The possible role of some enzymes in sclerotia formation in Aspergillus ochraceus

1983 ◽  
Vol 29 (6) ◽  
pp. 718-723 ◽  
Author(s):  
Nachman Paster ◽  
Ilan Chet
Keyword(s):  
Isocitrate Lyase ◽  
Tricarboxylic Acid Cycle ◽  
Glyoxylate Cycle ◽  
Pentose Phosphate ◽  
Aspergillus Ochraceus ◽  
Phosphogluconate Dehydrogenase ◽  
Cycle Plays ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
The Glyoxylate Cycle

The role of some enzymes in sclerotia production by Aspergillus ochraceus was studied using a sclerotia-producing strain grown under conditions in which sclerotia production was either favoured or inhibited. In addition, a mutant strain incapable of producing sclerotia was used. No significant differences in patterns of soluble proteins, polyphenol oxidase, and esterases could be detected electrophoretically by gel electrophoresis, while the peroxidase pattern of both the sclerotia-producing strain and the mutant showed three bands as compared with two bands that appeared when sclerotia formation was inhibited. The activities of the tricarboxylic acid cycle enzymes, malate dehydrogenase and succinate dehydrogenase, and those of the pentose-phosphate pathway, glucose-6 phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, were almost identical in sclerotia- and nonsclerotia-producing mycelia. The activities of isocitrate lyase and malate synthetase, key enzymes of the glyoxylate cycle, and that of glyoxylate dehydrogenase which is related to this cycle were significantly reduced when sclerotia formation was inhibited either by methionine or by high levels of CO2. It is suggested that the glyoxylate cycle plays an important role in sclerotia formation in the fungus.

scholarly journals Enzymes of the intermediary carbohydrate metabolism of Polyangium cellulosum

1985 ◽  
Vol 31 (12) ◽  
pp. 1142-1146 ◽  
Author(s):  
Renu Sarao ◽  
Howard D. McCurdy ◽  
Luciano Passador
Keyword(s):  
Carbohydrate Metabolism ◽  
Tricarboxylic Acid Cycle ◽  
Glyoxylate Cycle ◽  
Fold Increase ◽  
Pentose Phosphate ◽  
Acid Cycle ◽  
The Family ◽  
The Glyoxylate Cycle ◽  
Pentose Phosphate Shunt

Crude extracts of vegetative cells of the cellulolytic myxobacter Polyangium cellulosum contained significant levels of the enzymes of the tricarboxylic acid cycle and the glyoxylate cycle. Key enzymes of glycolysis and the pentose phosphate shunt were also detected. Specific activities of hexokinase and fructose- 1,6-diphosphate aldolase exhibited a 10-fold increase when the cells were grown in complex medium containing glucose. Cytochromes of a, b, and c type were demonstrated. By the use of a dispersly growing strain of P. cellulosum, its generation time was determined to be 22–24 h. This study suggests that the organism probably uses glycolysis and citric acid cycle for complete oxidation of glucose. The exact role of the glyoxylate cycle and pentose phosphate shunt cannot be deduced from this study. This is the first report on the study of intermediary carbohydrate metabolism in any member of the family Polyangiaceae.

The role of isocitrate lyase in the metabolism of algae

1966 ◽  
Vol 166 (1002) ◽  
pp. 11-29 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Soluble Fraction ◽  
Isocitrate Lyase ◽  
Tricarboxylic Acid Cycle ◽  
Glyoxylate Cycle ◽  
Tricarboxylic Acid ◽  
Chlamydomonas Reinhardii ◽  
The Glyoxylate Cycle ◽  
Do So

The incorporation of isotope from [2- 14 C]ethanol by cultures of the Brannon no. 1 strain of Chlorella vulgaris , growing on ethanol aerobically in the dark, was consistent with the operation of the tricarboxylic acid and glyoxylate cycles. Results obtained with [l- 14 C]acetate, added to similar cultures growing on glucose in the dark or on carbon dioxide in the light, indicated that the glyoxylate cycle did not function under these conditions. However, one of the key enzymes of this cycle, isocitrate lyase, was present in large amounts in extracts of this organism under all conditions of growth; in contrast, isocitrate lyase was inducibly formed by Chlamydomonas reinhardii prior to growth on acetate. No obvious dysfunction of the tricarboxylic acid cycle, which might necessitate the activity of isocitrate lyase during growth on other than C 2 -compounds, was detected in the Brannon no. 1 strain, nor were differences observed between the properties of the enzyme purified from cells grown on acetate and on glucose. But, whereas isocitrate lyase was wholly found in a soluble fraction of the organism after growth on glucose or on carbon dioxide, acetate-grown cells contained a major portion of their isocitrate lyase in a dense, particulate fraction. The Brannon no. 1 strain of Chlorella excreted labelled glycollate during growth in the dark on glucose in the presence of sodium [ 14 C]bicarbonate, but ceased to do so after transfer to acetate growth medium. The Pearsall’s strain of Chlorella , which does not form isocitrate lyase during growth on glucose, did not excrete labelled glycollate under these conditions. These results suggest that the Brannon no. 1 strain of Chlorella contained an active isocitrate lyase under all conditions of growth, but that this enzyme participates in the glyoxylate cycle only when it is incorporated into a particulate structure.

Comparison of glycolytic, pentose phosphate pathway, glyoxylate shunt, Krebs' cycle enzymes in Ganeo tigrinum parasitizing hibernating and non-hibernating Rana cyanophlyctis and R. tigrina

1983 ◽  
Vol 57 (1) ◽  
pp. 59-68 ◽  
Author(s):  
P. N. Sharma ◽  
Sushila Mandawat
Keyword(s):  
Isocitrate Lyase ◽  
Krebs Cycle ◽  
Pentose Phosphate ◽  
Glyoxylate Shunt ◽  
Strong Activity ◽  
Key Enzymes ◽  
Phosphogluconate Dehydrogenase ◽  
Weak Activity ◽  
Krebs Cycle Enzymes ◽  
Glucose 6 Phosphate Dehydrogenase

AbstractThe histochemical site and distribution of hexokinase, glycogen phosphorylase (GP Rylase), lactate dehydrogenase (LDH) (key enzymes of glycolysis), glucose-6-phosphate dehydrogenase (GPD) and 6-phosphogluconate dehydrogenase (6PGD) (pentose phosphate shunt enzymes), isocitrate dehydrogenase (IDH), succinate dehydrogenase (SDH), malate dehydrogenase (MDH), and α-ketoglutarate dehydrogenase (α-KDH) (key enzymes of Krebs' cycle), malate synthetase (MS) and isocitrate lyase (IL) (enzymes of glyoxylate shunt) in various tissues of Ganeo tigrinum from hibernating and non-hibernating Rana cyanophlyctis and R. tigrina were studied. Differences in their intensities were revealed. Weak activity of GP Rylase and strong activity of hexokinase in flukes from non-hibernating hosts indicates that they utilize glucose through glycolysis for energy turnover. Intense GP Rylase and weak hexokinase activity in worms from hibernating hosts indicates the utilization of glycogen. Strong activity of IDH, SDH, MDH, α-KGD, MS and IL was demonstrable in the tissues of flukes from non-hibernating hosts, suggesting that Krebs' cycle and glyoxylate shunt, respectively, were operating. Tissues of the fluke from hibernating hosts, on the other hand, displayed positive activity only for SDH and MDH; no activity for MS and IL, the enzymes of glyoxylate shunt, was observed, The activity of the above enzymes was found to be relatively low in worms from hibernating hosts.

Photo-induction sexuée du pyrénomycète Nectria galligena: influence de la mycosporine sur le rapport des activités NADPM+-socitrate déshydrogénase/isocitrate lyase

1989 ◽  
Vol 67 (2) ◽  
pp. 447-450 ◽  
Author(s):  
B. Dehorter ◽  
L. Lacoste
Keyword(s):  
Isocitrate Dehydrogenase ◽  
Isocitrate Lyase ◽  
Tricarboxylic Acid Cycle ◽  
Glyoxylate Cycle ◽  
Nectria Galligena ◽  
Lyase Activity ◽  
Growth Of Fungi ◽  
The Glyoxylate Cycle

The activity of two enzymes of the tricarboxylic acid cycle (NADP+-isocitrate dehydrogenase, EC 1.1.1.42) and the glyoxylate cycle (isocitrate lyase, EC 4.1.3.1) were assayed in vitro to determine the effects of darkness, light, and mycosporin (P310) on sexual morphogenesis in Nectria galligena Bres. In the absence of mycosporin, high isocitrate lyase activity was associated with vegetative growth of fungi kept in the dark. In contrast, light-induced perithecial development and mycosporin biosynthesis could be correlated with high ratios of isocitrate dehydrogenase to isocitrate lyase activity. This was confirmed by the fact that when mycosporin was added to the nutrient medium with incubation in darkness, the fertility of the fungus was partially expressed and the activity of isocitrate lyase was significantly reduced. Thus this enzyme would be repressed in vivo by mycosporin. Because of its photomimetic role in sexual differentiation and regulation of intermediate metabolism, mycosporin appears to be a biochemical transmitter of light energy required for the formation of ascocarps.

scholarly journals Activities of Catalase and Pentose Phosphate Pathway Dehydrogenases during Dormancy Release in Nectarine Seed

1990 ◽  
Vol 115 (6) ◽  
pp. 987-990 ◽  
Author(s):  
Hening Hu ◽  
Gary A. Couvillon
Keyword(s):  
Pentose Phosphate Pathway ◽  
Catalase Activity ◽  
Prunus Persica ◽  
Enzymic Activity ◽  
Pentose Phosphate ◽  
Significant Activity ◽  
Phosphogluconate Dehydrogenase ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Thiourea Treatment

The activities of catalase and of glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH), the two key enzymes in the pentose phosphate pathway (ppp), were measured in the seeds of Prunus persica (L.) Batsch var. nectarina Maxim `Nectarine 7'. The seeds were subjected to three imbibition treatments: 1) continuous 24C; 2) continuous 4C; and 3) application of thiourea (TU)/gibberellic acid (GA) at various concentrations to seed held at 24C then subsequently chilled at 4C. Treatments of continuous 24 or 4C indicated that catalase, G6PDH, and 6PGDH exhibited significant activity increases only when the seeds obtained germination potential, which occurred in the seeds chilled for 7 weeks at 4C. Seeds held at 24C did not germinate and showed little change with time in G6PDH and 6PGDH activity. There was only a slight increase in catalase activity beginning 3 weeks following treatment initiation and a decrease in activity following 13 weeks of treatment. Thiourea treatment resulted in an inhibition of catalase activity and a stimulation of G6PDH, but had no effect on 6PGDH activity. However, no correlation between enzymic activity and seed germination was found. The results strongly questioned the role of the ppp and catalase activity in dormancy control as previously hypothesized.

scholarly journals The localization of enzymes of intermediary metabolism in Astasia and Euglena

1973 ◽  
Vol 134 (2) ◽  
pp. 607-616 ◽  
Author(s):  
Nicole Bégin-Heick
Keyword(s):  
Succinate Dehydrogenase ◽  
Isocitrate Lyase ◽  
Tricarboxylic Acid Cycle ◽  
Glyoxylate Cycle ◽  
Intracellular Localization ◽  
Tricarboxylic Acid ◽  
Malate Synthase ◽  
Particulate Fraction ◽  
Acid Cycle ◽  
The Glyoxylate Cycle

Results are presented on the intracellular localization of some of the enzymes of gluconeogenesis, of the tricarboxylic acid cycle and of related enzymes in Astasia and Euglena grown with various substrates. The results indicate the particulate nature of at least part of the malate synthase of Astasia and of part of the malate synthase and isocitrate lyase in Euglena. However, the presence of glyoxysomes (microbodies) in Astasia and Euglena is still open to question, since it has not, so far, been possible to separate the enzymes of the glyoxylate cycle from succinate dehydrogenase in the particulate fraction.

The role of isocitrate lyase and the glyoxylate cycle in Escherichia coli growing under glucose limitation

2005 ◽  
Vol 156 (2) ◽  
pp. 178-183 ◽  
Author(s):  
Ram Prasad Maharjan ◽  
Pak-Lam Yu ◽  
Shona Seeto ◽  
Thomas Ferenci
Keyword(s):  
Escherichia Coli ◽  
Isocitrate Lyase ◽  
Glyoxylate Cycle ◽  
Glucose Limitation ◽  
The Glyoxylate Cycle

scholarly journals Anaerobic Induction of Isocitrate Lyase and Malate Synthase in Submerged Rice Seedlings Indicates the Important Metabolic Role of the Glyoxylate Cycle

2005 ◽  
Vol 37 (6) ◽  
pp. 406-414 ◽  
Author(s):  
Ying Lu ◽  
Yong-Rui Wu ◽  
Bin Han
Keyword(s):  
Isocitrate Lyase ◽  
Tricarboxylic Acid Cycle ◽  
Glyoxylate Cycle ◽  
Fold Increase ◽  
Malate Synthase ◽  
Acetate Metabolism ◽  
Activity Assay ◽  
Rice Seedlings ◽  
Metabolic Role ◽  
The Glyoxylate Cycle

Abstract The glyoxylate cycle is a modified form of the tricarboxylic acid cycle that converts C2 compounds into C4 dicarboxylic acids at plant developmental stages. By studying submerged rice seedlings, we revealed the activation of the glyoxylate cycle by identifying the increased transcripts of mRNAs of the genes of isocitrate lyase (ICL) and malate synthase (MS), two characteristic enzymes of the glyoxylate cycle. Northern blot analysis showed that ICL and MS were activated in the prolonged anaerobic environment. The activity assay of pyruvate decarboxylase and ICL in the submerged seedlings indicated an 8.8-fold and 3.5-fold increase over that in the unsubmerged seedlings, respectively. The activity assay of acetyl-coenzyme A synthetase in the submerged seedlings indicated a 3-fold increase over that in the unsubmerged seedlings, which is important for initiating acetate metabolism. Consequently, we concluded that the glyoxylate cycle was involved in acetate metabolism under anaerobic conditions.

scholarly journals Major roles of isocitrate lyase and malate synthase in bacterial and fungal pathogenesis

Microbiology ◽  
2009 ◽  
Vol 155 (10) ◽  
pp. 3166-3175 ◽  
Author(s):  
M. F. Dunn ◽  
J. A. Ramírez-Trujillo ◽  
I. Hernández-Lucas
Keyword(s):  
Isocitrate Lyase ◽  
Glyoxylate Cycle ◽  
Tca Cycle ◽  
Malate Synthase ◽  
The Tca Cycle ◽  
Plant Pathogenesis ◽  
Micro Organisms ◽  
The Glyoxylate Cycle ◽  
Anaplerotic Pathway

The glyoxylate cycle is an anaplerotic pathway of the tricarboxylic acid (TCA) cycle that allows growth on C2 compounds by bypassing the CO2-generating steps of the TCA cycle. The unique enzymes of this route are isocitrate lyase (ICL) and malate synthase (MS). ICL cleaves isocitrate to glyoxylate and succinate, and MS converts glyoxylate and acetyl-CoA to malate. The end products of the bypass can be used for gluconeogenesis and other biosynthetic processes. The glyoxylate cycle occurs in Eukarya, Bacteria and Archaea. Recent studies of ICL- and MS-deficient strains as well as proteomic and transcriptional analyses show that these enzymes are often important in human, animal and plant pathogenesis. These studies have extended our understanding of the metabolic pathways essential for the survival of pathogens inside the host and provide a more complete picture of the physiology of pathogenic micro-organisms. Hopefully, the recent knowledge generated about the role of the glyoxylate cycle in virulence can be used for the development of new vaccines, or specific inhibitors to combat bacterial and fungal diseases.

Regulation of proline content of Chlorella autotrophica in response to changes in salinity

1989 ◽  
Vol 67 (7) ◽  
pp. 1959-1965 ◽  
Author(s):  
Gilles Laliberté ◽  
Johan A. Hellebust
Keyword(s):  
De Novo ◽  
Isocitrate Lyase ◽  
Glyoxylate Cycle ◽  
Reducing Power ◽  
Proline Content ◽  
Artificial Seawater ◽  
Lag Phase ◽  
Cycle Plays ◽  
The Glyoxylate Cycle ◽  
Temporary Inhibition

In Chlorella autotrophica, proline, chlorophyll, and protein synthesis took place almost exclusively in the light. No evidence for proline degradation in the dark was obtained. An osmotic upshock from 50 to 150% artificial seawater caused a temporary inhibition of photosynthesis in this alga. An osmotic downshock from 150 to 50% artificial seawater had no effect on its photosynthetic rate. Synthesis of proline, the main osmoregulatory solute in C. autotrophica, showed no lag phase following an upshock and was not inhibited in the presence of cycloheximide. These results suggest that the enzymes of the proline pathway are not synthesized de novo in response to the upshock. In the dark, the rate of proline synthesis was lower, whereas the presence of acetate allowed a rate of proline synthesis similar to that of cells in the light. Synthesis of proline in the dark in the presence of acetate was dependent on the induction of isocitrate lyase. Thus the glyoxylate cycle plays a key role in furnishing carbon and reducing power for proline synthesis in the dark. Following a sudden downshock, more than 55% of the proline content leaked out of the cell in the first 5 min due to transient breakdown in membrane permeability. However, if the downshock is gradual, proline is oxidized by the cells rather than being leaking out.

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