scholarly journals Adaptation of central metabolite pools to variations in growth rate and cultivation conditions in Saccharomyces cerevisiae

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Kanhaiya Kumar ◽  
Vishwesh Venkatraman ◽  
Per Bruheim
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Growth Rate ◽  
Amino Acid ◽  
Growth Rates ◽  
Pentose Phosphate Pathway ◽  
Pentose Phosphate ◽  
Relative Reduction ◽  
Central Metabolism ◽  
Cultivation Conditions ◽  
Biological Studies

Abstract Background Saccharomyces cerevisiae is a well-known popular model system for basic biological studies and serves as a host organism for the heterologous production of commercially interesting small molecules and proteins. The central metabolism is at the core to provide building blocks and energy to support growth and survival in normal situations as well as during exogenous stresses and forced heterologous protein production. Here, we present a comprehensive study of intracellular central metabolite pool profiling when growing S. cerevisiae on different carbon sources in batch cultivations and at different growth rates in nutrient-limited glucose chemostats. The latest versions of absolute quantitative mass spectrometry-based metabolite profiling methodology were applied to cover glycolytic and pentose phosphate pathway metabolites, tricarboxylic acid cycle (TCA), complete amino acid, and deoxy-/nucleoside phosphate pools. Results Glutamate, glutamine, alanine, and citrate were the four most abundant metabolites for most conditions tested. The amino acid is the dominant metabolite class even though a marked relative reduction compared to the other metabolite classes was observed for nitrogen and phosphate limited chemostats. Interestingly, glycolytic and pentose phosphate pathway (PPP) metabolites display the largest variation among the cultivation conditions while the nucleoside phosphate pools are more stable and vary within a closer concentration window. The overall trends for glucose and nitrogen-limited chemostats were increased metabolite pools with the increasing growth rate. Next, comparing the chosen chemostat reference growth rate (0.12 h−1, approximate one-fourth of maximal unlimited growth rate) illuminates an interesting pattern: almost all pools are lower in nitrogen and phosphate limited conditions compared to glucose limitation, except for the TCA metabolites citrate, isocitrate and α-ketoglutarate. Conclusions This study provides new knowledge-how the central metabolism is adapting to various cultivations conditions and growth rates which is essential for expanding our understanding of cellular metabolism and the development of improved phenotypes in metabolic engineering.

scholarly journals Adaptation of Central Metabolite Pools to Variations in Growth Rate and Cultivation Conditions in Saccharomyces Cerevisiae

2020 ◽  
Author(s):  
Kanhaiya Kumar ◽  
Vishwesh Venkatraman ◽  
Per Bruheim
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Growth Rate ◽  
Amino Acid ◽  
Growth Rates ◽  
Building Blocks ◽  
Relative Reduction ◽  
Central Metabolism ◽  
Cultivation Conditions ◽  
Biological Studies ◽  
Metabolite Pool

Abstract Background: Saccharomyces cerevisiae is a well-known popular model system for basic biological studies and to serve as host organism for heterologous production of commercially interesting small molecules and proteins. The central metabolism is at the core to provide building blocks and energy to support growth and survival in normal situations as well as during exogeneous stresses and forced heterologous protein production. Here, we present a comprehensive study of intracellular central metabolite pool profiling when growing S. cerevisiae on different carbon sources in batch cultivations and at different growth rates in nutrient limited glucose chemostats. Latest versions of absolute quantitative mass spectrometry-based metabolite profiling methodology were applied to cover glycolytic and pentose phosphate pathway metabolites, TCA, complete amino acid and deoxy-/nucleoside phosphate pools. We have attempted to correlate the total metabolite pool composition with growth rates and nutrient limitation in both batch and chemostat cultivations. We have also tried to dissect the Crabtree-effect, i.e. ethanol-producing cultivation conditions, based on metabolite pool composition. Results: Glutamate, glutamine, alanine and citrate were the four most abundant metabolites for most conditions tested. Amino acid is the dominant metabolite class even though a marked relative reduction compared to the other metabolite classes was observed for nitrogen and phosphate limited chemostats. Interestingly, glycolytic and PPP metabolites display largest variation among the cultivation conditions while the nucleoside phosphate pools are more stable and vary within a closer concentration window. The overall trends for glucose and nitrogen limited chemostats were increased metabolite pools with increasing growth rate. Next, comparing the chosen chemostat reference growth rate (0.12 h -1 , approximate one-fourth of maximal unlimited growth rate) illuminates an interesting pattern: almost all pools are lower in nitrogen and phosphate limited conditions compared to glucose limitation, except for the TCA metabolites citrate, isocitrate and a-ketoglutarate. Conclusions: This study provides new knowledge how the central metabolism is adapting to various cultivations conditions and growth rates which is essential for expanding our understanding of cellular metabolism and development of improved phenotypes in metabolic engineering.

scholarly journals Identification of Enzymes and Quantification of Metabolic Fluxes in the Wild Type and in a Recombinant Aspergillus oryzae Strain

1999 ◽  
Vol 65 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Henrik Pedersen ◽  
Morten Carlsen ◽  
Jens Nielsen
Keyword(s):  
Growth Rate ◽  
Pentose Phosphate Pathway ◽  
Isocitrate Dehydrogenase ◽  
Type Strain ◽  
Wild Type Strain ◽  
Specific Growth ◽  
Pentose Phosphate ◽  
Central Metabolism ◽  
Wild Type ◽  
Metabolic Fluxes

ABSTRACT Two α-amylase-producing strains of Aspergillus oryzae, a wild-type strain and a recombinant containing additional copies of the α-amylase gene, were characterized with respect to enzyme activities, localization of enzymes to the mitochondria or cytosol, macromolecular composition, and metabolic fluxes through the central metabolism during glucose-limited chemostat cultivations. Citrate synthase and isocitrate dehydrogenase (NAD) activities were found only in the mitochondria, glucose-6-phosphate dehydrogenase and glutamate dehydrogenase (NADP) activities were found only in the cytosol, and isocitrate dehydrogenase (NADP), glutamate oxaloacetate transaminase, malate dehydrogenase, and glutamate dehydrogenase (NAD) activities were found in both the mitochondria and the cytosol. The measured biomass components and ash could account for 95% (wt/wt) of the biomass. The protein and RNA contents increased linearly with increasing specific growth rate, but the carbohydrate and chitin contents decreased. A metabolic model consisting of 69 fluxes and 59 intracellular metabolites was used to calculate the metabolic fluxes through the central metabolism at several specific growth rates, with ammonia or nitrate as the nitrogen source. The flux through the pentose phosphate pathway increased with increasing specific growth rate. The fluxes through the pentose phosphate pathway were 15 to 26% higher for the recombinant strain than for the wild-type strain.

CreA influences the metabolic fluxes of Aspergillus nidulans during growth on glucose and xylose

Microbiology ◽  
2005 ◽  
Vol 151 (7) ◽  
pp. 2209-2221 ◽  
Author(s):  
Helga David ◽  
Astrid Mørkeberg Krogh ◽  
Christophe Roca ◽  
Mats Åkesson ◽  
Jens Nielsen
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Mutant Strain ◽  
Pentose Phosphate Pathway ◽  
Reference Strain ◽  
Specific Growth ◽  
Pentose Phosphate ◽  
Central Metabolism ◽  
Metabolic Fluxes

The physiological phenotype of Aspergillus nidulans was investigated for different genetic and environmental conditions of glucose repression through the quantification of in vivo fluxes in the central carbon metabolism using 13C-metabolic-flux analysis. The particular focus was the role of the carbon repressor CreA, which is the major regulatory protein mediating carbon repression in many fungal species, in the primary metabolism of A. nidulans. Batch cultivations were performed with a reference strain and a deletion mutant strain (creAΔ4) using [1-13C]glucose as carbon source. The mutant strain was also grown on a mixture of [1-13C]glucose and unlabelled xylose. Fractional enrichment data were measured by gas chromatography-mass spectrometry. A model describing the central metabolism of A. nidulans was used in combination with fractional enrichment data, and measurements of extracellular rates and biomass composition for the estimation of the in vivo metabolic fluxes. The creA-mutant strain showed a lower maximum specific growth rate than the reference strain when grown on glucose (0·11 and 0·25 h−1, respectively), whereas the specific growth rate of the mutant strain grown on the glucose/xylose mixture was identical to that on glucose (0·11 h−1). Different patterns and increased levels of extracellular polyols were observed both upon deletion of the creA gene and upon addition of xylose to the growth medium of the mutant strain. Concerning metabolic fluxes, the major change observed in the flux distribution of A. nidulans upon deletion of the creA gene was a 20 % decrease in the flux through the oxidative part of the pentose-phosphate pathway. Addition of xylose to the growth medium of the mutant resulted in an increase of about 40 % in the activity of the oxidative part of the pentose-phosphate pathway, as well as decreases in the fluxes through the Embden–Meyerhof–Parnas pathway and the tricarboxylic acid cycle (in the range of 20–30 %). The derepression of key pathways leads to alterations in the demands for cofactors, thereby imposing changes in the central metabolism due to the coupling of the many different reactions via the redox and energy metabolism of the cells.

scholarly journals Metabolic Changes Induced by Deletion of Transcriptional Regulator GCR2 in Xylose-Fermenting Saccharomyces cerevisiae

2020 ◽  
Vol 8 (10) ◽  
pp. 1499
Author(s):  
Minhye Shin ◽  
Soo Rin Kim
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Carbon Source ◽  
Pentose Phosphate Pathway ◽  
Carbon Metabolism ◽  
Transcriptional Regulator ◽  
Central Carbon Metabolism ◽  
Pentose Phosphate ◽  
Metabolic Changes ◽  
Regulatory Systems ◽  
Central Carbon

Glucose repression has been extensively studied in Saccharomyces cerevisiae, including the regulatory systems responsible for efficient catabolism of glucose, the preferred carbon source. However, how these regulatory systems would alter central metabolism if new foreign pathways are introduced is unknown, and the regulatory networks between glycolysis and the pentose phosphate pathway, the two major pathways in central carbon metabolism, have not been systematically investigated. Here we disrupted gcr2, a key transcriptional regulator, in S. cerevisiae strain SR7 engineered to heterologously express the xylose-assimilating pathway, activating genes involved in glycolysis, and evaluated the global metabolic changes. gcr2 deletion reduced cellular growth in glucose but significantly increased growth when xylose was the sole carbon source. Global metabolite profiling revealed differential regulation of yeast metabolism in SR7-gcr2Δ, especially carbohydrate and nucleotide metabolism, depending on the carbon source. In glucose, the SR7-gcr2Δ mutant showed overall decreased abundance of metabolites, such as pyruvate and sedoheptulose-7-phosphate, associated with central carbon metabolism including glycolysis and the pentose phosphate pathway. However, SR7-gcr2Δ showed an increase in metabolites abundance (ribulose-5-phosphate, sedoheptulose-7-phosphate, and erythrose-4-phosphate) notably from the pentose phosphate pathway, as well as alteration in global metabolism when compared to SR7. These results provide insights into how the regulatory system GCR2 coordinates the transcription of glycolytic genes and associated metabolic pathways.

scholarly journals Single amino acid-promoted reactions link a non-enzymatic chemical network to the early evolution of enzymatic pentose phosphate pathway

2020 ◽  
Author(s):  
Gabriel Piedrafita ◽  
Sreejith Varma ◽  
Cecilia Castro ◽  
Christoph Messner ◽  
Lukasz Szyrwiel ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Pentose Phosphate Pathway ◽  
Metabolic Pathways ◽  
Metal Ion ◽  
Enzymatic Reaction ◽  
Pentose Phosphate ◽  
Early Evolution ◽  
Environmental Chemical ◽  
Rna Backbone

AbstractHow metabolic pathways emerged in early evolution remains largely unknown. Recently discovered chemical networks driven by iron and sulfur resemble reaction sequences found within glycolysis, gluconeogenesis, the oxidative and reductive Krebs cycle, the Wood Ljungdahl as well as the S-adenosylmethionine pathways, components of the core cellular metabolic network. These findings suggest that the evolution of central metabolism was primed by environmental chemical reactions, implying that non-enzymatic reaction networks served as a “template” in the evolution of enzymatic activities. We speculated that the turning point for this transition would depend on the catalytic properties of the simplest structural components of proteins, single amino acids. Here, we systematically combine constituents of Fe(II)-driven non-enzymatic reactions resembling glycolysis and pentose phosphate pathway (PPP), with single proteinogenic amino acids. Multiple reaction rates are enhanced by amino acids. In particular, cysteine is able to replace (and/or complement) the metal ion Fe(II) in driving the non-enzymatic formation of the RNA-backbone metabolite ribose 5-phosphate from 6-phosphogluconate, a rate-limiting reaction of the oxidative PPP. In the presence of both Fe(II) and cysteine, a complex is formed, enabling the non-enzymatic reaction to proceed at a wide range of temperatures. At mundane temperatures, this ‘minimal enzyme-like complex’ achieves a much higher specificity in the formation of ribose 5-phosphate than the Fe(II)-driven reaction at high temperatures. Hence, simple amino acids can accelerate key steps within metal-promoted metabolism-like chemical networks. Our results imply a stepwise scenario, in which environmental chemical networks served as primers in the early evolution of the metabolic network structure.Significance StatementThe evolutionary roots of metabolic pathways are barely understood. Here we show results consistent with a stepwise scenario during the evolution of (enzymatic) metabolism, starting from non-enzymatic chemical networks. By systematic screening of metabolic-like reactivities in vitro, and using high-throughput analytical techniques, we identify an iron/cysteine complex to act as a ‘minimal enzymelike complex’, which consists of a metal ion, an amino acid, and a sugar phosphate ligand. Integrated in a metal-driven, non-enzymatic pentose phosphate pathway, it promotes the formation of the RNA-backbone precursor ribose 5-phosphate at ambient temperature.

Quantification of Saccharomyces cerevisiae pentose-phosphate pathway intermediates by LC-MS/MS

2009 ◽  
Author(s):  
Mirjam Wamelink ◽  
Erwin Jansen ◽  
Eduard Struys ◽  
Hans Lehrach ◽  
Cornelis Jakobs ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Pentose Phosphate Pathway ◽  
Pentose Phosphate
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