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The Role of the Alternative Oxidase in Stabilizing the in Vivo
Reduction State of the Ubiquinone Pool and the
Activation State of the Alternative Oxidase 总被引:4,自引:3,他引:4 下载免费PDF全文
Frank F. Millenaar Joris J. Benschop Anneke M. Wagner Hans Lambers 《Plant physiology》1998,118(2):599-607
A possible function for the alternative (nonphosphorylating) pathway is to stabilize the reduction state of the ubiquinone pool (Qr/Qt), thereby avoiding an increase in free radical production. If the Qr/Qt were stabilized by the alternative pathway, then Qr/Qt should be less stable when the alternative pathway is blocked. Qr/Qt increased when we exposed roots of Poa annua (L.) to increasing concentrations of KCN (an inhibitor of the cytochrome pathway). However, when salicylhydroxamic acid, an inhibitor of the alternative pathway, was added at the same time, Qr/Qt increased significantly more. Therefore, we conclude that the alternative pathway stabilizes Qr/Qt. Salicylhydroxamic acid increasingly inhibited respiration with increasing concentrations of KCN. In the experiments described here the alternative oxidase protein was invariably in its reduced (high-activity) state. Therefore, changes in the reduction state of the alternative oxidase cannot account for an increase in activity of the alternative pathway upon titration with KCN. The pyruvate concentration in intact roots increased only after the alternative pathway was blocked or the cytochrome pathway was severely inhibited. The significance of the pyruvate concentration and Qr/Qt on the activity of the alternative pathway in intact roots is discussed. 相似文献
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Deep Chatterjee Denis Kudlinzki Verena Linhard Krishna Saxena Ulrich Schieborr Santosh L. Gande Jan Philip Wurm Jens W?hnert Rupert Abele Vladimir V. Rogov Volker D?tsch Heinz D. Osiewacz Sridhar Sreeramulu Harald Schwalbe 《The Journal of biological chemistry》2015,290(26):16415-16430
Low levels of reactive oxygen species (ROS) act as important signaling molecules, but in excess they can damage biomolecules. ROS regulation is therefore of key importance. Several polyphenols in general and flavonoids in particular have the potential to generate hydroxyl radicals, the most hazardous among all ROS. However, the generation of a hydroxyl radical and subsequent ROS formation can be prevented by methylation of the hydroxyl group of the flavonoids. O-Methylation is performed by O-methyltransferases, members of the S-adenosyl-l-methionine (SAM)-dependent O-methyltransferase superfamily involved in the secondary metabolism of many species across all kingdoms. In the filamentous fungus Podospora anserina, a well established aging model, the O-methyltransferase (PaMTH1) was reported to accumulate in total and mitochondrial protein extracts during aging. In vitro functional studies revealed flavonoids and in particular myricetin as its potential substrate. The molecular architecture of PaMTH1 and the mechanism of the methyl transfer reaction remain unknown. Here, we report the crystal structures of PaMTH1 apoenzyme, PaMTH1-SAM (co-factor), and PaMTH1-S-adenosyl homocysteine (by-product) co-complexes refined to 2.0, 1.9, and 1.9 Å, respectively. PaMTH1 forms a tight dimer through swapping of the N termini. Each monomer adopts the Rossmann fold typical for many SAM-binding methyltransferases. Structural comparisons between different O-methyltransferases reveal a strikingly similar co-factor binding pocket but differences in the substrate binding pocket, indicating specific molecular determinants required for substrate selection. Furthermore, using NMR, mass spectrometry, and site-directed active site mutagenesis, we show that PaMTH1 catalyzes the transfer of the methyl group from SAM to one hydroxyl group of the myricetin in a cation-dependent manner. 相似文献
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Increased Enzymatic O-GlcNAcylation of Mitochondrial Proteins Impairs
Mitochondrial Function in Cardiac Myocytes Exposed to High
Glucose 总被引:1,自引:0,他引:1
Yong Hu Jorge Suarez Eduardo Fricovsky Hong Wang Brian T. Scott Sunia A. Trauger Wenlong Han Ying Hu Mary O. Oyeleye Wolfgang H. Dillmann 《The Journal of biological chemistry》2009,284(1):547-555
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Hideo Yukioka Reiji Tanaka Shuichiro Inagaki Kenji Katoh Nobuo Miki Akira Mizutani Michio Masuko Hitoshi Kunoh 《Fungal genetics and biology : FG & B》1997,22(3):221-228
The phytopathogenic fungusMagnaporthe griseahas a cyanide-resistant respiratory pathway. The fungicide SSF-126 ((E)-2-methoxyimino-N-methyl-2-(2-phenoxyphenyl) acetamide) blocks the cytochrome electron transport ofM. griseaand induces the alternative respiratory pathway. Twelve mutants ofM. griseamore susceptible to SSF-126 than wild type were identified afterN-methyl-N′-nitro-N-nitrosoguanidine mutagenesis. Five mutants retained a reduced alternative respiration activity, and seven mutants lacked alternative pathway activity. A monoclonal antibody against the maize alternative oxidase cross-reacted against a 40-kDa mitochondrial protein ofM. grisea,indicating that the 40-kDa protein is an alternative oxidase. Immunoblot analysis indicated that the seven completely deficient mutants grouped into two classes: four mutants produced the 40-kDa proteins while the other three mutants failed to produce the functional protein. 相似文献
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Differential Expression of Alternative Oxidase Genes in Soybean
Cotyledons during Postgerminative Development 总被引:3,自引:2,他引:3 下载免费PDF全文
Tulene C. McCabe Patrick M. Finnegan A. Harvey Millar David A. Day James Whelan 《Plant physiology》1998,118(2):675-682
The expression of the alternative oxidase (AOX) was investigated during cotyledon development in soybean (Glycine max [L.] Merr.) seedlings. The total amount of AOX protein increased throughout development, not just in earlier stages as previously thought, and was correlated with the increase in capacity of the alternative pathway. Each AOX isoform (AOX1, AOX2, and AOX3) showed a different developmental trend in mRNA abundance, such that the increase in AOX protein and capacity appears to involve a shift in gene expression from AOX2 to AOX3. As the cotyledons aged, the size of the mitochondrial ubiquinone pool decreased. We discuss how this and other factors may affect the alternative pathway activity that results from the developmental regulation of AOX expression. 相似文献
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Saline Stress Alters the Temporal Patterns of Xylem
Differentiation and Alternative Oxidase Expression in Developing
Soybean Roots 总被引:2,自引:0,他引:2 下载免费PDF全文
Mirna Hilal Ana M. Zenoff Graciela Ponessa Hortensia Moreno Eddy M. Massa 《Plant physiology》1998,117(2):695-701
We conducted a coordinated biochemical and morphometric analysis of the effect of saline conditions on the differentiation zone of developing soybean (Glycine max L.) roots. Between d 3 and d 14 for seedlings grown in control or NaCl-supplemented medium, we studied (a) the temporal evolution of the respiratory alternative oxidase (AOX) capacity in correlation with the expression and localization of AOX protein analyzed by tissue-print immunoblotting; (b) the temporal evolution and tissue localization of a peroxidase activity involved in lignification; and (c) the structural changes, visualized by light microscopy and quantified by image digitization. The results revealed that saline stress retards primary xylem differentiation. There is a corresponding delay in the temporal pattern of AOX expression, which is consistent with the xylem-specific localization of AOX protein and the idea that this enzyme is linked to xylem development. An NaCl-induced acceleration of the development of secondary xylem was also observed. However, the temporal pattern of a peroxidase activity localized in the primary and secondary xylem was unaltered by NaCl treatment. Thus, the NaCl-stressed root was specifically affected in the temporal patterns of AOX expression and xylem development. 相似文献
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Intracellular cAMP Content and the Induction of Alternative Oxidase in the Yeast Yarrowia lipolytica
The effect of cyanide, antimycin A, ethanol, and acetate on the induction of alternative oxidase in the yeast Yarrowia lipolytica VKM Y-155 was studied. The aerobic incubation of logarithmic-phase cells, whose respiration is sensitive to cyanide, in the presence of the aforementioned compounds led to the development of cyanide-resistant respiration, which could be suppressed by benzohydroxamic acid, an inhibitor of alternative oxidases. The incubation of cells with cyanide, ethanol, or acetate raised the intracellular pool of cAMP, which attained maximal values after a 2- to 3-min incubation period, then rapidly decreased to the initial value and did not change over the next three hours of incubation. The possible role of cAMP in the induction of alternative oxidase in yeast cells is discussed. 相似文献
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Silvia Devars Rosa Hernandez Raul Covian Arturo Garcia-Horsman Blanca Barquera Rafael Moreno-Sanchez 《The Journal of eukaryotic microbiology》1998,45(1):122-130
ABSTRACT A study of the effect of respiratory inhibitors on O2 uptake of Euglena gracilis mitochondria, isolated from cells grown in the presence of cyanide or with ethanol as carbon source, was undertaken. The contents of cytochrome c oxidase and alternative oxidase were also determined. Inhibition of respiration by antimycin and cyanide was only partial and it was dependent on the oxidizable substrate used. Succinate oxidation was the most sensitive to cyanide whereas lactate oxidation was the most resistant. Cell growth in the presence of cyanide or with ethanol as carbon source brought about an enhanced content of alternative oxidase without a concomitant increase in cytochrome aa3 content. However, a correlation between cyanide-resistant respiration and alternative oxidase content was not found. Analysis of heme types in mitochondrial membranes revealed the absence of heme O. The data suggest the presence of an inducible alternative oxidase in Euglena mitochondria which has high resistance to cyanide and contains heme B. A close relationship between Euglena alternative oxidase and bacterial quinol oxidases containing B-type heme is proposed. 相似文献
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Shunkei Enoki Akinori Shimizu Chisato Hayashi Hirotake Imanishi Osamu Hashizume Kazuyuki Mekada Hitoshi Suzuki Tetsuo Hashimoto Kazuto Nakada Jun-Ichi Hayashi 《Experimental Animals》2014,63(1):21-30
Previous reports have shown that transmitochondrial mito-mice with nuclear DNA from
Mus musculus and mtDNA from M. spretus do not express
respiration defects, whereas those with mtDNA from Rattus norvegicus
cannot be generated from ES cybrids with mtDNA from R. norvegicus due to
inducing significant respiration defects and resultant losing multipotency. Here, we
isolated transmitochondrial cybrids with mtDNA from various rodent species classified
between M. spretus and R. norvegicus, and compared the
O2 consumption rates. The results showed a strong negative correlation
between phylogenetic distance and reduction of O2 consumption rates, which
would be due to the coevolution of nuclear and mitochondrial genomes and the resultant
incompatibility between the nuclear genome from M. musculus and the
mitochondrial genome from the other rodent species. These observations suggested that
M. caroli was an appropriate mtDNA donor to generate transmitochondrial
mito-mice with nuclear DNA from M. musculus. Then, we generated ES
cybrids with M. caroli mtDNA, and found that these ES cybrids expressed
respiration defects without losing multipotency and can be used to generate
transmitochondrial mito-mice expressing mitochondrial disorders. 相似文献
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Dorsaf Hedhli Olivier Denis Daniel Barkan Mamadou Daffé Michael S. Glickman Kris Huygen 《PloS one》2013,8(10)
The existing vaccine against tuberculosis (M. bovis BCG) exerts some protection against the extrapulmonary forms of the disease, particularly in young children, but is not very effective against the pulmonary form of TB, which often results from the reactivation of a latent M. tuberculosis (M.tb)infection. Among the new approaches in TB vaccine development, live attenuated M.tb mutants are a promising new avenue. Here we report on the vaccine potential of two highly attenuated M.tb mutants, MGM1991 and M.tbhma::hyg (HMA), lacking all oxygenated mycolates in their cell wall. In C57BL/6 mice, stronger Th1 (IFN-γ, IL-2 and TNF-α) and IL-17 responses could be induced following subcutaneous vaccination with either of the two mutants, than following vaccination with M. bovis BCG. Significantly more mycobacteria specific IFN-γ producing CD4+ and particularly CD8+ T cells could be detected by intracellular cytokine staining in mice vaccinated with the M.tb mutants. Finally, vaccination with either of the two mutants conferred stronger protection against intratracheal M.tb challenge than vaccination with BCG, as indicated by reduced bacterial replication in lungs at 4 to 12 weeks after challenge. Protection against M. tb dissemination, as indicated by reduced bacterial numbers in spleen, was comparable for both mutants to protection conferred by BCG. 相似文献
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Petals, sepals, pistils, and stamens from flowers of two landscape tree species (Elaeocarpus hainanensis Oliv and Michelia alba DC) were analyzed to determine the changes in levels of reactive oxygen species (ROS), lipoxygenase (LOX) activity, and alternative pathway respiration throughout flower development. Histochemical and quantitative analyses revealed that ROS levels differed among tissues and stages of flower development. ROS levels were high in all flower tissues early in development and then declined to low levels late in development. ROS levels were highest in the stamen. In contrast, LOX activity, heat energy evolution, and the percentage of total respiration represented by alternative respiration in M. alba petals increased with flower development. The results suggest that ROS are involved in the growth of various flower tissues at early developmental stages and not only located on the tip site of growing tissues. The reduction in ROS generation later in development is probably due to the significant elevation in alternative respiration. The increase in LOX activity and heat energy evolution might contribute to the formation and release of some aromatic compounds and to flower opening. LOX, however, might not mediate ROS generation in the petal during development. 相似文献
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Eleanor C. Saunders William W. Ng Joachim Kloehn Jennifer M. Chambers Milica Ng Malcolm J. McConville 《PLoS pathogens》2014,10(1)
Leishmania parasites alternate between extracellular promastigote stages in the insect vector and an obligate intracellular amastigote stage that proliferates within the phagolysosomal compartment of macrophages in the mammalian host. Most enzymes involved in Leishmania central carbon metabolism are constitutively expressed and stage-specific changes in energy metabolism remain poorly defined. Using 13C-stable isotope resolved metabolomics and 2H2O labelling, we show that amastigote differentiation is associated with reduction in growth rate and induction of a distinct stringent metabolic state. This state is characterized by a global decrease in the uptake and utilization of glucose and amino acids, a reduced secretion of organic acids and increased fatty acid β-oxidation. Isotopomer analysis showed that catabolism of hexose and fatty acids provide C4 dicarboxylic acids (succinate/malate) and acetyl-CoA for the synthesis of glutamate via a compartmentalized mitochondrial tricarboxylic acid (TCA) cycle. In vitro cultivated and intracellular amastigotes are acutely sensitive to inhibitors of mitochondrial aconitase and glutamine synthetase, indicating that these anabolic pathways are essential for intracellular growth and virulence. Lesion-derived amastigotes exhibit a similar metabolism to in vitro differentiated amastigotes, indicating that this stringent response is coupled to differentiation signals rather than exogenous nutrient levels. Induction of a stringent metabolic response may facilitate amastigote survival in a nutrient-poor intracellular niche and underlie the increased dependence of this stage on hexose and mitochondrial metabolism. 相似文献