Evidence for a Transcarboxylase Reaction in Maize Chloroplast Extracts

1981 ◽  
Vol 36 (7-8) ◽  
pp. 688-691 ◽  
Author(s):  
David Pan ◽  
Kim H. Tan
Keyword(s):  
Carbonyl Compound ◽  
Crude Extract ◽  
Pentose Phosphate ◽  
Assay System ◽  
Cooh Group ◽  
Sugar Phosphate ◽  
Considerable Evidence ◽  
Maize Chloroplast ◽  
Fructose 1,6 Bisphosphate

Abstract The authors have suggested (Can. J. Bot. 49, 631 (1971) that the — COOH group of the C4-P carbonyl compound of the thermostable P-enolpyruvate acid carboxylase reaction may transcarboxylase with a pentose phosphate as ac­ ceptor. We now have considerable evidence supporting this consideration. In an assay system (0.8 ml) containing soni­ cated chloroplast extract in 0.1 m Tris-HCl, pH 6.3; and PEP, 0.1 |imol; Mg2+, 0.5 nmol; NADH, 0.25 nmol; sugar phosphate, 0.5 nmol. The amount of 14C 0 2 fixation is con­ siderably enhanced by either ribose-5-phosphate, fructose-1,6-bisphosphate or ribulose-l,5-bisphosphate in the pres­ ence of PEP. The products of the reaction include malate as a product of /?-carboxylation, and glycerate or 3-phosphate glycerate, their proportion being determined by the ac­ ceptor sugar phosphate. The results provide evidence for a "transcarboxylase" presented in the crude extract of Maize chloroplasts.

scholarly journals Metabolic Fluxes in Corynebacterium glutamicum during Lysine Production with Sucrose as Carbon Source

2004 ◽  
Vol 70 (12) ◽  
pp. 7277-7287 ◽  
Author(s):  
Christoph Wittmann ◽  
Patrick Kiefer ◽  
Oskar Zelder
Keyword(s):  
Carbon Source ◽  
Corynebacterium Glutamicum ◽  
Metabolic Flux ◽  
Tca Cycle ◽  
Pentose Phosphate ◽  
Flux Analysis ◽  
Phosphotransferase System ◽  
Lysine Production ◽  
Metabolic Fluxes ◽  
Fructose 1,6 Bisphosphate

ABSTRACT Metabolic fluxes in the central metabolism were determined for lysine-producing Corynebacterium glutamicum ATCC 21526 with sucrose as a carbon source, providing an insight into molasses-based industrial production processes with this organism. For this purpose, 13C metabolic flux analysis with parallel studies on [1-13CFru]sucrose, [1-13CGlc]sucrose, and [13C6 Fru]sucrose was carried out. C. glutamicum directed 27.4% of sucrose toward extracellular lysine. The strain exhibited a relatively high flux of 55.7% (normalized to an uptake flux of hexose units of 100%) through the pentose phosphate pathway (PPP). The glucose monomer of sucrose was completely channeled into the PPP. After transient efflux, the fructose residue was mainly taken up by the fructose-specific phosphotransferase system (PTS) and entered glycolysis at the level of fructose-1,6-bisphosphate. Glucose-6-phosphate isomerase operated in the gluconeogenetic direction from fructose-6-phosphate to glucose-6-phosphate and supplied additional carbon (7.2%) from the fructose part of the substrate toward the PPP. This involved supply of fructose-6-phosphate from the fructose part of sucrose either by PTSMan or by fructose-1,6-bisphosphatase. C. glutamicum further exhibited a high tricarboxylic acid (TCA) cycle flux of 78.2%. Isocitrate dehydrogenase therefore significantly contributed to the total NADPH supply of 190%. The demands for lysine (110%) and anabolism (32%) were lower than the supply, resulting in an apparent NADPH excess. The high TCA cycle flux and the significant secretion of dihydroxyacetone and glycerol display interesting targets to be approached by genetic engineers for optimization of the strain investigated.

scholarly journals Sedoheptulose-1,7-bisphospate Accumulation and Metabolic Anomalies in Hepatoma Cells Exposed to Oxidative Stress

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Mei-Ling Cheng ◽  
Jui-Fen Lin ◽  
Cheng-Yu Huang ◽  
Guan-Jie Li ◽  
Lu-Min Shih ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Death ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Hepatoma Cells ◽  
Pentose Phosphate ◽  
Hep G2 ◽  
Hep G2 Cells ◽  
Metabolite Profiles ◽  
G2 Cells ◽  
Fructose 1,6 Bisphosphate

We have previously shown that GSH depletion alters global metabolism of cells. In the present study, we applied a metabolomic approach for studying the early changes in metabolism in hydrogen peroxide- (H2O2-) treated hepatoma cells which were destined to die. Levels of fructose 1,6-bisphosphate and an unusual metabolite, sedoheptulose 1,7-bisphosphate (S-1,7-BP), were elevated in hepatoma Hep G2 cells. Deficiency in G6PD activity significantly reduced S-1,7-BP formation, suggesting that S-1,7-BP is formed in the pentose phosphate pathway as a response to oxidative stress. Additionally, H2O2 treatment significantly increased the level of nicotinamide adenine dinucleotide phosphate (NADP+) and reduced the levels of ATP and NAD+. Severe depletion of ATP and NAD+ in H2O2-treated Hep G2 cells was associated with cell death. Inhibition of PARP-mediated NAD+ depletion partially protected cells from death. Comparison of metabolite profiles of G6PD-deficient cells and their normal counterparts revealed that changes in GSH and GSSG per se do not cause cell death. These findings suggest that the failure of hepatoma cells to maintain energy metabolism in the midst of oxidative stress may cause cell death.

Inhibition of glyceraldehyde 3-phosphate dehydrogenase in boar spermatozoa by bromohydroxypropanone

1995 ◽  
Vol 7 (1) ◽  
pp. 107 ◽  
Author(s):  
LM Porter ◽  
AR Jones
Keyword(s):  
Carbonyl Compound ◽  
Energy Charge ◽  
Mature Sperm ◽  
Dihydroxyacetone Phosphate ◽  
Epididymal Sperm ◽  
Charge Potential ◽  
Fructose 1,6 Bisphosphate ◽  
Boar Spermatozoa

In the presence of 3-bromo-1-hydroxypropanone (BOP), cauda epididymal sperm obtained from mature boars produced a carbonyl compound which is assumed to be (S)-3-bromolactaldehyde. Glyceraldehyde 3-phosphate dehydrogenase was rapidly inhibited which resulted in the accumulation of dihydroxyacetone phosphate and fructose-1,6-bisphosphate, and no accumulation of lactate when fructose was the substrate. The energy charge potential of the cells declined in the presence of BOP when either fructose or glycerol were substrates. It is suggested that BOP is transformed into (S)-3-bromolactaldehyde, which is the actual inhibitor of glyceraldehyde 3-phosphate dehydrogenase, thus demonstrating BOP to be the first brominated chemical to have an anti-glycolytic action on mature sperm in vitro.

scholarly journals Quantitative analysis of flux along the gluconeogenic, glycolytic and pentose phosphate pathways under reducing conditions in hepatocytes isolated from fed rats

1983 ◽  
Vol 212 (3) ◽  
pp. 585-598 ◽  
Author(s):  
J M Crawford ◽  
J J Blum
Keyword(s):  
Compartment Model ◽  
Pentose Phosphate ◽  
Improved Method ◽  
Single Compartment ◽  
Reducing Conditions ◽  
Single Compartment Model ◽  
Net Flux ◽  
Pentose Phosphate Pathways ◽  
Fructose 1,6 Bisphosphate ◽  
Hexose Phosphates

Hepatocytes were isolated from the livers of fed rats and incubated with a mixture of glucose (10 mM), ribose (1 mM), mannose (4 mM), glycerol (3 mM), acetate (1.25 mM), and ethanol (5 mM) with one substrate labelled with 14C in any given incubation. Incorporation of label into CO2, glucose, glycogen, lipid glycerol and fatty acids, acetate and C-1 of glucose was measured at 20 and 40 min after the start of the incubation. The data (about 48 measurements for each interval) were used in conjunction with a single-compartment model of the reactions of the gluconeogenic, glycolytic and pentose phosphate pathways and a simplified model of the relevant mitochondrial reactions. An improved method of computer analysis of the equations describing the flow of label through each carbon atom of each metabolite under steady-state conditions was used to compute values for the 34 independent flux parameters in this model. A good fit to the data was obtained, thereby permitting good estimates of most of the fluxes in the pathways under consideration. The data show that: net flux above the level of the triose phosphates is gluconeogenic; label in the hexose phosphates is fully equilibrated by the second 20 min interval; the triose phosphate isomerase step does not equilibrate label between the triose phosphates; substrate cycles are operating at the glucose-glucose 6-phosphate, fructose 6-phosphate-fructose 1,6-bisphosphate and phosphoenolpyruvate-pyruvate-oxaloacetate cycles; and, although net flux through the enzymes catalysing the non-oxidative steps of the pentose phosphate pathway is small, bidirectional fluxes are large.

scholarly journals Effector-Mediated Interaction of CbbRI and CbbRII Regulators with Target Sequences in Rhodobacter capsulatus

2004 ◽  
Vol 186 (23) ◽  
pp. 8026-8035 ◽  
Author(s):  
Padungsri Dubbs ◽  
James M. Dubbs ◽  
F. Robert Tabita
Keyword(s):  
Rhodobacter Capsulatus ◽  
Energy Charge ◽  
Dnase I ◽  
Pentose Phosphate ◽  
In Vivo Studies ◽  
Mobility Shift ◽  
Fructose 1,6 Bisphosphate ◽  
Target Promoters

ABSTRACT In Rhodobacter capsulatus, genes encoding enzymes of the Calvin-Benson-Bassham reductive pentose phosphate pathway are located in the cbbI and cbbII operons. Each operon contains a divergently transcribed LysR-type transcriptional activator (CbbRI and CbbRII) that regulates the expression of its cognate cbb promoter in response to an as yet unidentified effector molecule(s). Both CbbRI and CbbRII were purified, and the ability of a variety of potential effector molecules to induce changes in their DNA binding properties at their target promoters was assessed. The responses of CbbRI and CbbRII to potential effectors were not identical. In gel mobility shift assays, the affinity of both CbbRI and CbbRII for their target promoters was enhanced in the presence of ribulose-1,5-bisphosphate (RuBP), phosphoenolpyruvate, 3-phosphoglycerate, 2-phosphoglycolate. ATP, 2-phosphoglycerate, and KH2PO4 were found to enhance only CbbRI binding, while fructose-1,6-bisphosphate enhanced the binding of only CbbRII. The DNase I footprint of CbbRI was reduced in the presence of RuBP, while reductions in the CbbRII DNase I footprint were induced by fructose-1,6-bisphosphate, 3-phosphoglycerate, and KH2PO4. The current in vitro results plus recent in vivo studies suggest that CbbR-mediated regulation of cbb transcription is controlled by multiple metabolic signals in R. capsulatus. This control reflects not only intracellular levels of Calvin-Benson-Bassham cycle metabolic intermediates but also the fixed (organic) carbon status and energy charge of the cell.

scholarly journals Relationship between Glycolysis and Exopolysaccharide Biosynthesis in Lactococcus lactis

2001 ◽  
Vol 67 (1) ◽  
pp. 33-41 ◽  
Author(s):  
Ana Ramos ◽  
Ingeborg C. Boels ◽  
Willem M. de Vos ◽  
Helena Santos
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Lactococcus Lactis ◽  
Genetic Manipulation ◽  
Pentose Phosphate ◽  
Biosynthetic Pathways ◽  
Glycolytic Intermediates ◽  
Phosphoglyceric Acid ◽  
Exopolysaccharide Biosynthesis ◽  
Fructose 1,6 Bisphosphate ◽  
Sugar Derivatives

ABSTRACT The relationships between glucose metabolism and exopolysaccharide (EPS) production in a Lactococcus lactis strain containing the EPS gene cluster (Eps+) and in nonproducer strain MG5267 (Eps−) were characterized. The concentrations of relevant phosphorylated intermediates in EPS and cell wall biosynthetic pathways or glycolysis were determined by 31P nuclear magnetic resonance. The concentrations of two EPS precursors, UDP-glucose and UDP-galactose, were significantly lower in the Eps+ strain than in the Eps− strain. The precursors of the peptidoglycan pathway, UDP-N-acetylglucosamine and UDP-N-acetylmuramoyl-pentapeptide, were the major UDP-sugar derivatives detected in the two strains examined, but the concentration of the latter was greater in the Eps+ strain, indicating that there is competition between EPS synthesis and cell growth. An intermediate in biosynthesis of histidine and nucleotides, 5-phosphorylribose 1-pyrophosphate, accumulated at concentrations in the millimolar range, showing that the pentose phosphate pathway was operating. Fructose 1,6-bisphosphate and glucose 6-phosphate were the prominent glycolytic intermediates during exponential growth of both strains, whereas in the stationary phase the main metabolites were 3-phosphoglyceric acid, 2-phosphoglyceric acid, and phosphoenolpyruvate. The activities of relevant enzymes, such as phosphoglucose isomerase, α-phosphoglucomutase, and UDP-glucose pyrophosphorylase, were identical in the two strains. 13C enrichment on the sugar moieties of pure EPS showed that glucose 6-phosphate is the key metabolite at the branch point between glycolysis and EPS biosynthesis and ruled out involvement of the triose phosphate pool. This study provided clues for ways to enhance EPS production by genetic manipulation.

scholarly journals Profiling of Pentose Phosphate Pathway Intermediates in Blood Spots by Tandem Mass Spectrometry: Application to Transaldolase Deficiency

2003 ◽  
Vol 49 (8) ◽  
pp. 1375-1380 ◽  
Author(s):  
Jojanneke H J Huck ◽  
Eduard A Struys ◽  
Nanda M Verhoeven ◽  
Cornelis Jakobs ◽  
Marjo S van der Knaap
Keyword(s):  
Mass Spectrometry ◽  
Tandem Mass Spectrometry ◽  
Pentose Phosphate Pathway ◽  
Multiple Reaction Monitoring ◽  
Pentose Phosphate ◽  
Dihydroxyacetone Phosphate ◽  
Tandem Mass ◽  
Sugar Phosphate ◽  
Blood Spots ◽  
Sugar Phosphates

Abstract Background: Recently, several patients with abnormal polyol profiles in body fluids have been reported, but the origins of these polyols are unknown. We hypothesized that they are derived from sugar phosphate intermediates of the pentose phosphate pathway (PPP), and we developed a semiquantitative method for profiling of pentose phosphate pathway intermediates. Methods: Sugar phosphates in blood spots were simultaneously analyzed by liquid chromatography–tandem mass spectrometry using an ion-pair-loaded C18 HPLC column. The tandem mass spectrometer was operated in the multiple-reaction monitoring mode. Enzymatically prepared d-[13C6]glucose 6-phosphate was used as internal standard. The method was used to study sugar phosphates abnormalities in a patient affected with a deficiency of transaldolase (TALDO1; EC 2.2.1.2). Results: In control blood spots, dihydroxyacetone phosphate, pentulose 5-phosphates, pentose 5-phosphates, hexose 6-phosphates, and sedoheptulose 7-phosphate were detected. Detection limits ranged from ∼100 to ∼500 nmol/L. Glyceraldehyde 3-phosphate and erythrose 4-phosphate were undetectable. Intra- and interassay imprecision (CVs) were 10–17% and 12–21%, respectively. In blood from the TALDO1-deficient patient, sedoheptulose 7-phosphate was increased. Conclusions: The new method allows investigation of patients in whom a defect in the PPP is suspected. Measurements of sugar phosphate intermediates of the PPP may provide new insights into metabolic defects underlying the accumulating polyols.

scholarly journals Genetic and Physiological Characterization of Fructose-1,6-Bisphosphate Aldolase and Glyceraldehyde-3-Phosphate Dehydrogenase in the Crabtree-Negative Yeast Kluyveromyces lactis

2022 ◽  
Vol 23 (2) ◽  
pp. 772
Author(s):  
Rosaura Rodicio ◽  
Hans-Peter Schmitz ◽  
Jürgen J. Heinisch
Keyword(s):  
Kluyveromyces Lactis ◽  
Regulation Of Gene Expression ◽  
Carbon Sources ◽  
Pentose Phosphate ◽  
Gene Encoding ◽  
Physiological Characterization ◽  
Genes Encoding ◽  
Fructose 1,6 Bisphosphate

The milk yeast Kluyveromyces lactis degrades glucose through glycolysis and the pentose phosphate pathway and follows a mainly respiratory metabolism. Here, we investigated the role of two reactions which are required for the final steps of glucose degradation from both pathways, as well as for gluconeogenesis, namely fructose-1,6-bisphosphate aldolase (FBA) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). In silico analyses identified one gene encoding the former (KlFBA1), and three genes encoding isoforms of the latter (KlTDH1, KlTDH2, KlGDP1). Phenotypic analyses were performed by deleting the genes from the haploid K. lactis genome. While Klfba1 deletions lacked detectable FBA activity, they still grew poorly on glucose. To investigate the in vivo importance of the GAPDH isoforms, different mutant combinations were analyzed for their growth behavior and enzymatic activity. KlTdh2 represented the major glycolytic GAPDH isoform, as its lack caused a slower growth on glucose. Cells lacking both KlTdh1 and KlTdh2 failed to grow on glucose but were still able to use ethanol as sole carbon sources, indicating that KlGdp1 is sufficient to promote gluconeogenesis. Life-cell fluorescence microscopy revealed that KlTdh2 accumulated in the nucleus upon exposure to oxidative stress, suggesting a moonlighting function of this isoform in the regulation of gene expression. Heterologous complementation of the Klfba1 deletion by the human ALDOA gene renders K. lactis a promising host for heterologous expression of human disease alleles and/or a screening system for specific drugs.

scholarly journals The rise of diversity in metabolic platforms across the Candidate Phyla Radiation

2019 ◽  
Author(s):  
Alexander L. Jaffe ◽  
Cindy J. Castelle ◽  
Paula B. Matheus Carnevali ◽  
Simonetta Gribaldo ◽  
Jillian F. Banfield
Keyword(s):  
Gene Transfer ◽  
Gene Loss ◽  
Pentose Phosphate ◽  
Gene Gain ◽  
Reference Tree ◽  
Group 4 ◽  
Group 3 ◽  
Fructose 1,6 Bisphosphate ◽  
Ancient Gene ◽  
Candidate Phyla Radiation

ABSTRACTA unifying feature of the bacterial Candidate Phyla Radiation (CPR) is a limited and highly variable repertoire of biosynthetic capabilities. However, the distribution of metabolic traits across the CPR and the evolutionary processes underlying them are incompletely resolved. Here, we selected ∼1,000 genomes of CPR bacteria from diverse environments to construct a robust internal phylogeny that was consistent across two unlinked marker sets. Mapping of glycolysis, the pentose phosphate pathway, and pyruvate metabolism onto the tree showed that some components of these pathways are sparsely distributed and that similarity between metabolic platforms is only partially predicted by phylogenetic relationships. To evaluate the extent to which gene loss and lateral gene transfer have shaped trait distribution, we analyzed the patchiness of gene presence in a phylogenetic context, examined the phylogenetic depth of clades with shared traits, and compared the reference tree topology with those of specific metabolic proteins. While the central glycolytic pathway in CPR is widely conserved and has likely been shaped primarily by vertical transmission, there is evidence for both gene loss and transfer especially in steps that convert glucose into fructose 1,6-bisphosphate and glycerate 3P into pyruvate. Additionally, the distribution of Group 3 and Group 4-related NiFe hydrogenases is patchy and suggests multiple events of ancient gene transfer. Overall, patterns of gene gain and loss, including acquisition of accessory traits in independent transfer events, may have been driven by shifts in host-derived resources and led to sparse but varied genetic inventories.

Metabolism of hexoses and pentoses by Cellulomonas uda under aerobic conditions and during fermentation

1987 ◽  
Vol 33 (11) ◽  
pp. 1024-1031 ◽  
Author(s):  
S. Marschoun ◽  
P. Rapp ◽  
F. Wagner
Keyword(s):  
Acetic Acid ◽  
Lactic Acid ◽  
Lactate Dehydrogenase ◽  
Alcohol Dehydrogenase ◽  
Succinic Acid ◽  
Pentose Phosphate ◽  
Aerobic Conditions ◽  
Key Enzymes ◽  
Cellulomonas Uda ◽  
Fructose 1,6 Bisphosphate

Cellulomonas uda utilized the constituent carbohydrates of cellulose and hemicellulose under aerobic conditions and during fermentation. Balances of fermentation of cellobiose, glucose, xylose, L-arabinose, mannose, galactose, fructose, and sucrose were determined. Products formed were ethanol, L-lactic acid, acetic acid, formic acid, and succinic acid. In contrast to acetic acid, a small amount of succinic acid was utilized under aerobic conditions but only together with glucose. Ethanol was not consumed either under aerobic conditions or during fermentation. The rate of both glucose uptake and lactic acid excretion during fermentation increased with increasing initial pH values of 7 to 9. The intracellular concentration of ethanol at the end of glucose fermentation was 20 times higher than that in the culture supernatant. Switching from aerobic to fermentation conditions increased specific activities of fructose-6-phosphate kinase and fructose-1,6-bisphosphate aldolase, both key enzymes of the fructose-1,6-bisphosphate pathway, whereas those of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, key enzymes of the pentose phosphate cycle, were not affected significantly. Of the enzymes involved in pyruvic acid metabolism, pyruvate formate lyase, L-lactate dehydrogenase, and alcohol dehydrogenase were demonstrated in cell-free extracts. Fructose-1,6-bisphosphate had an activating effect on L-lactate dehydrogenase. Alcohol dehydrogenase was inhibited competitively by high concentrations of ethanol and noncompetitively by NAD.

Sign in / Sign up

Export Citation Format

Share Document