Regulation of "malic" isozymes and malic dehydrogenases in Neurospora crassa

1968 ◽  
Vol 14 (8) ◽  
pp. 907-912 ◽  
Author(s):  
M. W. Zink ◽  
D. A. Shaw
Keyword(s):  
Amino Acid ◽  
Neurospora Crassa ◽  
Malate Dehydrogenase ◽  
Malic Enzyme ◽  
Regulatory Mechanism ◽  
Glyoxylate Cycle ◽  
Cytoplasmic Enzyme ◽  
Stages Of Growth ◽  
Acetate Medium ◽  
The Glyoxylate Cycle

Electrophoretic studies on the "malic" enzyme from Neurospora crassa show the presence of three isozymes. The distribution of these isozymes varies with the age of the mycelium. Isozymes 1 and 2 appear during the early stages of growth and disappear after about 24 h while isozyme 3 appears at about 12 h and increases with the age of the culture. This increase in isozyme 3 occurs at a time when the levels of the first two enzymes are decreasing. Inhibition of the "malic" enzyme by aspartate increases gradually during the later stages of growth and parallels the increasing levels of isozyme 3. Since isozymes 1 and 2 are not inhibited by the amino acid it is concluded that the activity of isozyme 3 is regulated by aspartate.Mitochondrial and cytoplasmic malic dehydrogenases have been shown electrophoretically to be present in Neurospora crassa when the mycelium is grown in sucrose or acetate as the source of carbon. However, the amount of cytoplasmic enzyme increases in acetate medium. It is concluded that sucrose or a product of sucrose represses the cytoplasmic malate dehydrogenase. This regulatory mechanism is useful for the cell because in the glyoxylate cycle malate dehydrogenase participates in the gluconeogenesis from acetate. This enzyme is not necessary when glucose is in the medium.

Arabidopsis peroxisomal malate dehydrogenase functions in β-oxidation but not in the glyoxylate cycle

2007 ◽  
Vol 50 (3) ◽  
pp. 381-390 ◽  
Author(s):  
Itsara Pracharoenwattana ◽  
Johanna E. Cornah ◽  
Steven M. Smith
Keyword(s):  
Malate Dehydrogenase ◽  
Glyoxylate Cycle ◽  
The Glyoxylate Cycle

Acetate metabolism in Escherichia coli

1978 ◽  
Vol 24 (2) ◽  
pp. 149-153 ◽  
Author(s):  
T. M. Lakshmi ◽  
Robert B. Helling
Keyword(s):  
Isocitrate Dehydrogenase ◽  
Citrate Synthase ◽  
Isocitrate Lyase ◽  
Glyoxylate Cycle ◽  
Acetate Metabolism ◽  
Wild Type ◽  
Intermediary Metabolites ◽  
Lyase Activity ◽  
Acetate Medium ◽  
The Glyoxylate Cycle

Levels of several intermediary metabolites were measured in cells grown in acetate medium in order to test the hypothesis that the glyoxylate cycle is repressed by phosphoenolpyruvate (PEP). Wild-type cells had less PEP than either isocitrate dehydrogenase – deficient cells (which had greater isocitrate lyase activity than the wild type) or isocitrate dehydrogenase – deficient, citrate synthase – deficient cells (which are poorly inducible). Thus induction of the glyoxylate cycle is more complicated than a simple function of PEP concentration. No correlation between enzyme activity and the level of oxaloacetate, pyruvate, or citrate was found either. Citrate was synthesized in citrate synthase – deficient mutants, possibly via citrate lyase.

STUDIES ON RUMEN COLIFORM ORGANISMS: II. UTILIZATION OF ACETATE BY ESCHERICHIA COLI 64 ISOLATED FROM THE RUMEN FLUID OF A COW FED ALFALFA HAY

1967 ◽  
Vol 47 (3) ◽  
pp. 199-209 ◽  
Author(s):  
C. R. Krishnamurti ◽  
L. W. McElroy
Keyword(s):  
Sodium Acetate ◽  
Isocitrate Lyase ◽  
Protein Hydrolysate ◽  
Rumen Fluid ◽  
Glyoxylate Cycle ◽  
Malate Synthase ◽  
E Coli ◽  
Spectrophotometric Methods ◽  
Acetate Medium ◽  
The Glyoxylate Cycle

When cells of E. coli 64 were harvested in their exponential phase of growth in an acetate medium and incubated aerobically with sodium acetate-2-C14, about 33% of the label appeared in CO2 after 1 hr. Of the radioactivity in the cells, 72% was recovered in the protein hydrolysate, 8% in the nucleic acid, 6% in the lipid and 14% in the ethanol-soluble fractions. The radioactivity in the protein hydrolysate of cells incubated with sodium acetate-2-C14 was approximately 20 times that in the hydrolysate of cells incubated with C14O2 as the carbon source. By spectrophotometric methods, it was demonstrated that cell-free extracts of cells grown on acetate contained acetate kinase and phosphate acetyltransferase, plus, as demonstrated by spectrophotometric and isotopic methods, isocitrate lyase and malate synthase which are characteristic of the glyoxylate cycle. The enzymes of the glyoxylate cycle could not be demonstrated in cell-free extracts of E. coli 64 grown on glucose under either aerobic or anaerobic conditions. Possible functions that E. coli 64 may have in the maintenance of anaerobiosis in the rumen and utilization of acetate through the glyoxylate pathway are discussed.

THE TRICARBOXYLIC ACID AND GLYOXYLATE CYCLES IN XANTHOMONAS PHASEOLI (XP8)

1959 ◽  
Vol 5 (1) ◽  
pp. 1-8 ◽  
Author(s):  
N. B. Madsen ◽  
R. M. Hochster
Keyword(s):  
Tricarboxylic Acid Cycle ◽  
Glyoxylate Cycle ◽  
Sole Source ◽  
Tricarboxylic Acid ◽  
Acid Cycle ◽  
Main Pathway ◽  
The Individual ◽  
Acetate Medium ◽  
Terminal Oxidation ◽  
The Glyoxylate Cycle

Cell-free extracts of Xanthomonas phaseoli contain the individual enzymes of the tricarboxylic acid cycle, and it is suggested that this is the main pathway for the terminal oxidation of carbohydrate in this organism. X. phaseoli can grow on a medium containing acetate as the sole source of carbon. Cell-free extracts of such acetate-grown organisms contain the enzymes of the glyoxylate cycle, and it is concluded that the operation of this cycle permits the initial stages of synthesis of complex cell material from acetate at a rate sufficiently high to account for the observed rate of growth on the acetate medium. The two enzymes required to modify a tricarboxylic acid cycle into a glyoxylate cycle are present in very small amounts (malate synthetase) or absent entirely (isocitritase) in extracts of glucose-grown X. phaseoli.

scholarly journals Structure of glyoxysomal malate dehydrogenase (MDH3) from Saccharomyces cerevisiae

2018 ◽  
Vol 74 (10) ◽  
pp. 617-624 ◽  
Author(s):  
Shu Moriyama ◽  
Kazuya Nishio ◽  
Tsunehiro Mizushima
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Malate Dehydrogenase ◽  
Ternary Complex ◽  
Tricarboxylic Acid Cycle ◽  
Glyoxylate Cycle ◽  
Tricarboxylic Acid ◽  
Mitochondrial Enzyme ◽  
Open Conformation ◽  
Metabolism Enzyme ◽  
The Glyoxylate Cycle

Malate dehydrogenase (MDH), a carbohydrate and energy metabolism enzyme in eukaryotes, catalyzes the interconversion of malate to oxaloacetate (OAA) in conjunction with that of nicotinamide adenine dinucleotide (NAD+) to NADH. Three isozymes of MDH have been reported in Saccharomyces cerevisiae: MDH1, MDH2 and MDH3. MDH1 is a mitochondrial enzyme and a member of the tricarboxylic acid cycle, whereas MDH2 is a cytosolic enzyme that functions in the glyoxylate cycle. MDH3 is a glyoxysomal enzyme that is involved in the reoxidation of NADH, which is produced during fatty-acid β-oxidation. The affinity of MDH3 for OAA is lower than those of MDH1 and MDH2. Here, the crystal structures of yeast apo MDH3, the MDH3–NAD+ complex and the MDH3–NAD+–OAA ternary complex were determined. The structure of the ternary complex suggests that the active-site loop is in the open conformation, differing from the closed conformations in mitochondrial and cytosolic malate dehydrogenases.

Particulate enzymes of the glyoxylate cycle in Neurospora crassa

1969 ◽  
Vol 37 (4) ◽  
pp. 640-645 ◽  
Author(s):  
M.J. Kobr ◽  
Francine Vanderhaeghe ◽  
G. Combepine
Keyword(s):  
Neurospora Crassa ◽  
Glyoxylate Cycle ◽  
The Glyoxylate Cycle

Effect of Leaf Senescence on Glyoxylate Cycle Enzyme Activities

1992 ◽  
Vol 19 (6) ◽  
pp. 723 ◽  
Author(s):  
L Pistelli ◽  
P Perata ◽  
A Alpi
Keyword(s):  
Malate Dehydrogenase ◽  
Enzyme Activities ◽  
Citrate Synthase ◽  
Isocitrate Lyase ◽  
Glyoxylate Cycle ◽  
Malate Synthase ◽  
Cycle Enzyme ◽  
Hydroxypyruvate Reductase ◽  
Foliar Senescence ◽  
The Glyoxylate Cycle

In order to elucidate the metabolism of the peroxisomes during foliar senescence of leaf beet (Beta vulgaris L., var. cicla), peroxisomal activities have been determined at various stages of senescence. Catalase and hydroxypyruvate reductase activities decreased whereas those of the β-oxidation pathway and glyoxylate cycle enzymes increased at the same time. The increased activities of malate synthase, isocitrate lyase, malate dehydrogenase and citrate synthase indicate that the glyoxylate cycle might be activated during the foliar senescence of leaf beet.

scholarly journals Aconitase: To Be or not to Be Inside Plant Glyoxysomes, That Is the Question

Biology ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 162
Author(s):  
Luigi De Bellis ◽  
Andrea Luvisi ◽  
Amedeo Alpi
Keyword(s):  
Malate Dehydrogenase ◽  
Metabolic Pathways ◽  
Higher Plants ◽  
Glyoxylate Cycle ◽  
Genetic Research ◽  
Transcriptomic Analysis ◽  
Plant Biology ◽  
New Model ◽  
The Glyoxylate Cycle

After the discovery in 1967 of plant glyoxysomes, aconitase, one the five enzymes involved in the glyoxylate cycle, was thought to be present in the organelles, and although this was found not to be the case around 25 years ago, it is still suggested in some textbooks and recent scientific articles. Genetic research (including the study of mutants and transcriptomic analysis) is becoming increasingly important in plant biology, so metabolic pathways must be presented correctly to avoid misinterpretation and the dissemination of bad science. The focus of our study is therefore aconitase, from its first localization inside the glyoxysomes to its relocation. We also examine data concerning the role of the enzyme malate dehydrogenase in the glyoxylate cycle and data of the expression of aconitase genes in Arabidopsis and other selected higher plants. We then propose a new model concerning the interaction between glyoxysomes, mitochondria and cytosol in cotyledons or endosperm during the germination of oil-rich seeds.

Metabolite Oxidation and Transport in Mitochondria of Endosperm From Germinating Castor Bean

1983 ◽  
Vol 10 (2) ◽  
pp. 167 ◽  
Author(s):  
J Millhouse ◽  
JT Wiskich ◽  
H Beevers
Keyword(s):  
Malic Enzyme ◽  
Castor Bean ◽  
Glyoxylate Cycle ◽  
Density Gradients ◽  
Metabolite Transport ◽  
The Glyoxylate Cycle ◽  
Exchange Properties ◽  
Transport In Mitochondria

Mitochondria from germinating castor bean endosperm were purified on linear sucrose-density gradients. It is shown that succinate and malate plus glutamate are oxidized rapidly; other substrates including malate (via malic enzyme) and external NADH are oxidized slowly. It is proposed that the oxidation of NADH produced during β-oxidation and the glyoxylate cycle occurs intramitochondrially via malate. Castor bean mitochondria are relatively impermeable to oxaloacetate and a malate-aspartate type shuttle is required. Metabolite transport and exchange properties support the operation of malatein (or succinatein)/2-oxoglutarateout and glutamatein/aspartateout shuttles. Not all the exchange systems were reversible. The results support proposed schemes for metabolite transfer between glyoxysomes and mitochondria of castor bean endosperm during germination.

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