The cytochrome oxidase inhibitor azide also inhibits the alternative pathway of Neurospora crassa

1984 ◽  
Vol 62 (2-3) ◽  
pp. 129-136 ◽  
Author(s):  
Peter J. Bridge ◽  
Helmut Bertrand
Keyword(s):  
Neurospora Crassa ◽  
Cytochrome Oxidase ◽  
Alternative Oxidase ◽  
Alternative Pathway ◽  
Oxidase Inhibitor ◽  
The Novel ◽  
Respiratory Pathway ◽  
Maximal Inhibition ◽  
Cytochrome Pathway ◽  
Mutant Strains

Mutant strains of Neurospora crassa were used to investigate the effects of the inhibitor azide upon respiration mediated by either the cyanide-insensitive alternative mitochondrial respiratory pathway or the "standard" cyanide-sensitive cytochrome pathway. The use of appropriate cytochrome-oxidase-deficient and alternative-oxidase-deficient mutants permitted respiration to be restricted to the pathway of choice. In addition to its known effect upon cytochrome oxidase, azide was found to inhibit the alternative pathway of Neurospora with half-maximal inhibition occurring at 1.3 mM azide. This finding indicates that the activities of at least some of the "novel" azide-sensitive oxidases that have been discovered recently in organisms with inducible or constitutive cyanide-insensitive respiratory systems might be attributable to the "standard" salicylhydroxamate-sensitive mitochondrial alternative pathway.

Cloning and Analysis of the Alternative Oxidase Gene of Neurospora crassa

Genetics ◽  
1996 ◽  
Vol 142 (1) ◽  
pp. 129-140 ◽  
Author(s):  
Qiuhong Li ◽  
R Gary Ritzel ◽  
Lesley L T McLean ◽  
Lee McIntosh ◽  
Tak Ko ◽  
...  
Keyword(s):  
Neurospora Crassa ◽  
Alternative Oxidase ◽  
Electron Flow ◽  
Mitochondrial Protein ◽  
Transcriptional Level ◽  
Wild Type ◽  
Respiratory Pathway ◽  
Oxidase Gene ◽  
Alternative Respiratory Pathway ◽  
Cytochrome Pathway

Mitochondria of Neurospora crassa contain a cyanide-resistant alternative respiratory pathway in addition to the cytochrome pathway. The alternative oxidase is present only when electron flow through the cytochrome chain is restricted. Both genomic and cDNA copies for the alternative oxidase gene have been isolated and analyzed. The sequence of the predicted protein is homologous to that of other species. The mRNA for the alternative oxidase is scarce in wild-type cultures grown under normal conditions, but it is abundant in cultures grown in the presence of chloramphenicol, an inhibitor of mitochondrial protein synthesis, or in mutants deficient in mitochondrial cytochromes. Thus, induction of alternative oxidase appears to be at the transcriptional level. Restriction fragment length polymorphism mapping of the isolated gene demonstrated that it is located in a position corresponding to the aod-1 locus. Sequence analysis of mutant aod-1 alleles reveals mutations affecting the coding sequence of the alternative oxidase. The level of aod-1 mRNA in an aod-2 mutant strain that had been grown in the presence of chloramphenicol was reduced several fold relative to wild-type, supporting the hypothesis that the product of aod-2 is required for optimal expression of aod-1.

Functional analysis reveals effects of tobacco alternative oxidase gene (NtAOX1a) on regulation of defence responses against abiotic and biotic stresses

2009 ◽  
Vol 29 (6) ◽  
pp. 375-383 ◽  
Author(s):  
Yi Zhang ◽  
Dongmei Xi ◽  
Jian Wang ◽  
Dongfang Zhu ◽  
Xingqi Guo
Keyword(s):  
Oxidative Stress ◽  
Low Temperature ◽  
Alternative Oxidase ◽  
Alternative Pathway ◽  
Respiratory Pathway ◽  
Oxidase Gene ◽  
Biotic Stresses ◽  
Alternative Respiratory Pathway ◽  
Cytochrome Pathway ◽  
Defence Responses

Mitochondrial AOX (alternative oxidase) is the terminal oxidase of the CN (cyanide)-resistant alternative respiratory pathway in plants. To investigate the role of the tobacco AOX gene (NtAOX1a) (where Nt is Nicotiana tabacum) under deleterious conditions which could induce ROS (reactive oxygen species) accumulation, we generated and characterized a number of independent transgenic tobacco (N. tabacum) lines with altered NtAOX1a gene expression and AP (alternative pathway) capacity. AOX efficiently inhibited the production of low-temperature-induced H2O2 and might be a major enzyme for scavenging H2O2 at low temperature. Furthermore, NtAOX1a may act as a regulator of KCN-induced resistance to TMV (tobacco mosaic virus) through the regulation of H2O2. Notably, a moderate accumulation of H2O2 under the control of NtAOX1a was crucial in viral resistance. Analysis of seed germination indicated an important role for NtAOX1a in germination under H2O2-induced oxidative stress when the CP (cytochrome pathway) was inhibited. These results demonstrate that NtAOX1a is necessary for plants to survive low temperature, pathogen attack and oxidative stress by scavenging ROS under these adverse conditions when the CP is restricted.

scholarly journals Kinetic analysis of the mitochondrial quinol-oxidizing enzymes during development of thermogenesis in Arum maculatum L

1996 ◽  
Vol 317 (1) ◽  
pp. 313-319 ◽  
Author(s):  
Graeme R. LEACH ◽  
Klaas KRAB ◽  
David G. WHITEHOUSE ◽  
Anthony L. MOORE
Keyword(s):  
Respiratory Rate ◽  
Succinate Dehydrogenase ◽  
Oxidase Activity ◽  
Alternative Oxidase ◽  
Alternative Pathway ◽  
Respiratory Control ◽  
Stage Of Development ◽  
Activation Level ◽  
Cytochrome Pathway ◽  
Arum Maculatum

The dependence of the rate of oxygen uptake upon the ubiquinone (Q)-pool reduction level in mitochondria isolated during the development of thermogenesis of Arum maculatum spadices has been investigated. At the α-stage of development, the respiratory rate was linearly dependent upon the reduction level of the Q-pool (Qr) both under state-3 and -4 conditions. Progression through the β/γ to the Δ-stage resulted in a non-linear dependence of the state-4 rate on Qr. In the Δ-stage of development, both state-3 and -4 respiratory rates were linearly dependent upon Qr due to a shift in the engagement of the alternative oxidase to lower levels of Qr. Western blot analysis revealed that increased alternative oxidase activity could be correlated with expression of a 35 kDa protein. Respiratory control was only observed with mitochondria in the α-stage of development. At the β/γ-stage of development, the addition of ADP resulted in a significant oxidation of the Q-pool which was accompanied by a decrease in the respiratory rate. This was due either to decreased contribution of the alternative pathway to the overall respiratory rate under state 3 or by deactivation of succinate dehydrogenase activity by ADP. Cold-storage of the spadices at the β-stage of development led to increased activity of both the cytochrome pathway and succinate dehydrogenase, without any change in alternative oxidase activity. Results are discussed in terms of how changes in the activation level of the alternative oxidase and succinate dehydrogenase influence the activity and engagement of the quinol-oxidizing pathways during the development of thermogenesis in A. maculatum.

scholarly journals Basic energetic parameters of Acanthamoeba castellanii mitochondria and their resistance to oxidative stress.

2008 ◽  
Vol 55 (2) ◽  
pp. 349-356 ◽  
Author(s):  
Wieslawa Jarmuszkiewicz ◽  
Nina Antos-Krzeminska ◽  
Danuta Drachal-Chrul ◽  
Karolina Matkovic ◽  
Wioletta Nobik ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Alternative Oxidase ◽  
Membrane Integrity ◽  
Respiratory Control ◽  
Acanthamoeba Castellanii ◽  
Oxidase Inhibitor ◽  
Mitochondrial Outer Membrane ◽  
Cytochrome C Release ◽  
Cytochrome Pathway ◽  
Coupling Parameters

The purpose of this study was establishing the basic energetic parameters of amoeba Acanthamoeba castellanii mitochondria respiring with malate and their response to oxidative stress caused by hydrogen peroxide in the presence of Fe(2+) ions. It appeared that, contrary to a previous report (Trocha LK, Stobienia O (2007) Acta Biochim Polon 54: 797), H(2)O(2)-treated mitochondria of A. castellanii did not display any substantial impairment. No marked changes in cytochrome pathway activity were found, as in the presence of an inhibitor of alternative oxidase no effects were observed on the rates of uncoupled and phosphorylating respiration and on coupling parameters. Only in the absence of the alternative oxidase inhibitor, non-phosphorylating respiration progressively decreased with increasing concentration of H(2)O(2), while the coupling parameters (respiratory control ratio and ADP/O ratio) slightly improved, which may indicate some inactivation of the alternative oxidase. Moreover, our results show no change in membrane potential, Ca(2+) uptake and accumulation ability, mitochondrial outer membrane integrity and cytochrome c release for 0.5-25 mM H(2)O(2)-treated versus control (H(2)O(2)-untreated) mitochondria. These results indicate that short (5 min) incubation of A. castellanii mitochondria with H(2)O(2) in the presence of Fe(2+) does not damage their basic energetics.

scholarly journals Characterization of cyanide-insensitive respiration in mitochondria and submitochondrial particles of Moniliella tomentosa

1979 ◽  
Vol 182 (2) ◽  
pp. 437-443 ◽  
Author(s):  
Jos Vanderleyden ◽  
Jochen Kurth ◽  
Hubert Verachtert
Keyword(s):  
Alternative Oxidase ◽  
Alternative Pathway ◽  
Total Activity ◽  
Terminal Oxidase ◽  
Submitochondrial Particles ◽  
Terminal Electron Acceptor ◽  
Cytochrome Pathway ◽  
O2 Concentration ◽  
System 2

Mitochondria and submitochondrial particles of the osmophilic yeast-like fungus Moniliella tomentosa may respire by means of two pathways: a normal cytochrome pathway, sensitive to cyanide and antimycin A, and an alternative pathway, which is insensitive to these inhibitors but is specifically inhibited by salicylhydroxamic acid. The affinities of both oxidases for succinate and NADH as substrates, for O2 as terminal electron acceptor, and for AMP as stimulator of the alternative oxidase were determined. 1. Submitochondrial particles of M. tomentosa may also respire by means of a cyanide-sensitive and/or cyanide-insensitive system. 2. The activities of both oxidases as compared with the total activity are roughly the same in submitochondrial particles as in the original mitochondria. 3. The terminal oxidase of the cyanide-insensitive pathway requires a 10-fold higher O2 concentration for saturation than does cytochrome c oxidase. 4. The apparent Km for succinate is about 3 times higher for the alternative than for the normal oxidase when measured in mitochondria, and 4–10 times higher when measured in submitochondrial particles. The apparent Km for NADH is roughly the same for both oxidases. 5. The apparent Km values of both oxidases for succinate are always lower in submitochondrial particles than in mitochondria. 6. The apparent Km for AMP, acting as a stimulator of the alternative oxidase, is the same (25μm) in mitochondria as in sub-mitochondrial particles. These results are discussed in the light of the structure and localization of the components of the alternative oxidase.

scholarly journals The Oxa2 Protein ofNeurospora crassaPlays a Critical Role in the Biogenesis of Cytochrome Oxidase and Defines a Ubiquitous Subbranch of the Oxa1/YidC/Alb3 Protein Family

2004 ◽  
Vol 15 (4) ◽  
pp. 1853-1861 ◽  
Author(s):  
Soledad Funes ◽  
Frank E. Nargang ◽  
Walter Neupert ◽  
Johannes M. Herrmann
Keyword(s):  
Neurospora Crassa ◽  
Cytochrome Oxidase ◽  
Gene Product ◽  
Respiratory Chain ◽  
Alternative Oxidase ◽  
Critical Role ◽  
Complex Iv ◽  
Its Gene ◽  
Yeast Mutants ◽  
Common Function

Proteins of the Oxa1/YidC/Alb3 family mediate the insertion of proteins into membranes of mitochondria, bacteria, and chloroplasts. Here we report the identification of a second gene of the Oxa1/YidC/Alb3 family in the genome of Neurospora crassa, which we have named oxa2. Its gene product, Oxa2, is located in the inner membrane of mitochondria. Deletion of the oxa2 gene caused a specific defect in the biogenesis of cytochrome oxidase and resulted in induction of the alternative oxidase (AOD), which bypasses the need for complex IV of the respiratory chain. The Oxa2 protein of N. crassa complements Cox18-deficient yeast mutants suggesting a common function for both proteins. The oxa2 sequence allowed the identification of a new subfamily of Oxa1/YidC/Alb3 proteins whose members appear to be ubiquitously present in mitochondria of fungi, plants, and animals including humans.

scholarly journals Temperature-dependent alterations of respiration in leaves of two selected vascular plant species: the role of the alternative oxidase pathway

Bragantia ◽  
2002 ◽  
Vol 61 (2) ◽  
pp. 111-114 ◽  
Author(s):  
Natalia V. Pystina ◽  
Roman A. Danilov
Keyword(s):  
Alternative Oxidase ◽  
Alternative Pathway ◽  
Vascular Plant ◽  
Relative Activity ◽  
Temperature Dependent ◽  
Respiratory Pathway ◽  
Alternative Respiratory Pathway ◽  
Benzhydroxamic Acid ◽  
Increasing Temperature

Effects of higher temperatures on respiration and activity of alternative oxidase (AOX) were studied in mature leaves of Ajuga reptans L. and Rhodiola rosea L. Total respiration in both A. reptans and R. rosea increased exponentially with the increasing temperature of 10 °C to 35 °C. Respiration in the presence of benzhydroxamic acid (BHAM) also increased exponentially in accordance with the increasing temperature in the leaves of both A. reptans and R. rosea. Relative activity of the alternative pathway decreased significantly in the leaves of A. reptans with increasing temperatures. However, an increase in the relative activity of the alternative pathway was detected in the leaves of R. rosea. Thermoresistance of the alternative respiratory pathway was considered to be higher in R. rosea compared to A. reptans. We suppose that A. reptans and R. rosea have different mechanisms regulating partitioning of electrons to the alternative respiratory pathway.

scholarly journals Effect of growth at low temperature on the alternative pathway respiration in Acanthamoeba castellanii mitochondria.

2001 ◽  
Vol 48 (3) ◽  
pp. 729-737 ◽  
Author(s):  
W Jarmuszkiewicz ◽  
O Fraczyk ◽  
L Hryniewiecka
Keyword(s):  
Low Temperature ◽  
Alternative Oxidase ◽  
Alternative Pathway ◽  
Plant Mitochondria ◽  
Physiological Role ◽  
Acanthamoeba Castellanii ◽  
Control Culture ◽  
Cytochrome Pathway ◽  
Coupling Parameters ◽  
Unicellular Organisms

Mitochondria of amoeba Acanthamoeba castellanii in addition to the conventional cytochrome pathway possess, like plant mitochondria, a cyanide-resistant alternative quinol oxidase. In mitochondria isolated from amoeba batch culture grown temporarily at low temperature (6 degrees C), higher respiration was accompanied by lower coupling parameters as compared to control culture (grown at 28 degrees C). In the presence of benzohydroxamate, respiratory rates and coupling parameters were similar in both types of mitochondria indicating that growth in cold conditions did not disturb the cytochrome pathway. Increased contribution of alternative oxidase in total mitochondrial respiration in low-temperature-grown amoeba cells was confirmed by calculation of its contribution using ADP/O measurements. Furthermore, in mitochondria from low-temperature- grown cells the content of the alternative oxidase was increased and correlated with the increase in the unstimulated and GMP-stimulated cyanide-resistant respiratory activity. A possible physiological role of higher activity of alternative oxidase as response to growth at a low temperature in unicellular organisms, such as amoeba, is discussed.

scholarly journals Alternative Oxidase Inhibitors Potentiate the Activity of Atovaquone against Plasmodium falciparum

1999 ◽  
Vol 43 (3) ◽  
pp. 651-654 ◽  
Author(s):  
Anina D. Murphy ◽  
Naomi Lang-Unnasch
Keyword(s):  
Plasmodium Falciparum ◽  
Oxygen Consumption ◽  
Alternative Oxidase ◽  
Inhibitory Concentration ◽  
Oxidase Inhibitor ◽  
Dependent Manner ◽  
Fractional Inhibitory Concentration ◽  
Respiratory Pathway ◽  
Salicylhydroxamic Acid

ABSTRACT Recent evidence suggests that the malaria parasite Plasmodium falciparum utilizes a branched respiratory pathway including both a cytochrome chain and an alternative oxidase. This branched respiratory pathway model has been used as a basis for examining the mechanism of action of two antimalarial agents, atovaquone and proguanil. In polarographic assays, atovaquone immediately reduced the parasite oxygen consumption rate in a concentration-dependent manner. This is consistent with its previously described role as an inhibitor of the cytochrome bc1complex. Atovaquone maximally inhibited the rate of P. falciparum oxygen consumption by 73% ± 10%. At all atovaquone concentrations tested, the addition of the alternative oxidase inhibitor, salicylhydroxamic acid, resulted in a further decrease in the rate of parasite oxygen consumption. At the highest concentrations of atovaquone tested, the activities of salicylhydroxamic acid and atovaquone appear to overlap, suggesting that at these concentrations, atovaquone partially inhibits the alternative oxidase as well as the cytochrome chain. Drug interaction studies with atovaquone and salicylhydroxamic acid indicate atovaquone’s activity against P. falciparum in vitro is potentiated by this alternative oxidase inhibitor, with a sum fractional inhibitory concentration of 0.6. Propyl gallate, another alternative oxidase inhibitor, also potentiated atovaquone’s activity, with a sum fractional inhibitory concentration of 0.7. Proguanil, which potentiates atovaquone activity in vitro and in vivo, had a small effect on parasite oxygen consumption in polarographic assays when used alone or in the presence of atovaquone or salicylhydroxamic acid. This suggests that proguanil does not potentiate atovaquone by direct inhibition of either branch of the parasite respiratory chain.

scholarly journals Relative potency of a novel acaricidal compound from Xenorhabdus, a bacterial genus mutualistically associated with entomopathogenic nematodes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Gamze Incedayi ◽  
Harun Cimen ◽  
Derya Ulug ◽  
Mustapha Touray ◽  
Edna Bode ◽  
...  
Keyword(s):  
Adult Female ◽  
Entomopathogenic Nematodes ◽  
Field Experiments ◽  
Petri Dish ◽  
Phytoseiulus Persimilis ◽  
Mortality Rates ◽  
Predatory Mites ◽  
The Novel ◽  
Compound Identification ◽  
Mutant Strains

AbstractOur study aimed to identify the novel acaricidal compound in Xenorhabdus szentirmaii and X. nematophila using the easyPACId approach (easy Promoter Activated Compound Identification). We determined the (1) effects of cell-free supernatant (CFS) obtained from mutant strains against T. urticae females, (2) CFS of the acaricidal bioactive strain of X. nematophila (pCEP_kan_XNC1_1711) against different biological stages of T. urticae, and females of predatory mites, Phytoseiulus persimilis and Neoseiulus californicus, (3) effects of the extracted acaricidal compound on different biological stages of T. urticae, and (4) cytotoxicity of the active substance. The results showed that xenocoumacin produced by X. nematophila was the bioactive acaricidal compound, whereas the acaricidal compound in X. szentirmaii was not determined. The CFS of X. nematophila (pCEP_kan_XNC1_1711) caused 100, 100, 97.3, and 98.1% mortality on larvae, protonymph, deutonymph and adult female of T. urticae at 7 dpa in petri dish experiments; and significantly reduced T. urticae population in pot experiments. However, the same CFS caused less than 36% mortality on the predatory mites at 7dpa. The mortality rates of extracted acaricidal compound (xenocoumacin) on the larva, protonymph, deutonymph and adult female of T. urticae were 100, 100, 97, 96% at 7 dpa. Cytotoxicity assay showed that IC50 value of xenocoumacin extract was 17.71 μg/ml after 48 h. The data of this study showed that xenocoumacin could potentially be used as bio-acaricide in the control of T. urticae; however, its efficacy in field experiments and its phytotoxicity need to be assessed in future.

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