Synthesis Of Respiratory Enzymes Research Articles

Metal Oxide Nanostructures-Based Gas Sensor for Ethylene Detection: A Review

Increased ethylene content may induce the synthesis of respiratory enzymes and enhance respiration, which accelerated fruit ripening. Monitoring of ethylene concentration is critical in the fruit industry, avoid the fruit from passing through. Research interest has focused on the utilization of nano-sized semiconductor to monitor the ethylene through various processes. As detection for ethylene with excellent sensitivity, superior quantum efficiency, and fast response speed, nano-sized semiconductors are regarded as the most promising directions for nanomaterials. We review the latest achievements with nano-sized material gas sensors as for ethylene detector in the article. Firstly, the classification and structure of semiconductor detectors are introduced (such as resistive transducer; non-resistive transducer; organic semiconductor gas sensor), Then we present several kinds of and their performance, focusing on binary oxides with wide band gap (such as ZnO, SnO2, Ga2O3, Nb2O5, and WO3) and ternary oxides (such as Zn2SnO4, Zn2GeO4, and In2Ge2O7) Eventually, finally, we review and summarize the perspectives in this field and the prospects for future research. Perspectives and outlook on future research directions in this field.

Response to culture aeration mediated by the nitrate and nitrite sensor NarQ of Escherichia coli K-12.

Respiratory enzyme synthesis in enterobacteria is controlled in response to electron acceptor availability. The iron-sulphur protein Fnr and the sensor-regulator proteins ArcB-ArcA control respiratory gene transcription in response to oxygen and quinone pool redox status respectively. The sensor-regulator proteins NarX-NarL and NarQ-NarP control anaerobic respiratory gene expression in response to nitrate and nitrite. Our laboratory recently engineered the lac operon to replace the primary operator O1-lac with the NarL and NarP protein binding site from the nirB operon. Expression of the lacZ gene from this construct is repressed by nitrate in Nar+ strains. Here, we found that lacZ gene expression was repressed in aerated cultures of narQ+narX null strains. This repression was not observed in narX+narQ+ or narX+narQ null strains. Thus, the NarQ sensor responds to aeration as well as to nitrate and nitrite. The NarX and NarQ sensors are composed of three distinct modules: an amino-terminal sensory module, a carboxyl-terminal transmitter module and a central module of unknown function. Experiments with NarX-NarQ hybrid proteins suggest that the NarQ protein central module is necessary for response to aeration. The physiological significance of this additional sensory role for the NarQ sensor remains obscure.

Production of Bioingredients from Kluyveromyces marxianus Grown on Whey: An Alternative

Whey waste is a major problem for the dairy industry. Finding alternative means to reduce its pollution potential and produce high value-added bioingredients has been attempted by many researchers. Kluyveromyces marxianus var. marxianus is a dairy yeast that produces β-galactosidase, allowing for whey fermentation. Also, K. marxianus has been proposed as a source of: (1) oligonucleotides, used as flavor enhancers in food products; (2) oligosaccharides, used as prebiotics to stimulate the growth of Bifidobacterium sp. in the animal and human intestines; and (3) oligopeptides, immunostimulators added to dairy products that are released in the wort after whey protein proteolysis. Fed-batch fermentation can be used as an alternative process to avoid increases in lactose concentration and prevent the catabolite repression of the respiratory enzyme synthesis during aerobic fermentation, thus allowing for high biomass yields. The relevance of these factors on yeast fermentation of whey is summarized in this critical review.

Mitochondrial genes as sites of primary action of steroid hormones

Steroid and thyroid hormones act on nuclear gene transcription by activating protein receptors, which in turn bind to hormone response elements (HREs). Among the cell-specific processes regulated by steroid receptors is energy metabolism through increased synthesis of respiratory enzymes. As some of these enzymes are encoded by both nuclear and mitochondrial genes, coordination of their synthesis is probable, inter alia at the transcriptional level. We have postulated a direct effect of steroid hormones on mitochondrial gene transcription and here present the following evidence in support of this hypothesis. 1) The human and rodent mitochondrial genomes contain nucleotide sequences similar both to type I and type II HREs. 2) Glucocorticoid receptors (GR) rapidly translocate from the cytoplasm into mitochondria after administration of glucocorticoids. This process has been reproduced in vitro and deletion of the N-terminal part of the glucocorticoid receptor stops translocation into mitochondria. 3) Gel shift analysis has demonstrated binding of GR to putative mitochondrial GR elements. 4) In transfection experiments, mitochondrial HREs confer dexamethasone inducibility on hybrid reporter constructs, abolished in the presence of excess RU38486. 5) Similar results were obtained for thyroid hormone receptor (TR α) localization, import, and binding to TR elements. These findings, taken with the demonstrated effects of steroid (and thyroid) hormones on mitochondrial transcription and respiratory enzyme biosynthesis, strongly support the hypothesis of a direct effect of steroid (and thyroid) hormones on mitochondrial gene transcription.

The involvement of a vanadate‐sensitive ATPase in plasma membranes of a salt tolerant cyanobacterium

Plasma membranes of the marine cyanobacterium Spirulina subsalsa were tested for ATPase activity, and for involvement in salt stress. Transition of cells from saline to hypersaline medium enhances the respiratory activity associated with extrusion of Na+ and Cl−, and persisting salt stress induces synthesis of respiratory enzymes in the plasma membranes. The membranes possess an ATPase, specific for ATP and Mg2+ and sensitive to orthovanadate and dicyclohexylcarbodiimide. Immunoblot analysis of plasma membrane polypeptides from Spirulina subsalsa with anti‐Arabidopsis H+‐ATPase serum identified a single polypeptide of 100 kDa, which cross‐reacted with the antibodies. An unusual feature of this ATPase is a specific stimulation by Na+ ions. Prolonged adaptation of S. subsals cells to hypersaline conditions induced an increase in ATPase activity in subsequent plasma membrane preparations, as well as a higher content of the 100 kDa polypeptide. It is suggested that the ATPase investigated is an H+‐pump, which is involved in extrusion of Na+ and in conferring resistance to salt stress.

Regulation of nitrate and nitrite reductase synthesis in enterobacteria.

Enterobacteria use nitrate and nitrite both as electron acceptors and as sources of nitrogen for biosynthesis. Nitrate is reduced through nitrite to ammonium in both cases. The enzymes and structural genes for nitrate/nitrite respiration and assimilation are distinct, and are subject to different patterns of regulation. Respiratory enzyme synthesis is indifferent to the availability of ammonium, and is induced by anaerobiosis via the FNR protein. Respiratory enzyme synthesis is further induced by nitrate or nitrite via the NARL and NARP proteins, which are response regulators of two-component regulatory systems. The cognate sensor proteins NARX and NARQ monitor the availability of nitrate and nitrite, and control the activity of the NARL and NARP DNA-binding proteins accordingly. Additionally, nitrate represses the synthesis of respiratory nitrite reductase, and this control is mediated by the NARL protein. Assimilatory enzyme synthesis is indifferent to the availability of oxygen, and is induced by ammonium limitation via the NTRC protein. Assimilatory enzyme synthesis is further induced by nitrate or nitrite via the NASR protein, which may act as a transcription antiterminator. Even though the respiratory and assimilatory enzyme systems are genetically distinct and subject to different forms of regulation, the structural and regulatory genes are closely linked on the Klebsiella pneumoniae chromosome.

Nitrate regulation of anaerobic respiratory gene expression in narX deletion mutants of Escherichia coli K-12

Previous studies have shown that narL+ is required for nitrate regulation of anaerobic respiratory enzyme synthesis, including formate dehydrogenase-N, nitrate reductase, and fumarate reductase. Insertions in the closely linked narX gene decrease, but do not abolish, nitrate regulation of anaerobic enzyme synthesis. Analysis of sequence similarities suggests that NarX and NarL comprise a two-component regulatory pair. We constructed lacZ operon and gene fusions to investigate the operon structure of narXL. We found evidence for a complex operon with at least two promoters; PXL-narX-PL-narL. We also investigated the role of NarX in nitrate regulation of anaerobic respiratory enzyme synthesis by constructing nonpolar loss of function narX alleles. These deletions were studied on narL+ lambda specialized transducing bacteriophage. The narX deletions had no effect on nitrate regulation in delta (narXL) strains. This finding suggest that the subtle effects of previously studied narX insertions are due to decreased expression of narL and that narX+ is not essential for normal nitrate regulation. The role of NarX in nitrate regulation remains to be determined.

A yeast mutant with glucose-resistant formation of mitochondrial enzymes

Yeast mutants with glucose-insensitive formation of mitochondrial enzymes were isolated starting with a strain completely lacking alcohol dehydrogenase activity. The mutations could uniquely be attributed to a single nuclear gene, designated CCR80. They were largely dominant. Glucose-resistant enzyme formation was most prominent with regard to mitochondrial enzymes succinate dehydrogenase and NADH: cytochrome c oxidoreductase. The effect of CCR80r mutations was rather small but significant on the gluconeogenetic enzymes isocitrate lyase, malate synthase and fructose-1,6-bisphosphatase and on invertase synthesis. The repressive effect of maltose in CCR80r mutants was also reduced showing that glucose-resistance is not caused by a mere hexose uptake defect. This regulatory disorders were not accompanied by reduced levels of glycolytic enzymes or drastically altered levels of glycolytic intermediates. Aerobic fermentation of glucose was almost completely inhibited in the mutants; anaerobic glucose degradation was reduced but not completely abolished. Therefore, the mutants appear to be altered in the regulation of glycolysis. A largely glucose-resistant synthesis of respiratory enzymes is obviously a corollary of this alteration.

�ber Aktivit�tssteigerungen der Pyruvatkinase durch Blaulicht oder Glucose bei einer chlorophyllfreien Chlorella-Mutante

Crude extracts of dark-kept resting cells of a chlorophyll-free, carotenoid-containing mutant of Chlorella vulgaris Beijerinck (211-11h/20) were found to convert 14.44±0.77 nmol PEP per min and mg protein into pyruvate by the action of pyruvate kinase (=PK; EC 2.7.1.40). When such cells were exposed to blue light (λ<550 nm, ∼300 μW cm-2) for 3 hrs the PK-activity/protein of their crude extracts rose to 21.47±1.30, i.e., it was enhanced by 43%. Poisoning with 10-3 mol cycloheximide or with 150 μg actinomycin D/ml prevented the effect of blue light by 80–90% (Table 1). This result points to an induction of enzyme synthesis in blue light. Addition of 1% glucose in the dark resulted in an increase in PK-activity, too. Three hrs after application of glucose the PK-activity was 28.05±1.88 nmol/min and mg protein, which was 94% greater than in the control. The effect of glucose was also largely preventable by cycloheximide (10-3 mol) or by actinomycin D (150 μg/ml) (Table 2). These results lead to the conclusion that blue light may induce the synthesis of PK by supplying free sugars at the site of enzyme synthesis. The assumption is supported by the observation that in hot water extracts of blue illuminated cells in which glucose oxidation had been poisoned by. 10-2 mol monoiodoacetic acid there was 60% more glucose, glucose-6-phosphate, fructose-6-phosphate and sucrose detectable than in extracts of equally poisoned algae from darkness (Table 3). It is suggested that blue light activates a system for the transport of sugar out of the chloroplast, which results in the induction of respiratory enzyme synthesis and thus in enhanced respiration.

Derepression of mitochondria and their enzymes in yeast: Regulatory aspects

We have performed a detailed analysis of the properties of glucose-repressed cells of a commercial strain of Saccharomyces cerevisiae. They contain measurable amounts of the respiratory enzymes NADH oxidase, cytochrome c oxidase, succinate dehydrogenase, succinate:cytochrome c reductase and NADH:cytochrome c reductase (antimycin A-sensitive) as well as the dehydrogenases for l-malate, l-glutamate, and l 8-isocitrate. Cytochromes b, c 1, and aa 3 are present in amounts that may be in excess of those required for cytochrome-linked enzyme activities. Enzymes and cytochromes are localized in large, presumably mitochondrial organelles among which no compositional or functional heterogeneity could be detected. We have also analyzed the kinetics of synthesis of respiratory enzymes and cytochromes during the release from catabolite(glucose) repression. All activities assayed except for cytochrome c oxidase begin their derepression before the external glucose concentration falls below 0.4%; derepression of cytochrome oxidase occurs only after the glucose concentration falls below 0.1%. The earlier events comprise the “fermentative” phase of derepression while the later events comprise the “oxidative” phase. The two phases can be distinguished operationally by their sensitivity to antimycin A. Only the oxidative phase is blocked by the inhibitor. Respiratory enzymes and cytochromes appear to fall into two classes distinguishable by their increase during derepression. An apparently constitutive one consists of cytochrome c oxidase, ATPase, and cytochromes aa 3, b, and c 1; these entities increase in amount per cell but not in amount per unit of mitochondrial mass and are of the order of 5-fold or less. The second class consists of those activities that increase by more than 6-fold and may be considered derepressible in the strict sense. Thus, proliferation and differentiation of mitochondria both contribute to the cellular changes associated with derepression. The fermentative phase of derepression does not require mitochondrial function, mitochondrial protein, or RNA synthesis, or the gradual accumulation of regulatory elements for either its initiation or persistence. This phase of derepression also occurs in cytoplasmic petites. In contrast, the oxidative phase of derepression requires mitochondrial function. Mitochondrial gene expression is required for the biogenesis of fully functional mitochondria but, except for cytochrome c, it plays little or no role in regulating the expression of nuclear genes the products of which are localized in mitochondria.

Oxidative phosphorylation in yeast VII. Inhibition of oxidative phosphorylation and of respiratory enzyme synthesis by oligomycin in intact cells

Oxidative phosphorylation in yeast VII. Inhibition of oxidative phosphorylation and of respiratory enzyme synthesis by oligomycin in intact cells

Recombination of mitochondrial drug-resistance factors in [formula omitted

RECOMBINATION OF MITOCHONDRIAL DRUG-RESISTANCE FACTORS IN SACCHAROMYCES CEREVISIAE D.Y. Thomas and D. Wilkie Department of Botany, University College London. Received January 17, 1968 R&assortment of mitochondrially-located drug-resistance factors in the vegetative progeny of individual zygotes will be described and provides evidence of a recombinational process involving the genetic material of the organelle. The specific inhibition of respiratory enzyme synthesis in yeast by certain protein inhibitors of bacteria was first reported by Linnane and his collaborators (see Clark-Walker and Linnane,

Inhibition of respiratory enzyme synthesis in yeast by chloramphenicol: relationship between chloramphenicol tolerance and resistance to other antibacterial antibiotics.

Individual yeast strains show characteristic differences in the amount of chloramphenicol required to inhibit the synthesis of the respiratory system. This varies from 0·05 mg./ml. to 4 mg./ml. A correlation between chloramphenicol and tetracycline resistance appears likely but no correlation between chloramphenicol and erythromycin resistance was observed. These relationships were emphasized by cross-checking spontaneous resistant mutants for each antibiotic. Nearly all mutants showing spontaneous resistance to chloramphenicol had a simultaneous increase in tetracycline resistance but no increase in erythromycin resistance. Spontaneous resistance to erythromycin on the other hand, had no striking effect on tolerance levels to chloramphenicol and tetracycline. Increases in erythromycin resistance were commonly accompanied by an increase in resistance to other macrolide antibiotics. There are similarities between these effects and those described for certain bacterial systems.

Effet inhibiteur de Zn2+ sur la biosynthese induite par l'oxygene des enzymes respiratoires de la levure

To investigate what the function might be of the Zn-protoporphyrin present in yeast cells, the course of the O2-induced biosynthesis of respiratory enzymes was studied in yeast harvested from anaerobic culture on synthetic medium, either with Zn2+ added at a concentration which stimulates the growth ((+) Zn yeast) or without added Zn2+ ((−) Zn yeast). Zn2+ has an inhibitory effect of the respiratory adaptation. In (−) Zn yeast, the adaptive development of respiratory enzymes is much faster; there is an increase of cytochrome content, O2 consumption, succinate: cytochrome c reductase and NADH2: cytochrome c reductase activities and a decrease of fermentation. Different hypotheses are presented to explain the inhibitory effect of Zn2+ on the synthesis of respiratory enzymes. Pour rechercher quel est le rôle joué par la Zn-protoporphyrine présente dans les cellules de levures, l'évolution de la biosynthèse, induite par l'oxygène, des enzymes de la chaîne respiratoire a été étudiée chez des levures provenant de cultures anaérobies sur milieu synthétique soit additionné de Zn2+ à une concentration stimulatrice de la croissance (levure (+) Zn), soit non additionné de Zn2+ (levure (−) Zn). Cette étude met en évidence un rôle inhibiteur de Zn2+ sur l'adaptation respiratiore. Chez les levures (−) Zn, la synthèse des enzymes respiratoires s'effectue à une vitesse plus grande que chez les levures (+) Zn; le QO2, la teneur en cytochromes, l'activité succinate: cytochrome c réductase et NADH2: cytochrome c réductase sont toujours plus élevées chez les levures (−) Zn, tandis que la fermentation est plus faible. Différentes hypothèses sont envisagées pour expliquer l'inhibition par Zn2+ de la biosynthèse des enzymes respiratoires.

Changes in the activities of respiratory enzymes during the aerobic growth of yeast on different carbon sources

1. Unlike yeast cells grown on glucose (0.9%), cells grown on galactose aerobically or anaerobically as well as cells grown on very low glucose concentrations (0.09%) have been found to possess mitochondria. 2. Synthesis of respiratory enzymes was less in the presence of glucose than galactose. When either sugar was consumed, synthesis of these enzymes increased. 3. A possible mechanism is suggested for the repression of mitochondrial formation by glucose by means of a ;high-energy' substance easily derived from glucose.

On the necessity of molecular oxygen for the synthesis of respiratory enzymes in yeast

On the necessity of molecular oxygen for the synthesis of respiratory enzymes in yeast

The injury metabolism of the cecropia silkworm—II. Injury-induced alterations in oxidative enzyme systems and respiratory metabolism of the pupal wing epidermis

It is known that localized injury to the integument of diapausing silkmoth pupae causes an increase in the respiratory metabolism of an insect as a whole. In the present study, this ‘injury metabolism’ has been analysed in an individual tissue, the wing epidermis, both in terms of the oxygen consumption of the isolated intact wing, and through measurement of the activities of several oxidative enzyme systems in mitochondrial-microsomal preparations derived from homogenates of wing. The participation of the wing in the respiratory response of the pupa is clearly evident from both types of experiment. The oxygen consumption of isolated wings is a linear function of that of the pupa and shows a corresponding increase after injury. Moreover, an increase of several fold is observed in the activities of cytochrome c oxidase, DPNH-, TPNH-, and succinatecytochrome c reductase, and DPNH oxidase systems. The enzymatic changes appear to be associated with an increase in concentration of respiratory enzymes, similar in character and magnitude to that observed in the uninjured silkmoth when diapause is terminated. The oxygen consumption of the isolated wing also typifies the behaviour of the pupa as a whole in showing a substantial resistance to inhibition by carbon monoxide. In the intact pupa and in the isolated wing, the degree of sensitivity to this agent increases as a function of the prior respiratory rate in air. Thus the wings of injured pupae, whose respiration is augmented, exhibit greater sensitivity to carbon monoxide than do those isolated from uninjured diapausing pupae. These findings are considered in relation to the ‘excessoxidase’ hypothesis whereby cytochrome oxidase has previously been proposed to function as a carbon monoxide-resistant terminal oxidase in pupal tissues. The present findings are in accord with the hypothesis but do not rule out other explanations for the mechanism of resistance to carbon monoxide. The alterations in respiratory rate and enzyme concentration are of interest in relation to general problems of metabolic control in animal cells and, in particular, the control of specific protein synthesis. The increase in concentration and activity of respiratory enzymes after injury is correlated functionally with the enhanced biosynthetic activity that prevails at this time. Synthesis of respiratory enzymes is viewed as the action of an intracellular regulatory device to maintain a balance of exergonic and endergonic functions under the altered conditions of biological maintenance imposed by injury.

INDUCTION OF PETITE MUTATION AND INHIBITION OF SYNTHESIS OF RESPIRATORY ENZYMES IN VARIOUS YEASTS.

A systematic investigation covering a wide diversity of yeast species was made on the appearance of respiratory deficient (petite) mutants after treatment with acriflavine. Petite mutants were obtained from certain species only, but in these species all strains were found to have in common the property of giving rise to petite mutants; such species were designated as “petite positive”. Species failing to give rise to petite mutants were accordingly called “petite negative”. The primary action of acriflavine, namely the inhibition of the synthesis of the respiratory system, was shown to occur not only in petite positive yeasts, but also in petite negative ones. Some implications of the results are discussed.

Yeast Mitochondria: Subcellular Units involved in the Synthesis of Respiratory Enzymes in Yeast

Yeast Mitochondria: Subcellular Units involved in the Synthesis of Respiratory Enzymes in Yeast