding ◽  
Glucose Induction

ABSTRACT The yeast Saccharomyces cerevisiae senses glucose, its preferred carbon source, through multiple signal transduction pathways. In one pathway, glucose represses the expression of many genes through the Mig1 transcriptional repressor, which is regulated by the Snf1 protein kinase. In another pathway, glucose induces the expression of HXT genes encoding glucose transporters through two glucose sensors on the cell surface that generate an intracellular signal that affects function of the Rgt1 transcription factor. We profiled the yeast transcriptome to determine the range of genes targeted by this second pathway. Candidate target genes were verified by testing for Rgt1 binding to their promoters by chromatin immunoprecipitation and by measuring the regulation of the expression of promoter lacZ fusions. Relatively few genes could be validated as targets of this pathway, suggesting that this pathway is primarily dedicated to regulating the expression of HXT genes. Among the genes regulated by this glucose signaling pathway are several genes involved in the glucose induction and glucose repression pathways. The Snf3/Rgt2-Rgt1 glucose induction pathway contributes to glucose repression by inducing the transcription of MIG2, which encodes a repressor of glucose-repressed genes, and regulates itself by inducing the expression of STD1, which encodes a regulator of the Rgt1 transcription factor. The Snf1-Mig1 glucose repression pathway contributes to glucose induction by repressing the expression of SNF3 and MTH1, which encodes another regulator of Rgt1, and also regulates itself by repressing the transcription of MIG1. Thus, these two glucose signaling pathways are intertwined in a regulatory network that serves to integrate the different glucose signals operating in these two pathways.

scholarly journals Physiological and Transcriptional Responses of Saccharomyces cerevisiae tod-Limonene Show Changes to the Cell Wall but Not to the Plasma Membrane

2013 ◽  
Vol 79 (12) ◽  
pp. 3590-3600 ◽  
Author(s):  
Timothy C. R. Brennan ◽  
Jens O. Krömer ◽  
Lars K. Nielsen
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Wall ◽  
Plasma Membrane ◽  
Fatty Acid ◽  
Structural Integrity ◽  
Fatty Acid Biosynthesis ◽  
Membrane Integrity ◽  
Ethanol Exposure ◽  
Yeast Cells ◽  
Transcriptional Responses

ABSTRACTMonoterpenes can, upon hydrogenation, be used as light-fraction components of sustainable aviation fuels. Fermentative production of monoterpenes in engineered microorganisms, such asSaccharomyces cerevisiae, has gained attention as a potential route to deliver these next-generation fuels from renewable biomass. However, end product toxicity presents a formidable problem for microbial synthesis. Due to their hydrophobicity, monoterpene inhibition has long been attributed to membrane interference, but the molecular mechanism remains largely unsolved. In order to gain a better understanding of the mode of action, we analyzed the composition and structural integrity of the cell envelope as well as the transcriptional response of yeast cells treated with an inhibitory amount ofd-limonene (107 mg/liter). We found no alterations in membrane fluidity, structural membrane integrity, or fatty acid composition after the solvent challenge. A 4-fold increase in the mean fluorescence intensity per cell (using calcofluor white stain) and increased sensitivity to cell wall-degrading enzymes demonstrated that limonene disrupts cell wall properties. Global transcript measurements confirmed the membrane integrity observations by showing no upregulation of ergosterol or fatty acid biosynthesis pathways, which are commonly overexpressed in yeast to reinforce membrane rigidity during ethanol exposure. Limonene shock did cause a compensatory response to cell wall damage through overexpression of several genes (ROM1,RLM1,PIR3,CTT1,YGP1,MLP1,PST1, andCWP1) involved with the cell wall integrity signaling pathway. This is the first report demonstrating that cell wall, rather than plasma membrane, deterioration is the main source of monoterpene inhibition. We show that limonene can alter the structure and function of the cell wall, which has a clear effect on cytokinesis.

Respiratory pathways and fat synthesis in the developing castor oil seed

1979 ◽  
Vol 57 (9) ◽  
pp. 1008-1014 ◽  
Author(s):  
P. D. Simcox ◽  
W. Garland ◽  
V. DeLuca ◽  
D. T. Canvin ◽  
D. T. Dennis
Keyword(s):  
Fatty Acid ◽  
Castor Oil ◽  
Fatty Acid Biosynthesis ◽  
Acid Synthesis ◽  
Pentose Phosphate ◽  
Carboxylase Activity ◽  
Bisphosphate Carboxylase ◽  
Oil Seed ◽  
Pentose Phosphate Pathways ◽  
Glucose 6 Phosphate Dehydrogenase

During castor oil seed development, changes occur in the activities of enzymes involved in fatty acid biosynthesis, glycolysis, and the pentose phosphate pathways. The activities of acetyl-CoA carboxylase, phosphofructokinase, pyruvate kinase, glucose-6-phosphate dehydrogenase, and 6-phosphogluconate dehydrogenase per seed increase during the phase of rapid oil synthesis in the endosperm. As the seed matures and the rate of fatty acid synthesis decreases, there is a corresponding diminution in the activities of these enzymes. An indication of the metabolic capacity of the plastids was determined by monitoring the ribulose-1,5-bisphosphate carboxylase activity in the endosperm.

scholarly journals Inhibition of Acetyl Coenzyme A Carboxylase Activity Restores Expression of the INO1 Gene in a snf1Mutant Strain of Saccharomyces cerevisiae

2001 ◽  
Vol 21 (17) ◽  
pp. 5710-5722 ◽  
Author(s):  
Margaret K. Shirra ◽  
Jana Patton-Vogt ◽  
Andreas Ulrich ◽  
Oksana Liuta-Tehlivets ◽  
Sepp D. Kohlwein ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Fatty Acid ◽  
Fatty Acid Biosynthesis ◽  
Coenzyme A ◽  
Phospholipid Biosynthesis ◽  
Acid Biosynthesis ◽  
Acetyl Coenzyme A ◽  
Acetyl Coenzyme ◽  
Soraphen A ◽  
Acetyl Coenzyme A Carboxylase

ABSTRACT Mutations in the Saccharomyces cerevisiae SNF1 gene affect a number of cellular processes, including the expression of genes involved in carbon source utilization and phospholipid biosynthesis. To identify targets of the Snf1 kinase that modulate expression of INO1, a gene required for an early, rate-limiting step in phospholipid biosynthesis, we performed a genetic selection for suppressors of the inositol auxotrophy ofsnf1Δ strains. We identified mutations inACC1 and FAS1, two genes important for fatty acid biosynthesis in yeast; ACC1 encodes acetyl coenzyme A carboxylase (Acc1), and FAS1 encodes the β subunit of fatty acid synthase. Acc1 was shown previously to be phosphorylated and inactivated by Snf1. Here we show thatsnf1Δ strains with increased Acc1 activity exhibit decreased INO1 transcription. Strains carrying theACC1 suppressor mutation have reduced Acc1 activity in vitro and in vivo, as revealed by enzymatic assays and increased sensitivity to the Acc1-specific inhibitor soraphen A. Moreover, a reduction in Acc1 activity, caused by addition of soraphen A, provision of exogenous fatty acid, or conditional expression ofACC1, suppresses the inositol auxotrophy ofsnf1Δ strains. Together, these findings indicate that the inositol auxotrophy of snf1Δ strains arises in part from elevated Acc1 activity and that a reduction in this activity restores INO1 expression in these strains. These results reveal a Snf1-dependent connection between fatty acid production and phospholipid biosynthesis, identify Acc1 as a Snf1 target important forINO1 transcription, and suggest models in which metabolites that are generated or utilized during fatty acid biosynthesis can significantly influence gene expression in yeast.

scholarly journals SFH2 regulates fatty acid synthase activity in the yeast Saccharomyces cerevisiae and is critical to prevent saturated fatty acid accumulation in response to haem and oleic acid depletion

2007 ◽  
Vol 409 (1) ◽  
pp. 299-309 ◽  
Author(s):  
Thomas Desfougères ◽  
Thierry Ferreira ◽  
Thierry Bergès ◽  
Matthieu Régnacq
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Oleic Acid ◽  
Fatty Acid ◽  
Saturated Fatty Acid ◽  
Fatty Acid Synthase ◽  
Unsaturated Fatty Acids ◽  
Phospholipid Metabolism ◽  
Transcriptional Level ◽  
Yeast Saccharomyces Cerevisiae ◽  
Genes Encoding

The yeast Saccharomyces cerevisiae is a facultative anaerobic organism. Under anaerobiosis, sustained growth relies on the presence of exogenously supplied unsaturated fatty acids and ergosterol that yeast is unable to synthesize in the absence of oxygen or upon haem depletion. In the absence of exogenous supplementation with unsaturated fatty acid, a net accumulation of SFA (saturated fatty acid) is observed that induces significant modification of phospholipid profile [Ferreira, Régnacq, Alimardani, Moreau-Vauzelle and Bergès (2004) Biochem. J. 378, 899–908]. In the present paper, we focus on the role of SFH2/CSR1, a hypoxic gene related to SEC14 and its involvement in lipid metabolism upon haem depletion in the absence of oleic acid supplementation. We observed that inactivation of SFH2 results in enhanced accumulation of SFA and phospholipid metabolism alterations. It results in premature growth arrest and leads to an exacerbated sensitivity to exogenous SFA. This phenotype is suppressed in the presence of exogenous oleic acid, or by a controlled expression of FAS1, one of the two genes encoding FAS. We present several lines of evidence to suggest that Sfh2p and oleic acid regulate SFA synthase in yeast at different levels: whereas oleic acid acts on FAS2 at the transcriptional level, we show that Sfh2p inhibits fatty acid synthase activity in response to haem depletion.

scholarly journals CLN1 and Its Repression by Xbp1 Are Important for Efficient Sporulation in Budding Yeast

2000 ◽  
Vol 20 (2) ◽  
pp. 478-487 ◽  
Author(s):  
Bernard Mai ◽  
Linda Breeden
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Differential Display ◽  
Mitotic Cycle ◽  
Target Genes ◽  
Budding Yeast ◽  
Transcriptional Repressor ◽  
Primary Target ◽  
New Class ◽  
Genes Encoding ◽  
Meiotic Cycle

ABSTRACT Xbp1, a transcriptional repressor of Saccharomyces cerevisiae with homology to Swi4 and Mbp1, is induced by stress and starvation during the mitotic cycle. It is also induced late in the meiotic cycle. Using RNA differential display, we find that genes encoding three cyclins (CLN1, CLN3, andCLB2), CYS3, and SMF2 are downregulated when Xbp1 is overexpressed and that Xbp1 can bind to sequences in their promoters. During meiosis, XBP1 is highly induced and its mRNA appears at the same time asDIT1 mRNA, but its expression remains high for up to 24 h. As such, it represents a new class of meiosis-specific genes. Xbp1-deficient cells are capable of forming viable gametes, although ascus formation is delayed by several hours. Furthermore, Xbp1 target genes are normally repressed late in meiosis, and loss ofXBP1 results in their derepression. Interestingly, we find that a deletion of CLN1 also reduces the efficiency of sporulation and delays the meiotic program but that sporulation in a Δcln1 Δxbp1 strain is not further delayed. Thus, CLN1 may be Xbp1's primary target in meiotic cells. We hypothesize that CLN1 plays a role early in the meiotic program but must be repressed, by Xbp1, at later stages to promote efficient sporulation.

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