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.

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 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.

Alternative oxidase is an important player in the regulation of nitric oxide levels under normoxic and hypoxic conditions in plants

2019 ◽  
Vol 70 (17) ◽  
pp. 4345-4354 ◽  
Author(s):  
Aprajita Kumari ◽  
Pradeep Kumar Pathak ◽  
Mallesham Bulle ◽  
Abir U Igamberdiev ◽  
Kapuganti Jagadis Gupta
Keyword(s):  
Nitric Oxide ◽  
Alternative Oxidase ◽  
Plant Mitochondria ◽  
No Production ◽  
Complex Iv ◽  
Increase Energy Efficiency ◽  
Hypoxic Conditions ◽  
Cytochrome Pathway ◽  
Important Player ◽  
Elicitor Treatments

Abstract Plant mitochondria possess two different pathways for electron transport from ubiquinol: the cytochrome pathway and the alternative oxidase (AOX) pathway. The AOX pathway plays an important role in stress tolerance and is induced by various metabolites and signals. Previously, several lines of evidence indicated that the AOX pathway prevents overproduction of superoxide and other reactive oxygen species. More recent evidence suggests that AOX also plays a role in regulation of nitric oxide (NO) production and signalling. The AOX pathway is induced under low phosphate, hypoxia, pathogen infections, and elicitor treatments. The induction of AOX under aerobic conditions in response to various stresses can reduce electron transfer through complexes III and IV and thus prevents the leakage of electrons to nitrite and the subsequent accumulation of NO. Excess NO under various stresses can inhibit complex IV; thus, the AOX pathway minimizes nitrite-dependent NO synthesis that would arise from enhanced electron leakage in the cytochrome pathway. By preventing NO generation, AOX can reduce peroxynitrite formation and tyrosine nitration. In contrast to its function under normoxia, AOX has a specific role under hypoxia, where AOX can facilitate nitrite-dependent NO production. This reaction drives the phytoglobin–NO cycle to increase energy efficiency under hypoxia.

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.

Effects of Hydrogen Sulfide on Alternative Pathway Respiration and Induction of Alternative Oxidase Gene Expression in Rice Suspension Cells

2010 ◽  
Vol 65 (7-8) ◽  
pp. 463-471 ◽  
Author(s):  
Man Xiao ◽  
Jun Ma ◽  
Hongyu Li ◽  
Han Jin ◽  
Hanqing Feng
Keyword(s):  
Cell Viability ◽  
Molecular Mechanisms ◽  
Alternative Oxidase ◽  
Alternative Pathway ◽  
Plant Mitochondria ◽  
Transcript Level ◽  
Gene Transcript ◽  
Suspension Cells ◽  
Oxidase Gene ◽  
Culture Cells

The toxic effects of H2S on plants are well documented. However, the molecular mechanisms reponsible for inhibition of plants by H2S are still not completely understood. We determined the effects of NaHS in the range of 0.5 - 10 mM on the growth of rice suspension culture cells, as well as on the expression of the alternative oxidase (AOX) gene. AOX is the terminal oxidase of the alternative pathway (AP) and exists in plant mitochondria. The results showed that H2S treatment enhanced the AP activity. During the process of H2S treatment for 4 h, the AP activity increased dramatically and achieved the peak value at a concentration of 2 mM NaHS. Then it declined at higher concentrations of NaHS (5 - 10 mM) and maintained a steady level. The AOX1 gene transcript level also showed a similar change as the AP activity. Interestingly, different NaHS concentrations seemed to have different effects on the expression of AOX1a, AOX1b, and AOX1c. The induction of AOX expression by low concentrations of NaHS was inferred through a reactive oxygen species (ROS)-independent pathway. At the same time, rice cells grown in culture were very sensitive to H2S, different H2S concentrations induced an increase in the cell viability. These results indicate that the H2S-induced AOX induction might play a role in inhibiting the ROS production and have an influence on cell viability.

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.

Effects of Salicylic Acid on Alternative Pathway Respiration and Alternative Oxidase Expression in Tobacco Calli

2008 ◽  
Vol 63 (9-10) ◽  
pp. 706-712 ◽  
Author(s):  
Tao Lei ◽  
Ying-Cai Yan ◽  
De-Hui Xi ◽  
Hong Feng ◽  
Xin Sun ◽  
...  
Keyword(s):  
Salicylic Acid ◽  
Protein Level ◽  
Alternative Oxidase ◽  
Alternative Pathway ◽  
Plant Mitochondria ◽  
Transcript Level ◽  
Gene Transcript ◽  
Transport Pathway ◽  
Steady Level ◽  
Covalently Linked

The alternative pathway (AP) respiration of plants is a cyanide-resistant and non-phosphorylating electron transport pathway in mitochondria. Alternative oxidase (AOX) is the terminal oxidase of the AP and exists in plant mitochondria as two states: the reduced, noncovalently linked state or the oxidized, covalently cross-linked state. In the present study, the effects of 20 μm exogenous salicylic acid (SA) on both AP activity and AOX expression in mitochondria of tobacco (Nicotiana rustica L. cv. yellow flower) calli were investigated. The results showed that SA treatment enhanced the AP activity. During the process of SA treatment, the AP activity increased dramatically and achieved the peak value after 8 h of treatment. Then it declined until 16 h, and maintained a steady level between 16 and 24 h. Changes in both the total AOX protein level and the reduced state were in accordance with the AP activity, but the oxidized state changed differently. The aox1 gene transcript level also showed a similar change as the AP activity and AOX protein level. The induction of AOX expression by low concentrations of SA was inferred through a reactive oxygen species (ROS)-independent pathway. These results indicate that the enhancement of AP activity in response to SA is correlated to the expression of AOX, and the reduced, non-covalently linked state of AOX plays an important role during this process.

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.

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