Metabolism of glycolic acid by Azotobacter chroococcum PRL H62

1973 ◽  
Vol 19 (3) ◽  
pp. 321-324 ◽  
Author(s):  
W. G. W. Kurz ◽  
T. A. G. LaRue
Keyword(s):  
Nitrogen Fixation ◽  
Dicarboxylic Acid ◽  
Glycolic Acid ◽  
Tca Cycle ◽  
Azotobacter Chroococcum ◽  
Acid Cycle ◽  
Isocitric Dehydrogenase ◽  
Tca Cycle Enzymes ◽  
The Tca Cycle ◽  
Reduced Nitrogen

When Azotobacter chroococcum grows on glycolic acid as sole C source, it cannot utilize N2 and must be provided with reduced nitrogen. Glycolic acid is metabolized via Kornberg's dicarboxylic acid cycle. The TCA cycle enzymes are low in activity, and isocitric dehydrogenase is absent. It is likely that isocitric dehydrogenase is the source of reductant for nitrogen fixation by Azotobacter nitrogenase.

Tricarboxylic acid cycle enzymes of a pseudophyllid cestode Penetrocephalus ganapatii

1990 ◽  
Vol 64 (1) ◽  
pp. 51-53
Author(s):  
S. Dhandayuthapani ◽  
K. Nellaiappan
Keyword(s):  
Isocitrate Dehydrogenase ◽  
Citrate Synthase ◽  
Tricarboxylic Acid Cycle ◽  
Tca Cycle ◽  
Tricarboxylic Acid ◽  
Reverse Direction ◽  
Acid Cycle ◽  
Tca Cycle Enzymes ◽  
The Tca Cycle ◽  
Atp Generation

ABSTRACTStudies on the tricarboxylic acid cycle (TCA cycle) enzymes of Penetrocephalus ganapatii reveal that the TCA cycle is only partially operative, as some of the enzymes at the start of the cycle viz. citrate synthase, aconitase and isocitrate dehydrogenase are found to be low in their activities. The high activities of malate dehydrogenase and fumarase, showing affinity towards a reverse direction, indicate that the TCA cycle operates in the reverse direction resulting in the formation of fumarate. The low succinate dehydrogenase/fumarate reductase ratio suggests that ATP generation may occur at site I of the respiratory chain during the reduction of fumarate into succinate.

Effect of thermal injury on the TCA cycle enzymes of Staphylococcus aureus MF 31 and Salmonella typhimurium 7136

1971 ◽  
Vol 17 (6) ◽  
pp. 759-765 ◽  
Author(s):  
Richard I. Tomlins ◽  
Merle D. Pierson ◽  
Z. John Ordal
Keyword(s):  
Lactate Dehydrogenase ◽  
Malate Dehydrogenase ◽  
Thermal Injury ◽  
Specific Activity ◽  
Fumarate Hydratase ◽  
Tca Cycle ◽  
Tca Cycle Enzymes ◽  
The Tca Cycle ◽  
Oxoglutarate Dehydrogenase ◽  
Metabolic Activities

The heating of S. aureus MF-31 and S. typhimurium 7136 at 52C and 48C respectively, produced a sublethal heat injury. When injured cells were placed in fresh growth medium they recovered. The recovery of S. aureus was not inhibited by chloramphenicol. The metabolic activities of tricarboxylic acid (TCA) cycle enzymes, as well as other selected enzymes in crude extracts of normal and heat-injured cells of both microorganisms were assayed. In extracts from S. typhimurium there was some loss of specific activity with fumarate hydratase, glutamate dehydrogenase, fructose diphosphate aldolase, lactate dehydrogenase, and the NAD(P) oxidases as a result of heating. In extracts from S. aureus oxoglutarate dehydrogenase, malate dehydrogenase and lactate dehydrogenase were severely inactivated after heating. Other enzymes in comparison were only moderately sensitive to heat. No significant increase in enzyme activity was observed in extracts from injured cells of either microorganism. Re-naturation of lactate dehydrogenase and malate dehydrogenase occurred during the recovery of S. aureus both in the presence and absence of chloramphenicol. No renaturation of oxoglutarate dehydrogenase was found under the same conditions.

scholarly journals Staphylococcus epidermidis Polysaccharide Intercellular Adhesin Production Significantly Increases during Tricarboxylic Acid Cycle Stress

2005 ◽  
Vol 187 (9) ◽  
pp. 2967-2973 ◽  
Author(s):  
Cuong Vuong ◽  
Joshua B. Kidder ◽  
Erik R. Jacobson ◽  
Michael Otto ◽  
Richard A. Proctor ◽  
...  
Keyword(s):  
Staphylococcus Epidermidis ◽  
Tricarboxylic Acid Cycle ◽  
Tca Cycle ◽  
Redox Status ◽  
Tricarboxylic Acid ◽  
Polysaccharide Intercellular Adhesin ◽  
Low Oxygen ◽  
Acid Cycle ◽  
The Tca Cycle ◽  
High Concentrations

ABSTRACT Staphylococcal polysaccharide intercellular adhesin (PIA) is important for the development of a mature biofilm. PIA production is increased during growth in a nutrient-replete or iron-limited medium and under conditions of low oxygen availability. Additionally, stress-inducing stimuli such as heat, ethanol, and high concentrations of salt increase the production of PIA. These same environmental conditions are known to repress tricarboxylic acid (TCA) cycle activity, leading us to hypothesize that altering TCA cycle activity would affect PIA production. Culturing Staphylococcus epidermidis with a low concentration of the TCA cycle inhibitor fluorocitrate dramatically increased PIA production without impairing glucose catabolism, the growth rate, or the growth yields. These data lead us to speculate that one mechanism by which staphylococci perceive external environmental change is through alterations in TCA cycle activity leading to changes in the intracellular levels of biosynthetic intermediates, ATP, or the redox status of the cell. These changes in the metabolic status of the bacteria result in the attenuation or augmentation of PIA production.

scholarly journals New Insights into Heme Utilization Pathways

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. SCI-25-SCI-25
Author(s):  
Emanuela Tolosano
Keyword(s):  
Respiratory Chain ◽  
Tricarboxylic Acid Cycle ◽  
Tca Cycle ◽  
Tricarboxylic Acid ◽  
Energetic Metabolism ◽  
Acid Cycle ◽  
Heme Synthesis ◽  
Chain Complexes ◽  
The Tca Cycle

Heme, an iron-containing porphyrin, plays pivotal functions in cell energetic metabolism, serving as a cofactor for most of the respiratory chain complexes and interacting with the translocases responsible for the ADP/ATP exchange between mitochondria and cytosol. Moreover, heme biosynthesis is considered a cataplerotic pathway for the tricarboxylic acid cycle (TCA) cycle, as the process consumes succynil-CoA, an intermediate of the TCA cycle. Finally, heme synthesis is one of the major cellular iron-consuming processes, thus competing with mitochondrial biogenesis of iron-sulfur (Fe-S) clusters, the crucial cofactors of electron transport chain complexes and of some TCA cycle enzymes. The process of heme synthesis consists of eight enzymatic reactions starting in mitochondria with the condensation of glycine and succynil-CoA to form δ-aminolevulinic acid (ALA), catalyzed by amino levulinic acid synthase (ALAS), the rate-limiting enzyme in heme biosynthetic pathway. Two isoforms of ALAS exist, ALAS1, ubiquitously expressed and controlled by heme itself through a negative feedback, and ALAS2, specifically expressed in the erythroid cells and mainly controlled by iron availability. ALA is exported from mitochondria to cytosol and converted to coproporphyrinogenIII that is imported back into the mitochondrial intermembrane space and converted to protoporphyrinogen IX. The latter is oxidized to porphyrin IX. Finally, ferrous iron is inserted into porphyrin IX by ferrochelatase, a Fe-S cluster-containing enzyme. Heme is incorporated into mitochondrial heme-containing proteins including complexes of the respiratory chain or exported to cytosol for incorporation into cytosolic apo-hemoproteins. Cytosolic heme level is maintained by the rate of hemoprotein production, the activity of heme transporters, including both heme importers and exporters, and the rate of heme degradation mediated by heme oxygenases. The concerted action of all these mechanisms regulates heme level that in turn controls its own synthesis by regulating the expression and activity of ALAS1. During differentiation of erythroid progenitors, cells bypass the heme-mediated negative regulation of its production by expressing ALAS2 that is responsible for the high rate of heme synthesis required to sustain hemoglobin production. We showed that the process of heme efflux through the plasma membrane heme exporter Feline Leukemia Virus C Receptor (FLVCR)1a is required to sustain ALAS1-catalyzed heme synthesis. In tumor cells, the potentiation of heme synthesis/export axis contributes to the down-modulation of tricarboxylic acid cycle (TCA) cycle favoring a glycolysis- compared to an oxidative-based metabolism. Our data indicate that the heme synthesis/export axis slow down the TCA cycle through two mechanisms, on one hand, by consuming succynil-CoA, an intermediate of the cycle, and, on the other, by consuming mitochondrial iron thus limiting the production of Fe-S clusters, essential co-factors of complexes of the respiratory chain as well as of key enzymes of the cycle. The importance of heme synthesis/export axis in metabolic rewiring occurring during tumorigenesis is highlighted by the impaired proliferation and survival observed in FLVCR1a-silenced cancer cells. We speculate that the heme synthesis/export axis plays a role in metabolic adaptation also in proliferating cells in physiologic conditions, especially when oxygen concentration is limiting, as suggested by the phenotype of murine models of Flvcr1a deficiency. Finally, in post-mitotic cells the heme synthesis/export axis might contribute to modulate mitochondrial activity. This conclusion is supported by the observation that FLVCR1 gene was found mutated in human pathologies characterized by impaired function of neuronal cell populations strongly dependent on mitochondrial oxidative metabolism. In conclusion, our data highlight the crucial role of heme synthesis/export axis in the control of cell energetic metabolism. Future work is required to elucidate the role of exported heme in the extracellular environment. Disclosures No relevant conflicts of interest to declare.

scholarly journals Mll-Partial Tandem Duplication (Mll-PTD) Causes Pseudohypoxia and Hypermethylation of the Epigenome through Suppression of Mitochondrial Complex II

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 1311-1311
Author(s):  
Asumi Yokota ◽  
Lulu Zhang ◽  
Xiaomei Yan ◽  
Xiaomin Feng ◽  
Lijun Wen ◽  
...  
Keyword(s):  
Protein Level ◽  
Tandem Duplication ◽  
Tca Cycle ◽  
Mitochondrial Activity ◽  
Mitochondrial Complex ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Tca Cycle Enzymes ◽  
The Tca Cycle ◽  
Partial Tandem Duplication

Abstract The MLL-partial tandem duplication (MLL-PTD),characterized by the internal duplication of exons 3-9 or 3-11 in the MLL gene, produces an elongated protein, and is considered as a gain-of-function mutation. The MLL-PTD is primarily found in elderly patients with myelodysplastic syndromes and acute myeloid leukemiaas well as healthy individuals.Previously we showed that Mll-PTD knock-in (MllPTD/WT) mice presented enhanced self-renewal of hematopoietic stem cells (HSCs) and partially blocked differentiation of hematopoietic stem/progenitor cells (HSPCs). Interestingly, Mll-PTD increased the protein level of HIF1A in HSPCs, which is critical for enhanced self-renewal of HSCs. In the current study, we investigated the mechanisms for HIF1A activation by Mll-PTD. In normoxia, HIF1A is hydroxylated by prolyl hydroxylases (PHD), resulting in rapid protein degradation via ubiquitination. PHD is one of the well-known enzymes whose activity is dependent on the cellular level of α-ketoglutarate (α-KG), one of the metabolites in the tricarboxylic acid (TCA) cycle. Accumulation of subsequent metabolites of α-KG, such as succinate, fumarate, and malate, inhibits activity of α-KG-dependent enzymes. Indeed, mitochondrial dysfunction is known to result in accumulation of TCA cycle intermediates, leading to activation of HIF signaling. Thus, we first examined if Mll-PTD induces the alteration of mitochondrial functions. Interestingly, cellular respiration and activity of mitochondrial complexes (I, II, and III) were significantly decreased in HSPCs of MllPTD/WT mice, while the copy number of mitochondrial DNA was not altered. These results indicate that suppression of mitochondrial activity is not due to the decrease of the total mitochondria. We also examined mRNA expression levels of several major TCA cycle enzymes, and found that succinate dehydrogenase (Sdh) complex (Sdha, Sdhb, and Sdhd) was significantly downregulated in MllPTD/WT HSPCs. SDH is a critical TCA cycle enzyme which converts succinate to fumarate. Inactivation of SDH is known to result in impairment of mitochondrial biogenesis, a blockade of the TCA cycle, and accumulation of TCA cycle metabolites. We next quantified metabolites in glycolysis and TCA cycle in the plasma from WT control and MllPTD/WT mice. NMR analysis revealed that succinate, fumarate, and malate were increased in the plasma of MllPTD/WT mice. Especially, the ratios of fumarate and malate to α-KG were both significantly increased in MllPTD/WT compared to WT control. Indeed, post-α-KG metabolites increased HIF1A protein in human cord blood CD34+cells in vitro, indicating that higher levels of succinate, fumarate, and malate to α-KG levels stabilize HIF1A. We also confirmed that knockdown of Sdh increased the HIF1A protein level in murine cell line in normoxia. These results indicate that downregulation of Sdh in MllPTD/WT is one of the mechanisms for suppression of mitochondrial activity, leading to pseudohypoxia and HIF1A activation. Besides PHD, TET and histone lysine demethylases are also α-KG-dependent enzymes. We found that in MllPTD/WT HSPCs, the 5-methylcitosine (5-mC) level was increased in genomic DNA, and trimethylation levels at H3K4, H3K9, H3K36 and H3K79 were also increased. Collectively, these results suggest that metabolic pseudohypoxia due to lower mitochondrial activity not only activates HIF1A signaling but also induces hypermethylation in DNA and histones, through suppression of α-KG-dependent PHD and demethylases. In summary, we demonstrate that through suppression of mitochondrial complex II, Mll-PTD causes pseudohypoxia and hypermethylation of the epigenome, which may contribute to expansion of premalignant clones and accumulation of additional mutations in those cells. Interestingly, it has been proposed that IDH mutations are involved in tumorigenesis in leukemias and brain tumors through a similar mechanism. Moreover, loss-of-function mutations of the TCA cycle enzymes, SDH complex, and fumarate hydratase, are frequently found in various solid tumors associated with pseudohypoxia and hypermethylation phenotypes. Further investigations of the impact of metabolic-rewiring-mediated pseudohypoxia/hypermethylation on tumorigenesis may lead to the development of novel therapeutic strategies to prevent the onset and/or the progression of various types of malignant diseases. Disclosures No relevant conflicts of interest to declare.

The Glyoxylate Shunt, 60 Years On

2018 ◽  
Vol 72 (1) ◽  
pp. 309-330 ◽  
Author(s):  
Stephen K. Dolan ◽  
Martin Welch
Keyword(s):  
Citric Acid ◽  
Citric Acid Cycle ◽  
Tca Cycle ◽  
Oxidative Decarboxylation ◽  
Glyoxylate Shunt ◽  
Cellular Functions ◽  
Acid Cycle ◽  
E Coli ◽  
80Th Anniversary ◽  
The Tca Cycle

2017 marks the 60th anniversary of Krebs’ seminal paper on the glyoxylate shunt (and coincidentally, also the 80th anniversary of his discovery of the citric acid cycle). Sixty years on, we have witnessed substantial developments in our understanding of how flux is partitioned between the glyoxylate shunt and the oxidative decarboxylation steps of the citric acid cycle. The last decade has shown us that the beautifully elegant textbook mechanism that regulates carbon flux through the shunt in E. coli is an oversimplification of the situation in many other bacteria. The aim of this review is to assess how this new knowledge is impacting our understanding of flux control at the TCA cycle/glyoxylate shunt branch point in a wider range of genera, and to summarize recent findings implicating a role for the glyoxylate shunt in cellular functions other than metabolism.

scholarly journals OXIDATIVE ENZYME SYSTEMS OF THE HONEY BEE, APIS MELLIFERA L

1956 ◽  
Vol 39 (5) ◽  
pp. 705-713 ◽  
Author(s):  
Dale D. Hoskins ◽  
Vernon H. Cheldelin ◽  
R. W. Newburgh
Keyword(s):  
Apis Mellifera ◽  
Honey Bee ◽  
Tca Cycle ◽  
Oxidative Enzyme ◽  
Complete Oxidation ◽  
Isocitric Dehydrogenase ◽  
Isocitric Acid ◽  
Enzyme Systems ◽  
The Tca Cycle ◽  
Condensing Enzyme

1. Oxidative dissimilation has been studied in enzymes from the honey bee. Using mitochondria isolated from the thoraces, complete oxidation of most of the TCA cycle members has been shown. 2. The presence of the acetate-activating enzyme, citrate-condensing enzyme, isocitric dehydrogenase, α-ketoglutarate dehydrogenase, glucose-6-phosphate, and 6-phosphogluconic dehydrogenase has been demonstrated and the cofactor requirements established. 3. The oxidation of isocitric acid has been shown to be either non-specific for the D- or L-isomer, or the presence of a racemase is indicated. 4. The presence of the pentose cycle is indicated in the soluble portion of the thoracic homogenate.

scholarly journals Metabolic Engineering of the Tricarboxylic Acid Cycle for Improved Lysine Production by Corynebacterium glutamicum

2009 ◽  
Vol 75 (24) ◽  
pp. 7866-7869 ◽  
Author(s):  
Judith Becker ◽  
Corinna Klopprogge ◽  
Hartwig Schröder ◽  
Christoph Wittmann
Keyword(s):  
Metabolic Engineering ◽  
Corynebacterium Glutamicum ◽  
Tricarboxylic Acid Cycle ◽  
Tca Cycle ◽  
Tricarboxylic Acid ◽  
Start Codon ◽  
Flux Analysis ◽  
Lysine Production ◽  
Acid Cycle ◽  
The Tca Cycle

ABSTRACT In the present work, lysine production by Corynebacterium glutamicum was improved by metabolic engineering of the tricarboxylic acid (TCA) cycle. The 70% decreased activity of isocitrate dehydrogenase, achieved by start codon exchange, resulted in a >40% improved lysine production. By flux analysis, this could be correlated to a flux shift from the TCA cycle toward anaplerotic carboxylation.

Citric acid cycle enzymes and nitrogenase in nodules of Pisum sativum

1977 ◽  
Vol 23 (9) ◽  
pp. 1197-1200 ◽  
Author(s):  
W. G. W. Kurz ◽  
T. A. LaRue
Keyword(s):  
Nitrogen Fixation ◽  
Citric Acid ◽  
Pisum Sativum ◽  
Isocitrate Dehydrogenase ◽  
Citric Acid Cycle ◽  
Acid Cycle ◽  
Isocitric Dehydrogenase ◽  
Citric Acid Cycle Enzymes

Activity of isocitric dehydrogenase (isocitrate dehydrogenase (NADP+); EC 1.1.1.42) in bacterids is highest at the time of maximum nitrogen fixation. It is likely that isocitric dehydrogenase is the source of reductant fordinitrogen fixation.

scholarly journals Inactivation of the Tricarboxylic Acid Cycle Aconitase Gene from Streptomyces viridochromogenesTü494 Impairs Morphological and Physiological Differentiation

1999 ◽  
Vol 181 (22) ◽  
pp. 7131-7135 ◽  
Author(s):  
D. Schwartz ◽  
S. Kaspar ◽  
G. Kienzlen ◽  
K. Muschko ◽  
W. Wohlleben
Keyword(s):  
Escherichia Coli ◽  
Tricarboxylic Acid Cycle ◽  
Aerial Mycelium ◽  
Tca Cycle ◽  
Tricarboxylic Acid ◽  
Acid Cycle ◽  
The Tca Cycle

ABSTRACT The tricarboxylic acid (TCA) cycle aconitase gene acnAfrom Streptomyces viridochromogenes Tü494 was cloned and analyzed. AcnA catalyzes the isomerization of citrate to isocitrate in the TCA cycle, as indicated by the ability of acnA to complement the aconitase-deficient Escherichia coli mutant JRG3259. An acnA mutant was unable to develop aerial mycelium and to sporulate, resulting in a bald phenotype. Furthermore, the mutant did not produce the antibiotic phosphinothricin tripeptide, demonstrating that AcnA also affects physiological differentiation.

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