scholarly journals Non-haem iron and the dissociation of piericidin A sensitivity from site 1 energy conservation in mitochondria from Torulopsis utilis

1971 ◽  
Vol 124 (1) ◽  
pp. 135-151 ◽  
Author(s):  
R. A. Clegg ◽  
P. B. Garland
Keyword(s):  
Energy Conservation ◽  
Electron Flow ◽  
Iron Concentration ◽  
Normal Function ◽  
Aerobic Incubation ◽  
Submitochondrial Particles ◽  
Limited Growth ◽  
Iron Deficient ◽  
Haem Iron ◽  
Acid Labile

1. The aerobic incubation of iron-deficient Torulopsis utilis cells for 12h under non-growing conditions results in the recovery by mitochondria of the previously absent site 1 energy conservation and sensitivity to piericidin A. 2. The recovery of piericidin A sensitivity but not site 1 is prevented by the presence of cycloheximide (100μg/ml) in the medium used for aerobic incubation of the cells. Rotenone sensitivity behaved similarly. 3. Chloramphenicol, erythromycin and tetracycline were without effect on the recovery of site 1 and piericidin A sensitivity. 4. Inclusion of 59Fe in the growth medium can be used as the basis for a highly sensitive assay for non-haem iron. 5. Iron-limited growth of T. utilis lowers the concentration of both non-haem iron and acid-labile sulphide of submitochondrial particles by over 20-fold compared with the ‘normal’ situation with iron-supplemented glycerol-limited growth. 6. Increases in the non-haem iron and acid-labile sulphide concentrations of submitochondrial particles occur when site 1 and piericidin A sensitivity are recovered. The increase is approximately halved by the presence of cycloheximide. 7. The non-haem iron of T. utilis submitochondrial particles does not exchange with added iron. 8. Continuous culture of T. utilis at the transition between glycerol- and iron-limitation results in cells where mitochondria possess site 1 energy conservation but lack piericidin A sensitivity. 8. It is concluded, in contrast with widely held views to the opposite, that energy conservation at site 1 does not require electron flow to proceed through a piericidin A- or rotenone-sensitive route. 9. Restriction of the iron supplied to growing T. utilis to a concentration just above that required for growth limitation demonstrates that a 10- to 20-fold decrease of the ‘normal’ non-haem iron concentration of both cells and mitochondria is without effect on the growth yield per unit of carbon source. Submitochondrial particles prepared from such iron-restricted but otherwise functionally normal cells have a non-haem iron concentration of about 0.5–0.8ng-atom/mg of protein. It is concluded that the concentration of iron–sulphur protein required for normal function by the respiratory chain is close to the concentrations of cytochromes and flavoproteins.

scholarly journals Effect of sulphate-limited growth on mitochondrial electron transfer and energy conservation between reduced nicotinamide–adenine dinucleotide and the cytochromes in Torulopsis utilis

1971 ◽  
Vol 124 (1) ◽  
pp. 155-170 ◽  
Author(s):  
B. A. Haddock ◽  
P. B. Garland
Keyword(s):  
Energy Conservation ◽  
Cytochrome B ◽  
Antimycin A ◽  
Alternative Route ◽  
Aerobic Incubation ◽  
Submitochondrial Particles ◽  
Limited Growth ◽  
Sulphide Concentration ◽  
Haem Iron ◽  
Acid Labile

1. Conditions have been established for the sulphate-limited growth of Torulopsis utilis in continuous culture. 2. Mitochondria prepared from sulphate-limited cells lack both piericidin A sensitivity and the first energy-conservation site (site 1). Sensitivity to antimycin A or cyanide and the second and third energy-conservation sites were apparently unaffected by sulphate-limited growth. 3. Aerobic incubation for 8h of sulphate-limited cells with a low concentration of sulphate (50μm or less) resulted in the recovery of mitochondrial piericidin A sensitivity and site 1. The use of higher concentrations of sulphate (250μm or more) still resulted in the recovery of mitochondrial piericidin A sensitivity and site 1, but also resulted in the appearance of a non-phosphorylating oxidase, which mediated oxidation of the respiratory chain at about the level of cytochrome b in an antimycin A- and cyanide-insensitive manner. Both this alternative route and the conventional normal route of respiration were shown to coexist and to intercommunicate at the level of cytochrome b. 4. Low-temperature spectroscopy failed to identify any new respiratory component to explain the alternative route. 5. The apparent affinity of the alternative route for oxygen was similar to that for the conventional route through cytochrome oxidase, namely half-maximal activity at 0.1μm-oxygen or less. 6. The non-haem iron concentration of submitochondrial particles was unaffected by sulphate limitation, whereas the acid-labile sulphide concentration was lowered tenfold. Marked increases (between four- and 30-fold) in the acid-labile sulphide concentration of submitochondrial particles were observed in sulphate-limited cells after aerobic incubation with various concentrations of sulphate. The lowest increase (fourfold) was observed without added sulphate, the highest (30-fold) with 1.0mm added sulphate. 7. The ratio of non-haem iron to acid-labile sulphide in submitochondrial particles varied with different growth conditions from a maximum of 15.0 to a minimum of 0.72. It is suggested that analytical measurements of non-haem iron are an inadequate guide to the concentration of iron–sulphur protein in complex systems. 8. The effects of sulphate-limited growth on site 1 and piericidin sensitivity are interpreted to indicate a role for iron–sulphur protein in these properties. 9. The aerobic incubation of sulphate-limited cells with cycloheximide resulted in the recovery by mitochondria of site 1 but not of piericidin sensitivity. 10. The appearance of the alternative route for cyanide- and antimycin-A (but not piericidin A-) insensitive respiration on incubating sulphate-limited cells with sulphate concentrations higher than 250μm indicates that the alternative route involves an iron–sulphur protein.

scholarly journals A comparison of mitochondria from Torulopsis utilis grown in continous culture with glycerol, iron, ammonium, magnesium or phosphate as the growth-limiting nutrient

1971 ◽  
Vol 124 (1) ◽  
pp. 123-134 ◽  
Author(s):  
P. A Light ◽  
P. B. Garland
Keyword(s):  
Energy Conservation ◽  
Electron Flow ◽  
Respiratory Control ◽  
Indirect Evidence ◽  
Iron Limitation ◽  
Limited Growth ◽  
Respiratory Inhibitor ◽  
Limiting Nutrient ◽  
Haem Iron

1. Mitochondria prepared from Torulopsis utilis grown in a chemostat with iron-limited growth were found to lack energy conservation but not electron flow in that segment of the respiratory chain leading from intramitochondrial NADH to the cytochromes [i.e. the site 1 segment (Lehninger, 1964)]. 2. Site 1 energy conservation was present in mitochondria prepared from cells grown under conditions of limitation by glycerol, ammonium and magnesium. Phosphate-limited growth resulted in mitochondrial preparations without respiratory control. 3. Mitochondria from cells grown under conditions of iron limitation were insensitive to the respiratory inhibitor piericidin A, whereas sensitivity was present in mitochondria prepared from glycerol-, ammonium-, magnesium- or phosphate-limited cells. 4. These observations are considered to provide indirect evidence for a role of non-haem iron in the mechanism of energy conservation and also piericidin A sensitivity in T. utilis mitochondria. 5. A readily constructed and inexpensive pH-measuring and -controlling circuit is described for use with continuous-culture apparatus.

scholarly journals The purification and properties of the respiratory-chain reduced nicotinamide–adenine dinucleotide dehydrogenase of Torulopsis utilis

1971 ◽  
Vol 124 (5) ◽  
pp. 853-865 ◽  
Author(s):  
S. O. C. Tottmar ◽  
C. I. Ragan
Keyword(s):  
Respiratory Chain ◽  
Reductase Activity ◽  
Submitochondrial Particles ◽  
Ferricyanide Reduction ◽  
Paramagnetic Resonance ◽  
Ferricyanide Reductase ◽  
Starting Point ◽  
Nicotinamide Adenine Dinucleotide Dehydrogenase ◽  
Haem Iron ◽  
Acid Labile

1. An NADH–ferricyanide reductase activity has been isolated from the respiratory chain of Torulopsis utilis by using detergents. The isolated enzyme contains non-haem iron, acid-labile sulphide and FMN in the molar proportions 27.5:28.4:1. The preparation is free of FAD and largely free of cytochrome. 2. The enzyme catalyses ferricyanide reduction by NADPH at about 1% of the rate with NADH, and reacts poorly with acceptors other than ferricyanide. The rates of reduction of some acceptors are, as percentages of the rate with ferricyanide: menadione, 0.35%; lipoate, 0.01%; cytochrome c, 0.065%; dichlorophenolindophenol, 0.35%; ubiquinone-1, 0.08%. 3. Several properties of submitochondrial particles of T. utilis (non-haem iron, acid-labile sulphide, FMN and an NADH-reducible electron-paramagnetic-resonance signal) were found to co-purify with the NADH–ferricyanide reductase activity. Thus about 70% of the FMN and, within the limits of accuracy of the experiments, 100% of the non-haem iron and acid-labile sulphide of submitochondrial particles derived from T. utilis cells grown under conditions of glycerol limitation (but relatively low iron availability) can be attributed to the NADH–ferricyanide reductase. 4. It was also shown that the component of submitochondrial particles specifically bleached at 460nm by NADH [species 1 of Ragan & Garland (1971)] co-purifies with the NADH–ferricyanide reductase. 5. This successful purification of an NADH dehydrogenase from T. utilis forms a starting point for investigating the molecular properties of phenotypically modified mitochondrial NADH oxidation pathways that lack energy conservation between NADH and the cytochromes.

scholarly journals Spectroscopic studies of flavoproteins and non-haem iron proteins of submitochondrial particles of Torulopsis utilis modified by iron- and sulphate-limited growth in continuous culture

1971 ◽  
Vol 124 (1) ◽  
pp. 171-187 ◽  
Author(s):  
C. I. Ragan ◽  
P. B. Garland
Keyword(s):  
Electron Transport ◽  
Respiratory Chain ◽  
Nadh Dehydrogenase ◽  
Difference Spectrum ◽  
Spectroscopic Studies ◽  
Submitochondrial Particles ◽  
Limited Growth ◽  
Nadph Dehydrogenase ◽  
Haem Iron

1. A spectroscopic resolution has been made of the components contributing to the ‘iron-flavoprotein’ trough extending from 450 to 520nm in the reduced-minus-oxidized difference spectrum of submitochondrial particles of Torulopsis utilis. 2. Seven components were identified other than cytochrome b, ubiquinone and succinate dehydrogenase. On the basis of the effects of iron- and sulphate-limited growth of cells on their subsequently derived electron-transport particles, and also by consideration of analytical measurements of the concentration of FMN, FAD, non-haem iron and acid-labile sulphide in the electron-transport particles in relation to the magnitude of the spectroscopic changes, it was possible to identify five of these components as follows: species 1a, the flavin of NADH dehydrogenase ferroflavoprotein; species 1b, the iron–sulphur component of NADH dehydrogenase ferroflavoprotein; species 1′, the flavin of an NADPH dehydrogenase; species 2, an iron–sulphur or ferroflavoprotein component; species 3, the flavin of l-3-glycerophosphate dehydrogenase. Two additional components were a fluorescent flavoprotein, probably lipoamide dehydrogenase, and a b-type cytochrome reducible by NADH or NADPH but not reoxidizable by the respiratory chain. 3. Species 1b and 2 were undetectable in electron-transport particles from iron- or sulphate-limited cells, but could be recovered in vivo under non-growing conditions. 4. The recovery in vivo of species 2 but not species 1b was inhibited by cycloheximide. 5. The recovery of species 1b correlates with the recovery of site 1 conservation. 6. The recovery of species 1b with species 2 correlates with the recovery of piericidin A sensitivity. 7. Evidence is presented for an NADPH dehydrogenase distinct from NADH dehydrogenase. The oxidation of NADH and NADPH by the respiratory chain is sensitive to piericidin A, and an iron–sulphur protein common to both pathways (species 2) is suggested as the piericidin A-sensitive component. 8. The approximate E′0 (pH7.0) values of species 1 (a and b, low potential) and species 2 (high potential) indicate that site 1 energy conservation occurs between the levels of species 1 (a and b) and species 2.

Marginally excessive iron loading transiently blocks mucosal iron uptake in iron-deficient rats

2014 ◽  
Vol 307 (1) ◽  
pp. G89-G97 ◽  
Author(s):  
Shoko Shinoda ◽  
Shiho Yoshizawa ◽  
Eriko Nozaki ◽  
Kouki Tadai ◽  
Anna Arita
Keyword(s):  
Iron Uptake ◽  
Iron Concentration ◽  
Iron Loading ◽  
Short Acting ◽  
Excess Iron ◽  
Rapid Induction ◽  
Cellular Iron ◽  
Iron Load ◽  
Iron Deficient ◽  
Cellular Iron Uptake

Regular “mucosal block” is characterized by decreased uptake of a normal iron load 3–72 h after the administration of excess iron (generally 10 mg) to iron-deficient animals. We found that short-acting mucosal block could be induced by much lower iron concentration and much shorter induction time than previously reported, without affecting levels of gene expression. A rapid endocytic mechanism was reported to decrease intestinal iron absorption after a high iron load, but the activating iron load and the time to decreased absorption were undetermined. We assessed the effects of 30–2,000 μg iron load on iron uptake in the duodenal loop of iron-deficient and iron-sufficient rats under anesthesia. One hour later, mucosal cellular iron uptake in iron-deficient rats administered 30 μg iron was 76.1%, decreasing 25% to 50.7% in rats administered 2,000 μg iron. In contrast, iron uptake by iron-sufficient rats was 63% (range 60.3–65.5%) regardless of iron load. Duodenal mucosal iron concentration was significantly lower in iron-deficient than in iron-sufficient rats. Iron levels in portal blood were consistently higher in iron-deficient rats regardless of iron load, in contrast to the decreased iron uptake on the luminal side. Iron loading blocked mucosal uptake of marginally excess iron (1,000 μg), with a greater effect at 15 min than at 30 min. The rapid induction of short-acting mucosal block only in iron-deficient rats suggests DMT1 internalization.

scholarly journals The absence of iron deficiency effect on the humoral immune response of piglets to tetanus toxoid

2008 ◽  
Vol 52 (No. 5) ◽  
pp. 179-185 ◽  
Author(s):  
M. Svoboda ◽  
K. Nechvatalova ◽  
J. Krejci ◽  
J. Drabek ◽  
R. Ficek ◽  
...  
Keyword(s):  
Immune Response ◽  
Iron Deficiency ◽  
Tetanus Toxoid ◽  
Iron Concentration ◽  
Not Given ◽  
Dynamic Changes ◽  
Humoral Immune ◽  
Iron Deficient ◽  
Iron Preparation ◽  
Haematological Indices

The aim of this study was to investigate an antibody response to tetanus toxoid in iron-deficient piglets. Ten piglets were not given any iron preparation until the age of 21 days. Ten piglets were given 200 mg Fe<sup>3+</sup> dextran intramuscularly at the age of 3 days. All piglets were immunized with tetanus toxoid 14 days after birth. Reimmunization was performed 21 days after the first immunization. IgM and IgG titres were measured in weekly intervals after immunization. Haematological indices and iron concentration in the blood plasma of iron-deficient piglets characterized iron deficiency. The dynamic changes in IgM and IgG response to tetanus toxoid were similar in iron-deficient and iron-supplemented piglets and no significant differences in titres between the two groups were found in any period of the trial.

Photosynthesis, quenching of chlorophyll fluorescence and thermal energy dissipation in iron-deficient sugar beet leaves

1998 ◽  
Vol 25 (4) ◽  
pp. 403 ◽  
Author(s):  
Fermín Morales ◽  
Anunciación Abadía ◽  
Javier Abadía
Keyword(s):  
Energy Dissipation ◽  
Iron Deficiency ◽  
Photosystem Ii ◽  
Sugar Beet ◽  
Electron Flow ◽  
Reaction Centers ◽  
O2 Evolution ◽  
Photosystem Ii Efficiency ◽  
Iron Deficient ◽  
Additional Support

In sugar beet (Beta vulgaris L.) iron deficiency decreased not only the photosynthetic rate but also the actual photosystem II efficiency at steady-state photosynthesis. In moderate iron deficiency, the decrease in actual photosystem II efficiency under illumination was related to closure of photosystem II reaction centers, whereas in severe iron deficiency it was associated to decreases of intrinsic photosystem II efficiency. The O2 evolution, on an absorbed light basis, decreased more than the actual photosystem II efficiency, suggesting the presence of a significant fraction of electron transport to molecular oxygen or the existence of some form of cyclic electron flow. Iron-deficient leaves reduced the excess of light absorbed that cannot be used in photosynthesis not only by decreasing absorptance, but also by dissipating a large part of the light absorbed by the photosystem II antenna. This mechanism, that protects the photosystem II reaction centers through the enhancement of energy dissipation, was related to the de-epoxidation of violaxanthin (V) to antheraxanthin (A) and zeaxanthin (Z) in iron-deficient leaves. These data provide additional support for a role of Z+A in photoprotection under conditions of excess photosynthetic light absorption.

scholarly journals Unique Host Iron Utilization Mechanisms of Helicobacter pylori Revealed with Iron-Deficient Chemically Defined Media

2010 ◽  
Vol 78 (5) ◽  
pp. 1841-1849 ◽  
Author(s):  
Olga Senkovich ◽  
Shantelle Ceaser ◽  
David J. McGee ◽  
Traci L. Testerman
Keyword(s):  
Helicobacter Pylori ◽  
Defined Medium ◽  
Normal Serum ◽  
Chemically Defined Medium ◽  
Limited Growth ◽  
Defined Media ◽  
Iron Deficient ◽  
Novel Strategy ◽  
H Pylori

ABSTRACT Helicobacter pylori chronically infects the gastric mucosa, where it can be found free in mucus, attached to cells, and intracellularly. H. pylori requires iron for growth, but the sources of iron used in vivo are unclear. In previous studies, the inability to culture H. pylori without serum made it difficult to determine which host iron sources might be used by H. pylori. Using iron-deficient, chemically defined medium, we determined that H. pylori can bind and extract iron from hemoglobin, transferrin, and lactoferrin. H. pylori can use both bovine and human versions of both lactoferrin and transferrin, contrary to previous reports. Unlike other pathogens, H. pylori preferentially binds the iron-free forms of transferrin and lactoferrin, which limits its ability to extract iron from normal serum, which is not iron saturated. This novel strategy may have evolved to permit limited growth in host tissue during persistent colonization while excessive injury or iron depletion is prevented.

scholarly journals The Effect of Smut Gall Tumour Infection on Iron and Zinc Uptake and Distribution in Maize Seedlings

2004 ◽  
pp. 27-32
Author(s):  
László Lévai
Keyword(s):  
Biotic Stress ◽  
Iron Concentration ◽  
Iron Chlorosis ◽  
Maize Seedlings ◽  
High Iron Content ◽  
High Iron ◽  
Tumour Development ◽  
Iron Deficient ◽  
Iron And Zinc ◽  
Iron Concentrations

The amounts of Fe, and Zn were measured in maize seedlings infected by smut gall tumour (Ustilago maydis Dc. Cda.) and in healthy seedlings five days after infection. The amount of elements was also measured under different stress intensities. Due to the infection, as a biotic stress, the amount and distribution of examined elements have been changed. On the bases of the differences in the Fe distribution between the symptoms less and tumorial leaf parts, we have come to the conclusion that the infection also effects the mobilisation of Fe and Zn inside the plants. The Fe uptake was much higher in the infected plants and the tumour development also had an effect on the uptake and distribution of the examined elements. The experiments of infecting maize seedlings by monosporidial strain of crown gall tumour showed no tumour development. We found that the monosporidial strain also acts as a biotic stress and has an effect of iron and zinc distribution. We observed a slight difference in the iron and zinc contents in the roots of corn seedlings infected by different monosporidial sporidium concentrations, while the iron and zinc contents in the shoots were increased by the intensity of the infection. The roots do not form tumours. There is no difference between the roots of the infected and healthy corn seedlings. Since the Fe and Zn contents of the shoots of infected plants depend on the intensity of the infection, we have come to the conclusion that there must exist a „special” communication system regulating the transportation of the examined elements.In the experiments with infected maize seedlings, it became necessary to get the iron chlorosis before the disease reaches the lethal phase. Although most of the iron reserves are located in the embryo, to accelerate the chlorosis, the endosperm was removed, and it was observed, that the iron chlorosis appears later in maize seedlings when the endosperm is removed. The relative chlorophyll content of the first and second leaves was measured in iron efficient and iron deficient maize seedlings at different times.The higher IAA content of tumorial plant tissues is already known. The treatment with IAA decreases the iron concentration in the shoots and in the roots of +Fe precultured plants and increases at -Fe precultured ones. The TIBA retards the shoot-to-root transport of IAA. When the seedlings were treated simultaneously with IAA and TIBA, higher iron concentrations were observed in the shoots and in the roots of corn seedlings.We found extremely high iron concentrations in the roots of infected seedlings and, in line with this, serious damage to the roots was observed that this can be caused by the high iron content generated free radicals. The results demonstrate that IAA has a role in the shoot to root communication.

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