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Sample records for mitochondrial complex iii

  1. Suppressors of superoxide production from mitochondrial complex III

    PubMed Central

    Orr, Adam L.; Vargas, Leonardo; Turk, Carolina N.; Baaten, Janine E.; Matzen, Jason T.; Dardov, Victoria J.; Attle, Stephen J.; Li, Jing; Quackenbush, Douglas C.; Goncalves, Renata L. S.; Perevoshchikova, Irina V.; Petrassi, H. Michael; Meeusen, Shelly L.; Ainscow, Edward K.; Brand, Martin D.

    2015-01-01

    Mitochondrial electron transport drives ATP synthesis but also generates reactive oxygen species (ROS), which are both cellular signals and damaging oxidants. Superoxide production by respiratory complex III is implicated in diverse signaling events and pathologies but its role remains controversial. Using high-throughput screening we identified compounds that selectively eliminate superoxide production by complex III without altering oxidative phosphorylation; they modulate retrograde signaling including cellular responses to hypoxic and oxidative stress. PMID:26368590

  2. Suppressors of superoxide production from mitochondrial complex III.

    PubMed

    Orr, Adam L; Vargas, Leonardo; Turk, Carolina N; Baaten, Janine E; Matzen, Jason T; Dardov, Victoria J; Attle, Stephen J; Li, Jing; Quackenbush, Douglas C; Goncalves, Renata L S; Perevoshchikova, Irina V; Petrassi, H Michael; Meeusen, Shelly L; Ainscow, Edward K; Brand, Martin D

    2015-11-01

    Mitochondrial electron transport drives ATP synthesis but also generates reactive oxygen species, which are both cellular signals and damaging oxidants. Superoxide production by respiratory complex III is implicated in diverse signaling events and pathologies, but its role remains controversial. Using high-throughput screening, we identified compounds that selectively eliminate superoxide production by complex III without altering oxidative phosphorylation; they modulate retrograde signaling including cellular responses to hypoxic and oxidative stress. PMID:26368590

  3. Genetics Home Reference: mitochondrial complex III deficiency

    MedlinePlus

    ... species, which are harmful molecules that can damage DNA and tissues. MT-CYB and BCS1L gene mutations ... genes, the MT-CYB gene is found in DNA located in mitochondria, called mitochondrial DNA (mtDNA). This ...

  4. Real-time tracking mitochondrial dynamic remodeling with two-photon phosphorescent iridium (III) complexes.

    PubMed

    Huang, Huaiyi; Yang, Liang; Zhang, Pingyu; Qiu, Kangqiang; Huang, Juanjuan; Chen, Yu; Diao, JiaJie; Liu, Jiankang; Ji, Liangnian; Long, Jiangang; Chao, Hui

    2016-03-01

    Mitochondrial fission and fusion control the shape, size, number, and function of mitochondria in the cells of organisms from yeast to mammals. The disruption of mitochondrial fission and fusion is involved in severe human diseases such as Parkinson's disease, Alzheimer's disease, metabolic diseases, and cancers. Agents that can real-time track the mitochondrial dynamics are of great importance. However, the short excitation wavelengths and rapidly photo-bleaching properties of commercial mitochondrial dyes render them unsuitable for tracking mitochondrial dynamics. Thus, mitochondrial targeting agents that exhibit superior photo-stability under continual light irradiation, deep tissue penetration and at intrinsically high three-dimensional resolutions are urgently needed. Two-photon-excited compounds employ low-energy near-infrared light and have emerged as a non-invasive tool for real-time cell imaging. Here, cyclometalated Ir(III) complexes (Ir1-Ir5) are demonstrated as one- and two-photon phosphorescent probes for the real-time imaging and tracking of mitochondrial fission and fusion. The results indicate that Ir2 is well suited for two-photon phosphorescent tracking of mitochondrial fission and fusion in living cells and in Caenorhabditis elegans (C. elegans). This study provides a practical use for mitochondrial targeting two-photon phosphorescent Ir(III) complexes. PMID:26796044

  5. Thiol-based antioxidants elicit mitochondrial oxidation via respiratory complex III

    PubMed Central

    Beaudoin, Jessica N.; Ponnuraj, Nagendraprabhu; DiLiberto, Stephen J.; Hanafin, William P.; Kenis, Paul J. A.; Gaskins, H. Rex

    2015-01-01

    Excessive oxidation is widely accepted as a precursor to deleterious cellular function. On the other hand, an awareness of the role of reductive stress as a similar pathological insult is emerging. Here we report early dynamic changes in compartmentalized glutathione (GSH) redox potentials in living cells in response to exogenously supplied thiol-based antioxidants. Noninvasive monitoring of intracellular thiol-disulfide exchange via a genetically encoded biosensor targeted to cytosol and mitochondria revealed unexpectedly rapid oxidation of the mitochondrial matrix in response to GSH ethyl ester or N-acetyl-l-cysteine. Oxidation of the probe occurred within seconds in a concentration-dependent manner and was attenuated with the membrane-permeable ROS scavenger tiron. In contrast, the cytosolic sensor did not respond to similar treatments. Surprisingly, the immediate mitochondrial oxidation was not abrogated by depolarization of mitochondrial membrane potential or inhibition of mitochondrial GSH uptake. After detection of elevated levels of mitochondrial ROS, we systematically inhibited multisubunit protein complexes of the mitochondrial respiratory chain and determined that respiratory complex III is a downstream target of thiol-based compounds. Disabling complex III with myxothiazol completely blocked matrix oxidation induced with GSH ethyl ester or N-acetyl-l-cysteine. Our findings provide new evidence of a functional link between exogenous thiol-containing antioxidants and mitochondrial respiration. PMID:25994788

  6. Thiol-based antioxidants elicit mitochondrial oxidation via respiratory complex III.

    PubMed

    Kolossov, Vladimir L; Beaudoin, Jessica N; Ponnuraj, Nagendraprabhu; DiLiberto, Stephen J; Hanafin, William P; Kenis, Paul J A; Gaskins, H Rex

    2015-07-15

    Excessive oxidation is widely accepted as a precursor to deleterious cellular function. On the other hand, an awareness of the role of reductive stress as a similar pathological insult is emerging. Here we report early dynamic changes in compartmentalized glutathione (GSH) redox potentials in living cells in response to exogenously supplied thiol-based antioxidants. Noninvasive monitoring of intracellular thiol-disulfide exchange via a genetically encoded biosensor targeted to cytosol and mitochondria revealed unexpectedly rapid oxidation of the mitochondrial matrix in response to GSH ethyl ester or N-acetyl-l-cysteine. Oxidation of the probe occurred within seconds in a concentration-dependent manner and was attenuated with the membrane-permeable ROS scavenger tiron. In contrast, the cytosolic sensor did not respond to similar treatments. Surprisingly, the immediate mitochondrial oxidation was not abrogated by depolarization of mitochondrial membrane potential or inhibition of mitochondrial GSH uptake. After detection of elevated levels of mitochondrial ROS, we systematically inhibited multisubunit protein complexes of the mitochondrial respiratory chain and determined that respiratory complex III is a downstream target of thiol-based compounds. Disabling complex III with myxothiazol completely blocked matrix oxidation induced with GSH ethyl ester or N-acetyl-l-cysteine. Our findings provide new evidence of a functional link between exogenous thiol-containing antioxidants and mitochondrial respiration. PMID:25994788

  7. Impaired complex III assembly associated with BCS1L gene mutations in isolated mitochondrial encephalopathy.

    PubMed

    Fernandez-Vizarra, Erika; Bugiani, Marianna; Goffrini, Paola; Carrara, Franco; Farina, Laura; Procopio, Elena; Donati, Alice; Uziel, Graziella; Ferrero, Iliana; Zeviani, Massimo

    2007-05-15

    We investigated two unrelated children with an isolated defect of mitochondrial complex III activity. The clinical picture was characterized by a progressive encephalopathy featuring early-onset developmental delay, spasticity, seizures, lactic acidosis, brain atrophy and MRI signal changes in the basal ganglia. Both children were compound heterozygotes for novel mutations in the human bc1 synthesis like (BCS1L) gene, which encodes an AAA mitochondrial protein putatively involved in both iron homeostasis and complex III assembly. The pathogenic role of the mutations was confirmed by complementation assays, using a DeltaBcs1 strain of Saccharomyces cerevisiae. By investigating complex III assembly and the structural features of the BCS1L gene product in skeletal muscle, cultured fibroblasts and lymphoblastoid cell lines from our patients, we have demonstrated, for the first time in a mammalian system, that a major function of BCS1L is to promote the maturation of complex III and, more specifically, the incorporation of the Rieske iron-sulfur protein into the nascent complex. Defective BCS1L leads to the formation of a catalytically inactive, structurally unstable complex III. We have also shown that BCS1L is contained within a high-molecular-weight supramolecular complex which is clearly distinct from complex III intermediates. PMID:17403714

  8. Mitochondrial Dynamics Tracking with Two-Photon Phosphorescent Terpyridyl Iridium(III) Complexes

    NASA Astrophysics Data System (ADS)

    Huang, Huaiyi; Zhang, Pingyu; Qiu, Kangqiang; Huang, Juanjuan; Chen, Yu; Ji, Liangnian; Chao, Hui

    2016-02-01

    Mitochondrial dynamics, including fission and fusion, control the morphology and function of mitochondria, and disruption of mitochondrial dynamics leads to Parkinson’s disease, Alzheimer’s disease, metabolic diseases, and cancers. Currently, many types of commercial mitochondria probes are available, but high excitation energy and low photo-stability render them unsuitable for tracking mitochondrial dynamics in living cells. Therefore, mitochondrial targeting agents that exhibit superior anti-photo-bleaching ability, deep tissue penetration and intrinsically high three-dimensional resolutions are urgently needed. Two-photon-excited compounds that use low-energy near-infrared excitation lasers have emerged as non-invasive tools for cell imaging. In this work, terpyridyl cyclometalated Ir(III) complexes (Ir1-Ir3) are demonstrated as one- and two-photon phosphorescent probes for real-time imaging and tracking of mitochondrial morphology changes in living cells.

  9. Mitochondrial Dynamics Tracking with Two-Photon Phosphorescent Terpyridyl Iridium(III) Complexes.

    PubMed

    Huang, Huaiyi; Zhang, Pingyu; Qiu, Kangqiang; Huang, Juanjuan; Chen, Yu; Ji, Liangnian; Chao, Hui

    2016-01-01

    Mitochondrial dynamics, including fission and fusion, control the morphology and function of mitochondria, and disruption of mitochondrial dynamics leads to Parkinson's disease, Alzheimer's disease, metabolic diseases, and cancers. Currently, many types of commercial mitochondria probes are available, but high excitation energy and low photo-stability render them unsuitable for tracking mitochondrial dynamics in living cells. Therefore, mitochondrial targeting agents that exhibit superior anti-photo-bleaching ability, deep tissue penetration and intrinsically high three-dimensional resolutions are urgently needed. Two-photon-excited compounds that use low-energy near-infrared excitation lasers have emerged as non-invasive tools for cell imaging. In this work, terpyridyl cyclometalated Ir(III) complexes (Ir1-Ir3) are demonstrated as one- and two-photon phosphorescent probes for real-time imaging and tracking of mitochondrial morphology changes in living cells. PMID:26864567

  10. Mitochondrial Dynamics Tracking with Two-Photon Phosphorescent Terpyridyl Iridium(III) Complexes

    PubMed Central

    Huang, Huaiyi; Zhang, Pingyu; Qiu, Kangqiang; Huang, Juanjuan; Chen, Yu; Ji, Liangnian; Chao, Hui

    2016-01-01

    Mitochondrial dynamics, including fission and fusion, control the morphology and function of mitochondria, and disruption of mitochondrial dynamics leads to Parkinson’s disease, Alzheimer’s disease, metabolic diseases, and cancers. Currently, many types of commercial mitochondria probes are available, but high excitation energy and low photo-stability render them unsuitable for tracking mitochondrial dynamics in living cells. Therefore, mitochondrial targeting agents that exhibit superior anti-photo-bleaching ability, deep tissue penetration and intrinsically high three-dimensional resolutions are urgently needed. Two-photon-excited compounds that use low-energy near-infrared excitation lasers have emerged as non-invasive tools for cell imaging. In this work, terpyridyl cyclometalated Ir(III) complexes (Ir1-Ir3) are demonstrated as one- and two-photon phosphorescent probes for real-time imaging and tracking of mitochondrial morphology changes in living cells. PMID:26864567

  11. Low-dose ionizing radiation induces mitochondrial fusion and increases expression of mitochondrial complexes I and III in hippocampal neurons

    PubMed Central

    Chang, Chuang-Rung; Kao, Mou-Chieh; Chen, Kuan-Wei; Chiu, Shih-Che; Hsu, Ming-Ling; Hsiang, I-Chou; Chen, Yu-Jen; Chen, Linyi

    2015-01-01

    High energy ionizing radiation can cause DNA damage and cell death. During clinical radiation therapy, the radiation dose could range from 15 to 60 Gy depending on targets. While 2 Gy radiation has been shown to cause cancer cell death, studies also suggest a protective potential by low dose radiation. In this study, we examined the effect of 0.2-2 Gy radiation on hippocampal neurons. Low dose 0.2 Gy radiation treatment increased the levels of MTT. Since hippocampal neurons are post-mitotic, this result reveals a possibility that 0.2 Gy irradiation may increase mitochondrial activity to cope with stimuli. Maintaining neural plasticity is an energy-demanding process that requires high efficient mitochondrial function. We thus hypothesized that low dose radiation may regulate mitochondrial dynamics and function to ensure survival of neurons. Our results showed that five days after 0.2 Gy irradiation, no obvious changes on neuronal survival, neuronal synapses, membrane potential of mitochondria, reactive oxygen species levels, and mitochondrial DNA copy numbers. Interestingly, 0.2 Gy irradiation promoted the mitochondria fusion, resulting in part from the increased level of a mitochondrial fusion protein, Mfn2, and inhibition of Drp1 fission protein trafficking to the mitochondria. Accompanying with the increased mitochondrial fusion, the expressions of complexes I and III of the electron transport chain were also increased. These findings suggest that, hippocampal neurons undergo increased mitochondrial fusion to modulate cellular activity as an adaptive mechanism in response to low dose radiation. PMID:26415228

  12. Identification and functional prediction of mitochondrial complex III and IV mutations associated with glioblastoma

    PubMed Central

    Lloyd, Rhiannon E.; Keatley, Kathleen; Littlewood, D. Timothy J.; Meunier, Brigitte; Holt, William V.; An, Qian; Higgins, Samantha C.; Polyzoidis, Stavros; Stephenson, Katie F.; Ashkan, Keyoumars; Fillmore, Helen L.; Pilkington, Geoffrey J.; McGeehan, John E.

    2015-01-01

    Background Glioblastoma (GBM) is the most common primary brain tumor in adults, with a dismal prognosis. Treatment is hampered by GBM's unique biology, including differential cell response to therapy. Although several mitochondrial abnormalities have been identified, how mitochondrial DNA (mtDNA) mutations contribute to GBM biology and therapeutic response remains poorly described. We sought to determine the spectrum of functional complex III and IV mtDNA mutations in GBM. Methods The complete mitochondrial genomes of 10 GBM cell lines were obtained using next-generation sequencing and combined with another set obtained from 32 GBM tissues. Three-dimensional structural mapping and analysis of all the nonsynonymous mutations identified in complex III and IV proteins was then performed to investigate functional importance. Results Over 200 mutations were identified in the mtDNAs, including a significant proportion with very low mutational loads. Twenty-five were nonsynonymous mutations in complex III and IV, 9 of which were predicted to be functional and affect mitochondrial respiratory chain activity. Most of the functional candidates were GBM specific and not found in the general population, and 2 were present in the germ-line. Patient-specific maps reveal that 43% of tumors carry at least one functional candidate. Conclusions We reveal that the spectrum of GBM-associated mtDNA mutations is wider than previously thought, as well as novel structural-functional links between specific mtDNA mutations, abnormal mitochondria, and the biology of GBM. These results could provide tangible new prognostic indicators as well as targets with which to guide the development of patient-specific mitochondrially mediated chemotherapeutic approaches. PMID:25731774

  13. Differential proteomic profiling unveils new molecular mechanisms associated with mitochondrial complex III deficiency

    PubMed Central

    Morán, María; López-Bernardo, Elia; Cadenas, Susana; Hidalgo, Beatriz; Sánchez, Ricardo; Seneca, Sara; Arenas, Joaquín; Martín, Miguel A.; Ugalde, Cristina

    2014-01-01

    We have analyzed the cellular pathways and metabolic adaptations that take place in primary skin fibroblasts from patients with mutations in BCS1L, a major genetic cause of mitochondrial complex III enzyme deficiency. Mutant fibroblasts exhibited low oxygen consumption rates and intracellular ATP levels, indicating that the main altered molecular event probably is a limited respiration-coupled ATP production through the OXPHOS system. Two-dimensional DIGE and MALDI-TOF/TOF mass spectrometry analyses unambiguously identified 39 proteins whose expression was significantly altered in complex III-deficient fibroblasts. Extensive statistical and cluster analyses revealed a protein profile characteristic for the BCS1L mutant fibroblasts that included alterations in energy metabolism, cell signaling and gene expression regulation, cytoskeleton formation and maintenance, and intracellular stress responses. The physiological validation of the predicted functional adaptations of human cultured fibroblasts to complex III deficiency confirmed the up-regulation of glycolytic enzyme activities and the accumulation of branched-chain among other amino acids, suggesting the activation of anaerobic glycolysis and cellular catabolic states, in particular protein catabolism, together with autophagy as adaptive responses to mitochondrial respiratory chain dysfunction and ATP deficiency. Our data point to an overall metabolic and genetic reprogramming that could contribute to explain the clinical manifestations of complex III deficiency in patients. PMID:25239759

  14. A mouse model of mitochondrial complex III dysfunction induced by myxothiazol

    SciTech Connect

    Davoudi, Mina; Kallijärvi, Jukka; Marjavaara, Sanna; Kotarsky, Heike; Hansson, Eva; Levéen, Per; Fellman, Vineta

    2014-04-18

    Highlights: • Reversible chemical inhibition of complex III in wild type mouse. • Myxothiazol causes decreased complex III activity in mouse liver. • The model is useful for therapeutic trials to improve mitochondrial function. - Abstract: Myxothiazol is a respiratory chain complex III (CIII) inhibitor that binds to the ubiquinol oxidation site Qo of CIII. It blocks electron transfer from ubiquinol to cytochrome b and thus inhibits CIII activity. It has been utilized as a tool in studies of respiratory chain function in in vitro and cell culture models. We developed a mouse model of biochemically induced and reversible CIII inhibition using myxothiazol. We administered myxothiazol intraperitoneally at a dose of 0.56 mg/kg to C57Bl/J6 mice every 24 h and assessed CIII activity, histology, lipid content, supercomplex formation, and gene expression in the livers of the mice. A reversible CIII activity decrease to 50% of control value occurred at 2 h post-injection. At 74 h only minor histological changes in the liver were found, supercomplex formation was preserved and no significant changes in the expression of genes indicating hepatotoxicity or inflammation were found. Thus, myxothiazol-induced CIII inhibition can be induced in mice for four days in a row without overt hepatotoxicity or lethality. This model could be utilized in further studies of respiratory chain function and pharmacological approaches to mitochondrial hepatopathies.

  15. Nuclear gene mutations as the cause of mitochondrial complex III deficiency

    PubMed Central

    Fernández-Vizarra, Erika; Zeviani, Massimo

    2015-01-01

    Complex III (CIII) deficiency is one of the least common oxidative phosphorylation defects associated to mitochondrial disease. CIII constitutes the center of the mitochondrial respiratory chain, as well as a crossroad for several other metabolic pathways. For more than 10 years, of all the potential candidate genes encoding structural subunits and assembly factors, only three were known to be associated to CIII defects in human pathology. Thus, leaving many of these cases unresolved. These first identified genes were MT-CYB, the only CIII subunit encoded in the mitochondrial DNA; BCS1L, encoding an assembly factor, and UQCRB, a nuclear-encoded structural subunit. Nowadays, thanks to the fast progress that has taken place in the last 3–4 years, pathological changes in seven more genes are known to be associated to these conditions. This review will focus on the strategies that have permitted the latest discovery of mutations in factors that are necessary for a correct CIII assembly and activity, in relation with their function. In addition, new data further establishing the molecular role of LYRM7/MZM1L as a chaperone involved in CIII biogenesis are provided. PMID:25914718

  16. Nitric oxide interacts with mitochondrial complex III producing antimycin-like effects.

    PubMed

    Iglesias, Darío E; Bombicino, Silvina S; Valdez, Laura B; Boveris, Alberto

    2015-12-01

    The effect of NO between cytochromes b and c of the mitochondrial respiratory chain were studied using submitochondrial particles (SMP) from bovine heart and GSNO and SPER-NO as NO sources. Succinate-cytochrome c reductase (complex II-III) activity (222 ± 4 nmol/min. mg protein) was inhibited by 51% in the presence of 500 μM GSNO and by 48% in the presence of 30 μM SPER-NO, in both cases at ~1.25 μM NO. Neither GSNO nor SPER-NO were able to inhibit succinate-Q reductase activity (complex II; 220 ± 9 nmol/min. mg protein), showing that NO affects complex III. Complex II-III activity was decreased (36%) when SMP were incubated with l-arginine and mtNOS cofactors, indicating that this effect is also produced by endogenous NO. GSNO (500 μM) reduced cytochrome b562 by 71%, in an [O2] independent manner. Hyperbolic increases in O2(•-) (up to 1.3 ± 0.1 nmol/min. mg protein) and H2O2 (up to 0.64 ± 0.05 nmol/min. mg protein) productions were observed with a maximal effect at 500 μM GSNO. The O2(•-)/H2O2 ratio was 1.98 in accordance with the stoichiometry of the O2(•-) disproportionation. Moreover, H2O2 production was increased by 72-74% when heart coupled mitochondria were exposed to 500 μM GSNO or 30 μM SPER-NO. SMP incubated in the presence of succinate showed an EPR signal (g=1.99) compatible with a stable semiquinone. This EPR signal was increased not only by antimycin but also by GSNO and SPER-NO. These signals were not modified under N2 atmosphere, indicating that they are not a consequence to the effect of NOx species on complex III area. These results show that NO interacts with ubiquinone-cytochrome b area producing antimycin-like effects. This behaviour comprises the inhibition of electron transfer, the interruption of the oxidation of cytochromes b, and the enhancement of [UQH(•)]ss which, in turn, leads to an increase in O2(•-) and H2O2 mitochondrial production rates. PMID:26456055

  17. COX7A2L Is a Mitochondrial Complex III Binding Protein that Stabilizes the III2+IV Supercomplex without Affecting Respirasome Formation.

    PubMed

    Pérez-Pérez, Rafael; Lobo-Jarne, Teresa; Milenkovic, Dusanka; Mourier, Arnaud; Bratic, Ana; García-Bartolomé, Alberto; Fernández-Vizarra, Erika; Cadenas, Susana; Delmiro, Aitor; García-Consuegra, Inés; Arenas, Joaquín; Martín, Miguel A; Larsson, Nils-Göran; Ugalde, Cristina

    2016-08-30

    Mitochondrial respiratory chain (MRC) complexes I, III, and IV associate into a variety of supramolecular structures known as supercomplexes and respirasomes. While COX7A2L was originally described as a supercomplex-specific factor responsible for the dynamic association of complex IV into these structures to adapt MRC function to metabolic variations, this role has been disputed. Here, we further examine the functional significance of COX7A2L in the structural organization of the mammalian respiratory chain. As in the mouse, human COX7A2L binds primarily to free mitochondrial complex III and, to a minor extent, to complex IV to specifically promote the stabilization of the III2+IV supercomplex without affecting respirasome formation. Furthermore, COX7A2L does not affect the biogenesis, stabilization, and function of the individual oxidative phosphorylation complexes. These data show that independent regulatory mechanisms for the biogenesis and turnover of different MRC supercomplex structures co-exist. PMID:27545886

  18. The Role of Dihydroorotate Dehydrogenase in Apoptosis Induction in Response to Inhibition of the Mitochondrial Respiratory Chain Complex III

    PubMed Central

    Khutornenko, A. A.; Dalina, A. A.; Chernyak, B. V.; Chumakov, P. M.; Evstafieva, A. G.

    2014-01-01

    A mechanism for the induction of programmed cell death (apoptosis) upon dysfunction of the mitochondrial respiratory chain has been studied. Previously, we had found that inhibition of mitochondrial cytochrome bc1, a component of the electron transport chain complex III, leads to activation of tumor suppressor p53, followed by apoptosis induction. The mitochondrial respiratory chain is coupled to the de novo pyrimidine biosynthesis pathway via the mitochondrial enzyme dihydroorotate dehydrogenase (DHODH). The p53 activation induced in response to the inhibition of the electron transport chain complex III has been shown to be triggered by the impairment of the de novo pyrimidine biosynthesis due to the suppression of DHODH. However, it remained unclear whether the suppression of the DHODH function is the main cause of the observed apoptotic cell death. Here, we show that apoptosis in human colon carcinoma cells induced by the mitochondrial respiratory chain complex III inhibition can be prevented by supplementation with uridine or orotate (products of the reaction catalyzed by DHODH) rather than with dihydroorotate (a DHODH substrate). We conclude that apoptosis is induced in response to the impairment of the de novo pyrimidine biosynthesis caused by the inhibition of DHODH. The conclusion is supported by the experiment showing that downregulation of DHODH by RNA interference leads to accumulation of the p53 tumor suppressor and to apoptotic cell death. PMID:24772329

  19. Differential effects of buffer pH on Ca2+-induced ROS emission with inhibited mitochondrial complexes I and III

    PubMed Central

    Lindsay, Daniel P.; Camara, Amadou K. S.; Stowe, David F.; Lubbe, Ryan; Aldakkak, Mohammed

    2015-01-01

    Excessive mitochondrial reactive oxygen species (ROS) emission is a critical component in the etiology of ischemic injury. Complex I and complex III of the electron transport chain are considered the primary sources of ROS emission during cardiac ischemia and reperfusion (IR) injury. Several factors modulate ischemic ROS emission, such as an increase in extra-matrix Ca2+, a decrease in extra-matrix pH, and a change in substrate utilization. Here we examined the combined effects of these factors on ROS emission from respiratory complexes I and III under conditions of simulated IR injury. Guinea pig heart mitochondria were suspended in experimental buffer at a given pH and incubated with or without CaCl2. Mitochondria were then treated with either pyruvate, a complex I substrate, followed by rotenone, a complex I inhibitor, or succinate, a complex II substrate, followed by antimycin A, a complex III inhibitor. H2O2 release rate and matrix volume were compared with and without adding CaCl2 and at pH 7.15, 6.9, or 6.5 with pyruvate + rotenone or succinate + antimycin A to simulate conditions that may occur during in vivo cardiac IR injury. We found a large increase in H2O2 release with high [CaCl2] and pyruvate + rotenone at pH 6.9, but not at pHs 7.15 or 6.5. Large increases in H2O2 release rate also occurred at each pH with high [CaCl2] and succinate + antimycin A, with the highest levels observed at pH 7.15. The increases in H2O2 release were associated with significant mitochondrial swelling, and both H2O2 release and swelling were abolished by cyclosporine A, a desensitizer of the mitochondrial permeability transition pore (mPTP). These results indicate that ROS production by complex I and by complex III is differently affected by buffer pH and Ca2+ loading with mPTP opening. The study suggests that changes in the levels of cytosolic Ca2+ and pH during IR alter the relative amounts of ROS produced at mitochondrial respiratory complex I and complex III. PMID

  20. Defective oxidative phosphorylation in thyroid oncocytic carcinoma is associated with pathogenic mitochondrial DNA mutations affecting complexes I and III.

    PubMed

    Bonora, Elena; Porcelli, Anna Maria; Gasparre, Giuseppe; Biondi, Annalisa; Ghelli, Anna; Carelli, Valerio; Baracca, Alessandra; Tallini, Giovanni; Martinuzzi, Andrea; Lenaz, Giorgio; Rugolo, Michela; Romeo, Giovanni

    2006-06-15

    Oncocytic tumors are characterized by cells with an aberrant accumulation of mitochondria. To assess mitochondrial function in neoplastic oncocytic cells, we studied the thyroid oncocytic cell line XTC.UC1 and compared it with other thyroid non-oncocytic cell lines. Only XTC.UC1 cells were unable to survive in galactose, a condition forcing cells to rely solely on mitochondria for energy production. The rate of respiration and mitochondrial ATP synthesis driven by complex I substrates was severely reduced in XTC.UC1 cells. Furthermore, the enzymatic activity of complexes I and III was dramatically decreased in these cells compared with controls, in conjunction with a strongly enhanced production of reactive oxygen species. Osteosarcoma-derived transmitochondrial cell hybrids (cybrids) carrying XTC.UC1 mitochondrial DNA (mtDNA) were generated to discriminate whether the energetic failure depended on mitochondrial or nuclear DNA mutations. In galactose medium, XTC.UC1 cybrid clones showed reduced viability and ATP content, similarly to the parental XTC.UC1, clearly pointing to the existence of mtDNA alterations. Sequencing of XTC.UC1 mtDNA identified a frameshift mutation in ND1 and a nonconservative substitution in cytochrome b, two mutations with a clear pathogenic potential. In conclusion, this is the first demonstration that mitochondrial dysfunction of XTC.UC1 is due to a combined complex I/III defect associated with mtDNA mutations, as proven by the transfer of the defective energetic phenotype with the mitochondrial genome into the cybrids. PMID:16778181

  1. Autism associated to a deficiency of complexes III and IV of the mitochondrial respiratory chain.

    PubMed

    Guevara-Campos, José; González-Guevara, Lucía; Briones, Paz; López-Gallardo, Ester; Bulán, Nuria; Ruiz-Pesini, Eduardo; Ramnarine, Denisse; Montoya, Julio

    2010-09-01

    Autism is the prototype of generalized developmental disorders or what today are called autism spectrum disorders. In most cases it is impossible to detect a specific etiology. It is estimated that a causative diagnosis may be shown in approximately 10-37% of the cases, including, congenital rubella, tuberous sclerosis, chromosome abnormalities such as fragile X syndrome and 22q13.3 deletion syndrome, Angelman, Williams, Smith-Magenis, Sotos, Cornelia de Lange, Möbius, Joubert and Goldenhar syndromes, Ito's hypomelanosis, as well as certain cerebral malformations and several inherited metabolic disorders. The case of a 3-year old girl is described, who was considered as autistic according to the criteria established by the DSM-IV manual for psychiatric disorders. She showed a delay in psychomotor development since she was 18 months old; she pronounces very few words (10), points to some objects, does not look up and it is hard to establish eye contact with her. She has paradoxical deafness and therefore, does not respond when called or when she is given orders, she is beginning to walk. She has not convulsions. Laboratory tests showed an anion gap of 31.6 mEq/L, lactate: 2.55: mmol/L, pyruvate: 0.06 mmol/L, and elevated lactate to/pyruvate ratio: 42.5. Under optical microscopy a muscular biopsy showed a reduction of the diameter of muscular fibers. The study of energy metabolism showed a partial deficiency of complexes III and IV of the respiratory chain, which allowed us to conclude that this was a mitochondrial dysfunction with an autistic clinical spectrum. PMID:21302592

  2. Reduced levels of mitochondrial complex I subunit NDUFB8 and linked complex I + III oxidoreductase activity in the TgCRND8 mouse model of Alzheimer's disease.

    PubMed

    Francis, Beverly M; Yang, Jimao; Song, Byung Jun; Gupta, Saurabh; Maj, Mary; Bazinet, Richard P; Robinson, Brian; Mount, Howard T J

    2014-01-01

    Bioenergetic failure is a feature of Alzheimer's disease (AD). We examined mitochondrial function in the amyloid-β protein precursor transgenic 'TgCRND8' mouse model of AD. Activities of NADH: cytochrome c reductase (complex I + III) and cytochrome oxidase (complex IV) of the electron transport chain, as well as those of α-ketoglutarate dehydrogenase (α-KGDH) and pyruvate dehydrogenase (PDH) were assessed in brains of 45 week-old mice. Complex I + III activity was reduced by almost 50%, whereas complex IV, α-KGDH, and PDH activities were unaffected. Reduced activity coincided with decreased expression of NDUFB8, a nuclear-DNA encoded subunit integral to the assembly of complex I. The composition and availability of cardiolipin, a major phospholipid in inner mitochondrial membranes, was not altered. To determine whether mitochondrial output is affected by the selective reduction in complex I + III activity, we examined tissue levels of high-energy phosphates. ATP was maintained whereas creatine increased in the cortex and hippocampus. These results suggest disruption of complex I function and the likely role of creatine in sustaining ATP at late stages of dysfunction in TgCRND8 mice. PMID:24217272

  3. Organometallic Iridium(III) Anticancer Complexes with New Mechanisms of Action: NCI-60 Screening, Mitochondrial Targeting, and Apoptosis

    PubMed Central

    2013-01-01

    Platinum complexes related to cisplatin, cis-[PtCl2(NH3)2], are successful anticancer drugs; however, other transition metal complexes offer potential for combating cisplatin resistance, decreasing side effects, and widening the spectrum of activity. Organometallic half-sandwich iridium (IrIII) complexes [Ir(Cpx)(XY)Cl]+/0 (Cpx = biphenyltetramethylcyclopentadienyl and XY = phenanthroline (1), bipyridine (2), or phenylpyridine (3)) all hydrolyze rapidly, forming monofunctional G adducts on DNA with additional intercalation of the phenyl substituents on the Cpx ring. In comparison, highly potent complex 4 (Cpx = phenyltetramethylcyclopentadienyl and XY = N,N-dimethylphenylazopyridine) does not hydrolyze. All show higher potency toward A2780 human ovarian cancer cells compared to cisplatin, with 1, 3, and 4 also demonstrating higher potency in the National Cancer Institute (NCI) NCI-60 cell-line screen. Use of the NCI COMPARE algorithm (which predicts mechanisms of action (MoAs) for emerging anticancer compounds by correlating NCI-60 patterns of sensitivity) shows that the MoA of these IrIII complexes has no correlation to cisplatin (or oxaliplatin), with 3 and 4 emerging as particularly novel compounds. Those findings by COMPARE were experimentally probed by transmission electron microscopy (TEM) of A2780 cells exposed to 1, showing mitochondrial swelling and activation of apoptosis after 24 h. Significant changes in mitochondrial membrane polarization were detected by flow cytometry, and the potency of the complexes was enhanced ca. 5× by co-administration with a low concentration (5 μM) of the γ-glutamyl cysteine synthetase inhibitor L-buthionine sulfoximine (L-BSO). These studies reveal potential polypharmacology of organometallic IrIII complexes, with MoA and cell selectivity governed by structural changes in the chelating ligands. PMID:23618382

  4. Organometallic Iridium(III) anticancer complexes with new mechanisms of action: NCI-60 screening, mitochondrial targeting, and apoptosis.

    PubMed

    Hearn, Jessica M; Romero-Canelón, Isolda; Qamar, Bushra; Liu, Zhe; Hands-Portman, Ian; Sadler, Peter J

    2013-01-01

    Platinum complexes related to cisplatin, cis-[PtCl2(NH3)2], are successful anticancer drugs; however, other transition metal complexes offer potential for combating cisplatin resistance, decreasing side effects, and widening the spectrum of activity. Organometallic half-sandwich iridium (Ir(III)) complexes [Ir(Cp(x))(XY)Cl](+/0) (Cp(x) = biphenyltetramethylcyclopentadienyl and XY = phenanthroline (1), bipyridine (2), or phenylpyridine (3)) all hydrolyze rapidly, forming monofunctional G adducts on DNA with additional intercalation of the phenyl substituents on the Cp(x) ring. In comparison, highly potent complex 4 (Cp(x) = phenyltetramethylcyclopentadienyl and XY = N,N-dimethylphenylazopyridine) does not hydrolyze. All show higher potency toward A2780 human ovarian cancer cells compared to cisplatin, with 1, 3, and 4 also demonstrating higher potency in the National Cancer Institute (NCI) NCI-60 cell-line screen. Use of the NCI COMPARE algorithm (which predicts mechanisms of action (MoAs) for emerging anticancer compounds by correlating NCI-60 patterns of sensitivity) shows that the MoA of these Ir(III) complexes has no correlation to cisplatin (or oxaliplatin), with 3 and 4 emerging as particularly novel compounds. Those findings by COMPARE were experimentally probed by transmission electron microscopy (TEM) of A2780 cells exposed to 1, showing mitochondrial swelling and activation of apoptosis after 24 h. Significant changes in mitochondrial membrane polarization were detected by flow cytometry, and the potency of the complexes was enhanced ca. 5× by co-administration with a low concentration (5 μM) of the γ-glutamyl cysteine synthetase inhibitor L-buthionine sulfoximine (L-BSO). These studies reveal potential polypharmacology of organometallic Ir(III) complexes, with MoA and cell selectivity governed by structural changes in the chelating ligands. PMID:23618382

  5. A novel gly290asp mitochondrial cytochrome b mutation linked to a complex III deficiency in progressive exercise intolerance.

    PubMed

    Dumoulin, R; Sagnol, I; Ferlin, T; Bozon, D; Stepien, G; Mousson, B

    1996-10-01

    We have identified a new mitochondrial (mt) cytochrome b mutation in a 29-year-old man with progressive exercise muscle intolerance associated with a marked deficiency of complex III activity and a decreased amount of mitochondrial-encoded cytochrome b. This G to A transition at mtDNA position 15615 leads to the substitution (G290D) of a very highly conserved amino acid of cytochrome b during evolution. The mutant mtDNA was heteroplasmic (80% mutant) in patient muscle but was undetectable in blood from the patient and his healthy mother and sisters. A maternally inherited cytochrome b polymorphism was also identified in this patient. Molecular screening of 150 individuals showed that the G290D mutation associated with the described phenotype. We suggest that this molecular defect is the primary cause of the muscle disease in this patient. PMID:8910895

  6. Iminophosphorane-organogold(III) complexes induce cell death through mitochondrial ROS production

    PubMed Central

    Vela, Laura; Contel, María; Palomera, Luis; Azaceta, Gemma; Marzo, Isabel

    2011-01-01

    Gold compounds are being investigated as potential antitumor drugs. Some gold(III) derivatives have shown to induce cell death in solid tumors but their mechanism of action differs from that of cisplatin, since most of these compounds do not bind to DNA. We have explored cellular events triggered by three different iminophosphorane-organo gold(III) compounds in leukemia cells (a neutral compound with two chloride ligands [Au{κ2-C,N-C6H4(PPh2=N(C6H5)-2}Cl2] 1, and two cationic compounds with either a dithiocarbamate ligand [Au{κ2-C,N-C6H4(PPh2=N(C6H5)-2}(S2CN-Me2)]PF6 2, or a water-soluble phosphine and a chloride ligand [Au{κ2-C,N-C6H4(PPh2=N(C6H5)-2}(P{Cp(m-C6H4-SO3Na)2}3) Cl]PF6 3). All three compounds showed higher toxicity against leukemia cells when compared to normal T-lymphocytes. Compounds 1 and 2 induced both necrosis and apoptosis, while 3 was mainly apoptotic. Necrotic cell death induced by 1 and 2 was Bax/Bak- and caspase-independent, while apoptosis induced by 3 was Bax/Bak-dependent. Reactive oxygen species (ROS) production at the mitochondrial level was a critical step in the antitumor effect of these compounds. PMID:21864808

  7. Iminophosphorane-organogold(III) complexes induce cell death through mitochondrial ROS production.

    PubMed

    Vela, Laura; Contel, María; Palomera, Luis; Azaceta, Gemma; Marzo, Isabel

    2011-10-01

    Gold compounds are being investigated as potential antitumor drugs. Some gold(III) derivatives have been shown to induce cell death in solid tumors but their mechanism of action differs from that of cisplatin, since most of these compounds do not bind to DNA. We have explored cellular events triggered by three different iminophosphorane-organogold(III) compounds in leukemia cells (a neutral compound with two chloride ligands [Au{κ(2)-C,N-C(6)H(4)(PPh(2)=N(C(6)H(5))-2}Cl(2)] 1, and two cationic compounds with either a dithiocarbamate ligand [Au{κ(2)-C,N-C(6)H(4)(PPh(2)=N(C(6)H(5))-2}(S(2)CN-Me(2))]PF(6)2, or a water-soluble phosphine and a chloride ligand [Au{κ(2)-C,N-C(6)H(4)(PPh(2)=N(C(6)H(5))-2}(P{Cp(m-C(6)H(4)-SO(3)Na)(2)}(3)) Cl]PF(6)3). All three compounds showed higher toxicity against leukemia cells when compared to normal T-lymphocytes. Compounds 1 and 2 induced both necrosis and apoptosis, while 3 was mainly apoptotic. Necrotic cell death induced by 1 and 2 was Bax/Bak- and caspase-independent, while apoptosis induced by 3 was Bax/Bak-dependent. Reactive oxygen species (ROS) production at the mitochondrial level was a critical step in the antitumor effect of these compounds. PMID:21864808

  8. Ametoctradin is a potent Qo site inhibitor of the mitochondrial respiration complex III.

    PubMed

    Zhu, Xiaolei; Zhang, Mengmeng; Liu, Jingjing; Ge, Jingming; Yang, Guangfu

    2015-04-01

    Ametoctradin is a new Oomycete-specific fungicide under development by BASF. It is a potent inhibitor of the bc1 complex in mitochondrial respiration. However, its detailed action mechanism remains unknown. In the present work, the binding mode of ametoctradin was first uncovered by integrating molecular docking, MD simulations, and MM/PBSA calculations, which showed that ametoctradin should be a Q(o) site inhibitor of bc1 complex. Subsequently, a series of new 1,2,4-triazolo[1,5-a]pyrimidine derivatives were designed and synthesized to further understand the substituent effects on the 5- and 6-position of 1,2,4-triazolo[1,5-a]pyrimidine. The calculated binding free energies (ΔG(cal)) of newly synthesized analogues as Qo site inhibitors correlated very well (R(2) = 0.96) with their experimental binding free energies (ΔG(exp)). Two compounds (4a and 4c) with higher inhibitory activity against porcine SQR than ametoctradin were successfully identified. The structural and mechanistic insights obtained from the present study will provide a valuable clue for future designing of a new promising bc1 inhibitor. PMID:25784492

  9. Mitochondrial selectivity and remarkable photocytotoxicity of a ferrocenyl neodymium(III) complex of terpyridine and curcumin in cancer cells.

    PubMed

    Sarkar, Tukki; Banerjee, Samya; Mukherjee, Sanjoy; Hussain, Akhtar

    2016-04-21

    A series of four novel neodymium(iii) complexes of the formulation [Nd(R-tpy)(O-O)(NO3)2] (), where R-tpy is 4'-phenyl-2,2':6',2''-terpyridine (Ph-tpy; , ) and 4'-ferrocenyl-2,2':6',2''-terpyridine (Fc-tpy; , ); O-O is the conjugate base of acetylacetone (Hacac; , ) or curcumin (Hcurc; , ), are synthesized and characterized. The single crystal structure of shows that the complex is a discrete mononuclear species with the Nd(iii) centre in a nine coordinate environment provided by a set of O6N3 donor atoms. Complexes and having the simple acac ligand are prepared as control compounds. Complex , possessing an appended ferrocenyl (Fc) and the curcumin moiety, is remarkably photocytotoxic to HeLa and MCF-7 cancer cells in visible light giving respective IC50 values of 0.7 μM and 2.1 μM while being significantly less toxic to MCF-10A normal cells (IC50 = 34 μM) and in the dark (IC50 > 50 μM). The phenyl appended complex , lacking a ferrocenyl moiety, is significantly less toxic to both the cell lines when compared with . Complexes and , lacking the photoactive curcumin moiety, do not show any apparent toxicity both in light and in the dark. The cell death is apoptotic in nature and is mediated by the light-induced formation of reactive oxygen species (ROS). Fluorescence imaging experiment with HeLa cells reveals mitochondrial accumulation of complex within 4 h of incubation. The complexes bind to calf thymus (ct) DNA with moderate affinity giving Kb values in the range of 10(4)-10(5) M(-1). The curcumin complexes and cleave plasmid supercoiled DNA to its nicked circular form in visible light via(1)O2 and ˙OH pathways. The presence of the ferrocenyl moiety is likely to be responsible for the enhanced cellular uptake and photocytotoxicity of complex . Thus, the mitochondria targeting complex , being remarkably cytotoxic in light but non-toxic in the dark and to normal cells, is a potential candidate for photochemotherapeutic applications. PMID:26947919

  10. A Homozygous Mutation in LYRM7/MZM1L Associated with Early Onset Encephalopathy, Lactic Acidosis, and Severe Reduction of Mitochondrial Complex III Activity

    PubMed Central

    Invernizzi, Federica; Tigano, Marco; Dallabona, Cristina; Donnini, Claudia; Ferrero, Ileana; Cremonte, Maurizio; Ghezzi, Daniele; Lamperti, Costanza; Zeviani, Massimo

    2013-01-01

    Mutations in nuclear genes associated with defective complex III (cIII) of the mitochondrial respiratory chain are rare, having been found in only two cIII assembly factors and, as private changes in single families, three cIII structural subunits. Recently, human LYRM7/MZM1L, the ortholog of yeast MZM1, has been identified as a new assembly factor for cIII. In a baby patient with early onset, severe encephalopathy, lactic acidosis and profound, isolated cIII deficiency in skeletal muscle, we identified a disease-segregating homozygous mutation (c.73G>A) in LYRM7/MZM1L, predicting a drastic change in a highly conserved amino-acid residue (p.Asp25Asn). In a mzm1Δ yeast strain, the expression of a mzm1D25N mutant allele caused temperature-sensitive respiratory growth defect, decreased oxygen consumption, impaired maturation/stabilization of the Rieske Fe–S protein, and reduced complex III activity and amount. LYRM7/MZM1L is a novel disease gene, causing cIII-defective, early onset, severe mitochondrial encephalopathy. PMID:24014394

  11. A defect in the mitochondrial complex III, but not complex IV, triggers early ROS-dependent damage in defined brain regions

    PubMed Central

    Diaz, Francisca; Garcia, Sofia; Padgett, Kyle R.; Moraes, Carlos T.

    2012-01-01

    We have created two neuron-specific mouse models of mitochondrial electron transport chain deficiencies involving defects in complex III (CIII) or complex IV (CIV). These conditional knockouts (cKOs) were created by ablation of the genes coding for the Rieske iron–sulfur protein (RISP) and COX10, respectively. RISP is one of the catalytic subunits of CIII and COX10 is an assembly factor indispensable for the maturation of Cox1, one of the catalytic subunits of CIV. Although the rates of gene deletion, protein loss and complex dysfunction were similar, the RISP cKO survived 3.5 months of age, whereas the COX10 cKO survived for 10–12 months. The RISP cKO had a sudden death, with minimal behavioral changes. In contrast, the COX10 cKO showed a distinctive behavioral phenotype with onset at 4 months of age followed by a slower but progressive neurodegeneration. Curiously, the piriform and somatosensory cortices were more vulnerable to the CIII defect whereas cingulate cortex and to a less extent piriform cortex were affected preferentially by the CIV defect. In addition, the CIII model showed severe and early reactive oxygen species damage, a feature not observed until very late in the pathology of the CIV model. These findings illustrate how specific respiratory chain defects have distinct molecular mechanisms, leading to distinct pathologies, akin to the clinical heterogeneity observed in patients with mitochondrial diseases. PMID:22914734

  12. Copper deficiency decreases the protein expression of Complex IV but not Complex I, II, III and V in mitochondrial respiratory chain in rat heart

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dietary copper (Cu) deficiency impairs mitochondrial respiratory function which is catalyzed by protein complexes. However, there are few reports showing the effect of Cu on the simultaneous expression of the protein subunits for all five respiratory complexes. The present study was undertaken to de...

  13. The life of plant mitochondrial complex I.

    PubMed

    Braun, Hans-Peter; Binder, Stefan; Brennicke, Axel; Eubel, Holger; Fernie, Alisdair R; Finkemeier, Iris; Klodmann, Jennifer; König, Ann-Christine; Kühn, Kristina; Meyer, Etienne; Obata, Toshihiro; Schwarzländer, Markus; Takenaka, Mizuki; Zehrmann, Anja

    2014-11-01

    The mitochondrial NADH dehydrogenase complex (complex I) of the respiratory chain has several remarkable features in plants: (i) particularly many of its subunits are encoded by the mitochondrial genome, (ii) its mitochondrial transcripts undergo extensive maturation processes (e.g. RNA editing, trans-splicing), (iii) its assembly follows unique routes, (iv) it includes an additional functional domain which contains carbonic anhydrases and (v) it is, indirectly, involved in photosynthesis. Comprising about 50 distinct protein subunits, complex I of plants is very large. However, an even larger number of proteins are required to synthesize these subunits and assemble the enzyme complex. This review aims to follow the complete "life cycle" of plant complex I from various molecular perspectives. We provide arguments that complex I represents an ideal model system for studying the interplay of respiration and photosynthesis, the cooperation of mitochondria and the nucleus during organelle biogenesis and the evolution of the mitochondrial oxidative phosphorylation system. PMID:24561573

  14. Exome sequencing identifies NFS1 deficiency in a novel Fe-S cluster disease, infantile mitochondrial complex II/III deficiency.

    PubMed

    Farhan, Sali M K; Wang, Jian; Robinson, John F; Lahiry, Piya; Siu, Victoria M; Prasad, Chitra; Kronick, Jonathan B; Ramsay, David A; Rupar, C Anthony; Hegele, Robert A

    2014-01-01

    Iron-sulfur (Fe-S) clusters are a class of highly conserved and ubiquitous prosthetic groups with unique chemical properties that allow the proteins that contain them, Fe-S proteins, to assist in various key biochemical pathways. Mutations in Fe-S proteins often disrupt Fe-S cluster assembly leading to a spectrum of severe disorders such as Friedreich's ataxia or iron-sulfur cluster assembly enzyme (ISCU) myopathy. Herein, we describe infantile mitochondrial complex II/III deficiency, a novel autosomal recessive mitochondrial disease characterized by lactic acidemia, hypotonia, respiratory chain complex II and III deficiency, multisystem organ failure and abnormal mitochondria. Through autozygosity mapping, exome sequencing, in silico analyses, population studies and functional tests, we identified c.215G>A, p.Arg72Gln in NFS1 as the likely causative mutation. We describe the first disease in man likely caused by deficiency in NFS1, a cysteine desulfurase that is implicated in respiratory chain function and iron maintenance by initiating Fe-S cluster biosynthesis. Our results further demonstrate the importance of sufficient NFS1 expression in human physiology. PMID:24498631

  15. Copper deficiency decreases the protein expression of Complex IV but not Complex I, II, III, or V in mitochondrial respiratory chain in rat heart

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It has been documented that dietary copper (Cu) deficiency impairs mitochondrial respiratory function which is catalyzed by five membrane-bound multiple protein complexes. However, there are few reports on the simultaneous analysis of Cu effect on the subunit protein expression on all five protein c...

  16. Complex I function in mitochondrial supercomplexes.

    PubMed

    Lenaz, Giorgio; Tioli, Gaia; Falasca, Anna Ida; Genova, Maria Luisa

    2016-07-01

    This review discusses the functional properties of mitochondrial Complex I originating from its presence in an assembled form as a supercomplex comprising Complex III and Complex IV in stoichiometric ratios. In particular several lines of evidence are presented favouring the concept that electron transfer from Complex I to Complex III is operated by channelling of electrons through Coenzyme Q molecules bound to the supercomplex, in contrast with the hypothesis that the transfer of reducing equivalents from Complex I to Complex III occurs via random diffusion of the Coenzyme Q molecules in the lipid bilayer. Furthermore, another property provided by the supercomplex assembly is the control of generation of reactive oxygen species by Complex I. This article is part of a Special Issue entitled Respiratory Complex I, edited by Volker Zickermann and Ulrich Brandt. PMID:26820434

  17. LYRM7/MZM1L is a UQCRFS1 chaperone involved in the last steps of mitochondrial Complex III assembly in human cells.

    PubMed

    Sánchez, Ester; Lobo, Teresa; Fox, Jennifer L; Zeviani, Massimo; Winge, Dennis R; Fernández-Vizarra, Erika

    2013-03-01

    The mammalian Complex III (CIII) assembly process is yet to be completely understood. There is still a lack in understanding of how the structural subunits are put together and which additional factors are involved. Here we describe the identification and characterization of LYRM7, a human protein displaying high sequence homology to the Saccharomyces cerevisiae protein Mzm1, which was recently shown as an assembly factor for Rieske Fe-S protein incorporation into the yeast cytochrome bc(1) complex. We conclude that human LYRM7, which we propose to be renamed MZM1L (MZM1-like), works as a human Rieske Fe-S protein (UQCRFS1) chaperone, binding to this subunit within the mitochondrial matrix and stabilizing it prior to its translocation and insertion into the late CIII dimeric intermediate within the mitochondrial inner membrane. Thus, LYRM7/MZM1L is a novel human CIII assembly factor involved in the UQCRFS1 insertion step, which enables formation of the mature and functional CIII enzyme. PMID:23168492

  18. Mitochondrial electron transfer chain complexes inhibition by different organochalcogens.

    PubMed

    Puntel, Robson L; Roos, Daniel H; Seeger, Rodrigo Lopes; Rocha, João B T

    2013-02-01

    Mitochondrial dysfunction plays a pivotal role in the cell toxicology and death decision. The aim of the present study was to investigate the effect of three organocompounds (ebselen [Ebs], diphenyl diselenide [(PhSe)(2)] and diphenyl ditelluride [(PhTe)(2)]) on mitochondrial complexes (I, II, I-III, II-III and IV) activity from rat liver and kidney to determine their potential role as molecular targets of organochalcogens. All studied organochalcogens caused a statistically significant inhibition of the mitochondrial complex I activity. Ebs and (PhTe)(2) caused a statistically significant inhibition of the mitochondrial complex II activity in both hepatic and renal membranes. Hepatic mitochondrial complex II activity was practically unchanged by (PhSe)(2), whereas it significantly inhibited renal complex II activity. Mitochondrial complex IV activity was practically unchanged by the organochalcogens. Furthermore, organochalcogens inhibited the mitochondrial respiration supported by complex I or complex II substrates. The inhibitory effect of Ebs, (PhSe)(2) and (PhTe)(2) on mitochondrial complex I was prevented by NADH, but it was not prevented by catalase (CAT) and/or superoxide dismutase (SOD). Additionally, the organochalcogens-induced inhibition of complex I and II was completely reversed by reduced glutathione (GSH). In conclusion, Ebs, (PhSe)(2) and (PhTe)(2) were more effective inhibitors of renal and hepatic mitochondrial complex I than complex II, whereas complexes III and IV were little modified by these compounds. Taking into account the presented results, we suggest that organochalcogen-induced mitochondrial complexes I and II inhibition can be mediated by their thiol oxidation activity, i.e., Ebs, (PhSe)(2) and (PhTe)(2) can oxidize critical thiol groups from mitochondrial complexes I and II. So, mitochondrial dysfunction can be considered an important factor in the toxicity of Ebs, (PhSe)(2) and (PhTe)(2). PMID:23103426

  19. Membrane-surfactant interactions. The role of surfactant in mitochondrial complex III-phospholipid-Triton X-100 mixed micelles.

    PubMed

    Valpuesta, J M; Arrondo, J L; Barbero, M C; Pons, M; Goñi, F M

    1986-05-15

    Complex III (ubiquinol-cytochrome c reductase) was purified from beef heart mitochondria in the form of protein-phospholipid-Triton X-100 mixed micelles (about 1:80:100 molar ratio). Detergent may be totally removed by sucrose density gradient centrifugation, and the resulting lipoprotein complexes retain full enzyme activity. In order to understand the role of surfactant in the mixed micelles, and the interaction of Triton X-100 with integral membrane proteins and phospholipid bilayers, both the protein-lipid-surfactant mixed micelles and the detergent-free lipoprotein system were examined from the point of view of particle size and ultrastructure, enzyme activity, tryptophan fluorescence quenching, 31P NMR, and Fourier transform infrared spectroscopy. The NMR and IR spectroscopic studies show that surfactant withdrawal induces a profound change in phospholipid architecture, from a micellar to a lamellar-like phase. However, electron microscopic observations fail to reveal the existence of lipid bilayers in the absence of detergent. We suggest that, under these conditions, the lipid:protein molar ratio (80:1) is too low to permit the formation of lipid bilayer planes, but the relative orientation and mobility of phospholipids with respect to proteins is similar to that of the lamellar phase. Protein conformational changes are also detected as a consequence of surfactant removal. Fourier transform infrared spectroscopy indicates an increase of peptide beta-structure in the absence of Triton X-100; changes in the amide II/amide I intensity ratio are also detected, although the precise meaning of these observations is unclear. Tryptophanyl fluorescence quenching by acrylamide shows that a significant fraction of the Trp residues sensing the quencher become less readily available to it in the absence of surfactant. The temperature dependence of enzyme activity (expressed in the form of Arrhenius plots) is also different in the presence and absence of detergent. The

  20. Membrane-surfactant interactions. The role of surfactant in mitochondrial complex III-phospholipid-Triton X-100 mixed micelles

    SciTech Connect

    Valpuesta, J.M.; Arrondo, J.L.; Barbero, M.C.; Pons, M.; Goni, F.M.

    1986-05-15

    Complex III (ubiquinol-cytochrome c reductase) was purified from beef heart mitochondria in the form of protein-phospholipid-Triton X-100 mixed micelles (about 1:80:100 molar ratio). Detergent may be totally removed by sucrose density gradient centrifugation, and the resulting lipoprotein complexes retain full enzyme activity. In order to understand the role of surfactant in the mixed micelles, and the interaction of Triton X-100 with integral membrane proteins and phospholipid bilayers, both the protein-lipid-surfactant mixed micelles and the detergent-free lipoprotein system were examined from the point of view of particle size and ultrastructure, enzyme activity, tryptophan fluorescence quenching, 31P NMR, and Fourier transform infrared spectroscopy. The NMR and IR spectroscopic studies show that surfactant withdrawal induces a profound change in phospholipid architecture, from a micellar to a lamellar-like phase. However, electron microscopic observations fail to reveal the existence of lipid bilayers in the absence of detergent. We suggest that, under these conditions, the lipid:protein molar ratio (80:1) is too low to permit the formation of lipid bilayer planes, but the relative orientation and mobility of phospholipids with respect to proteins is similar to that of the lamellar phase. Protein conformational changes are also detected as a consequence of surfactant removal. Fourier transform infrared spectroscopy indicates an increase of peptide beta-structure in the absence of Triton X-100; changes in the amide II/amide I intensity ratio are also detected, although the precise meaning of these observations is unclear.

  1. A sustained deficiency of mitochondrial respiratory complex III induces an apoptotic cell death through the p53-mediated inhibition of pro-survival activities of the activating transcription factor 4

    PubMed Central

    Evstafieva, A G; Garaeva, A A; Khutornenko, A A; Klepikova, A V; Logacheva, M D; Penin, A A; Novakovsky, G E; Kovaleva, I E; Chumakov, P M

    2014-01-01

    Generation of energy in mitochondria is subjected to physiological regulation at many levels, and its malfunction may result in mitochondrial diseases. Mitochondrial dysfunction is associated with different environmental influences or certain genetic conditions, and can be artificially induced by inhibitors acting at different steps of the mitochondrial electron transport chain (ETC). We found that a short-term (5 h) inhibition of ETC complex III with myxothiazol results in the phosphorylation of translation initiation factor eIF2α and upregulation of mRNA for the activating transcription factor 4 (ATF4) and several ATF4-regulated genes. The changes are characteristic for the adaptive integrated stress response (ISR), which is known to be triggered by unfolded proteins, nutrient and metabolic deficiency, and mitochondrial dysfunctions. However, after a prolonged incubation with myxothiazol (13–17 h), levels of ATF4 mRNA and ATF4-regulated transcripts were found substantially suppressed. The suppression was dependent on the p53 response, which is triggered by the impairment of the complex III-dependent de novo biosynthesis of pyrimidines by mitochondrial dihydroorotate dehydrogenase. The initial adaptive induction of ATF4/ISR acted to promote viability of cells by attenuating apoptosis. In contrast, the induction of p53 upon a sustained inhibition of ETC complex III produced a pro-apoptotic effect, which was additionally stimulated by the p53-mediated abrogation of the pro-survival activities of the ISR. Interestingly, a sustained inhibition of ETC complex I by piericidine did not induce the p53 response and stably maintained the pro-survival activation of ATF4/ISR. We conclude that a downregulation of mitochondrial ETC generally induces adaptive pro-survival responses, which are specifically abrogated by the suicidal p53 response triggered by the genetic risks of the pyrimidine nucleotide deficiency. PMID:25375376

  2. OM2, a Novel Oligomannuronate-Chromium(III) Complex, Promotes Mitochondrial Biogenesis and Lipid Metabolism in 3T3-L1 Adipocytes via the AMPK-PGC1α Pathway

    PubMed Central

    Hao, Jiejie; Hao, Cui; Zhang, Lijuan; Liu, Xin; Zhou, Xiaolin; Dun, Yunlou; Li, Haihua; Li, Guangsheng; Zhao, Xiaoliang; An, Yuanyuan; Liu, Jiankang; Yu, Guangli

    2015-01-01

    Background In our previous studies, we prepared novel oligomannuronate-chromium(III) complexes (OM2, OM4) from marine alginate, and found that these compounds sensitize insulin action better than oligomannuronate(OM), chromium, and metformin in C2C12 skeletal muscle cells. In the present study, we studied their effects on mitochondrial biogenesis, lipid metabolism, and the underlying molecular mechanisms in differentiated 3T3-L1 adipocytes. Methodology/Principal Findings We firstly used the pGL3-PGC1α and pGL3-ATGL promoter plasmids to compare their effects on PGC1α and ATGL transcription activities. Then mitochondrial biogenesis was quantified by transmission electron microscopy and MitoTracker staining. Mitochondrial oxygen consumption and fatty acid oxidation were measured by an oxygen biosensor system and ³H-labelled water scintillation. The mitochondrial DNA and mRNA involved in mitochondrial biogenesis and lipid oxidation were evaluated by real-time PCR. AMPK together with other protein expression levels were measured by western blotting. The inhibitor compound C and siRNA of PGC1α were used to inhibit the OM2-induced AMPK-PGC1α signaling pathway. And we found that OM2 stimulated AMPK-PGC1α pathway in the 3T3-L1 adipocytes, which were correlated with induced mitochondrial biogenesis, improved mitochondrial function, and reduced lipid accumulation by enhanced fatty acid β-oxidation and augmented ATGL protein expression. Conclusions/Significance Our data indicated that the marine oligosaccharide-derived OM2 might represent a novel class of molecules that could be useful for type 2 diabetes prevention and treatment by up-regulating AMPK-PGC1α signaling pathway. PMID:26176781

  3. Grape seed extract targets mitochondrial electron transport chain complex III and induces oxidative and metabolic stress leading to cytoprotective autophagy and apoptotic death in human head and neck cancer cells.

    PubMed

    Shrotriya, Sangeeta; Deep, Gagan; Lopert, Pamela; Patel, Manisha; Agarwal, Rajesh; Agarwal, Chapla

    2015-12-01

    Head and neck squamous cell carcinoma (HNSCC) is a major killer worldwide and innovative measures are urgently warranted to lower the morbidity and mortality caused by this malignancy. Aberrant redox and metabolic status in HNSCC cells offer a unique opportunity to specifically target cancer cells. Therefore, we investigated the efficacy of grape seed extract (GSE) to target the redox and bioenergetic alterations in HNSCC cells. GSE treatment decreased the mitochondrial electron transport chain complex III activity, increased the mitochondrial superoxide levels and depleted the levels of cellular antioxidant (glutathione), thus resulting in the loss of mitochondrial membrane potential in human HNSCC Detroit 562 and FaDu cells. Polyethylene glycol-SOD addition reversed the GSE-mediated apoptosis without restoring complex III activity. Along with redox changes, GSE inhibited the extracellular acidification rate (representing glycolysis) and oxygen consumption rate (indicating oxidative phosphorylation) leading to metabolic stress in HNSCC cells. Molecular studies revealed that GSE activated AMP-activated protein kinase (AMPK), and suppressed Akt/mTOR/4E-BP1/S6K signaling in both Detroit 562 and FaDu cells. Interestingly, GSE increased the autophagic load specifically in FaDu cells, and autophagy inhibition significantly augmented the apoptosis in these cells. Consistent with in vitro results, in vivo analyses also showed that GSE feeding in nude mice activated AMPK and induced-autophagy in FaDu xenograft tumor tissues. Overall, these findings are innovative as we for the first time showed that GSE targets ETC complex III and induces oxidative and metabolic stress, thereby, causing autophagy and apoptotic death in HNSCC cells. PMID:25557495

  4. Arrangement of electron transport chain components in bovine mitochondrial supercomplex I1III2IV1

    PubMed Central

    Althoff, Thorsten; Mills, Deryck J; Popot, Jean-Luc; Kühlbrandt, Werner

    2011-01-01

    The respiratory chain in the inner mitochondrial membrane contains three large multi-enzyme complexes that together establish the proton gradient for ATP synthesis, and assemble into a supercomplex. A 19-Å 3D map of the 1.7-MDa amphipol-solubilized supercomplex I1III2IV1 from bovine heart obtained by single-particle electron cryo-microscopy reveals an amphipol belt replacing the membrane lipid bilayer. A precise fit of the X-ray structures of complex I, the complex III dimer, and monomeric complex IV indicates distances of 13 nm between the ubiquinol-binding sites of complexes I and III, and of 10–11 nm between the cytochrome c binding sites of complexes III and IV. The arrangement of respiratory chain complexes suggests two possible pathways for efficient electron transfer through the supercomplex, of which the shorter branch through the complex III monomer proximal to complex I may be preferred. PMID:21909073

  5. Anticancer Gold(III) Porphyrins Target Mitochondrial Chaperone Hsp60.

    PubMed

    Hu, Di; Liu, Yungen; Lai, Yau-Tsz; Tong, Ka-Chung; Fung, Yi-Man; Lok, Chun-Nam; Che, Chi-Ming

    2016-01-22

    Identification of the molecular target(s) of anticancer metal complexes is a formidable challenge since most of them are unstable toward ligand exchange reaction(s) or biological reduction under physiological conditions. Gold(III) meso-tetraphenylporphyrin (gold-1 a) is notable for its high stability in biological milieux and potent in vitro and in vivo anticancer activities. Herein, extensive chemical biology approaches employing photo-affinity labeling, click chemistry, chemical proteomics, cellular thermal shift, saturation-transfer difference NMR, protein fluorescence quenching, and protein chaperone assays were used to provide compelling evidence that heat-shock protein 60 (Hsp60), a mitochondrial chaperone and potential anticancer target, is a direct target of gold-1 a in vitro and in cells. Structure-activity studies with a panel of non-porphyrin gold(III) complexes and other metalloporphyrins revealed that Hsp60 inhibition is specifically dependent on both the gold(III) ion and the porphyrin ligand. PMID:26663758

  6. Organometallic neptunium(III) complexes.

    PubMed

    Dutkiewicz, Michał S; Farnaby, Joy H; Apostolidis, Christos; Colineau, Eric; Walter, Olaf; Magnani, Nicola; Gardiner, Michael G; Love, Jason B; Kaltsoyannis, Nikolas; Caciuffo, Roberto; Arnold, Polly L

    2016-08-01

    Studies of transuranic organometallic complexes provide a particularly valuable insight into covalent contributions to the metal-ligand bonding, in which the subtle differences between the transuranium actinide ions and their lighter lanthanide counterparts are of fundamental importance for the effective remediation of nuclear waste. Unlike the organometallic chemistry of uranium, which has focused strongly on U(III) and has seen some spectacular advances, that of the transuranics is significantly technically more challenging and has remained dormant. In the case of neptunium, it is limited mainly to Np(IV). Here we report the synthesis of three new Np(III) organometallic compounds and the characterization of their molecular and electronic structures. These studies suggest that Np(III) complexes could act as single-molecule magnets, and that the lower oxidation state of Np(II) is chemically accessible. In comparison with lanthanide analogues, significant d- and f-electron contributions to key Np(III) orbitals are observed, which shows that fundamental neptunium organometallic chemistry can provide new insights into the behaviour of f-elements. PMID:27442286

  7. Organometallic neptunium(III) complexes

    NASA Astrophysics Data System (ADS)

    Dutkiewicz, Michał S.; Farnaby, Joy H.; Apostolidis, Christos; Colineau, Eric; Walter, Olaf; Magnani, Nicola; Gardiner, Michael G.; Love, Jason B.; Kaltsoyannis, Nikolas; Caciuffo, Roberto; Arnold, Polly L.

    2016-08-01

    Studies of transuranic organometallic complexes provide a particularly valuable insight into covalent contributions to the metal–ligand bonding, in which the subtle differences between the transuranium actinide ions and their lighter lanthanide counterparts are of fundamental importance for the effective remediation of nuclear waste. Unlike the organometallic chemistry of uranium, which has focused strongly on UIII and has seen some spectacular advances, that of the transuranics is significantly technically more challenging and has remained dormant. In the case of neptunium, it is limited mainly to NpIV. Here we report the synthesis of three new NpIII organometallic compounds and the characterization of their molecular and electronic structures. These studies suggest that NpIII complexes could act as single-molecule magnets, and that the lower oxidation state of NpII is chemically accessible. In comparison with lanthanide analogues, significant d- and f-electron contributions to key NpIII orbitals are observed, which shows that fundamental neptunium organometallic chemistry can provide new insights into the behaviour of f-elements.

  8. Mitochondrial Peroxiredoxin III is a Potential Target for Cancer Therapy

    PubMed Central

    Song, In-Sung; Kim, Hyoung-Kyu; Jeong, Seung-Hun; Lee, Sung-Ryul; Kim, Nari; Rhee, Byoung Doo; Ko, Kyung Soo; Han, Jin

    2011-01-01

    Mitochondria are involved either directly or indirectly in oncogenesis and the alteration of metabolism in cancer cells. Cancer cells contain large numbers of abnormal mitochondria and produce large amounts of reactive oxygen species (ROS). Oxidative stress is caused by an imbalance between the production of ROS and the antioxidant capacity of the cell. Several cancer therapies, such as chemotherapeutic drugs and radiation, disrupt mitochondrial homeostasis and release cytochrome c, leading to apoptosome formation, which activates the intrinsic pathway. This is modulated by the extent of mitochondrial oxidative stress. The peroxiredoxin (Prx) system is a cellular defense system against oxidative stress, and mitochondria in cancer cells are known to contain high levels of Prx III. Here, we review accumulating evidence suggesting that mitochondrial oxidative stress is involved in cancer, and discuss the role of the mitochondrial Prx III antioxidant system as a potential target for cancer therapy. We hope that this review will provide the basis for new strategic approaches in the development of effective cancer treatments. PMID:22072940

  9. Mitochondrial impairment by PPAR agonists and statins identified via immunocaptured OXPHOS complex activities and respiration.

    PubMed

    Nadanaciva, Sashi; Dykens, James A; Bernal, Autumn; Capaldi, Roderick A; Will, Yvonne

    2007-09-15

    Mitochondrial impairment is increasingly implicated in the etiology of toxicity caused by some thiazolidinediones, fibrates, and statins. We examined the effects of members of these drug classes on respiration of isolated rat liver mitochondria using a phosphorescent oxygen sensitive probe and on the activity of individual oxidative phosphorylation (OXPHOS) complexes using a recently developed immunocapture technique. Of the six thiazolidinediones examined, ciglitazone, troglitazone, and darglitazone potently disrupted mitochondrial respiration. In accord with these data, ciglitazone and troglitazone were also potent inhibitors of Complexes II+III, IV, and V, while darglitazone predominantly inhibited Complex IV. Of the six statins evaluated, lovastatin, simvastatin, and cerivastatin impaired mitochondrial respiration the most, with simvastatin and lovastatin impairing multiple OXPHOS Complexes. Within the class of fibrates, gemfibrozil more potently impaired respiration than fenofibrate, clofibrate, or ciprofibrate. Gemfibrozil only modestly inhibited Complex I, fenofibrate inhibited Complexes I, II+III, and V, and clofibrate inhibited Complex V. Our findings with the two complementary methods indicate that (1) some members of each class impair mitochondrial respiration, whereas others have little or no effect, and (2) the rank order of mitochondrial impairment accords with clinical adverse events observed with these drugs. Since the statins are frequently co-prescribed with the fibrates or thiazolidinediones, various combinations of these three drug classes were also analyzed for their mitochondrial effects. In several cases, the combination additively uncoupled or inhibited respiration, suggesting that some combinations are more likely to yield clinically relevant drug-induced mitochondrial side effects than others. PMID:17658574

  10. Mitochondrial impairment by PPAR agonists and statins identified via immunocaptured OXPHOS complex activities and respiration

    SciTech Connect

    Nadanaciva, Sashi; Dykens, James A.; Bernal, Autumn; Capaldi, Roderick A.; Will, Yvonne

    2007-09-15

    Mitochondrial impairment is increasingly implicated in the etiology of toxicity caused by some thiazolidinediones, fibrates, and statins. We examined the effects of members of these drug classes on respiration of isolated rat liver mitochondria using a phosphorescent oxygen sensitive probe and on the activity of individual oxidative phosphorylation (OXPHOS) complexes using a recently developed immunocapture technique. Of the six thiazolidinediones examined, ciglitazone, troglitazone, and darglitazone potently disrupted mitochondrial respiration. In accord with these data, ciglitazone and troglitazone were also potent inhibitors of Complexes II + III, IV, and V, while darglitazone predominantly inhibited Complex IV. Of the six statins evaluated, lovastatin, simvastatin, and cerivastatin impaired mitochondrial respiration the most, with simvastatin and lovastatin impairing multiple OXPHOS Complexes. Within the class of fibrates, gemfibrozil more potently impaired respiration than fenofibrate, clofibrate, or ciprofibrate. Gemfibrozil only modestly inhibited Complex I, fenofibrate inhibited Complexes I, II + III, and V, and clofibrate inhibited Complex V. Our findings with the two complementary methods indicate that (1) some members of each class impair mitochondrial respiration, whereas others have little or no effect, and (2) the rank order of mitochondrial impairment accords with clinical adverse events observed with these drugs. Since the statins are frequently co-prescribed with the fibrates or thiazolidinediones, various combinations of these three drug classes were also analyzed for their mitochondrial effects. In several cases, the combination additively uncoupled or inhibited respiration, suggesting that some combinations are more likely to yield clinically relevant drug-induced mitochondrial side effects than others.

  11. Mitochondrial complex I-linked disease.

    PubMed

    Rodenburg, Richard J

    2016-07-01

    Complex I deficiency is the most frequently encountered single mitochondrial single enzyme deficiency in patients with a mitochondrial disorder. Although specific genotype-phenotype correlations are very difficult to identify, the majority of patients present with symptoms caused by leukodystrophy. The poor genotype-phenotype correlations can make establishing a diagnosis a challenge. The classical way to establish a complex I deficiency in patients is by performing spectrophotometric measurements of the enzyme in a muscle biopsy or other patient-derived material (liver or heart biopsy, cultured skin fibroblasts). Complex I is encoded by both the mtDNA and nuclear DNA and pathogenic mutations have been identified in the majority of the 44 genes encoding the structural subunits of complex I. In recent years, the increasing possibilities for diagnostic molecular genetic tests of large gene panels, exomes, and even entire genomes has led to the identification of many novel genetic defects causing complex I deficiency. Complex I mutations not only result in a reduced enzyme activity but also induce secondary effects at the cellular level, such as elevated reactive oxygen species production, altered membrane potential and mitochondrial morphology. At this moment there is no cure for complex I deficiency and the treatment options for complex I patients are restricted to symptomatic treatment. Recent developments, amongst others based on the treatment of the secondary effects of complex I deficiency, have shown to be promising as new therapeutic strategies in vitro and have entered clinical trials. This article is part of a Special Issue entitled Respiratory complex I, edited by Volker Zickermann and Ulrich Brandt. PMID:26906428

  12. Complex patterns of mitochondrial dynamics in human pancreatic cells revealed by fluorescent confocal imaging.

    PubMed

    Kuznetsov, Andrey V; Hermann, Martin; Troppmair, Jakob; Margreiter, Raimund; Hengster, Paul

    2010-01-01

    Mitochondrial morphology and intracellular organization are tightly controlled by the processes of mitochondrial fission-fusion. Moreover, mitochondrial movement and redistribution provide a local ATP supply at cellular sites of particular demands. Here we analysed mitochondrial dynamics in isolated primary human pancreatic cells. Using real time confocal microscopy and mitochondria-specific fluorescent probes tetramethylrhodamine methyl ester and MitoTracker Green we documented complex and novel patterns of spatial and temporal organization of mitochondria, mitochondrial morphology and motility. The most commonly observed types of mitochondrial dynamics were (i) fast fission and fusion; (ii) small oscillating movements of the mitochondrial network; (iii) larger movements, including filament extension, retraction, fast (0.1-0.3 mum/sec.) and frequent oscillating (back and forth) branching in the mitochondrial network; (iv) as well as combinations of these actions and (v) long-distance intracellular translocation of single spherical mitochondria or separated mitochondrial filaments with velocity up to 0.5 mum/sec. Moreover, we show here for the first time, a formation of unusual mitochondrial shapes like rings, loops, and astonishingly even knots created from one or more mitochondrial filaments. These data demonstrate the presence of extensive heterogeneity in mitochondrial morphology and dynamics in living cells under primary culture conditions. In summary, this study reports new patterns of morphological changes and dynamic motion of mitochondria in human pancreatic cells, suggesting an important role of integrations of mitochondria with other intracellular structures and systems. PMID:19382913

  13. Structure and function of mitochondrial complex I.

    PubMed

    Wirth, Christophe; Brandt, Ulrich; Hunte, Carola; Zickermann, Volker

    2016-07-01

    Proton-pumping NADH:ubiquinone oxidoreductase (complex I) is the largest and most complicated enzyme of the respiratory chain. Fourteen central subunits represent the minimal form of complex I and can be assigned to functional modules for NADH oxidation, ubiquinone reduction, and proton pumping. In addition, the mitochondrial enzyme comprises some 30 accessory subunits surrounding the central subunits that are not directly associated with energy conservation. Complex I is known to release deleterious oxygen radicals (ROS) and its dysfunction has been linked to a number of hereditary and degenerative diseases. We here review recent progress in structure determination, and in understanding the role of accessory subunits and functional analysis of mitochondrial complex I. For the central subunits, structures provide insight into the arrangement of functional modules including the substrate binding sites, redox-centers and putative proton channels and pump sites. Only for two of the accessory subunits, detailed structures are available. Nevertheless, many of them could be localized in the overall structure of complex I, but most of these assignments have to be considered tentative. Strikingly, redox reactions and proton pumping machinery are spatially completely separated and the site of reduction for the hydrophobic substrate ubiquinone is found deeply buried in the hydrophilic domain of the complex. The X-ray structure of complex I from Yarrowia lipolytica provides clues supporting the previously proposed two-state stabilization change mechanism, in which ubiquinone redox chemistry induces conformational states and thereby drives proton pumping. The same structural rearrangements may explain the active/deactive transition of complex I implying an integrated mechanistic model for energy conversion and regulation. This article is part of a Special Issue entitled Respiratory complex I, edited by Volker Zickermann and Ulrich Brandt. PMID:26921811

  14. Identification of the Mitochondrial Heme Metabolism Complex

    PubMed Central

    Medlock, Amy E.; Shiferaw, Mesafint T.; Marcero, Jason R.; Vashisht, Ajay A.; Wohlschlegel, James A.; Phillips, John D.; Dailey, Harry A.

    2015-01-01

    Heme is an essential cofactor for most organisms and all metazoans. While the individual enzymes involved in synthesis and utilization of heme are fairly well known, less is known about the intracellular trafficking of porphyrins and heme, or regulation of heme biosynthesis via protein complexes. To better understand this process we have undertaken a study of macromolecular assemblies associated with heme synthesis. Herein we have utilized mass spectrometry with coimmunoprecipitation of tagged enzymes of the heme biosynthetic pathway in a developing erythroid cell culture model to identify putative protein partners. The validity of these data obtained in the tagged protein system is confirmed by normal porphyrin/heme production by the engineered cells. Data obtained are consistent with the presence of a mitochondrial heme metabolism complex which minimally consists of ferrochelatase, protoporphyrinogen oxidase and aminolevulinic acid synthase-2. Additional proteins involved in iron and intermediary metabolism as well as mitochondrial transporters were identified as potential partners in this complex. The data are consistent with the known location of protein components and support a model of transient protein-protein interactions within a dynamic protein complex. PMID:26287972

  15. Mitochondrial complex 1 gene analysis in keratoconus

    PubMed Central

    Pathak, Dhananjay; Nayak, Bhagabat; Singh, Manvendra; Sharma, Namrata; Tandon, Radhika; Sinha, Rajesh; Titiyal, Jeewan S.

    2011-01-01

    Purpose Keratoconus is characterized by the thinning of corneal stroma, resulting in reduced vision. The exact etiology of keratoconus (KC) is still unknown. The involvement of oxidative stress (OS) in this disease has been reported. However, the exact mechanism of OS in keratoconus is still unknown. Thus we planned this study to screen mitochondrial complex I genes for sequence changes in keratoconus patients and controls, as mitochondrial complex I is the chief source of reactive oxygen species (ROS) production. Methods A total of 20 keratoconus cases and 20 healthy controls without any ocular disorder were enrolled in this study. Mitochondrial complex I genes (ND1, 2, 3, 4, 4L, 5, and 6) were amplified in all patients and controls using 12 pairs of primers by PCR. After sequencing, DNA sequences were analyzed against the mitochondrial reference sequence NC_012920. Haplogroup frequency based Principle Component Analysis (PCA) was constructed to determine whether the gene pool of keratoconus patients is closer to major populations in India. Results DNA sequencing revealed a total 84 nucleotide variations in patients and 29 in controls. Of 84 nucleotide changes, 18 variations were non-synonymous and two novel frame-shift mutations were detected in cases. Non-synonymous mtDNA sequence variations may account for increased ROS and decreased ATP production. This ultimately leads to OS; which is a known cause for variety of corneal abnormalities. Haplotype analysis showed that most of the patients were clustered under the haplogroups: T, C4a2a, R2’TJ, M21’Q1a, M12’G2a2a, M8’CZ and M7a2a, which are present as negligible frequency in normal Indian population, whereas only few patients were found to be a part of the other haplogroups like U7 (Indo-European), R2 and R31, whose origin is contentious. Conclusions Mt complex I sequence variations are the main cause of elevated ROS production which leads oxidative stress. This oxidative stress then starts a cascade of

  16. The mitochondrial PHB complex: roles in mitochondrial respiratory complex assembly, ageing and degenerative disease.

    PubMed

    Nijtmans, L G J; Artal, Sanz M; Grivell, L A; Coates, P J

    2002-01-01

    Although originally identified as putative negative regulators of the cell cycle, recent studies have demonstrated that the PHB proteins act as a chaperone in the assembly of subunits of mitochondrial respiratory chain complexes. The two PHB proteins, Phblp and Phb2p, are located in the mitochondrial inner membrane where they form a large complex that represents a novel type of membrane-bound chaperone. On the basis of its native molecular weight, the PHB-complex should contain 12-14 copies of both Phblp and Phb2p. The PHB complex binds directly to newly synthesised mitochondrial translation products and stabilises them against degradation by membrane-bound metalloproteases belonging to the family of mitochondrial triple-A proteins. Sequence homology assigns Phb1p and Phb2p to a family of proteins which also contains stomatins, HflKC, flotillins and plant defence proteins. However, to date only the bacterial HflKC proteins have been shown to possess a direct functional homology with the PHB complex. Previously assigned actions of the PHB proteins, including roles in tumour suppression, cell cycle regulation, immunoglobulin M receptor binding and apoptosis seem unlikely in view of any hard evidence in their support. Nevertheless, because the proteins are probably indirectly involved in ageing and cancer, we assess their possible role in these processes. Finally, we suggest that the original name for these proteins, the prohibitins, should be amended to reflect their roles as proteins that hold badly formed subunits, thereby keeping the nomenclature already in use but altering its meaning to reflect their true function more accurately. PMID:11852914

  17. Stoichiometries of arsenazo III-Ca complexes.

    PubMed Central

    Palade, P; Vergara, J

    1983-01-01

    The equilibrium interactions of the metallochromic indicator arsenazo III with calcium at physiological ionic strength and pH were investigated spectrophotometrically and with the aid of a calcium electrode. Evidence suggests the formation of more than one dye-calcium complex. The analysis of data obtained over a 10,000-fold range of dye concentrations concludes that at the concentrations used for in vitro biochemical studies (10--100 microM), arsenazo III absorbance changes in response to calcium binding primarily involve the formation of a complex involving two dye molecules and two calcium ions. At millimolar dye concentrations, typical of physiological calcium transient determinations in situ, a second complex involving two arsenazo III molecules and one calcium ion is additionally formed. A third complex, involving one arsenazo III molecule and one calcium ion, is formed at very low dye concentrations. The results reported here suggest that equilibrium calibration of the dye with calcium cannot be used directly to satisfactorily relate transient absorbance changes in physiological preparations to calcium concentration changes since several stoichiometrically distinct complexes with different absorbances could be formed at different rates. The results of this study do not permit the elucidation of a unique kinetic scheme of arsenazo III complexation with calcium; for this, in vitro kinetic analysis is required. Results of similar analysis of the dye interaction with magnesium are also reported, and these appear compatible with a much simpler model of complexation. PMID:6626673

  18. A human mitochondrial poly(A) polymerase mutation reveals the complexities of post-transcriptional mitochondrial gene expression.

    PubMed

    Wilson, William C; Hornig-Do, Hue-Tran; Bruni, Francesco; Chang, Jeong Ho; Jourdain, Alexis A; Martinou, Jean-Claude; Falkenberg, Maria; Spåhr, Henrik; Larsson, Nils-Göran; Lewis, Richard J; Hewitt, Lorraine; Baslé, Arnaud; Cross, Harold E; Tong, Liang; Lebel, Robert R; Crosby, Andrew H; Chrzanowska-Lightowlers, Zofia M A; Lightowlers, Robert N

    2014-12-01

    The p.N478D missense mutation in human mitochondrial poly(A) polymerase (mtPAP) has previously been implicated in a form of spastic ataxia with optic atrophy. In this study, we have investigated fibroblast cell lines established from family members. The homozygous mutation resulted in the loss of polyadenylation of all mitochondrial transcripts assessed; however, oligoadenylation was retained. Interestingly, this had differential effects on transcript stability that were dependent on the particular species of transcript. These changes were accompanied by a severe loss of oxidative phosphorylation complexes I and IV, and perturbation of de novo mitochondrial protein synthesis. Decreases in transcript polyadenylation and in respiratory chain complexes were effectively rescued by overexpression of wild-type mtPAP. Both mutated and wild-type mtPAP localized to the mitochondrial RNA-processing granules thereby eliminating mislocalization as a cause of defective polyadenylation. In vitro polyadenylation assays revealed severely compromised activity by the mutated protein, which generated only short oligo(A) extensions on RNA substrates, irrespective of RNA secondary structure. The addition of LRPPRC/SLIRP, a mitochondrial RNA-binding complex, enhanced activity of the wild-type mtPAP resulting in increased overall tail length. The LRPPRC/SLIRP effect although present was less marked with mutated mtPAP, independent of RNA secondary structure. We conclude that (i) the polymerase activity of mtPAP can be modulated by the presence of LRPPRC/SLIRP, (ii) N478D mtPAP mutation decreases polymerase activity and (iii) the alteration in poly(A) length is sufficient to cause dysregulation of post-transcriptional expression and the pathogenic lack of respiratory chain complexes. PMID:25008111

  19. Luminescence of europium (III) complexes for visualization

    NASA Astrophysics Data System (ADS)

    Kolontaeva, Olga A.; Pozharov, Mikhail V.; Korolovich, Vladimir F.; Khokhlova, Anastasia R.; Kirdyanova, Anna N.; Burmistrova, Natalia A.; Zakharova, Tamara V.; Goryacheva, Irina Y.

    2016-04-01

    With the purpose to develop bright non-toxic luminescent label for theranostic application we have studied complexation of lanthanide dipicolinates (2,6-pyridinedicarboxylates) by sodium alginate and effect of thermal exposure of synthesized micro-capsules on their luminescent properties. Synthesized micro-capsules are stable in acidic medium but dissolve at pH ~ 4 due to transformation of cationic europium dipicolinate complex to anionic. Luminescence studies have shown that emission spectra of europium(III)-alginate complexes (both chloride and dipicolinate) contain two intensive bands characteristic to Eu3+ ion (5D0 --> 7F1 (590 nm) and 5D0 --> 7F1 (612 nm)). We have also found that at 160ºC europium(III)- alginate micro-capsules decompose to black, soot-like substance, therefore, their thermal treatment must be performed in closed environment (i.e., sealed ampoules).

  20. Mitochondrial Targeted Endonuclease III DNA Repair Enzyme Protects against Ventilator Induced Lung Injury in Mice.

    PubMed

    Hashizume, Masahiro; Mouner, Marc; Chouteau, Joshua M; Gorodnya, Olena M; Ruchko, Mykhaylo V; Wilson, Glenn L; Gillespie, Mark N; Parker, James C

    2014-01-01

    The mitochondrial targeted DNA repair enzyme, 8-oxoguanine DNA glycosylase 1, was previously reported to protect against mitochondrial DNA (mtDNA) damage and ventilator induced lung injury (VILI). In the present study we determined whether mitochondrial targeted endonuclease III (EndoIII) which cleaves oxidized pyrimidines rather than purines from damaged DNA would also protect the lung. Minimal injury from 1 h ventilation at 40 cmH2O peak inflation pressure (PIP) was reversed by EndoIII pretreatment. Moderate lung injury due to ventilation for 2 h at 40 cmH2O PIP produced a 25-fold increase in total extravascular albumin space, a 60% increase in W/D weight ratio, and marked increases in MIP-2 and IL-6. Oxidative mtDNA damage and decreases in the total tissue glutathione (GSH) and the GSH/GSSH ratio also occurred. All of these indices of injury were attenuated by mitochondrial targeted EndoIII. Massive lung injury caused by 2 h ventilation at 50 cmH2O PIP was not attenuated by EndoIII pretreatment, but all untreated mice died prior to completing the two hour ventilation protocol, whereas all EndoIII-treated mice lived for the duration of ventilation. Thus, mitochondrial targeted DNA repair enzymes were protective against mild and moderate lung damage and they enhanced survival in the most severely injured group. PMID:25153040

  1. In vitro import and assembly of the nucleus-encoded mitochondrial subunit III of cytochrome c oxidase (Cox3).

    PubMed

    Vázquez-Acevedo, Miriam; Rubalcava-Gracia, Diana; González-Halphen, Diego

    2014-11-01

    The cox3 gene, encoding subunit III of cytochrome c oxidase (Cox3) is in mitochondrial genomes except in chlorophycean algae, where it is localized in the nucleus. Therefore, algae like Chlamydomonas reinhardtii, Polytomella sp. and Volvox carteri, synthesize the Cox3 polypeptide in the cytosol, import it into mitochondria, and integrate it into the cytochrome c oxidase complex. In this work, we followed the in vitro internalization of the Cox3 precursor by isolated, import-competent mitochondria of Polytomella sp. In this colorless alga, the precursor Cox3 protein is synthesized with a long, cleavable, N-terminal mitochondrial targeting sequence (MTS) of 98 residues. In an import time course, a transient Cox3 intermediate was identified, suggesting that the long MTS is processed more than once. The first processing step is sensitive to the metalo-protease inhibitor 1,10-ortophenantroline, suggesting that it is probably carried out by the matrix-located Mitochondrial Processing Protease. Cox3 is readily imported through an energy-dependent import pathway and integrated into the inner mitochondrial membrane, becoming resistant to carbonate extraction. Furthermore, the imported Cox3 protein was assembled into cytochrome c oxidase, as judged by the presence of a labeled band co-migrating with complex IV in Blue Native Electrophoresis. A model for the biogenesis of Cox3 in chlorophycean algae is proposed. This is the first time that the in vitro mitochondrial import of a cytosol-synthesized Cox3 subunit is described. PMID:24561572

  2. Mitochondrial protein synthesis: Figuring the fundamentals, complexities and complications, of mammalian mitochondrial translation

    PubMed Central

    Lightowlers, Robert N.; Rozanska, Agata; Chrzanowska-Lightowlers, Zofia M.

    2014-01-01

    Mitochondrial protein synthesis is essential for all mammals, being responsible for providing key components of the oxidative phosphorylation complexes. Although only thirteen different polypeptides are made, the molecular details of this deceptively simple process remain incomplete. Central to this process is a non-canonical ribosome, the mitoribosome, which has evolved to address its unique mandate. In this review, we integrate the current understanding of the molecular aspects of mitochondrial translation with recent advances in structural biology. We identify numerous key questions that we will need to answer if we are to increase our knowledge of the molecular mechanisms underlying mitochondrial protein synthesis. PMID:24911204

  3. Effects of tramadol, clonazepam, and their combination on brain mitochondrial complexes.

    PubMed

    Mohamed, Tarek Mostafa; Ghaffar, Hamdy M Abdel; El Husseiny, Rabee M R

    2015-12-01

    The present study is an unsubstantiated qualitative assessment of the abused drugs-tramadol and clonazepam. The aim of this study is to evaluate whether the effects of tramadol, clonazepam, and their combination on mitochondrial electron transport chain (ETC) complexes were influential at therapeutic or at progressively increasing doses. The study comprised of a total of 70 healthy male rats, aged 3 months. According to the drug intake regimen, animals were divided into seven groups: control, tramadol therapeutic, clonazepam therapeutic, combination therapeutic, tramadol abuse, clonazepam abuse, and combination abuse group. At the end of the experiment, brain mitochondrial ETC complexes (I, II, III, and IV) were evaluated. Histopathological examinations were also performed on brain tissues. The results showed that groups that received tramadol (therapeutic and abuse) suffered from weight loss. Tramadol abuse group and combination abuse group showed significant decrease in the activities of I, III, and IV complexes but not in the activity of complex II. In conclusion, tramadol but not clonazepam has been found to partially inhibit the activities of respiratory chain complexes I, III, and IV but not the activity of complex II and such inhibition occurred only at doses that exceeded the maximum recommended adult human daily therapeutic doses. This result explains the clinical and histopathological effects of tramadol, such as seizures and red neurons (marker for apoptosis), respectively. PMID:23843224

  4. Structure and function of the Mitochondrial Calcium Uniporter complex

    PubMed Central

    De Stefani, Diego; Patron, Maria; Rizzuto, Rosario

    2015-01-01

    The Mitochondrial Calcium Uniporter (MCU) is the critical protein of the inner mitochondrial membrane mediating the electrophoretic Ca2+ uptake into the matrix. It plays a fundamental role in the shaping of global calcium signaling and in the control of aerobic metabolism as well as apoptosis. Two features of mitochondrial calcium signaling have been known for a long time: i) mitochondrial Ca2+ uptake widely varies among cells and tissues, and ii) channel opening strongly relies on the extramitochondrial Ca2+ concentration, with low activity at resting [Ca2+] and high capacity as soon as calcium signaling is activated. Such complexity requires a specialized molecular machinery, with several primary components can be variably gathered together in order to match energy demands and protect from toxic stimuli. In line with this, MCU is now recognized to be part of a macromolecular complex known as the MCU complex. Our understanding of the structure and function of the MCU complex is now growing promptly, revealing an unexpected complexity that highlights the pleiotropic role of mitochondrial Ca2+ signals. PMID:25896525

  5. Structure and function of the mitochondrial calcium uniporter complex.

    PubMed

    De Stefani, Diego; Patron, Maria; Rizzuto, Rosario

    2015-09-01

    The mitochondrial calcium uniporter (MCU) is the critical protein of the inner mitochondrial membrane mediating the electrophoretic Ca²⁺ uptake into the matrix. It plays a fundamental role in the shaping of global calcium signaling and in the control of aerobic metabolism as well as apoptosis. Two features of mitochondrial calcium signaling have been known for a long time: i) mitochondrial Ca²⁺ uptake widely varies among cells and tissues, and ii) channel opening strongly relies on the extramitochondrial Ca²⁺ concentration, with low activity at resting [Ca²⁺] and high capacity as soon as calcium signaling is activated. Such complexity requires a specialized molecular machinery, with several primary components can be variably gathered together in order to match energy demands and protect from toxic stimuli. In line with this, MCU is now recognized to be part of a macromolecular complex known as the MCU complex. Our understanding of the structure and function of the MCU complex is now growing promptly, revealing an unexpected complexity that highlights the pleiotropic role of mitochondrial Ca²⁺ signals. This article is part of a Special Issue entitled: 13th European Symposium on Calcium. PMID:25896525

  6. Inactivation of Mitochondrial Complex I Induces the Expression of a Twin Cysteine Protein that Targets and Affects Cytosolic, Chloroplastidic and Mitochondrial Function.

    PubMed

    Wang, Yan; Lyu, Wenhui; Berkowitz, Oliver; Radomiljac, Jordan D; Law, Simon R; Murcha, Monika W; Carrie, Chris; Teixeira, Pedro F; Kmiec, Beata; Duncan, Owen; Van Aken, Olivier; Narsai, Reena; Glaser, Elzbieta; Huang, Shaobai; Roessner, Ute; Millar, A Harvey; Whelan, James

    2016-05-01

    At12Cys-1 (At5g64400) and At12Cys-2 (At5g09570) are two closely related isogenes that encode small, twin cysteine proteins, typically located in mitochondria. At12Cys-2 transcript is induced in a variety of mutants with disrupted mitochondrial proteins, but an increase in At12Cys protein is only detected in mutants with reduced mitochondrial complex I abundance. Induction of At12Cys protein in mutants that lack mitochondrial complex I is accompanied by At12Cys protein located in mitochondria, chloroplasts, and the cytosol. Biochemical analyses revealed that even single gene deletions, i.e., At12cys-1 or At12cys-2, have an effect on mitochondrial and chloroplast functions. However, only double mutants, i.e., At12cys-1:At12cys-2, affect the abundance of protein and mRNA transcripts encoding translation elongation factors as well as rRNA abundance. Blue native PAGE showed that At12Cys co-migrated with mitochondrial supercomplex I + III. Likewise, deletion of both At12cys-1 and At12cys-2 genes, but not single gene deletions, results in enhanced tolerance to drought and light stress and increased anti-oxidant capacity. The induction and multiple localization of At12Cys upon a reduction in complex I abundance provides a mechanism to specifically signal mitochondrial dysfunction to the cytosol and then beyond to other organelles in the cell. PMID:26829715

  7. Crystal structure of the human mitochondrial chaperonin symmetrical football complex.

    PubMed

    Nisemblat, Shahar; Yaniv, Oren; Parnas, Avital; Frolow, Felix; Azem, Abdussalam

    2015-05-12

    Human mitochondria harbor a single type I chaperonin system that is generally thought to function via a unique single-ring intermediate. To date, no crystal structure has been published for any mammalian type I chaperonin complex. In this study, we describe the crystal structure of a football-shaped, double-ring human mitochondrial chaperonin complex at 3.15 Å, which is a novel intermediate, likely representing the complex in an early stage of dissociation. Interestingly, the mitochondrial chaperonin was captured in a state that exhibits subunit asymmetry within the rings and nucleotide symmetry between the rings. Moreover, the chaperonin tetradecamers show a different interring subunit arrangement when compared to GroEL. Our findings suggest that the mitochondrial chaperonins use a mechanism that is distinct from the mechanism of the well-studied Escherichia coli system. PMID:25918392

  8. Crystal structure of the human mitochondrial chaperonin symmetrical football complex

    PubMed Central

    Nisemblat, Shahar; Yaniv, Oren; Parnas, Avital; Frolow, Felix; Azem, Abdussalam

    2015-01-01

    Human mitochondria harbor a single type I chaperonin system that is generally thought to function via a unique single-ring intermediate. To date, no crystal structure has been published for any mammalian type I chaperonin complex. In this study, we describe the crystal structure of a football-shaped, double-ring human mitochondrial chaperonin complex at 3.15 Å, which is a novel intermediate, likely representing the complex in an early stage of dissociation. Interestingly, the mitochondrial chaperonin was captured in a state that exhibits subunit asymmetry within the rings and nucleotide symmetry between the rings. Moreover, the chaperonin tetradecamers show a different interring subunit arrangement when compared to GroEL. Our findings suggest that the mitochondrial chaperonins use a mechanism that is distinct from the mechanism of the well-studied Escherichia coli system. PMID:25918392

  9. Mitochondrial respiratory complex I probed by delayed luminescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Baran, Irina; Ionescu, Diana; Privitera, Simona; Scordino, Agata; Mocanu, Maria Magdalena; Musumeci, Francesco; Grasso, Rosaria; Gulino, Marisa; Iftime, Adrian; Tofolean, Ioana Teodora; Garaiman, Alexandru; Goicea, Alexandru; Irimia, Ruxandra; Dimancea, Alexandru; Ganea, Constanta

    2013-12-01

    The role of mitochondrial complex I in ultraweak photon-induced delayed photon emission [delayed luminescence (DL)] of human leukemia Jurkat T cells was probed by using complex I targeting agents like rotenone, menadione, and quercetin. Rotenone, a complex I-specific inhibitor, dose-dependently increased the mitochondrial level of reduced nicotinamide adenine dinucleotide (NADH), decreased clonogenic survival, and induced apoptosis. A strong correlation was found between the mitochondrial levels of NADH and oxidized flavin mononucleotide (FMNox) in rotenone-, menadione- and quercetin-treated cells. Rotenone enhanced DL dose-dependently, whereas quercetin and menadione inhibited DL as well as NADH or FMNox. Collectively, the data suggest that DL of Jurkat cells originates mainly from mitochondrial complex I, which functions predominantly as a dimer and less frequently as a tetramer. In individual monomers, both pairs of pyridine nucleotide (NADH/reduced nicotinamide adenine dinucleotide phosphate) sites and flavin (FMN-a/FMN-b) sites appear to bind cooperatively their specific ligands. Enhancement of delayed red-light emission by rotenone suggests that the mean time for one-electron reduction of ubiquinone or FMN-a by the terminal Fe/S center (N2) is 20 or 284 μs, respectively. All these findings suggest that DL spectroscopy could be used as a reliable, sensitive, and robust technique to probe electron flow within complex I in situ.

  10. Mutations in the UQCC1-Interacting Protein, UQCC2, Cause Human Complex III Deficiency Associated with Perturbed Cytochrome b Protein Expression

    PubMed Central

    Wijeyeratne, Xiaonan W.; van den Brand, Mariël A. M.; Leenders, Anne M.; Rodenburg, Richard J.; Reljić, Boris; Compton, Alison G.; Frazier, Ann E.; Bruno, Damien L.; Christodoulou, John; Endo, Hitoshi; Ryan, Michael T.; Nijtmans, Leo G.; Huynen, Martijn A.; Thorburn, David R.

    2013-01-01

    Mitochondrial oxidative phosphorylation (OXPHOS) is responsible for generating the majority of cellular ATP. Complex III (ubiquinol-cytochrome c oxidoreductase) is the third of five OXPHOS complexes. Complex III assembly relies on the coordinated expression of the mitochondrial and nuclear genomes, with 10 subunits encoded by nuclear DNA and one by mitochondrial DNA (mtDNA). Complex III deficiency is a debilitating and often fatal disorder that can arise from mutations in complex III subunit genes or one of three known complex III assembly factors. The molecular cause for complex III deficiency in about half of cases, however, is unknown and there are likely many complex III assembly factors yet to be identified. Here, we used Massively Parallel Sequencing to identify a homozygous splicing mutation in the gene encoding Ubiquinol-Cytochrome c Reductase Complex Assembly Factor 2 (UQCC2) in a consanguineous Lebanese patient displaying complex III deficiency, severe intrauterine growth retardation, neonatal lactic acidosis and renal tubular dysfunction. We prove causality of the mutation via lentiviral correction studies in patient fibroblasts. Sequence-profile based orthology prediction shows UQCC2 is an ortholog of the Saccharomyces cerevisiae complex III assembly factor, Cbp6p, although its sequence has diverged substantially. Co-purification studies show that UQCC2 interacts with UQCC1, the predicted ortholog of the Cbp6p binding partner, Cbp3p. Fibroblasts from the patient with UQCC2 mutations have deficiency of UQCC1, while UQCC1-depleted cells have reduced levels of UQCC2 and complex III. We show that UQCC1 binds the newly synthesized mtDNA-encoded cytochrome b subunit of complex III and that UQCC2 patient fibroblasts have specific defects in the synthesis or stability of cytochrome b. This work reveals a new cause for complex III deficiency that can assist future patient diagnosis, and provides insight into human complex III assembly by establishing that UQCC1

  11. Rabies virus phosphoprotein interacts with mitochondrial Complex I and induces mitochondrial dysfunction and oxidative stress.

    PubMed

    Kammouni, Wafa; Wood, Heidi; Saleh, Ali; Appolinario, Camila M; Fernyhough, Paul; Jackson, Alan C

    2015-08-01

    Our previous studies in an experimental model of rabies showed neuronal process degeneration in association with severe clinical disease. Cultured adult rodent dorsal root ganglion neurons infected with challenge virus standard (CVS)-11 strain of rabies virus (RABV) showed axonal swellings and reduced axonal growth with evidence of oxidative stress. We have shown that CVS infection alters a variety of mitochondrial parameters and increases reactive oxygen species (ROS) production and mitochondrial Complex I activity vs. mock infection. We have hypothesized that a RABV protein targets mitochondria and triggers dysfunction. Mitochondrial extracts of mouse neuroblastoma cells were analyzed with a proteomics approach. We have identified peptides belonging to the RABV nucleocapsid protein (N), phosphoprotein (P), and glycoprotein (G), and our data indicate that the extract was most highly enriched with P. P was also detected by immunoblotting in RABV-infected purified mitochondrial extracts and also in Complex I immunoprecipitates from the extracts but not in mock-infected extracts. A plasmid expressing P in cells increased Complex I activity and increased ROS generation, whereas expression of other RABV proteins did not. We have analyzed recombinant plasmids encoding various P gene segments. Expression of a peptide from amino acid 139-172 increased Complex I activity and ROS generation similar to expression of the entire P protein, whereas peptides that did not contain this region did not increase Complex I activity or induce ROS generation. These results indicate that a region of the RABV P interacts with Complex I in mitochondria causing mitochondrial dysfunction, increased generation of ROS, and oxidative stress. PMID:25698500

  12. Complex III deficiency due to an in-frame MT-CYB deletion presenting as ketotic hypoglycemia and lactic acidosis☆

    PubMed Central

    Mori, Mari; Goldstein, Jennifer; Young, Sarah P.; Bossen, Edward H.; Shoffner, John; Koeberl, Dwight D.

    2015-01-01

    Complex III deficiency due to a MT-CYB mutation has been reported in patients with myopathy. Here, we describe a 15-year-old boy who presented with metabolic acidosis, ketotic hypoglycemia and carnitine deficiency. Electron transport chain analysis and mitochondrial DNA sequencing on muscle tissue lead to the eventual diagnosis of complex III deficiency. This case demonstrates the critical role of muscle biopsies in a myopathy work-up, and the clinical efficacy of supplement therapy. PMID:26937408

  13. Complex III deficiency due to an in-frame MT-CYB deletion presenting as ketotic hypoglycemia and lactic acidosis.

    PubMed

    Mori, Mari; Goldstein, Jennifer; Young, Sarah P; Bossen, Edward H; Shoffner, John; Koeberl, Dwight D

    2015-09-01

    Complex III deficiency due to a MT-CYB mutation has been reported in patients with myopathy. Here, we describe a 15-year-old boy who presented with metabolic acidosis, ketotic hypoglycemia and carnitine deficiency. Electron transport chain analysis and mitochondrial DNA sequencing on muscle tissue lead to the eventual diagnosis of complex III deficiency. This case demonstrates the critical role of muscle biopsies in a myopathy work-up, and the clinical efficacy of supplement therapy. PMID:26937408

  14. Heptachlor induced mitochondria-mediated cell death via impairing electron transport chain complex III

    SciTech Connect

    Hong, Seokheon; Kim, Joo Yeon; Hwang, Joohyun; Shin, Ki Soon; Kang, Shin Jung

    2013-08-09

    Highlights: •Heptachlor inhibited mitochondrial electron transport chain complex III activity. •Heptachlor promoted generation of reactive oxygen species. •Heptachlor induced Bax activation. •Heptachlor induced mitochondria-mediated and caspase-dependent apoptosis. -- Abstract: Environmental toxins like pesticides have been implicated in the pathogenesis of Parkinson’s disease (PD). Epidemiological studies suggested that exposures to organochlorine pesticides have an association with an increased PD risk. In the present study, we examined the mechanism of toxicity induced by an organochlorine pesticide heptachlor. In a human dopaminergic neuroblastoma SH-SY5Y cells, heptachlor induced both morphological and functional damages in mitochondria. Interestingly, the compound inhibited mitochondrial electron transport chain complex III activity. Rapid generation of reactive oxygen species and the activation of Bax were then detected. Subsequently, mitochondria-mediated, caspase-dependent apoptosis followed. Our results raise a possibility that an organochlorine pesticide heptachlor can act as a neurotoxicant associated with PD.

  15. Parallel Structural Evolution of Mitochondrial Ribosomes and OXPHOS Complexes.

    PubMed

    van der Sluis, Eli O; Bauerschmitt, Heike; Becker, Thomas; Mielke, Thorsten; Frauenfeld, Jens; Berninghausen, Otto; Neupert, Walter; Herrmann, Johannes M; Beckmann, Roland

    2015-05-01

    The five macromolecular complexes that jointly mediate oxidative phosphorylation (OXPHOS) in mitochondria consist of many more subunits than those of bacteria, yet, it remains unclear by which evolutionary mechanism(s) these novel subunits were recruited. Even less well understood is the structural evolution of mitochondrial ribosomes (mitoribosomes): while it was long thought that their exceptionally high protein content would physically compensate for their uniquely low amount of ribosomal RNA (rRNA), this hypothesis has been refuted by structural studies. Here, we present a cryo-electron microscopy structure of the 73S mitoribosome from Neurospora crassa, together with genomic and proteomic analyses of mitoribosome composition across the eukaryotic domain. Surprisingly, our findings reveal that both structurally and compositionally, mitoribosomes have evolved very similarly to mitochondrial OXPHOS complexes via two distinct phases: A constructive phase that mainly acted early in eukaryote evolution, resulting in the recruitment of altogether approximately 75 novel subunits, and a reductive phase that acted during metazoan evolution, resulting in gradual length-reduction of mitochondrially encoded rRNAs and OXPHOS proteins. Both phases can be well explained by the accumulation of (slightly) deleterious mutations and deletions, respectively, in mitochondrially encoded rRNAs and OXPHOS proteins. We argue that the main role of the newly recruited (nuclear encoded) ribosomal- and OXPHOS proteins is to provide structural compensation to the mutationally destabilized mitochondrially encoded components. While the newly recruited proteins probably provide a selective advantage owing to their compensatory nature, and while their presence may have opened evolutionary pathways toward novel mitochondrion-specific functions, we emphasize that the initial events that resulted in their recruitment was nonadaptive in nature. Our framework is supported by population genetic

  16. Parallel Structural Evolution of Mitochondrial Ribosomes and OXPHOS Complexes

    PubMed Central

    van der Sluis, Eli O.; Bauerschmitt, Heike; Becker, Thomas; Mielke, Thorsten; Frauenfeld, Jens; Berninghausen, Otto; Neupert, Walter; Herrmann, Johannes M.; Beckmann, Roland

    2015-01-01

    The five macromolecular complexes that jointly mediate oxidative phosphorylation (OXPHOS) in mitochondria consist of many more subunits than those of bacteria, yet, it remains unclear by which evolutionary mechanism(s) these novel subunits were recruited. Even less well understood is the structural evolution of mitochondrial ribosomes (mitoribosomes): while it was long thought that their exceptionally high protein content would physically compensate for their uniquely low amount of ribosomal RNA (rRNA), this hypothesis has been refuted by structural studies. Here, we present a cryo-electron microscopy structure of the 73S mitoribosome from Neurospora crassa, together with genomic and proteomic analyses of mitoribosome composition across the eukaryotic domain. Surprisingly, our findings reveal that both structurally and compositionally, mitoribosomes have evolved very similarly to mitochondrial OXPHOS complexes via two distinct phases: A constructive phase that mainly acted early in eukaryote evolution, resulting in the recruitment of altogether approximately 75 novel subunits, and a reductive phase that acted during metazoan evolution, resulting in gradual length-reduction of mitochondrially encoded rRNAs and OXPHOS proteins. Both phases can be well explained by the accumulation of (slightly) deleterious mutations and deletions, respectively, in mitochondrially encoded rRNAs and OXPHOS proteins. We argue that the main role of the newly recruited (nuclear encoded) ribosomal- and OXPHOS proteins is to provide structural compensation to the mutationally destabilized mitochondrially encoded components. While the newly recruited proteins probably provide a selective advantage owing to their compensatory nature, and while their presence may have opened evolutionary pathways toward novel mitochondrion-specific functions, we emphasize that the initial events that resulted in their recruitment was nonadaptive in nature. Our framework is supported by population genetic

  17. Structure, function, and assembly of heme centers in mitochondrial respiratory complexes.

    PubMed

    Kim, Hyung J; Khalimonchuk, Oleh; Smith, Pamela M; Winge, Dennis R

    2012-09-01

    The sequential flow of electrons in the respiratory chain, from a low reduction potential substrate to O(2), is mediated by protein-bound redox cofactors. In mitochondria, hemes-together with flavin, iron-sulfur, and copper cofactors-mediate this multi-electron transfer. Hemes, in three different forms, are used as a protein-bound prosthetic group in succinate dehydrogenase (complex II), in bc(1) complex (complex III) and in cytochrome c oxidase (complex IV). The exact function of heme b in complex II is still unclear, and lags behind in operational detail that is available for the hemes of complex III and IV. The two b hemes of complex III participate in the unique bifurcation of electron flow from the oxidation of ubiquinol, while heme c of the cytochrome c subunit, Cyt1, transfers these electrons to the peripheral cytochrome c. The unique heme a(3), with Cu(B), form a catalytic site in complex IV that binds and reduces molecular oxygen. In addition to providing catalytic and electron transfer operations, hemes also serve a critical role in the assembly of these respiratory complexes, which is just beginning to be understood. In the absence of heme, the assembly of complex II is impaired, especially in mammalian cells. In complex III, a covalent attachment of the heme to apo-Cyt1 is a prerequisite for the complete assembly of bc(1), whereas in complex IV, heme a is required for the proper folding of the Cox 1 subunit and subsequent assembly. In this review, we provide further details of the aforementioned processes with respect to the hemes of the mitochondrial respiratory complexes. This article is part of a Special Issue entitled: Cell Biology of Metals. PMID:22554985

  18. Inactivation of renal mitochondrial respiratory complexes and manganese superoxide dismutase during sepsis: mitochondria-targeted antioxidant mitigates injury.

    PubMed

    Patil, Naeem K; Parajuli, Nirmala; MacMillan-Crow, Lee Ann; Mayeux, Philip R

    2014-04-01

    Acute kidney injury (AKI) is a complication of sepsis and leads to a high mortality rate. Human and animal studies suggest that mitochondrial dysfunction plays an important role in sepsis-induced multi-organ failure; however, the specific mitochondrial targets damaged during sepsis remain elusive. We used a clinically relevant cecal ligation and puncture (CLP) murine model of sepsis and assessed renal mitochondrial function using high-resolution respirometry, renal microcirculation using intravital microscopy, and renal function. CLP caused a time-dependent decrease in mitochondrial complex I and II/III respiration and reduced ATP. By 4 h after CLP, activity of manganese superoxide dismutase (MnSOD) was decreased by 50% and inhibition was sustained through 36 h. These events were associated with increased mitochondrial superoxide generation. We then evaluated whether the mitochondria-targeted antioxidant Mito-TEMPO could reverse renal mitochondrial dysfunction and attenuate sepsis-induced AKI. Mito-TEMPO (10 mg/kg) given at 6 h post-CLP decreased mitochondrial superoxide levels, protected complex I and II/III respiration, and restored MnSOD activity by 18 h. Mito-TEMPO also improved renal microcirculation and glomerular filtration rate. Importantly, even delayed therapy with a single dose of Mito-TEMPO significantly increased 96-h survival rate from 40% in untreated septic mice to 80%. Thus, sepsis causes sustained inactivation of three mitochondrial targets that can lead to increased mitochondrial superoxide. Importantly, even delayed therapy with Mito-TEMPO alleviated kidney injury, suggesting that it may be a promising approach to treat septic AKI. PMID:24500690

  19. Inactivation of renal mitochondrial respiratory complexes and manganese superoxide dismutase during sepsis: mitochondria-targeted antioxidant mitigates injury

    PubMed Central

    Patil, Naeem K.; Parajuli, Nirmala; Mayeux, Philip R.

    2014-01-01

    Acute kidney injury (AKI) is a complication of sepsis and leads to a high mortality rate. Human and animal studies suggest that mitochondrial dysfunction plays an important role in sepsis-induced multi-organ failure; however, the specific mitochondrial targets damaged during sepsis remain elusive. We used a clinically relevant cecal ligation and puncture (CLP) murine model of sepsis and assessed renal mitochondrial function using high-resolution respirometry, renal microcirculation using intravital microscopy, and renal function. CLP caused a time-dependent decrease in mitochondrial complex I and II/III respiration and reduced ATP. By 4 h after CLP, activity of manganese superoxide dismutase (MnSOD) was decreased by 50% and inhibition was sustained through 36 h. These events were associated with increased mitochondrial superoxide generation. We then evaluated whether the mitochondria-targeted antioxidant Mito-TEMPO could reverse renal mitochondrial dysfunction and attenuate sepsis-induced AKI. Mito-TEMPO (10 mg/kg) given at 6 h post-CLP decreased mitochondrial superoxide levels, protected complex I and II/III respiration, and restored MnSOD activity by 18 h. Mito-TEMPO also improved renal microcirculation and glomerular filtration rate. Importantly, even delayed therapy with a single dose of Mito-TEMPO significantly increased 96-h survival rate from 40% in untreated septic mice to 80%. Thus, sepsis causes sustained inactivation of three mitochondrial targets that can lead to increased mitochondrial superoxide. Importantly, even delayed therapy with Mito-TEMPO alleviated kidney injury, suggesting that it may be a promising approach to treat septic AKI. PMID:24500690

  20. Evolution and structural organization of the mitochondrial contact site (MICOS) complex and the mitochondrial intermembrane space bridging (MIB) complex.

    PubMed

    Huynen, Martijn A; Mühlmeister, Mareike; Gotthardt, Katherina; Guerrero-Castillo, Sergio; Brandt, Ulrich

    2016-01-01

    We have analyzed the distribution of mitochondrial contact site and cristae organizing system (MICOS) complex proteins and mitochondrial intermembrane space bridging complex (MIB) proteins over (sub)complexes and over species. The MICOS proteins are associated with the formation and maintenance of mitochondrial cristae. Indeed, the presence of MICOS genes in genomes correlates well with the presence of cristae: all cristae containing species have at least one MICOS gene and cristae-less species have none. Mic10 is the most widespread MICOS gene, while Mic60 appears be the oldest one, as it originates in the ancestors of mitochondria, the proteobacteria. In proteobacteria the gene occurs in clusters with genes involved in heme synthesis while the protein has been observed in intracellular membranes of the alphaproteobacterium Rhodobacter sphaeroides. In contrast, Mic23 and Mic27 appear to be the youngest MICOS proteins, as they only occur in opisthokonts. The remaining MICOS proteins, Mic10, Mic19, Mic25 and Mic12, the latter we show to be orthologous to human C19orf70/QIL1, trace back to the root of the eukaryotes. Of the remaining MIB proteins, also DNAJC11 shows a high correlation with the presence of cristae. In mitochondrial protein complexome profiles, the MIB complex occurs as a defined complex and as separate subcomplexes, potentially reflecting various assembly stages. We find three main forms of the complex: A) The MICOS complex, containing all the MICOS proteins, B) a membrane bridging subcomplex, containing in addition SAMM50, MTX2 and the previously uncharacterized MTX3, and C) the complete MIB complex containing in addition DNAJC11 and MTX1. PMID:26477565

  1. Nd(III)-induced rice mitochondrial dysfunction investigated by spectroscopic and microscopic methods.

    PubMed

    Xia, Cai-Fen; Lv, Long; Chen, Xin-You; Fu, Bo-Qiao; Lei, Ke-Lin; Qin, Cai-Qin; Liu, Yi

    2015-04-01

    The production capacity and yield of neodymium (Nd) in China have ranked the first in the world. Because of its unique biophysical and biochemical properties, Nd compounds have entered into the agricultural environment greatly to promote plant growth. Mitochondria play a crucial role in respiration and metabolism during the growth of plants. However, little is known about the mechanism by which Nd act at the mitochondrial level in plant cells. In this study, rice mitochondrial swelling, collapsed transmembrane potential and decreased membrane fluidity were examined to be important factors for mitochondria permeability transition pore (mPTP) opening induced by Nd(III). The protection of cyclosporin A (CsA) and dithiothreitol (DTT) could confirm that Nd(III) could trigger mPTP opening. Additionally, mitochondrial membrane breakdown observed by TEM and the release of cytochrome c (Cyt c) could also elucidate the mPTP opening from another point of view. At last, the study showed that Nd(III) could restrain the mitochondrial membrane lipid peroxide, so it might interact with anionic lipid too. This detection will be conductive to the safe application of Nd compounds in agriculture and food industry. PMID:25650179

  2. Cell-permeable succinate prodrugs bypass mitochondrial complex I deficiency.

    PubMed

    Ehinger, Johannes K; Piel, Sarah; Ford, Rhonan; Karlsson, Michael; Sjövall, Fredrik; Frostner, Eleonor Åsander; Morota, Saori; Taylor, Robert W; Turnbull, Doug M; Cornell, Clive; Moss, Steven J; Metzsch, Carsten; Hansson, Magnus J; Fliri, Hans; Elmér, Eskil

    2016-01-01

    Mitochondrial complex I (CI) deficiency is the most prevalent defect in the respiratory chain in paediatric mitochondrial disease. This heterogeneous group of diseases includes serious or fatal neurological presentations such as Leigh syndrome and there are very limited evidence-based treatment options available. Here we describe that cell membrane-permeable prodrugs of the complex II substrate succinate increase ATP-linked mitochondrial respiration in CI-deficient human blood cells, fibroblasts and heart fibres. Lactate accumulation in platelets due to rotenone-induced CI inhibition is reversed and rotenone-induced increase in lactate:pyruvate ratio in white blood cells is alleviated. Metabolomic analyses demonstrate delivery and metabolism of [(13)C]succinate. In Leigh syndrome patient fibroblasts, with a recessive NDUFS2 mutation, respiration and spare respiratory capacity are increased by prodrug administration. We conclude that prodrug-delivered succinate bypasses CI and supports electron transport, membrane potential and ATP production. This strategy offers a potential future therapy for metabolic decompensation due to mitochondrial CI dysfunction. PMID:27502960

  3. Cell-permeable succinate prodrugs bypass mitochondrial complex I deficiency

    PubMed Central

    Ehinger, Johannes K.; Piel, Sarah; Ford, Rhonan; Karlsson, Michael; Sjövall, Fredrik; Frostner, Eleonor Åsander; Morota, Saori; Taylor, Robert W.; Turnbull, Doug M.; Cornell, Clive; Moss, Steven J.; Metzsch, Carsten; Hansson, Magnus J.; Fliri, Hans; Elmér, Eskil

    2016-01-01

    Mitochondrial complex I (CI) deficiency is the most prevalent defect in the respiratory chain in paediatric mitochondrial disease. This heterogeneous group of diseases includes serious or fatal neurological presentations such as Leigh syndrome and there are very limited evidence-based treatment options available. Here we describe that cell membrane-permeable prodrugs of the complex II substrate succinate increase ATP-linked mitochondrial respiration in CI-deficient human blood cells, fibroblasts and heart fibres. Lactate accumulation in platelets due to rotenone-induced CI inhibition is reversed and rotenone-induced increase in lactate:pyruvate ratio in white blood cells is alleviated. Metabolomic analyses demonstrate delivery and metabolism of [13C]succinate. In Leigh syndrome patient fibroblasts, with a recessive NDUFS2 mutation, respiration and spare respiratory capacity are increased by prodrug administration. We conclude that prodrug-delivered succinate bypasses CI and supports electron transport, membrane potential and ATP production. This strategy offers a potential future therapy for metabolic decompensation due to mitochondrial CI dysfunction. PMID:27502960

  4. Organization of the human mitochondrial transcription initiation complex

    PubMed Central

    Yakubovskaya, Elena; Guja, Kip E.; Eng, Edward T.; Choi, Woo Suk; Mejia, Edison; Beglov, Dmitri; Lukin, Mark; Kozakov, Dima; Garcia-Diaz, Miguel

    2014-01-01

    Initiation of transcription in human mitochondria involves two factors, TFAM and TFB2M, in addition to the mitochondrial RNA polymerase, POLRMT. We have investigated the organization of the human mitochondrial transcription initiation complex on the light-strand promoter (LSP) through solution X-ray scattering, electron microscopy (EM) and biochemical studies. Our EM results demonstrate a compact organization of the initiation complex, suggesting that protein–protein interactions might help mediate initiation. We demonstrate that, in the absence of DNA, only POLRMT and TFAM form a stable interaction, albeit one with low affinity. This is consistent with the expected transient nature of the interactions necessary for initiation and implies that the promoter DNA acts as a scaffold that enables formation of the full initiation complex. Docking of known crystal structures into our EM maps results in a model for transcriptional initiation that strongly correlates with new and existing biochemical observations. Our results reveal the organization of TFAM, POLRMT and TFB2M around the LSP and represent the first structural characterization of the entire mitochondrial transcriptional initiation complex. PMID:24413562

  5. Increased production of mitochondrial superoxide in the spinal cord induces pain behaviors in mice: the effect of mitochondrial electron transport complex inhibitors.

    PubMed

    Kim, Hee Young; Chung, Jin Mo; Chung, Kyungsoon

    2008-12-01

    Scavengers of reactive oxygen species (ROS) have been shown to produce a strong antinociceptive effect on persistent pain, and mitochondria are suggested to be the main source of ROS in the spinal dorsal horn. To explore whether excessive generation of mitochondrial superoxide alone can induce pain, the effect of mitochondrial electron transport complex inhibitors on the development of mechanical hyperalgesia was examined in mice. Intrathecal injection of an electron transport complex inhibitor, antimycin A or rotenone, in normal mice resulted in a slowly developing but long-lasting and dose-dependent mechanical hyperalgesia. The levels of mechanical hyperalgesia after antimycin A, a complex III inhibitor, were higher than that with rotenone, a complex I inhibitor. A large increase of mitochondrial superoxide in the spinal dorsal horn and a strong antinociceptive effect of ROS scavengers, phenyl-N-tert-butylnitrone (PBN) and 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL) were observed in antimycin A-treated mice. The study indicates that the enhanced production of spinal mitochondrial superoxide alone without nerve injury can produce mechanical hyperalgesia. PMID:18832013

  6. Isoflurane Selectively Inhibits Distal Mitochondrial Complex I in Caenorhabditis Elegans

    PubMed Central

    Kayser, Ernst-Bernhard; Suthammarak, Wichit; Morgan, Phil G.; Sedensky, Margaret M.

    2011-01-01

    BACKGROUND Complex I of the electron transport chain (ETC) is a possible target of volatile anesthetics (VAs). Complex I enzymatic activities are inhibited by VAs, and dysfunction of complex I can lead to hypersensitivity to VAs in worms and in people. Mutant analysis in Caenorhabditis (C.) elegans suggests that VAs may specifically interfere with complex I function at the binding site for its substrate ubiquinone. We hypothesized that isoflurane inhibits electron transport by competing with ubiquinone for binding to complex I. METHODS Wildtype and mutant C. elegans were used to study the effects of isoflurane on isolated mitochondria. Enzymatic activities of the ETC were assayed and dose-response curves determined using established techniques. Two-dimensional native gels of mitochondrial proteins were performed after exposure of mitochondria to isoflurane. RESULTS Complex I is the most sensitive component of the ETC to isoflurane inhibition; however the proximal portion of complex I (the flavoprotein) is relatively insensitive to isoflurane. Isoflurane and quinone do not compete for a common binding site on complex I. The absolute rate of complex I enzymatic activity in vitro does not predict immobilization of the animal by isoflurane. Isoflurane had no measurable effect on stability of mitochondrial supercomplexes. Reduction of ubiquinone by complex I displayed positive cooperative kinetics not disrupted by isoflurane. CONCLUSIONS Isoflurane directly inhibits complex I at a site distal to the flavoprotein subcomplex. However, we have excluded our original hypothesis that isoflurane and ubiquinone compete for a common hydrophobic binding site on complex I. In addition, immobilization of the nematode by isoflurane is not due to limiting absolute amounts of complex I electron transport as measured in isolated mitochondria. PMID:21467554

  7. Xanthohumol induces generation of reactive oxygen species and triggers apoptosis through inhibition of mitochondrial electron transfer chain complex I.

    PubMed

    Zhang, Bo; Chu, Wei; Wei, Peng; Liu, Ying; Wei, Taotao

    2015-12-01

    Xanthohumol is a prenylflavonoid extracted from hops (Humulus lupulus). It possesses anti-cancer and anti-inflammatory activities in vitro and in vivo, and offers therapeutic benefits for treatment of metabolic syndromes. However, the precise mechanisms underlying its pharmacological effects remain to be elucidated, together with its cellular target. Here, we provide evidence that xanthohumol directly interacts with the mitochondrial electron transfer chain complex I (NADH dehydrogenase), inhibits the oxidative phosphorylation, triggers the production of reactive oxygen species, and induces apoptosis. In addition, we show that as a result of the inhibition of the mitochondrial oxidative phosphorylation, xanthohumol exposure causes a rapid decrease of mitochondrial transmembrane potential. Furthermore, we showed that xanthohumol up-regulates the glycolytic capacity in cells, and thus compensates cellular ATP generation. Dissection of the multiple steps of aerobic respiration by extracellular flux assays revealed that xanthohumol specifically inhibits the activity of mitochondrial complex I, but had little effect on that of complex II, III and IV. Inhibition of complex I by xanthohumol caused the overproduction of reactive oxygen species, which are responsible for the induction of apoptosis in cancer cells. We also found that isoxanthohumol, the structural isomer of xanthohumol, is inactive to cells, suggesting that the reactive 2-hydroxyl group of xanthohumol is crucial for its targeting to the mitochondrial complex I. Together, the remodeling of cell metabolism revealed here has therapeutic potential for the use of xanthohumol. PMID:26453927

  8. Development and evaluation of a spectrophotometric assay for complex III in isolated mitochondria, tissues and fibroblasts from rats and humans.

    PubMed

    Krähenbühl, S; Talos, C; Wiesmann, U; Hoppel, C L

    1994-10-31

    A spectrophotometric method to assay the activity of complex III in isolated mitochondria, tissues and fibroblasts from patients and rats has been developed and validated. Decylubiquinol was shown to be a suitable substrate with a saturating concentration between 100 and 200 mumol/l. The optimal pH was found to range from 7.4 to 8.0. The enzyme reaction was linear for incubations containing up to 15 micrograms/ml mitochondrial protein, 250 micrograms/ml liver tissue, 375 micrograms/ml skeletal muscle or 100 micrograms/ml fibroblast protein. Intraday and interday variability of the assay for different enzyme sources was below 15% and 10%, respectively. Assessment of complex III activity in liver and fibroblasts from patients with signs of mitochondrial dysfunction revealed the usefulness of the newly developed assay in the diagnosis of complex III deficiency. PMID:7834868

  9. Gallium(iii) and iron(iii) complexes of quinolone antimicrobials.

    PubMed

    Mjos, Katja Dralle; Cawthray, Jacqueline F; Polishchuk, Elena; Abrams, Michael J; Orvig, Chris

    2016-08-16

    Iron is an essential nutrient for many microbes. According to the "Trojan Horse Hypothesis", biological systems have difficulties distinguishing between Fe(3+) and Ga(3+), which constitutes the antimicrobial efficacy of the gallium(iii) ion. Nine novel tris(quinolono)gallium(iii) complexes and their corresponding iron(iii) analogs have been synthesized and fully characterized. Quinolone antimicrobial agents from three drug generations were used in this study: ciprofloxacin, enoxacin, fleroxacin, levofloxacin, lomefloxacin, nalidixic acid, norfloxacin, oxolinic acid, and pipemidic acid. The antimicrobial efficacy of the tris(quinolono)gallium(iii) complexes was studied against E. faecalis and S. aureus (both Gram-positive), as well as E. coli, K. pneumonia, and P. aeruginosa (all Gram-negative) in direct comparison to the tris(quinolono)iron(iii) complexes and the corresponding free quinolone ligands at various concentrations. For the tris(quinolono)gallium(iii) complexes, no combinational antimicrobial effects between Ga(3+) and the quinolone antimicrobial agents were observed. PMID:27315225

  10. Hexaammine Complexes of Cr(III) and Co(III): A Spectral Study.

    ERIC Educational Resources Information Center

    Brown, D. R.; Pavlis, R. R.

    1985-01-01

    Procedures are provided for experiments containing complex ions with octahedral symmetry, hexaamminecobalt(III) chloride and hexaamminechromium(III) nitrate, so students can interpret fully the ultra violet/visible spectra of the complex cations in terms of the ligand field parameters, 10 "Dq," the Racah interelectron repulsion parameters, "B,"…

  11. Synthesis, thermal and spectroscopic behaviors of metal-drug complexes: La(III), Ce(III), Sm(III) and Y(III) amoxicillin trihydrate antibiotic drug complexes

    NASA Astrophysics Data System (ADS)

    Refat, Moamen S.; Al-Maydama, Hussein M. A.; Al-Azab, Fathi M.; Amin, Ragab R.; Jamil, Yasmin M. S.

    2014-07-01

    The metal complexes of Amoxicillin trihydrate with La(III), Ce(III), Sm(III) and Y(III) are synthesized with 1:1 (metal:Amox) molar ratio. The suggested formula structures of the complexes are based on the results of the elemental analyses, molar conductivity, (infrared, UV-visible and fluorescence) spectra, effective magnetic moment in Bohr magnetons, as well as the thermal analysis (TG), and characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The results obtained suggested that Amoxicillin reacted with metal ions as tridentate ligands, coordinating the metal ion through its amino, imino, and β-lactamic carbonyl. The kinetic thermodynamic parameters such as: Ea, ΔH*, ΔS* and ΔG* were estimated from the DTG curves.

  12. Targeting insect mitochondrial complex I for plant protection.

    PubMed

    Wu, Xiu-Ming; Yang, Chang-Qing; Mao, Ying-Bo; Wang, Ling-Jian; Shangguan, Xiao-Xia; Chen, Xiao-Ya

    2016-09-01

    Plant engineered to express double-stranded RNA (dsRNA) can target the herbivorous insect gene for silencing. Although mounting evidence has emerged to support feasibility of this new pest control technology, field application is slow largely due to lack of potent targets. Here, we show that suppression of the gene encoding NDUFV2, a subunit of mitochondrial complex I that catalyses NADH dehydrogenation in respiratory chain, was highly lethal to insects. Feeding cotton bollworm (Helicoverpa armigera) larvae with transgenic cotton tissues expressing NDUFV2 dsRNA led to mortality up to 80% within 5 days, and almost no larvae survived after 7 days of feeding, due to the altered mitochondrial structure and activity. Transcriptome comparisons showed a drastic repression of dopa decarboxylase genes. Reciprocal assays with Asian corn borer (Ostrinia furnacalis), another lepidopteran species, revealed the sequence-specific effect of NDUFV2 suppression. Furthermore, the hemipteran lugus Apolygus lucorum was also liable to NDUFV2 repression. These data demonstrate that the mitochondrial complex I is a promising target with both sequence specificity and wide applicability for the development of new-generation insect-proof crops. PMID:26914579

  13. Age-related alterations in oxidatively damaged proteins of mouse skeletal muscle mitochondrial electron transport chain complexes

    PubMed Central

    Choksi, Kashyap B.; Nuss, Jonathan E.; DeFord, James H.; Papaconstantinou, John

    2010-01-01

    Age-associated mitochondrial dysfunction is a major source of reactive oxygen species (ROS) and oxidative modification to proteins. Mitochondrial electron transport chain (ETC) complexes I and III are the sites of ROS production and we hypothesize that proteins of the ETC complexes are primary targets of ROS-mediated modification which impairs their structure and function. The pectoralis, primarily an aerobic red muscle, and quadriceps, primarily an anaerobic white muscle, have different rates of respiration and oxygen-carrying capacity, and hence, different rates of ROS production. This raises the question of whether these muscles exhibit different levels of oxidative protein modification. Our studies reveal that the pectoralis shows a dramatic age-related decline in almost all complex activities that correlates with increased oxidative modification. Similar complex proteins were modified in the quadriceps, at a significantly lower level with less change in enzyme and ETC coupling function. We postulate that mitochondrial ROS causes damage to specific ETC subunits which increases with age and leads to further mitochondrial dysfunction. We conclude that physiological characteristics of the pectoralis vs quadriceps may play a role in age-associated rate of mitochondrial dysfunction and in the decline in tissue function. PMID:18598756

  14. Potentiometry: A Chromium (III) -- EDTA Complex

    ERIC Educational Resources Information Center

    Hoppe, J. I.; Howell, P. J.

    1975-01-01

    Describes an experiment that involves the preparation of a chromium (III)-EDTA compound, a study of its infrared spectrum, and the potentiometric determination of two successive acid dissociation constants. (Author/GS)

  15. Water-soluble Co(III) complexes of substituted phenanthrolines with cell selective anticancer activity.

    PubMed

    Jagadeesan, Sivaraman; Balasubramanian, Vimalkumar; Baumann, Patric; Neuburger, Markus; Häussinger, Daniel; Palivan, Cornelia G

    2013-11-01

    Transition metal complexes with substituted phenanthrolines as ligands represent potential anticancer products without the drawbacks of platinum complexes that are currently marketed. Here, we report the synthesis and cell selective anticancer activity of five new water-soluble Co(III) complexes with methyl substituted phenanthroline ligands. The complexes were characterized by elemental analysis, NMR, FAB-mass spectrometry, FTIR, electronic spectroscopy, and single crystal X-ray diffraction. Possible interaction of these complexes with DNA was assessed by a combination of circular dichroism, UV-vis spectroscopy titration, and ethidium bromide displacement assay, and the results indicated that DNA interaction is weak for these complexes. Cellular uptake and cytotoxicity of complexes at low concentrations were assessed by flow cytometry on PC-3 cells, while their effect on intracellular mitochondrial function was measured by MTS assay on HeLa and PC-3 cell lines. These complexes showed selective cytotoxicity with a significantly higher effect on intracellular mitochondrial function in PC-3 cells than in HeLa cells. At low concentrations, complex 2 had the highest cytotoxic effect on PC-3 cells, inducing around 38% cell death, and the correlation of cytotoxicity of these complexes to their hydrophobicity indicates that an appropriate value of the hydrophobicity is essential for high antitumor activity. PMID:24127683

  16. Complexation of N4-Tetradentate Ligands with Nd(III) and Am(III)

    SciTech Connect

    Ogden, Mark D.; Sinkov, Sergey I.; Meier, G. Patrick; Lumetta, Gregg J.; Nash, Kenneth L.

    2012-12-06

    To improve understanding of aza-complexants in trivalent actinide–lanthanide separations, a series of tetradentate N-donor ligands have been synthesized and their complexation of americium(III) and neodymium(III) investigated by UV–visible spectrophotometry in methanolic solutions. The six pyridine/alkyl amine/imine ligands are N,N0-bis(2-methylpyridyl)-1,2-diaminoethane, N,N0-bis(2-methylpyridyl)-1,3-diaminopropane, trans-N,N-bis(2-pyridylmethyl)-1,2-diaminocyclohexane (BPMDAC), N,N’-bis(2-pyridylmethyl)piperazine, N,N’-bis-[pyridin-2-ylmethylene]ethane-1,2-diamine, and trans-N,Nbis-([pyridin-2-ylmethylene]-cyclohexane-1,2-diamine. Each ligand has two pyridine groups and two aliphatic amine/imine N-donor atoms arranged with different degrees of preorganization and structural backbone rigidity. Conditional stability constants for the complexes of Am(III) and Nd(III) by these ligands establish the selectivity patterns. The overall selectivity of Am(III) over Nd(III) is similar to that reported for the terdentate bis(dialkyltriazinyl)pyridine molecules. The cyclohexane amine derivative (BPMDAC) is the strongest complexant and shows the highest selectivity for Am(III) over Nd(III) while the imines appear to prefer a bridging arrangement between two cations. These results suggest that this series of ligands could be employed to develop an enhanced actinide(III)– lanthanide(III) separation system.

  17. Photorelease and Cellular Delivery of Mitocurcumin from Its Cytotoxic Cobalt(III) Complex in Visible Light.

    PubMed

    Garai, Aditya; Pant, Ila; Banerjee, Samya; Banik, Bhabatosh; Kondaiah, Paturu; Chakravarty, Akhil R

    2016-06-20

    Ternary cobalt(III) complexes of curcumin (Hcur) and mitocurcumin [Hmitocur, a dicationic bis(triphenylphosphonium) derivative of curcumin] having a tetradentate phenolate-based ligand (H2L), namely, [Co(cur)(L)] (1) and [Co(mitocur)(L)]Cl2 (2), were prepared and structurally characterized, and their photoinduced cytotoxicity was studied. The diamagnetic cobalt(III) complexes show an irreversible Co(III)-Co(II) redox response and a quasireversible curcuminoid-based reduction near -1.45 and -1.74 V SCE, respectively, in DMF/0.1 M [(n)Bu4N](ClO4). The complexes exhibit a curcumin/mitocurcumin-based absorption band near 420 nm. Complex 1 was structurally characterized by X-ray crystallography. The structure contains the metal in a CoN2O4 distorted octahedral coordination arrangement with curcumin binding to the metal in its enolic form. Binding to cobalt(III) increases the hydrolytic stability of curcumin. Complex 2, having a dicationic curcuminoid, shows significant cellular uptake and photoinduced cytotoxicity compared to its curcumin analogue 1. The dicationic cobalt(III) complex 2 has significantly better cellular uptake and bioactivity than the neutral species 1. Complex 2 with mitochondrial localization releases the mitocurcumin dye upon exposure to visible light (400-700 nm) in human breast cancer MCF-7 cells through photoreduction of cobalt(III) to cobalt(II). Complex 2 displays a remarkable photodynamic therapy (PDT) effect, giving an IC50 value of ∼3.9 μM in visible light (400-700 nm) in MCF-7 cells while being much less toxic in the dark (>50 μM). The released mitocurcumin acts as a phototoxin, generating intracellular reactive oxygen species (ROSs). The overall process leads to light-controlled delivery of a curcuminoid (mitocur) into the tumor cells while the dye alone suffers from hydrolytic instability and poor bioavailability. PMID:27244480

  18. Complex I and complex III inhibition specifically increase cytosolic hydrogen peroxide levels without inducing oxidative stress in HEK293 cells

    PubMed Central

    Forkink, Marleen; Basit, Farhan; Teixeira, José; Swarts, Herman G.; Koopman, Werner J.H.; Willems, Peter H.G.M.

    2015-01-01

    Inhibitor studies with isolated mitochondria demonstrated that complex I (CI) and III (CIII) of the electron transport chain (ETC) can act as relevant sources of mitochondrial reactive oxygen species (ROS). Here we studied ROS generation and oxidative stress induction during chronic (24 h) inhibition of CI and CIII using rotenone (ROT) and antimycin A (AA), respectively, in intact HEK293 cells. Both inhibitors stimulated oxidation of the ROS sensor hydroethidine (HEt) and increased mitochondrial NAD(P)H levels without major effects on cell viability. Integrated analysis of cells stably expressing cytosolic- or mitochondria-targeted variants of the reporter molecules HyPer (H2O2-sensitive and pH-sensitive) and SypHer (H2O2-insensitive and pH-sensitive), revealed that CI- and CIII inhibition increased cytosolic but not mitochondrial H2O2 levels. Total and mitochondria-specific lipid peroxidation was not increased in the inhibited cells as reported by the C11-BODIPY581/591 and MitoPerOx biosensors. Also expression of the superoxide-detoxifying enzymes CuZnSOD (cytosolic) and MnSOD (mitochondrial) was not affected. Oxyblot analysis revealed that protein carbonylation was not stimulated by CI and CIII inhibition. Our findings suggest that chronic inhibition of CI and CIII: (i) increases the levels of HEt-oxidizing ROS and (ii) specifically elevates cytosolic but not mitochondrial H2O2 levels, (iii) does not induce oxidative stress or substantial cell death. We conclude that the increased ROS levels are below the stress-inducing level and might play a role in redox signaling. PMID:26516986

  19. Pedigree models for complex human traits involving the mitochondrial genome.

    PubMed Central

    Schork, N J; Guo, S W

    1993-01-01

    Recent biochemical and molecular-genetic discoveries concerning variations in human mtDNA have suggested a role for mtDNA mutations in a number of human traits and disorders. Although the importance of these discoveries cannot be emphasized enough, the complex natures of mitochondrial biogenesis, mutant mtDNA phenotype expression, and the maternal inheritance pattern exhibited by mtDNA transmission make it difficult to develop models that can be used routinely in pedigree analyses to quantify and test hypotheses about the role of mtDNA in the expression of a trait. In the present paper, we describe complexities inherent in mitochondrial biogenesis and genetic transmission and show how these complexities can be incorporated into appropriate mathematical models. We offer a variety of likelihood-based models which account for the complexities discussed. The derivation of our models is meant to stimulate the construction of statistical tests for putative mtDNA contribution to a trait. Results of simulation studies which make use of the proposed models are described. The results of the simulation studies suggest that, although pedigree models of mtDNA effects can be reliable, success in mapping chromosomal determinants of a trait does not preclude the possibility that mtDNA determinants exists for the trait as well. Shortcomings inherent in the proposed models are described in an effort to expose areas in need of additional research. PMID:8250048

  20. Mechanisms of Sb(III) Photooxidation by the Excitation of Organic Fe(III) Complexes.

    PubMed

    Kong, Linghao; He, Mengchang

    2016-07-01

    Organic Fe(III) complexes are widely distributed in the aqueous environment, which can efficiently generate free radicals under light illumination, playing a significant role in heavy metal speciation. However, the potential importance of the photooxidation of Sb(III) by organic Fe(III) complexes remains unclear. Therefore, the photooxidation mechanisms of Sb(III) were comprehensively investigated in Fe(III)-oxalate, Fe(III)-citrate and Fe(III)-fulvic acid (FA) solutions by kinetic measurements and modeling. Rapid photooxidation of Sb(III) was observed in an Fe(III)-oxalate solution over the pH range of 3 to 7. The addition of tert-butyl alcohol (TBA) as an ·OH scavenger quenched the Sb(III) oxidation, suggesting that ·OH is an important oxidant for Sb(III). However, the incomplete quenching of Sb(III) oxidation indicated the existence of other oxidants, presumably an Fe(IV) species in irradiated Fe(III)-oxalate solution. In acidic solutions, ·OH may be formed by the reaction of Fe(II)(C2O4) with H2O2, but a hypothetical Fe(IV) species may be generated by the reaction of Fe(II)(C2O4)2(2-) with H2O2 at higher pH. Kinetic modeling provides a quantitative explanation of the results. Evidence for the existence of ·OH and hypothetical Fe(IV) was also observed in an irradiated Fe(III)-citrate and Fe(III)-FA system. This study demonstrated an important pathway of Sb(III) oxidation in surface waters. PMID:27267512

  1. Thermal and optical properties of Tb(III), Eu(III) and Tb(III)/Eu(III) co-complexed silicone fluorinated acrylate copolymer

    NASA Astrophysics Data System (ADS)

    Zhai, Yinfeng; Xie, Hongde; Cai, Haijun; Cai, Peiqing; Seo, Hyo Jin

    2015-07-01

    Tb(III), Eu(III) and Tb(III)/Eu(III) activated silicone fluorinated acrylate (SFA) have been successfully synthesized using the method of semi-continuous emulsion polymerization. The copolymers are characterized by flourier transform infrared (FT-IR), thermal gravity analysis (TGA), photoluminescence excitation (PLE) and emission (PL) spectroscopy. The copolymer containing Tb(III) and Eu(III) ions display green and red luminescent colors under UV light excitation, respectively. The TGA curves show the thermal decomposition temperatures of the copolymers are up to about 300 °C. The PL spectra show a strong green emission at 546 nm (5D4 → 7F5) of Tb(III) complexed copolymers, and show a prominent red emission at 615 nm (5D0 → 7F2) of Eu(III) complexed copolymers. Different concentrations of Eu(III) and Tb(III) ions are introduced into the copolymer and the energy transfer from Tb(III) to Eu(III) ions in the copolymer was found. Thus, based on the results it can be suggested that SFA:Eu(III), SFA:Tb(III) and SFA:Tb(III)/Eu(III) can be used potentially as luminescent materials.

  2. Antioxidant property of quercetin-Cr(III) complex: The role of Cr(III) ion

    NASA Astrophysics Data System (ADS)

    Chen, Weijun; Sun, Shaofang; cao, Wei; Liang, Yan; Song, Jirong

    2009-01-01

    Flavonoid-metal complex is reported to exhibit a higher antioxidant activity than parent flavonoid. In this paper, experimental and theoretical methods are applied to study the antioxidant properties of quercetin and quercetin-Cr(III) complex, to find out the antioxidant activity variation and the role of Cr(III) ion on the antioxidant activity of the complex. Bond dissociation energy (BDE) and ionization potential (IP) of quercetin and the complex are calculated at the B3LYP/6-311++G(2d,2p)//B3LYP/LANL2DZ level. The experimental results show that the complex has a higher DPPH radical scavenging activity than quercetin. The calculated results show that the complex displays lower BDE and IP than quercetin. The IP of the complex declines obviously, indicating that the Cr (III) ion has more impact on the electron donating ability than on the hydrogen atom transferring ability of the complex.

  3. Luminescent cyclometallated iridium(III) complexes having acetylide ligands

    SciTech Connect

    Thompson, Mark E.; Bossi, Alberto; Djurovich, Peter Ivan

    2014-09-02

    The present invention relates to phosphorescent (triplet-emitting) organometallic materials. The phosphorescent materials of the present invention comprise Ir(III)cyclometallated alkynyl complexes for use as triplet light-emitting materials. The Ir(III)cyclometallated alkynyl complexes comprise at least one cyclometallating ligand and at least one alkynyl ligand bonded to the iridium. Also provided is an organic light emitting device comprising an anode, a cathode and an emissive layer between the anode and the cathode, wherein the emissive layer comprises a Ir(III)cyclometallated alkynyl complex as a triplet emitting material.

  4. Plant mitochondrial Complex I composition and assembly: A review.

    PubMed

    Subrahmanian, Nitya; Remacle, Claire; Hamel, Patrice Paul

    2016-07-01

    In the mitochondrial inner membrane, oxidative phosphorylation generates ATP via the operation of several multimeric enzymes. The proton-pumping Complex I (NADH:ubiquinone oxidoreductase) is the first and most complicated enzyme required in this process. Complex I is an L-shaped enzyme consisting of more than 40 subunits, one FMN molecule and eight Fe-S clusters. In recent years, genetic and proteomic analyses of Complex I mutants in various model systems, including plants, have provided valuable insights into the assembly of this multimeric enzyme. Assisted by a number of key players, referred to as "assembly factors", the assembly of Complex I takes place in a sequential and modular manner. Although a number of factors have been identified, their precise function in mediating Complex I assembly still remains to be elucidated. This review summarizes our current knowledge of plant Complex I composition and assembly derived from studies in plant model systems such as Arabidopsis thaliana and Chlamydomonas reinhardtii. Plant Complex I is highly conserved and comprises a significant number of subunits also present in mammalian and fungal Complexes I. Plant Complex I also contains additional subunits absent from the mammalian and fungal counterpart, whose function in enzyme activity and assembly is not clearly understood. While 14 assembly factors have been identified for human Complex I, only two proteins, namely GLDH and INDH, have been established as bona fide assembly factors for plant Complex I. This article is part of a Special Issue entitled Respiratory complex I, edited by Volker Zickermann and Ulrich Brandt. PMID:26801215

  5. Bis-Histidine-Coordinated Hemes in Four-Helix Bundles: How the Geometry of the Bundle Controls the Axial Imidazole Plane Orientations in Transmembrane Cytochromes of Mitochondrial Complexes II and III and Related Proteins

    PubMed Central

    Berry, Edward A.; Walker, F. Ann

    2009-01-01

    Early investigation of the EPR spectra of bis-histidine-coordinated membrane-bound ferriheme proteins led to the description of a spectral signal that had only one resolved feature. These became known as “highly anisotropic low-spin” (HALS) or “large gmax” ferriheme centers. Extensive work with small-molecule model heme complexes showed that this spectroscopic signature occurs in bis-imidazole ferrihemes in which the planes of the imidazole ligands are nearly perpendicular, Δϕ = 57–90°. In the last decade protein crystallographic studies have revealed the atomic structures of a number of examples of bis-histidine heme proteins. A frequent characteristic of these large gmax ferrihemes in membrane-bound proteins is the occurrence of the heme within a four-helix bundle with a left-handed twist. The histidine ligands occur at the same level on two diametrically opposed helices of the bundle. These ligands have the same side chain conformation and ligate heme iron on the bundle axis, resulting in a quasi-2-fold symmetric structure. The two non-ligand-bearing helices also obey this symmetry, and have a conserved small residue, usually glycine, where the edge of the heme ring makes contact with the helix backbones. In many cases this small residue is preceded by a threonine or serine residue whose side chain hydroxyl oxygen acts as a hydrogen-bond acceptor from the Nδ1 atom of the heme-ligating histidine. The Δϕ angle is thus determined by the common histidine side-chain conformation and the crossing angle of the ligand-bearing helices, in some cases constrained by H-bonds to the Ser/Thr residues on the non-ligand-bearing helices. PMID:18418633

  6. Complexation of Cm(III)/Eu(III) with Silicate in Basic Solutions

    SciTech Connect

    Wang, Zheming; Felmy, Andrew R; Xia, Yuanxian; Qafoku, Odeta; Yantasee, Wassana; Cho, Herman M

    2005-12-01

    The complexation of Cm(III) and Eu(III) with dissolved silica was studied by time resolved laser fluorescence spectroscopy (TRLFS) in basic solutions over a range of total silica concentrations and ionic strengths (NaNO3). In highly basic solutions, both the fluorescence spectra and lifetime data indicate the formation of Eu(III)/Cm(III) complexes with oligomeric silicates as well as hydroxide groups and/or nitrate in the presence of concentrated NaNO3. At high silica concentration the inner-sphere complexation caused the shift of the fluorescence spectral maximum for Cm(III)(aq) from 594 nm to up to 607 nm and a significant increase of the hypersensitive 5D0 → 7F2 band around 615 nm relative to the non-hypersensitive 5D0 → 7F1 band at 592 nm for Eu(III). At the same time, the fluorescence lifetime increased from 68 s to up to 202 s for Cm(III) in 0.1 M NaNO3 and from 115 s to 1.8 ms for Eu(III) in 3.0 M and 5.0 M NaNO3, consistent with the removal of 6 or more water molecules upon silicate complexation. Linear correlations between the spectral intensity of Cm(III) complexes and the concentrations of the dissolved silicates suggest that Cm(III) complexation with the silicate dimer, Si2O2(OH)22-, may play a role.

  7. Autoantibodies to the mitochondrial RNA processing (MRP) complex also known as Th/To autoantigen.

    PubMed

    Mahler, Michael; Fritzler, Marvin J; Satoh, Minoru

    2015-03-01

    Antinuclear antibodies (ANA) represent valuable biomarkers in the diagnosis of systemic sclerosis (SSc) being present in the vast majority of the patients. Besides anti-topoisomerase I, anti-centromere and anti-RNA polymerase III antibodies as the main specificities, several other autoantibodies can be present in SSc patients including autoantibodies targeting the PM/Scl complex (also known as the exosome), U3-RNP/fibrillarin and the Th/To autoantigens. Anti-Th/To antibodies are one of the specificities that reportedly show homogenous nucleolar staining in conventional indirect immunofluorescence (IIF) ANA tests. Almost all protein components of the mitochondrial RNA processing (MRP) and the evolutionarily related RNase P complex have been reported to be the target of anti-Th/To antibodies in systemic autoimmune rheumatic disease (SARD) patients. However, Rpp25, Rpp38 and hPop1 have been described as the main autoantigen. PMID:25462581

  8. Neuroinflammation, mitochondrial defects and neurodegeneration in mucopolysaccharidosis III type C mouse model.

    PubMed

    Martins, Carla; Hůlková, Helena; Dridi, Larbi; Dormoy-Raclet, Virginie; Grigoryeva, Lubov; Choi, Yoo; Langford-Smith, Alexander; Wilkinson, Fiona L; Ohmi, Kazuhiro; DiCristo, Graziella; Hamel, Edith; Ausseil, Jerôme; Cheillan, David; Moreau, Alain; Svobodová, Eva; Hájková, Zuzana; Tesařová, Markéta; Hansíková, Hana; Bigger, Brian W; Hrebícek, Martin; Pshezhetsky, Alexey V

    2015-02-01

    Severe progressive neurological paediatric disease mucopolysaccharidosis III type C is caused by mutations in the HGSNAT gene leading to deficiency of acetyl-CoA: α-glucosaminide N-acetyltransferase involved in the lysosomal catabolism of heparan sulphate. To understand the pathophysiology of the disease we generated a mouse model of mucopolysaccharidosis III type C by germline inactivation of the Hgsnat gene. At 6-8 months mice showed hyperactivity, and reduced anxiety. Cognitive memory decline was detected at 10 months and at 12-13 months mice showed signs of unbalanced hesitant walk and urinary retention. Lysosomal accumulation of heparan sulphate was observed in hepatocytes, splenic sinus endothelium, cerebral microglia, liver Kupffer cells, fibroblasts and pericytes. Starting from 5 months, brain neurons showed enlarged, structurally abnormal mitochondria, impaired mitochondrial energy metabolism, and storage of densely packed autofluorescent material, gangliosides, lysozyme, phosphorylated tau, and amyloid-β. Taken together, our data demonstrate for the first time that deficiency of acetyl-CoA: α-glucosaminide N-acetyltransferase causes lysosomal accumulation of heparan sulphate in microglial cells followed by their activation and cytokine release. They also show mitochondrial dysfunction in the neurons and neuronal loss explaining why mucopolysaccharidosis III type C manifests primarily as a neurodegenerative disease. PMID:25567323

  9. Neuroinflammation, mitochondrial defects and neurodegeneration in mucopolysaccharidosis III type C mouse model

    PubMed Central

    Martins, Carla; Hůlková, Helena; Dridi, Larbi; Dormoy-Raclet, Virginie; Grigoryeva, Lubov; Choi, Yoo; Langford-Smith, Alexander; Wilkinson, Fiona L.; Ohmi, Kazuhiro; DiCristo, Graziella; Hamel, Edith; Ausseil, Jerôme; Cheillan, David; Moreau, Alain; Svobodová, Eva; Hájková, Zuzana; Tesařová, Markéta; Hansíková, Hana; Bigger, Brian W.; Hrebícek, Martin

    2015-01-01

    Severe progressive neurological paediatric disease mucopolysaccharidosis III type C is caused by mutations in the HGSNAT gene leading to deficiency of acetyl-CoA: α-glucosaminide N-acetyltransferase involved in the lysosomal catabolism of heparan sulphate. To understand the pathophysiology of the disease we generated a mouse model of mucopolysaccharidosis III type C by germline inactivation of the Hgsnat gene. At 6–8 months mice showed hyperactivity, and reduced anxiety. Cognitive memory decline was detected at 10 months and at 12–13 months mice showed signs of unbalanced hesitant walk and urinary retention. Lysosomal accumulation of heparan sulphate was observed in hepatocytes, splenic sinus endothelium, cerebral microglia, liver Kupffer cells, fibroblasts and pericytes. Starting from 5 months, brain neurons showed enlarged, structurally abnormal mitochondria, impaired mitochondrial energy metabolism, and storage of densely packed autofluorescent material, gangliosides, lysozyme, phosphorylated tau, and amyloid-β. Taken together, our data demonstrate for the first time that deficiency of acetyl-CoA: α-glucosaminide N-acetyltransferase causes lysosomal accumulation of heparan sulphate in microglial cells followed by their activation and cytokine release. They also show mitochondrial dysfunction in the neurons and neuronal loss explaining why mucopolysaccharidosis III type C manifests primarily as a neurodegenerative disease. PMID:25567323

  10. Structural Basis for Recruitment of Mitochondrial Fission Complexes By Fis1

    SciTech Connect

    Zhang, Y.; Chan, D.C.

    2009-06-04

    Mitochondrial fission controls mitochondrial shape and physiology, including mitochondrial remodeling in apoptosis. During assembly of the yeast mitochondrial fission complex, the outer membrane protein Fis1 recruits the dynamin-related GTPase Dnm1 to mitochondria. Fis1 contains a tetratricopeptide repeat (TPR) domain and interacts with Dnm1 via the molecular adaptors Mdv1 and Caf4. By using crystallographic analysis of adaptor-Fis1 complexes, we show that these adaptors use two helices to bind to both the concave and convex surfaces of the Fis1 TPR domain. Fis1 therefore contains two interaction interfaces, a binding mode that, to our knowledge, has not been observed previously for TPR domains. Genetic and biochemical studies indicate that both binding interfaces are important for binding of Mdv1 and Caf4 to Fis1 and for mitochondrial fission activity in vivo. Our results reveal how Fis1 recruits the mitochondrial fission complex and will facilitate efforts to manipulate mitochondrial fission.

  11. Life without complex I: proteome analyses of an Arabidopsis mutant lacking the mitochondrial NADH dehydrogenase complex.

    PubMed

    Fromm, Steffanie; Senkler, Jennifer; Eubel, Holger; Peterhänsel, Christoph; Braun, Hans-Peter

    2016-05-01

    The mitochondrial NADH dehydrogenase complex (complex I) is of particular importance for the respiratory chain in mitochondria. It is the major electron entry site for the mitochondrial electron transport chain (mETC) and therefore of great significance for mitochondrial ATP generation. We recently described an Arabidopsis thaliana double-mutant lacking the genes encoding the carbonic anhydrases CA1 and CA2, which both form part of a plant-specific 'carbonic anhydrase domain' of mitochondrial complex I. The mutant lacks complex I completely. Here we report extended analyses for systematically characterizing the proteome of the ca1ca2 mutant. Using various proteomic tools, we show that lack of complex I causes reorganization of the cellular respiration system. Reduced electron entry into the respiratory chain at the first segment of the mETC leads to induction of complexes II and IV as well as alternative oxidase. Increased electron entry at later segments of the mETC requires an increase in oxidation of organic substrates. This is reflected by higher abundance of proteins involved in glycolysis, the tricarboxylic acid cycle and branched-chain amino acid catabolism. Proteins involved in the light reaction of photosynthesis, the Calvin cycle, tetrapyrrole biosynthesis, and photorespiration are clearly reduced, contributing to the significant delay in growth and development of the double-mutant. Finally, enzymes involved in defense against reactive oxygen species and stress symptoms are much induced. These together with previously reported insights into the function of plant complex I, which were obtained by analysing other complex I mutants, are integrated in order to comprehensively describe 'life without complex I'. PMID:27122571

  12. Life without complex I: proteome analyses of an Arabidopsis mutant lacking the mitochondrial NADH dehydrogenase complex

    PubMed Central

    Fromm, Steffanie; Senkler, Jennifer; Eubel, Holger; Peterhänsel, Christoph; Braun, Hans-Peter

    2016-01-01

    The mitochondrial NADH dehydrogenase complex (complex I) is of particular importance for the respiratory chain in mitochondria. It is the major electron entry site for the mitochondrial electron transport chain (mETC) and therefore of great significance for mitochondrial ATP generation. We recently described an Arabidopsis thaliana double-mutant lacking the genes encoding the carbonic anhydrases CA1 and CA2, which both form part of a plant-specific ‘carbonic anhydrase domain’ of mitochondrial complex I. The mutant lacks complex I completely. Here we report extended analyses for systematically characterizing the proteome of the ca1ca2 mutant. Using various proteomic tools, we show that lack of complex I causes reorganization of the cellular respiration system. Reduced electron entry into the respiratory chain at the first segment of the mETC leads to induction of complexes II and IV as well as alternative oxidase. Increased electron entry at later segments of the mETC requires an increase in oxidation of organic substrates. This is reflected by higher abundance of proteins involved in glycolysis, the tricarboxylic acid cycle and branched-chain amino acid catabolism. Proteins involved in the light reaction of photosynthesis, the Calvin cycle, tetrapyrrole biosynthesis, and photorespiration are clearly reduced, contributing to the significant delay in growth and development of the double-mutant. Finally, enzymes involved in defense against reactive oxygen species and stress symptoms are much induced. These together with previously reported insights into the function of plant complex I, which were obtained by analysing other complex I mutants, are integrated in order to comprehensively describe ‘life without complex I’. PMID:27122571

  13. Mutation in NDUFA13/GRIM19 leads to early onset hypotonia, dyskinesia and sensorial deficiencies, and mitochondrial complex I instability.

    PubMed

    Angebault, Claire; Charif, Majida; Guegen, Naig; Piro-Megy, Camille; Mousson de Camaret, Benedicte; Procaccio, Vincent; Guichet, Pierre-Olivier; Hebrard, Maxime; Manes, Gael; Leboucq, Nicolas; Rivier, François; Hamel, Christian P; Lenaers, Guy; Roubertie, Agathe

    2015-07-15

    Mitochondrial complex I (CI) deficiencies are causing debilitating neurological diseases, among which, the Leber Hereditary Optic Neuropathy and Leigh Syndrome are the most frequent. Here, we describe the first germinal pathogenic mutation in the NDUFA13/GRIM19 gene encoding a CI subunit, in two sisters with early onset hypotonia, dyskinesia and sensorial deficiencies, including a severe optic neuropathy. Biochemical analysis revealed a drastic decrease in CI enzymatic activity in patient muscle biopsies, and reduction of CI-driven respiration in fibroblasts, while the activities of complex II, III and IV were hardly affected. Western blots disclosed that the abundances of NDUFA13 protein, CI holoenzyme and super complexes were drastically reduced in mitochondrial fractions, a situation that was reproduced by silencing NDUFA13 in control cells. Thus, we established here a correlation between the first mutation yet identified in the NDUFA13 gene, which induces CI instability and a severe but slowly evolving clinical presentation affecting the central nervous system. PMID:25901006

  14. Synthesis and in vitro microbial evaluation of La(III), Ce(III), Sm(III) and Y(III) metal complexes of vitamin B6 drug

    NASA Astrophysics Data System (ADS)

    Refat, Moamen S.; Al-Azab, Fathi M.; Al-Maydama, Hussein M. A.; Amin, Ragab R.; Jamil, Yasmin M. S.

    2014-06-01

    Metal complexes of pyridoxine mono hydrochloride (vitamin B6) are prepared using La(III), Ce(III), Sm(III) and Y(III). The resulting complexes are investigated. Some physical properties, conductivity, analytical data and the composition of the four pyridoxine complexes are discussed. The elemental analysis shows that the formed complexes of La(III), Ce(III), Sm(III) and Y(III) with pyridoxine are of 1:2 (metal:PN) molar ratio. All the synthesized complexes are brown in color and possess high melting points. These complexes are partially soluble in hot methanol, dimethylsulfoxide and dimethylformamide and insoluble in water and some other organic solvents. Elemental analysis data, spectroscopic (IR, UV-vis. and florescence), effective magnetic moment in Bohr magnetons and the proton NMR suggest the structures. However, definite particle size is determined by invoking the X-ray powder diffraction and scanning electron microscopy data. The results obtained suggested that pyridoxine reacted with metal ions as a bidentate ligand through its phenolate oxygen and the oxygen of the adjacent group at the 4‧-position. The molar conductance measurements proved that the pyridoxine complexes are electrolytic in nature. The kinetic and thermodynamic parameters such as: Ea, ΔH*, ΔS* and ΔG* were estimated from the DTG curves. The antibacterial evaluation of the pyridoxine and their complexes were also performed against some gram positive, negative bacteria as well as fungi.

  15. Molecular magnets based on homometallic hexanuclear lanthanide(III) complexes.

    PubMed

    Das, Sourav; Hossain, Sakiat; Dey, Atanu; Biswas, Sourav; Sutter, Jean-Pascal; Chandrasekhar, Vadapalli

    2014-05-19

    The reaction of lanthanide(III) chloride salts (Gd(III), Dy(III), Tb(III), and Ho(III)) with the hetero donor chelating ligand N'-(2-hydroxy-3-methoxybenzylidene)-6-(hydroxymethyl)picolinohydrazide (LH3) in the presence of triethylamine afforded the hexanuclear Ln(III) complexes [{Ln6(L)2(LH)2}(μ3-OH)4][MeOH]p[H2O]q[Cl]4·xH2O·yCH3OH (1, Ln = Gd(III), p = 4, q = 4, x = 8, y = 2; 2, Ln = Dy(III), p = 2, q = 6, x = 8, y = 4; 3, Ln = Tb(III), p = 2, q = 6, x = 10, y = 4; 4, Ln = Ho(III), p = 2, q = 6, x = 10, y = 2). X-ray diffraction studies revealed that these compounds possess a hexanuclear [Ln6(OH)4](14+) core consisting of four fused [Ln3(OH)](8+) subunits. Both static (dc) and dynamic (ac) magnetic properties of 1-4 have been studied. Single-molecule magnetic behavior has been observed in compound 2 with an effective energy barrier and relaxation time pre-exponential parameters of Δ/kB = 46.2 K and τ0 = 2.85 × 10(-7) s, respectively. PMID:24766539

  16. DJ-1 binds to mitochondrial complex I and maintains its activity

    SciTech Connect

    Hayashi, Takuya; Ishimori, Chikako; Takahashi-Niki, Kazuko; Taira, Takahiro; Kim, Yun-chul; Maita, Hiroshi; Maita, Chinatsu; Ariga, Hiroyoshi; Iguchi-Ariga, Sanae M.M.

    2009-12-18

    Parkinson's disease (PD) is caused by neuronal cell death, and oxidative stress and mitochondrial dysfunction are thought to be responsible for onset of PD. DJ-1, a causative gene product of a familial form of Parkinson's disease, PARK7, plays roles in transcriptional regulation and anti-oxidative stress. The possible mitochondrial function of DJ-1 has been proposed, but its exact function remains unclear. In this study, we found that DJ-1 directly bound to NDUFA4 and ND1, nuclear and mitochondrial DNA-encoding subunits of mitochondrial complex I, respectively, and was colocalized with complex I and that complex I activity was reduced in DJ-1-knockdown NIH3T3 and HEK293 cells. These findings suggest that DJ-1 is an integral mitochondrial protein and that DJ-1 plays a role in maintenance of mitochondrial complex I activity.

  17. Unequivocal synthetic pathway to heterodinuclear (4f,4f') complexes: magnetic study of relevant (Ln(III), Gd(III)) and (Gd(III), Ln(III)) complexes.

    PubMed

    Costes, Jean-Pierre; Nicodème, Franck

    2002-08-01

    The tripodal ligand tris[4-(2-hydroxy-3-methoxyphenyl)-3-aza-3-buten]amine (LH(3)) is capable of coordinating to two different lanthanide ions to give complexes formulated as [LLnLn'(NO(3))(3)].x H(2)O. The stepwise synthetic procedure consists of introducing first a Ln(III) ion in the inner N(4)O(3) coordination site. The isolated neutral complex LLn is then allowed to react with a second and different Ln' ion that occupies the outer O(6) site, thus yielding a [LLnLn'(NO(3))(3)].x H(2)O complex. A FAB(+) study has confirmed the existence of (Ln, Ln') entities as genuine, when the Ln' ion in the outer site has a larger ionic radius than the Ln ion in the inner site. The qualitative magnetic study of the (Gd, Ln) and (Ln, Gd) complexes, based on the comparison of the magnetic properties of (Gd, Ln) (or (Ln, Gd)) pairs and (Y, Ln) (or (Ln, La)) pairs, is very informative. Indeed, these former complexes are governed by the thermal population of the Ln(III) Stark levels and the Ln-Gd interaction, while the latter are influenced by the thermal population of the Ln(III) Stark levels. We have been able to show that a ferromagnetic interaction exists at low temperature in the (Gd, Nd), (Gd, Ce), and (Yb, Gd) complexes. In contrast, an antiferromagnetic interaction occurs in the (Dy, Gd) and (Er, Gd) complexes. Although we cannot give a quantitative value to these interactions, we can affirm that their magnitudes are weak since they are only perceptible at very low temperature. PMID:12203324

  18. Prototypical phosphine complexes of antimony(III).

    PubMed

    Chitnis, Saurabh S; Burford, Neil; McDonald, Robert; Ferguson, Michael J

    2014-05-19

    Complexes of the generic formula [Cln(PR3)mSb]((3-n)+) (n = 1, 2, 3, or 4 and m = 1 or 2) have been prepared featuring [ClSb](2+), [Cl2Sb](1+), Cl3Sb, or [Cl4Sb](1-) as acceptors with one or two phosphine ligands {PMe3, PPh3, PCy3 (Cy = C6H11)}. The solid-state structures of the complexes reveal foundational features that define the coordination chemistry of a lone pair bearing stibine acceptor site. The experimental observations are interpreted with dispersion-corrected density functional theory calculations to develop an understanding of the bonding and structural diversity. PMID:24773563

  19. Fe(III) Is Essential for Porcine Embryonic Development via Mitochondrial Function Maintenance

    PubMed Central

    Zhao, Ming-Hui; Liang, Shuang; Kim, Seon-Hyang; Cui, Xiang-Shun; Kim, Nam-Hyung

    2015-01-01

    Iron is an important trace element involved in several biological processes. The role of iron in porcine early embryonic development remains unknown. In the present study, we depleted iron (III, Fe3+) with deferoxamine (DFM), a specific Fe3+ chelator, in cultured porcine parthenotes and monitored embryonic development, apoptosis, mitochondrial membrane potential, and ATP production. Results showed biphasic function of Fe3+ in porcine embryo development. 0.5 μM DFM obviously increased blastocyst formation (57.49 ± 2.18% vs. control, 43.99 ± 1.72%, P < 0.05) via reduced (P < 0.05) production of reactive oxygen species (ROS), further increased mitochondrial membrane potential and ATP production in blastocysts (P < 0.05). 0.5 μM DFM decreased mRNA expression of Caspase 3 (Casp3) and increased Bcl-xL. However, results showed a significant reduction in blastocyst formation in the presence of 5.0 μM DFM compared with the control group (DFM, 21.62 ± 3.92% vs. control, 43.99 ± 1.73%, P < 0.05). Fe3+ depletion reduced the total (DFM, 21.10 ± 8.78 vs. control, 44.09 ± 13.65, P < 0.05) and increased apoptotic cell number (DFM, 11.10 ± 5.24 vs. control, 2.64 ± 1.43, P < 0.05) in the blastocyst. An obvious reduction in mitochondrial membrane potential and ATP level after 5.0 μM DFM treatment was observed. Co-localization between mitochondria and cytochrome c was reduced after high concentration of DFM treatment. In conclusion, Fe3+ is essential for porcine embryonic development via mitochondrial function maintenance, but redundant Fe3+ impairs the function of mitochondria. PMID:26161974

  20. Luminescent properties of europium(III) and terbium(III) complexes with para- and ortho-ethoxybenzoic acids

    NASA Astrophysics Data System (ADS)

    Panyushkin, V. T.; Mutuzova, M. Kh.; Shamsutdinova, M. Kh.

    2016-02-01

    The luminescent properties of europium(III) and terbium(III) complexes with para- and ortho-ethoxybenzoic acids are studied. The excitation energies of the triplet states of ligands are determined, a hypothesis is made about the efficient luminescence of europium(III) and terbium(III) complexes, the geometry of the coordination polyhedron of a europium complex is established, and the luminescence quantum yields of the complexes in solution are determined.

  1. Cardiac mitochondrial matrix and respiratory complex protein phosphorylation

    PubMed Central

    Covian, Raul

    2012-01-01

    It has become appreciated over the last several years that protein phosphorylation within the cardiac mitochondrial matrix and respiratory complexes is extensive. Given the importance of oxidative phosphorylation and the balance of energy metabolism in the heart, the potential regulatory effect of these classical signaling events on mitochondrial function is of interest. However, the functional impact of protein phosphorylation and the kinase/phosphatase system responsible for it are relatively unknown. Exceptions include the well-characterized pyruvate dehydrogenase and branched chain α-ketoacid dehydrogenase regulatory system. The first task of this review is to update the current status of protein phosphorylation detection primarily in the matrix and evaluate evidence linking these events with enzymatic function or protein processing. To manage the scope of this effort, we have focused on the pathways involved in energy metabolism. The high sensitivity of modern methods of detecting protein phosphorylation and the low specificity of many kinases suggests that detection of protein phosphorylation sites without information on the mole fraction of phosphorylation is difficult to interpret, especially in metabolic enzymes, and is likely irrelevant to function. However, several systems including protein translocation, adenine nucleotide translocase, cytochrome c, and complex IV protein phosphorylation have been well correlated with enzymatic function along with the classical dehydrogenase systems. The second task is to review the current understanding of the kinase/phosphatase system within the matrix. Though it is clear that protein phosphorylation occurs within the matrix, based on 32P incorporation and quantitative mass spectrometry measures, the kinase/phosphatase system responsible for this process is ill-defined. An argument is presented that remnants of the much more labile bacterial protein phosphoryl transfer system may be present in the matrix and that the

  2. An oxygen-sensitive luminescent Dy(iii) complex.

    PubMed

    Nakai, Hidetaka; Seo, Juncheol; Kitagawa, Kazuhiro; Goto, Takahiro; Matsumoto, Takahiro; Ogo, Seiji

    2016-06-21

    This paper presents the first dysprosium(iii) complex, [{((MeMe)ArO)3tacn}Dy(III)(THF)] (1(Dy)), that shows oxygen-sensitive luminescence. The synthesis, structure and oxygen-sensitive luminescence properties of 1(Dy) are reported (Φ = 0.050 and τ = 17.7 μs under N2, Φ = 0.011 and τ = 4.1 μs under O2 and KSV = 305 M(-1) in THF; KSV = 0.0077%(-1) in polystyrene film). The oxygen sensitive mechanism of 1(Dy) is discussed based on the photophysical properties of the corresponding gadolinium(iii) complex, [{((MeMe)ArO)3tacn}Gd(III)(THF)]. PMID:27191980

  3. Sparkle/PM3 Parameters for the Modeling of Neodymium(III), Promethium(III), and Samarium(III) Complexes.

    PubMed

    Freire, Ricardo O; da Costa, Nivan B; Rocha, Gerd B; Simas, Alfredo M

    2007-07-01

    The Sparkle/PM3 model is extended to neodymium(III), promethium(III), and samarium(III) complexes. The unsigned mean error, for all Sparkle/PM3 interatomic distances between the trivalent lanthanide ion and the ligand atoms of the first sphere of coordination, is 0.074 Å for Nd(III); 0.057 Å for Pm(III); and 0.075 Å for Sm(III). These figures are similar to the Sparkle/AM1 ones of 0.076 Å, 0.059 Å, and 0.075 Å, respectively, indicating they are all comparable models. Moreover, their accuracy is similar to what can be obtained by present-day ab initio effective potential calculations on such lanthanide complexes. Hence, the choice of which model to utilize will depend on the assessment of the effect of either AM1 or PM3 on the quantum chemical description of the organic ligands. Finally, we present a preliminary attempt to verify the geometry prediction consistency of Sparkle/PM3. Since lanthanide complexes are usually flexible, we randomly generated 200 different input geometries for the samarium complex QIPQOV which were then fully optimized by Sparkle/PM3. A trend appeared in that, on average, the lower the total energy of the local minima found, the lower the unsigned mean errors, and the higher the accuracy of the model. These preliminary results do indicate that attempting to find, with Sparkle/PM3, a global minimum for the geometry of a given complex, with the understanding that it will tend to be closer to the experimental geometry, appears to be warranted. Therefore, the sparkle model is seemingly a trustworthy semiempirical quantum chemical model for the prediction of lanthanide complexes geometries. PMID:26633229

  4. Photoswitchable azobenzene-appended iridium(iii) complexes.

    PubMed

    Pérez-Miqueo, J; Altube, A; García-Lecina, E; Tron, A; McClenaghan, N D; Freixa, Z

    2016-09-21

    Iridium(iii) cyclometalated complexes have been used as models to study the effect that extended conjugation and substitution pattern has on the photochromic behavior of azobenzene-appended 2-phenylpyridyl (ppy) ligands. For this purpose four azobenzene-containing ppy ligands were synthesized. With these ligands, nine iridium(iii) complexes containing up to three appended azobenzenes were synthesized. Analysis of their photochromic behaviour by means of UV-vis and (1)H-NMR spectroscopy permitted us to conclude that the light-induced trans-to-cis isomerization of the azobenzene was strongly inhibited upon coordination to the Ir(iii) cation when the electronic conjugation was extended along the whole ligand. The use of an aliphatic spacer unit (either -CH2- or -OCH2-) between the azobenzene and the ppy fragment of the ligand sufficed to disrupt the electronic communication, and obtain photochromic organometallic complexes. PMID:27460186

  5. A well-defined terminal vanadium(III) oxo complex.

    PubMed

    King, Amanda E; Nippe, Michael; Atanasov, Mihail; Chantarojsiri, Teera; Wray, Curtis A; Bill, Eckhard; Neese, Frank; Long, Jeffrey R; Chang, Christopher J

    2014-11-01

    The ubiquity of vanadium oxo complexes in the V+ and IV+ oxidation states has contributed to a comprehensive understanding of their electronic structure and reactivity. However, despite being predicted to be stable by ligand-field theory, the isolation and characterization of a well-defined terminal mononuclear vanadium(III) oxo complex has remained elusive. We present the synthesis and characterization of a unique terminal mononuclear vanadium(III) oxo species supported by the pentadentate polypyridyl ligand 2,6-bis[1,1-bis(2-pyridyl)ethyl]pyridine (PY5Me2). Exposure of [V(II)(NCCH3)(PY5Me2)](2+) (1) to either dioxygen or selected O-atom-transfer reagents yields [V(IV)(O)(PY5Me2)](2+) (2). The metal-centered one-electron reduction of this vanadium(IV) oxo complex furnishes a stable, diamagnetic [V(III)(O)(PY5Me2)](+) (3) species. The vanadium(III) oxo species is unreactive toward H- and O-atom transfer but readily reacts with protons to form a putative vanadium hydroxo complex. Computational results predict that further one-electron reduction of the vanadium(III) oxo species will result in ligand-based reduction, even though pyridine is generally considered to be a poor π-accepting ligand. These results have implications for future efforts toward low-valent vanadyl chemistry, particularly with regard to the isolation and study of formal vanadium(II) oxo species. PMID:25097094

  6. Unraveling the complexity of mitochondrial complex I assembly: A dynamic process.

    PubMed

    Sánchez-Caballero, Laura; Guerrero-Castillo, Sergio; Nijtmans, Leo

    2016-07-01

    Mammalian complex I is composed of 44 different subunits and its assembly requires at least 13 specific assembly factors. Proper function of the mitochondrial respiratory chain enzyme is of crucial importance for cell survival due to its major participation in energy production and cell signaling. Complex I assembly depends on the coordination of several crucial processes that need to be tightly interconnected and orchestrated by a number of assembly factors. The understanding of complex I assembly evolved from simple sequential concept to the more sophisticated modular assembly model describing a convoluted process. According to this model, the different modules assemble independently and associate afterwards with each other to form the final enzyme. In this review, we aim to unravel the complexity of complex I assembly and provide the latest insights in this fundamental and fascinating process. This article is part of a Special Issue entitled Respiratory complex I, edited by Volker Zickermann and Ulrich Brandt. PMID:27040506

  7. Dihydro-orotate dehydrogenase is physically associated with the respiratory complex and its loss leads to mitochondrial dysfunction

    PubMed Central

    Fang, JingXian; Uchiumi, Takeshi; Yagi, Mikako; Matsumoto, Shinya; Amamoto, Rie; Takazaki, Shinya; Yamaza, Haruyoshi; Nonaka, Kazuaki; Kang, Dongchon

    2012-01-01

    Some mutations of the DHODH (dihydro-orotate dehydrogenase) gene lead to postaxial acrofacial dysostosis or Miller syndrome. Only DHODH is localized at mitochondria among enzymes of the de novo pyrimidine biosynthesis pathway. Since the pyrimidine biosynthesis pathway is coupled to the mitochondrial RC (respiratory chain) via DHODH, impairment of DHODH should affect the RC function. To investigate this, we used siRNA (small interfering RNA)-mediated knockdown and observed that DHODH knockdown induced cell growth retardation because of G2/M cell-cycle arrest, whereas pyrimidine deficiency usually causes G1/S arrest. Inconsistent with this, the cell retardation was not rescued by exogenous uridine, which should bypass the DHODH reaction for pyrimidine synthesis. DHODH depletion partially inhibited the RC complex III, decreased the mitochondrial membrane potential, and increased the generation of ROS (reactive oxygen species). We observed that DHODH physically interacts with respiratory complexes II and III by IP (immunoprecipitation) and BN (blue native)/SDS/PAGE analysis. Considering that pyrimidine deficiency alone does not induce craniofacial dysmorphism, the DHODH mutations may contribute to the Miller syndrome in part through somehow altered mitochondrial function. PMID:23216091

  8. Lanthanum(III) and praseodymium(III) complexes with isatin thiosemicarbazones

    NASA Astrophysics Data System (ADS)

    Rai, Anita; Sengupta, Soumitra K.; Pandey, Om P.

    2005-09-01

    Ten new lanthanum(III) and praseodymium(III) complexes of the general formula Na[La(L) 2H 2O] (Ln = La(III) or Pr(III); LH 2 = thiosemicarbazones) derived from the condensation of isatin with 4-phenyl thiosemicarbazide, 4-(4-chlorophenyl) thiosemicarbazide, 4-(2-nitrophenyl) thiosemicarbazide, 4-(2-bromophenyl) thiosemicarbazide and 4-(2-methylphenyl) thiosemicarbazide, have been synthesized in methanol in presence of sodium hydroxide. The XRD spectra of the complexes were monitored to verify complex formation. The complexes have also been characterized by elemental analysis, molar conductance, electronic absorption and fluorescence, infrared, far infrared, 1H and 13C NMR spectral studies. Thermal studies of these complexes have been carried out in the temperature range 25-800 °C using TG, DTG and DTA techniques. All these complexes decompose gradually with the formation of Ln 2O 3 as the end product. The Judd-ofelt intensity parameter, oscillator strength, transition probability, stimulated emission cross section for different transitions of Pr 3+ for 4-phenyl thiosemicarbazones have been calculated.

  9. Coumarin-appended phosphorescent cyclometalated iridium(iii) complexes as mitochondria-targeted theranostic anticancer agents.

    PubMed

    Ye, Rui-Rong; Tan, Cai-Ping; Ji, Liang-Nian; Mao, Zong-Wan

    2016-08-16

    Theranostic anticancer agents incorporating anticancer properties with capabilities for real-time treatment assessment are appealing candidates for chemotherapy. The design of mitochondria-targeted cytotoxic drugs represents a promising approach to target tumors selectively and overcome resistance to current anticancer therapies. In this work, three coumarin-appended phosphorescent cyclometalated iridium(iii) complexes 1-3 have been explored as mitochondria-targeted theranostic anticancer agents. These complexes display rich photophysical properties, which facilitate the study of their intracellular fate. All three complexes can specifically target mitochondria and show much higher antiproliferative activities than cisplatin against various cancer cells including cisplatin-resistant cells. 1-3 can penetrate into human cervical carcinoma (HeLa) cells quickly and efficiently, and they can carry out theranostic functions by simultaneously inducing and monitoring the morphological changes in mitochondria. Mechanism studies show that 1-3 exert their anticancer efficacy by initiating a cascade of events related to mitochondrial dysfunction. Genome-wide transcriptional and Connectivity Map analyses reveal that the cytotoxicity of complex 3 is associated with pathways involved in mitochondrial dysfunction and apoptosis. PMID:27139504

  10. Negative regulation of mitochondrial transcription by mitochondrial topoisomerase I

    PubMed Central

    Sobek, Stefan; Dalla Rosa, Ilaria; Pommier, Yves; Bornholz, Beatrice; Kalfalah, Faiza; Zhang, Hongliang; Wiesner, Rudolf J.; von Kleist-Retzow, Jürgen-Christoph; Hillebrand, Frank; Schaal, Heiner; Mielke, Christian; Christensen, Morten O.; Boege, Fritz

    2013-01-01

    Mitochondrial topoisomerase I is a genetically distinct mitochondria-dedicated enzyme with a crucial but so far unknown role in the homeostasis of mitochondrial DNA metabolism. Here, we present data suggesting a negative regulatory function in mitochondrial transcription or transcript stability. Deficiency or depletion of mitochondrial topoisomerase I increased mitochondrial transcripts, whereas overexpression lowered mitochondrial transcripts, depleted respiratory complexes I, III and IV, decreased cell respiration and raised superoxide levels. Acute depletion of mitochondrial topoisomerase I triggered neither a nuclear mito-biogenic stress response nor compensatory topoisomerase IIβ upregulation, suggesting the concomitant increase in mitochondrial transcripts was due to release of a local inhibitory effect. Mitochondrial topoisomerase I was co-immunoprecipitated with mitochondrial RNA polymerase. It selectively accumulated and rapidly exchanged at a subset of nucleoids distinguished by the presence of newly synthesized RNA and/or mitochondrial RNA polymerase. The inactive Y559F-mutant behaved similarly without affecting mitochondrial transcripts. In conclusion, mitochondrial topoisomerase I dampens mitochondrial transcription and thereby alters respiratory capacity. The mechanism involves selective association of the active enzyme with transcriptionally active nucleoids and a direct interaction with mitochondrial RNA polymerase. The inhibitory role of topoisomerase I in mitochondrial transcription is strikingly different from the stimulatory role of topoisomerase I in nuclear transcription. PMID:23982517

  11. Highly Divergent Mitochondrial ATP Synthase Complexes in Tetrahymena thermophila

    PubMed Central

    Balabaskaran Nina, Praveen; Dudkina, Natalya V.; Kane, Lesley A.; van Eyk, Jennifer E.; Boekema, Egbert J.; Mather, Michael W.; Vaidya, Akhil B.

    2010-01-01

    The F-type ATP synthase complex is a rotary nano-motor driven by proton motive force to synthesize ATP. Its F1 sector catalyzes ATP synthesis, whereas the Fo sector conducts the protons and provides a stator for the rotary action of the complex. Components of both F1 and Fo sectors are highly conserved across prokaryotes and eukaryotes. Therefore, it was a surprise that genes encoding the a and b subunits as well as other components of the Fo sector were undetectable in the sequenced genomes of a variety of apicomplexan parasites. While the parasitic existence of these organisms could explain the apparent incomplete nature of ATP synthase in Apicomplexa, genes for these essential components were absent even in Tetrahymena thermophila, a free-living ciliate belonging to a sister clade of Apicomplexa, which demonstrates robust oxidative phosphorylation. This observation raises the possibility that the entire clade of Alveolata may have invented novel means to operate ATP synthase complexes. To assess this remarkable possibility, we have carried out an investigation of the ATP synthase from T. thermophila. Blue native polyacrylamide gel electrophoresis (BN-PAGE) revealed the ATP synthase to be present as a large complex. Structural study based on single particle electron microscopy analysis suggested the complex to be a dimer with several unique structures including an unusually large domain on the intermembrane side of the ATP synthase and novel domains flanking the c subunit rings. The two monomers were in a parallel configuration rather than the angled configuration previously observed in other organisms. Proteomic analyses of well-resolved ATP synthase complexes from 2-D BN/BN-PAGE identified orthologs of seven canonical ATP synthase subunits, and at least 13 novel proteins that constitute subunits apparently limited to the ciliate lineage. A mitochondrially encoded protein, Ymf66, with predicted eight transmembrane domains could be a substitute for the subunit a

  12. Metabolites from invasive pests inhibit mitochondrial complex II: A potential strategy for the treatment of human ovarian carcinoma?

    PubMed

    Ferramosca, Alessandra; Conte, Annalea; Guerra, Flora; Felline, Serena; Rimoli, Maria Grazia; Mollo, Ernesto; Zara, Vincenzo; Terlizzi, Antonio

    2016-05-13

    The red pigment caulerpin, a secondary metabolite from the marine invasive green algae Caulerpa cylindracea can be accumulated and transferred along the trophic chain, with detrimental consequences on biodiversity and ecosystem functioning. Despite increasing research efforts to understand how caulerpin modifies fish physiology, little is known on the effects of algal metabolites on mammalian cells. Here we report for the first time the mitochondrial targeting activity of both caulerpin, and its closely related derivative caulerpinic acid, by using as experimental model rat liver mitochondria, a system in which bioenergetics mechanisms are not altered. Mitochondrial function was tested by polarographic and spectrophotometric methods. Both compounds were found to selectively inhibit respiratory complex II activity, while complexes I, III, and IV remained functional. These results led us to hypothesize that both algal metabolites could be used as antitumor agents in cell lines with defects in mitochondrial complex I. Ovarian cancer cisplatin-resistant cells are a good example of cell lines with a defective complex I function on which these molecules seem to have a toxic effect on proliferation. This provided novel insight toward the potential use of metabolites from invasive Caulerpa species for the treatment of human ovarian carcinoma cisplatin-resistant cells. PMID:27091429

  13. The Impact of Mitochondrial Complex Inhibition on mESC Differentiation

    EPA Science Inventory

    The Impact of Mitochondrial Complex Inhibition on mESC Differentiation JE Royland, SH Warren, S Jeffay, MR Hoopes, HP Nichols, ES Hunter U.S. Environmental Protection Agency, Integrated Systems Toxicology Division, Research Triangle Park, NC The importance of mitochondrial funct...

  14. A Comprehensive Genomic Analysis Reveals the Genetic Landscape of Mitochondrial Respiratory Chain Complex Deficiencies

    PubMed Central

    Nyuzuki, Hiromi; Moriyama, Yohsuke; Mizuno, Yosuke; Hirata, Tomoko; Yatsuka, Yukiko; Yamashita-Sugahara, Yzumi; Nakachi, Yutaka; Kato, Hidemasa; Okuda, Akihiko; Tamaru, Shunsuke; Borna, Nurun Nahar; Banshoya, Kengo; Aigaki, Toshiro; Sato-Miyata, Yukiko; Ohnuma, Kohei; Suzuki, Tsutomu; Nagao, Asuteka; Maehata, Hazuki; Matsuda, Fumihiko; Higasa, Koichiro; Nagasaki, Masao; Yasuda, Jun; Yamamoto, Masayuki; Fushimi, Takuya; Shimura, Masaru; Kaiho-Ichimoto, Keiko; Harashima, Hiroko; Yamazaki, Taro; Mori, Masato; Murayama, Kei; Ohtake, Akira; Okazaki, Yasushi

    2016-01-01

    Mitochondrial disorders have the highest incidence among congenital metabolic disorders characterized by biochemical respiratory chain complex deficiencies. It occurs at a rate of 1 in 5,000 births, and has phenotypic and genetic heterogeneity. Mutations in about 1,500 nuclear encoded mitochondrial proteins may cause mitochondrial dysfunction of energy production and mitochondrial disorders. More than 250 genes that cause mitochondrial disorders have been reported to date. However exact genetic diagnosis for patients still remained largely unknown. To reveal this heterogeneity, we performed comprehensive genomic analyses for 142 patients with childhood-onset mitochondrial respiratory chain complex deficiencies. The approach includes whole mtDNA and exome analyses using high-throughput sequencing, and chromosomal aberration analyses using high-density oligonucleotide arrays. We identified 37 novel mutations in known mitochondrial disease genes and 3 mitochondria-related genes (MRPS23, QRSL1, and PNPLA4) as novel causative genes. We also identified 2 genes known to cause monogenic diseases (MECP2 and TNNI3) and 3 chromosomal aberrations (6q24.3-q25.1, 17p12, and 22q11.21) as causes in this cohort. Our approaches enhance the ability to identify pathogenic gene mutations in patients with biochemically defined mitochondrial respiratory chain complex deficiencies in clinical settings. They also underscore clinical and genetic heterogeneity and will improve patient care of this complex disorder. PMID:26741492

  15. A Comprehensive Genomic Analysis Reveals the Genetic Landscape of Mitochondrial Respiratory Chain Complex Deficiencies.

    PubMed

    Kohda, Masakazu; Tokuzawa, Yoshimi; Kishita, Yoshihito; Nyuzuki, Hiromi; Moriyama, Yohsuke; Mizuno, Yosuke; Hirata, Tomoko; Yatsuka, Yukiko; Yamashita-Sugahara, Yzumi; Nakachi, Yutaka; Kato, Hidemasa; Okuda, Akihiko; Tamaru, Shunsuke; Borna, Nurun Nahar; Banshoya, Kengo; Aigaki, Toshiro; Sato-Miyata, Yukiko; Ohnuma, Kohei; Suzuki, Tsutomu; Nagao, Asuteka; Maehata, Hazuki; Matsuda, Fumihiko; Higasa, Koichiro; Nagasaki, Masao; Yasuda, Jun; Yamamoto, Masayuki; Fushimi, Takuya; Shimura, Masaru; Kaiho-Ichimoto, Keiko; Harashima, Hiroko; Yamazaki, Taro; Mori, Masato; Murayama, Kei; Ohtake, Akira; Okazaki, Yasushi

    2016-01-01

    Mitochondrial disorders have the highest incidence among congenital metabolic disorders characterized by biochemical respiratory chain complex deficiencies. It occurs at a rate of 1 in 5,000 births, and has phenotypic and genetic heterogeneity. Mutations in about 1,500 nuclear encoded mitochondrial proteins may cause mitochondrial dysfunction of energy production and mitochondrial disorders. More than 250 genes that cause mitochondrial disorders have been reported to date. However exact genetic diagnosis for patients still remained largely unknown. To reveal this heterogeneity, we performed comprehensive genomic analyses for 142 patients with childhood-onset mitochondrial respiratory chain complex deficiencies. The approach includes whole mtDNA and exome analyses using high-throughput sequencing, and chromosomal aberration analyses using high-density oligonucleotide arrays. We identified 37 novel mutations in known mitochondrial disease genes and 3 mitochondria-related genes (MRPS23, QRSL1, and PNPLA4) as novel causative genes. We also identified 2 genes known to cause monogenic diseases (MECP2 and TNNI3) and 3 chromosomal aberrations (6q24.3-q25.1, 17p12, and 22q11.21) as causes in this cohort. Our approaches enhance the ability to identify pathogenic gene mutations in patients with biochemically defined mitochondrial respiratory chain complex deficiencies in clinical settings. They also underscore clinical and genetic heterogeneity and will improve patient care of this complex disorder. PMID:26741492

  16. Role of Mitochondrial Complex IV in Age-Dependent Obesity.

    PubMed

    Soro-Arnaiz, Ines; Li, Qilong Oscar Yang; Torres-Capelli, Mar; Meléndez-Rodríguez, Florinda; Veiga, Sónia; Veys, Koen; Sebastian, David; Elorza, Ainara; Tello, Daniel; Hernansanz-Agustín, Pablo; Cogliati, Sara; Moreno-Navarrete, Jose Maria; Balsa, Eduardo; Fuertes, Esther; Romanos, Eduardo; Martínez-Ruiz, Antonio; Enriquez, Jose Antonio; Fernandez-Real, Jose Manuel; Zorzano, Antonio; De Bock, Katrien; Aragonés, Julián

    2016-09-13

    Aging is associated with progressive white adipose tissue (WAT) enlargement initiated early in life, but the molecular mechanisms involved remain unknown. Here we show that mitochondrial complex IV (CIV) activity and assembly are already repressed in white adipocytes of middle-aged mice and involve a HIF1A-dependent decline of essential CIV components such as COX5B. At the molecular level, HIF1A binds to the Cox5b proximal promoter and represses its expression. Silencing of Cox5b decreased fatty acid oxidation and promoted intracellular lipid accumulation. Moreover, local in vivo Cox5b silencing in WAT of young mice increased the size of adipocytes, whereas restoration of COX5B expression in aging mice counteracted adipocyte enlargement. An age-dependent reduction in COX5B gene expression was also found in human visceral adipose tissue. Collectively, our findings establish a pivotal role for CIV dysfunction in progressive white adipocyte enlargement during aging, which can be restored to alleviate age-dependent WAT expansion. PMID:27626667

  17. Does As(III) interact with Fe(II), Fe(III) and organic matter through ternary complexes?

    PubMed

    Catrouillet, Charlotte; Davranche, Mélanie; Dia, Aline; Bouhnik-Le Coz, Martine; Demangeat, Edwige; Gruau, Gérard

    2016-05-15

    Up until now, only a small number of studies have been dedicated to the binding processes of As(III) with organic matter (OM) via ionic Fe(III) bridges; none was interested in Fe (II). Complexation isotherms were carried out with As(III), Fe(II) or Fe(III) and Leonardite humic acid (HA). Although PHREEQC/Model VI, implemented with OM thiol groups, reproduced the experimental datasets with Fe(III), the poor fit between the experimental and modeled Fe(II) data suggested another binding mechanism for As(III) to OM. PHREEQC/Model VI was modified to take various possible As(III)-Fe(II)-OM ternary complex conformations into account. The complexation of As(III) as a mononuclear bidentate complex to a bidentate Fe(II)-HA complex was evidenced. However, the model needed to be improved since the distribution of the bidentate sites appeared to be unrealistic with regards to the published XAS data. In the presence of Fe(III), As(III) was bound to thiol groups which are more competitive with regards to the low density of formed Fe(III)-HA complexes. Based on the new data and previously published results, we propose a general scheme describing the various As(III)-Fe-MO complexes that are able to form in Fe and OM-rich waters. PMID:26939079

  18. A silybin-phospholipid complex prevents mitochondrial dysfunction in a rodent model of nonalcoholic steatohepatitis.

    PubMed

    Serviddio, Gaetano; Bellanti, Francesco; Giudetti, Anna Maria; Gnoni, Gabriele Vincenzo; Petrella, Antonio; Tamborra, Rosanna; Romano, Antonino Davide; Rollo, Tiziana; Vendemiale, Gianluigi; Altomare, Emanuele

    2010-03-01

    Mitochondrial dysfunction and oxidative stress are determinant events in the pathogenesis of nonalcoholic steatohepatitis. Silybin has shown antioxidant, anti-inflammatory, and antifibrotic effects in chronic liver disease. We aimed to study the effect of the silybin-phospholipid complex (SILIPHOS) on liver redox balance and mitochondrial function in a dietary model of nonalcoholic steatohepatitis. To accomplish this, glutathione oxidation, mitochondrial oxygen uptake, proton leak, ATP homeostasis, and H(2)O(2) production rate were evaluated in isolated liver mitochondria from rats fed a methionine- and choline-deficient (MCD) diet and the MCD diet plus SILIPHOS for 7 and 14 weeks. Oxidative proteins, hydroxynonenal (HNE)- and malondialdehyde (MDA)-protein adducts, and mitochondrial membrane lipid composition were also measured. Treatment with SILIPHOS limited glutathione depletion and mitochondrial H(2)O(2) production. Moreover, SILIPHOS preserved mitochondrial bioenergetics and prevented mitochondrial proton leak and ATP reduction. Finally, SILIPHOS limited the formation of HNE- and MDA-protein adducts. In conclusion, SILIPHOS is effective in preventing severe oxidative stress and preserving hepatic mitochondrial bioenergetics in nonalcoholic steatohepatitis induced by the MCD diet. The modifications of mitochondrial membrane fatty acid composition induced by the MCD diet are partially prevented by SILIPHOS, conferring anti-inflammatory and antifibrotic effects. The increased vulnerability of lipid membranes to oxidative damage is limited by SILIPHOS through preserved mitochondrial function. PMID:20008062

  19. Assembly of nuclear DNA-encoded subunits into mitochondrial complex IV, and their preferential integration into supercomplex forms in patient mitochondria.

    PubMed

    Lazarou, Michael; Smith, Stacey M; Thorburn, David R; Ryan, Michael T; McKenzie, Matthew

    2009-11-01

    Complex IV is the terminal enzyme of the mitochondrial respiratory chain. In humans, biogenesis of complex IV involves the coordinated assembly of 13 subunits encoded by both mitochondrial and nuclear genomes. The early stages of complex IV assembly involving mitochondrial DNA-encoded subunits CO1 and CO2 have been well studied. However, the latter stages, during which many of the nuclear DNA-encoded subunits are incorporated, are less well understood. Using in vitro import and assembly assays, we found that subunits Cox6a, Cox6b and Cox7a assembled into pre-existing complex IV, while Cox4-1 and Cox6c subunits assembled into subcomplexes that may represent rate-limiting intermediates. We also found that Cox6a and Cox7a are incorporated into a novel intermediate complex of approximately 250 kDa, and that transition of subunits from this complex to the mature holoenzyme had stalled in the mitochondria of patients with isolated complex IV deficiency. A number of complex IV subunits were also found to integrate into supercomplexes containing combinations of complex I, dimeric complex III and complex IV. Subunit assembly into these supercomplexes was also observed in mitochondria of patients in whom monomeric complex IV was selectively reduced. We conclude that newly imported nuclear DNA-encoded subunits can integrate into the complex IV holoenzyme and supercomplex forms by associating with pre-existing subunits and intermediate assembly complexes. PMID:19843159

  20. Gastrin-releasing peptide receptor antagonist or N-acetylcysteine combined with omeprazol protect against mitochondrial complex II inhibition in a rat model of gastritis.

    PubMed

    Rezin, Gislaine T; Petronilho, Fabricia C; Araújo, João H; Gonçalves, Cinara L; Daufenbach, Juliana F; Cardoso, Mariane R; Roesler, Rafael; Schwartsmann, Gilberto; Dal-Pizzol, Felipe; Streck, Emilio L

    2011-03-01

    The pathophysiology of gastritis involves an imbalance between gastric acid attack and mucosal defence. In addition, the gastric mucosal injury results in adenosine triphosphate (ATP) depletion leading to mitochondrial dysfunction. Several studies have shown the association of mitochondrial disorders with gastrointestinal dysfunction. In the present study, we investigated the activity of mitochondrial respiratory chain complexes activity in the stomach of rats with gastritis induced by indomethacin (IDM) and treated with omeprazole (OM), N-acetylcysteine (NAC) and the gastrin-releasing peptide receptor (GRPR) antagonist RC-3095. Adult male Wistar rats were pre-treated for 7 days with OM, NAC, RC-3095, combination of OM plus RC-3095, OM plus NAC and water (control). The animals were then submitted to fasting for 24 hr; IDM was administered. The rats were killed 6 hr later, and the stomachs were used for evaluation of macroscopic damage and respiratory chain activity. Our results showed that complex I and IV activities were not affected by administration of IDM. On the other hand, complex II and III activities were inhibited. In addition, OM plus RC-3095 and OM plus NAC did not reverse complex II activity inhibition. However, the complex III activity inhibition was reversed only with the combined use of OM plus RC-3095 and OM plus NAC. Our results are in agreement with previous studies indicating mitochondrial dysfunction in the pathophysiology of gastrointestinal tract disease and we suggest that GRPR antagonism might be a novel therapeutic strategy in gastritis. PMID:21138529

  1. Ganoderma lucidum (Fr.) P. Karst enhances activities of heart mitochondrial enzymes and respiratory chain complexes in the aged rat.

    PubMed

    Sudheesh, N P; Ajith, T A; Janardhanan, K K

    2009-10-01

    Aging is associated with increased oxidative damage at multiple cellular levels, decline in cellular energy production and enhanced free radical status. The effect of the medicinal mushroom, Ganoderma lucidum on the activities of tricarboxylic acid (Krebs) cycle enzymes and mitochondrial complexes I-IV of the electron transport chain in aged rats were investigated. The activity of Krebs cycle enzymes, isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase, succinate dehydrogenase, and malate dehydrogenase as well as mitochondrial complexes I, II, III, and IV were determined in heart of aged male Wistar rats orally administrated with 70% ethanolic extract (50 and 250 mg/kg) of G. lucidum. DL-alpha-lipoic acid (100 mg/kg) was taken as the positive control. Administration of the G. lucidum, once daily for 15 days, was significantly (P < 0.05) effective to enhance the Krebs cycle dehydrogenases, and mitochondrial electron transport chain complex IV activities in aged rats. The profound activity of the extract can be correlated to the significant antioxidant property of G. lucidum. The results of the study revealed that G. lucidum is effective to ameliorate the age associated decline of cellular energy status. PMID:19123066

  2. Synthesis and structural characterization of new dithiocarbamate complexes from Sb(III) and Bi(III)

    SciTech Connect

    Jamaluddin, Nur Amirah; Baba, Ibrahim

    2013-11-27

    Twenty new antimony and bismuth dithiocarbamate complexes which employed ten different type of amines have been successfully synthesized. The synthesized complexes with metal to dithiocarbamate ratio at 1:3. Elemental analysis of the complexes gave the general formula of MCl[S{sub 2}CNR’R”]{sub 2} where M = Sb(III), Bi(III); R’ = methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, benzyl; R” = ethanol, methyl, ethyl, propyl, isopropyl, cyclohexyl, benzyl. The complexes were analysed by IR and NMR spectroscopy. The crystal structure of five-coordinated antimony (III) complex have been determined by X-ray single crystal diffraction. Single crystal X-ray diffraction studies on SbCl[S{sub 2}CN(C{sub 4}H{sub 9})(C{sub 2}H{sub 5})]{sub 2} adopted a triclinic system with a space group P1 with a = 10.0141(8) Å, b = 10.1394(7) Å, c = 11.8665(9) Å, α = 67.960°, β =87.616°, γ = 80.172°.

  3. Synthesis and structural characterization of new dithiocarbamate complexes from Sb(III) and Bi(III)

    NASA Astrophysics Data System (ADS)

    Jamaluddin, Nur Amirah; Baba, Ibrahim

    2013-11-01

    Twenty new antimony and bismuth dithiocarbamate complexes which employed ten different type of amines have been successfully synthesized. The synthesized complexes with metal to dithiocarbamate ratio at 1:3. Elemental analysis of the complexes gave the general formula of MCl[S2CNR'R"]2 where M = Sb(III), Bi(III); R' = methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, benzyl; R" = ethanol, methyl, ethyl, propyl, isopropyl, cyclohexyl, benzyl. The complexes were analysed by IR and NMR spectroscopy. The crystal structure of five-coordinated antimony (III) complex have been determined by X-ray single crystal diffraction. Single crystal X-ray diffraction studies on SbCl[S2CN(C4H9)(C2H5)]2 adopted a triclinic system with a space group P1 with a = 10.0141(8) Å, b = 10.1394(7) Å, c = 11.8665(9) Å, α = 67.960°, β =87.616°, γ = 80.172°.

  4. Electrochemistry and spectroscopy of ortho-metalated complexes of Ir(III) and Rh(III)

    SciTech Connect

    Ohsawa, Y.; Sprouse, S.; King, K.A.; DeArmond, M.K.; Hanck, K.W.; Watts, R.J.

    1987-02-26

    The electrochemical and UV-visible spectroscopic properties of Rh(III) and Ir(III) complexes of the ortho-metalating (NC) ligands, 2-phenylpyridine (ppy) and benzo(h)quinone (bzq), have been studied. Cyclic voltammetric studies of several of the dimeric species, (M(NC)/sub 2/Cl)/sub 2/, indicate metal-centered oxidation occurs at moderate potentials. Cationic monomers of the type M(NC)/sub 2/(NN)/sup +/ where (NN) = 2,2'-bipyridine or 1,10-phenanthroline have been prepared by reaction of the chelating ligands with the parent dimers. Cyclic voltammetric studies of these monomers indicate that several reversible ligand-centered reductions are generally observed and that the chelating ligand is more easily reduced than is the ortho-metalating ligand. Spectroscopic studies of the mixed ligand monomers indicate that dual emissions from MLCT states associated with the ortho-metalating and chelating ligands occur in the Ir(III) complexes whereas a single emission from a ligand-localized excited state is observed in the Rh(III) complexes. These results are discussed in terms of electronic and nuclear coupling factors analogous to those encountered in descriptions of bimolecular energy and electron-transfer processes.

  5. Pharmacological NAD-Boosting Strategies Improve Mitochondrial Homeostasis in Human Complex I-Mutant Fibroblasts.

    PubMed

    Felici, Roberta; Lapucci, Andrea; Cavone, Leonardo; Pratesi, Sara; Berlinguer-Palmini, Rolando; Chiarugi, Alberto

    2015-06-01

    Mitochondrial disorders are devastating genetic diseases for which efficacious therapies are still an unmet need. Recent studies report that increased availability of intracellular NAD obtained by inhibition of the NAD-consuming enzyme poly(ADP-ribose) polymerase (PARP)-1 or supplementation with the NAD-precursor nicotinamide riboside (NR) ameliorates energetic derangement and symptoms in mouse models of mitochondrial disorders. Whether these pharmacological approaches also improve bioenergetics of human cells harboring mitochondrial defects is unknown. It is also unclear whether the same signaling cascade is prompted by PARP-1 inhibitors and NR supplementation to improve mitochondrial homeostasis. Here, we show that human fibroblasts mutant for the NADH dehydrogenase (ubiquinone) Fe-S protein 1 (NDUFS1) subunit of respiratory complex I have similar ATP, NAD, and mitochondrial content compared with control cells, but show reduced mitochondrial membrane potential. Interestingly, mutant cells also show increased transcript levels of mitochondrial DNA but not nuclear DNA respiratory complex subunits, suggesting activation of a compensatory response. At variance with prior work in mice, however, NR supplementation, but not PARP-1 inhibition, increased intracellular NAD content in NDUFS1 mutant human fibroblasts. Conversely, PARP-1 inhibitors, but not NR supplementation, increased transcription of mitochondrial transcription factor A and mitochondrial DNA-encoded respiratory complexes constitutively induced in mutant cells. Still, both NR and PARP-1 inhibitors restored mitochondrial membrane potential and increased organelle content as well as oxidative activity of NDUFS1-deficient fibroblasts. Overall, data provide the first evidence that in human cells harboring a mitochondrial respiratory defect exposure to NR or PARP-1, inhibitors activate different signaling pathways that are not invariantly prompted by NAD increases, but equally able to improve energetic

  6. Mitochondrial complex I and cell death: a semi-automatic shotgun model

    PubMed Central

    Gonzalez-Halphen, D; Ghelli, A; Iommarini, L; Carelli, V; Esposti, M D

    2011-01-01

    Mitochondrial dysfunction often leads to cell death and disease. We can now draw correlations between the dysfunction of one of the most important mitochondrial enzymes, NADH:ubiquinone reductase or complex I, and its structural organization thanks to the recent advances in the X-ray structure of its bacterial homologs. The new structural information on bacterial complex I provide essential clues to finally understand how complex I may work. However, the same information remains difficult to interpret for many scientists working on mitochondrial complex I from different angles, especially in the field of cell death. Here, we present a novel way of interpreting the bacterial structural information in accessible terms. On the basis of the analogy to semi-automatic shotguns, we propose a novel functional model that incorporates recent structural information with previous evidence derived from studies on mitochondrial diseases, as well as functional bioenergetics. PMID:22030538

  7. The complex interplay between mitochondrial dynamics and cardiac metabolism.

    PubMed

    Parra, Valentina; Verdejo, Hugo; del Campo, Andrea; Pennanen, Christian; Kuzmicic, Jovan; Iglewski, Myriam; Hill, Joseph A; Rothermel, Beverly A; Lavandero, Sergio

    2011-02-01

    Mitochondria are highly dynamic organelles, capable of undergoing constant fission and fusion events, forming networks. These dynamic events allow the transmission of chemical and physical messengers and the exchange of metabolites within the cell. In this article we review the signaling mechanisms controlling mitochondrial fission and fusion, and its relationship with cell bioenergetics, especially in the heart. Furthermore we also discuss how defects in mitochondrial dynamics might be involved in the pathogenesis of metabolic cardiac diseases. PMID:21258852

  8. The complex interplay between mitochondrial dynamics and cardiac metabolism

    PubMed Central

    Parra, Valentina; Verdejo, Hugo; del Campo, Andrea; Pennanen, Christian; Kuzmicic, Jovan; Iglewski, Myriam; Hill, Joseph A.; Rothermel, Beverly A.

    2012-01-01

    Mitochondria are highly dynamic organelles, capable of undergoing constant fission and fusion events, forming networks. These dynamic events allow the transmission of chemical and physical messengers and the exchange of metabolites within the cell. In this article we review the signaling mechanisms controlling mitochondrial fission and fusion, and its relationship with cell bioenergetics, especially in the heart. Furthermore we also discuss how defects in mitochondrial dynamics might be involved in the pathogenesis of metabolic cardiac diseases. PMID:21258852

  9. Ubisemiquinone is the electron donor for superoxide formation by complex III of heart mitochondria.

    PubMed

    Turrens, J F; Alexandre, A; Lehninger, A L

    1985-03-01

    Much evidence indicates that superoxide is generated from O2 in a cyanide-sensitive reaction involving a reduced component of complex III of the mitochondrial respiratory chain, particularly when antimycin A is present. Although it is generally believed that ubisemiquinone is the electron donor to O2, little experimental evidence supporting this view has been reported. Experiments with succinate as electron donor in the presence of antimycin A in intact rat heart mitochondria, which contain much superoxide dismutase but little catalase, showed that myxothiazol, which inhibits reduction of the Rieske iron-sulfur center, prevented formation of hydrogen peroxide, determined spectrophotometrically as the H2O2-peroxidase complex. Similarly, depletion of the mitochondria of their cytochrome c also inhibited formation of H2O2, which was restored by addition of cytochrome c. These observations indicate that factors preventing the formation of ubisemiquinone also prevent H2O2 formation. They also exclude ubiquinol, which remains reduced under these conditions, as the reductant of O2. Since cytochrome b also remains fully reduced when myxothiazol is added to succinate- and antimycin A-supplemented mitochondria, reduced cytochrome b may also be excluded as the reductant of O2. These observations, which are consistent with the Q-cycle reactions, by exclusion of other possibilities leave ubisemiquinone as the only reduced electron carrier in complex III capable of reducing O2 to O2-. PMID:2983613

  10. Mitochondrial introgression and complex biogeographic history of the genus Picea.

    PubMed

    Ran, Jin-Hua; Shen, Ting-Ting; Liu, Wen-Juan; Wang, Pei-Pei; Wang, Xiao-Quan

    2015-12-01

    Biogeographic history of plants is much more complex in the Northern Hemisphere than in the Southern Hemisphere due to that both the Bering and the North Atlantic land bridges contributed to floristic exchanges in the Cenozoic, which led to hybridization between congeneric species from different continents. It would be interesting to know how intercontinental gene flow and introgression have affected plant phylogenetic reconstruction and biogeographic inference. In this study, we reinvestigated the phylogenetic and biogeographic history of Picea, a main component of the Northern Hemisphere forest with many species that originated from recent radiation, using two chloroplast (cp), one mitochondrial (mt) and three single-copy nuclear gene markers. The generated gene trees are topologically highly discordant and the geographically closely related species generally show a close affinity of mtDNA rather than cp- or nuclear DNA, suggesting that inter- and intra-continental gene flow and mtDNA introgression might have occurred commonly. However, all gene trees resolved Picea breweriana as the basal-most lineage, which, together with fossil evidence, supports the North American origin hypothesis for the genus. Both dispersal and vicariance have played important roles in the evolution of Picea, and the Bering Land Bridge could have mediated the "North America to Eurasia" dispersal at least two times during the Miocene and Pliocene. Our study again demonstrates the importance of applying data from three genomes for a clear understanding of evolutionary histories in the pine family. Any markers from a single genome alone will not reveal a clear picture of the phylogenetic relationships among closely related congeneric species. In particular, mtDNA markers should be cautiously used, considering that introgression of the maternally inherited mtDNA with a lower rate of gene flow (by seeds) could have occurred much more frequently than that of the paternally inherited cpDNA with

  11. Mapping the Escherichia coli transcription elongation complex with exonuclease III

    PubMed Central

    Liu, Zhaokun; Artsimovitch, Irina

    2014-01-01

    Summary RNA polymerase interactions with the nucleic acids control every step of the transcription cycle. These contacts mediate RNA polymerase recruitment to promoters; induce pausing during RNA chain synthesis, and control transcription termination. These interactions are dissected using footprinting assays, in which a bound protein protects nucleic acids from the digestion by nucleases or modification by chemical probes. Exonuclease III is frequently employed to study protein-DNA interactions owing to relatively simple procedures and low background. Exonuclease III has been used to determine RNA polymerase position in transcription initiation and elongation complexes and to infer the translocation register of the enzyme. In this chapter, we describe probing the location and the conformation of transcription elongation complexes formed by walking of the RNA polymerase along an immobilized template. PMID:25665555

  12. Targeting mitochondrial cardiolipin and the cytochrome c/cardiolipin complex to promote electron transport and optimize mitochondrial ATP synthesis

    PubMed Central

    Birk, A V; Chao, W M; Bracken, C; Warren, J D; Szeto, H H

    2014-01-01

    BACKGROUND AND PURPOSE Cardiolipin plays an important role in mitochondrial respiration and cardiolipin peroxidation is associated with age-related diseases. Hydrophobic interactions between cytochrome c and cardiolipin converts cytochrome c from an electron carrier to a peroxidase. In addition to cardiolipin peroxidation, this impedes electron flux and inhibits mitochondrial ATP synthesis. SS-31 (D-Arg-dimethylTyr-Lys-Phe-NH2) selectively binds to cardiolipin and inhibits cytochrome c peroxidase activity. Here, we examined whether SS-31 also protected the electron carrier function of cytochrome c. EXPERIMENTAL APPROACH Interactions of SS-31 with cardiolipin were studied using liposomes and bicelles containing phosphatidylcholine alone or with cardiolipin. Structural interactions were assessed by fluorescence spectroscopy, turbidity and nuclear magnetic resonance. Effects of cardiolipin on electron transfer kinetics of cytochrome c were determined by cytochrome c reduction in vitro and oxygen consumption using mitoplasts, frozen and fresh mitochondria. KEY RESULTS SS-31 interacted only with liposomes and bicelles containing cardiolipin in about 1:1 ratio. NMR studies demonstrated that the aromatic residues of SS-31 penetrated deep into cardiolipin-containing bilayers. SS-31 restored cytochrome c reduction and mitochondrial oxygen consumption in the presence of added cardiolipin. In fresh mitochondria, SS-31 increased state 3 respiration and efficiency of ATP synthesis. CONCLUSIONS AND IMPLICATIONS SS-31 selectively targeted cardiolipin and modulated its interaction with cytochrome c. SS-31 inhibited the cytochrome c/cardiolipin complex peroxidase activity while protecting its ability to serve as an electron carrier, thus optimizing mitochondrial electron transport and ATP synthesis. This novel class of cardiolipin therapeutics has the potential to restore mitochondrial bioenergetics for treatment of numerous age-related diseases. LINKED ARTICLES This article is

  13. Oxalate complexation with aluminum(III) and iron(III) at moderately elevated temperatures

    SciTech Connect

    Tait, C.D.; Janecky, D.R.; Clark, D.L.; Bennett, P.C.

    1992-05-01

    To add to our understanding of the weathering of rocks in organic rich environments such as sedimentary brines and oil field waters, we have examined the temperature dependent complexation of aluminum with oxalate. Raman vibrational studies show that even the association constant for the highly charged Al(ox){sub 3}{sup 3{minus}} unexpectedly increases with moderate temperature increases to 80{degrees}C. To evaluate the potential importance of these Al-oxalate species in complex natural systems, temperature dependent competition experiments Fe(III) and Al(III) for oxalate have been initiated. Similar to aluminum, ferric oxalates show increases in association constants at higher temperatures. In competition experiments, the first association constant for Fe(ox){sup +} increases faster than that for Al(ox){sup +} to 90{degrees}C.

  14. Oxalate complexation with aluminum(III) and iron(III) at moderately elevated temperatures

    SciTech Connect

    Tait, C.D.; Janecky, D.R.; Clark, D.L. ); Bennett, P.C. . Dept. of Geological Sciences)

    1992-01-01

    To add to our understanding of the weathering of rocks in organic rich environments such as sedimentary brines and oil field waters, we have examined the temperature dependent complexation of aluminum with oxalate. Raman vibrational studies show that even the association constant for the highly charged Al(ox){sub 3}{sup 3{minus}} unexpectedly increases with moderate temperature increases to 80{degrees}C. To evaluate the potential importance of these Al-oxalate species in complex natural systems, temperature dependent competition experiments Fe(III) and Al(III) for oxalate have been initiated. Similar to aluminum, ferric oxalates show increases in association constants at higher temperatures. In competition experiments, the first association constant for Fe(ox){sup +} increases faster than that for Al(ox){sup +} to 90{degrees}C.

  15. Gaining mass: the structure of respiratory complex I-from bacterial towards mitochondrial versions.

    PubMed

    Letts, James A; Sazanov, Leonid A

    2015-08-01

    The 1MDa, 45-subunit proton-pumping NADH-ubiquinone oxidoreductase (complex I) is the largest complex of the mitochondrial electron transport chain. The molecular mechanism of complex I is central to the metabolism of cells, but has yet to be fully characterized. The last two years have seen steady progress towards this goal with the first atomic-resolution structure of the entire bacterial complex I, a 5Å cryo-electron microscopy map of bovine mitochondrial complex I and a ∼3.8Å resolution X-ray crystallographic study of mitochondrial complex I from yeast Yarrowia lipotytica. In this review we will discuss what we have learned from these studies and what remains to be elucidated. PMID:26387075

  16. Bioactivity of pyridine-2-thiolato-1-oxide metal complexes: Bi(III), Fe(III) and Ga(III) complexes as potent anti-Mycobacterium tuberculosis prospective agents.

    PubMed

    Machado, Ignacio; Marino, Leonardo Biancolino; Demoro, Bruno; Echeverría, Gustavo A; Piro, Oscar E; Leite, Clarice Q F; Pavan, Fernando R; Gambino, Dinorah

    2014-11-24

    In the search for new therapeutic tools against tuberculosis and to further address the therapeutic potential of pyridine-2-thiol 1-oxide (Hmpo) metal complexes, two new octahedral [M(III)(mpo)3] complexes, with M = Ga or Bi, were synthesized and characterized in the solid state and in solution. Attempts to crystallize [Ga(III)(mpo)3] in CH2Cl2 led to single crystals of the reaction product [GaCl(mpo)2], where the gallium(III) ion is in a square basis pyramidal environment, trans-coordinated at the basis to two pyridine-2-thiolato 1-oxide anions acting as bidentate ligands through their oxygen and sulfur atoms. The biological activity of the new [M(III)(mpo)3] complexes together with that of the previously reported Fe(III) analogous compound and the pyridine-2-thiol 1-oxide sodium salt (Na mpo) was evaluated on Mycobacterium tuberculosis. The compounds showed excellent activity, both in the standard strain H37Rv ATCC 27294 (pan-susceptible) and in five clinical isolates that are resistant to the standard first-line anti-tuberculosis drugs isoniazid and rifampicin. These pyridine-2-thiol 1-oxide derivatives are promising compounds for the treatment of resistant tuberculosis. PMID:25261824

  17. The electronic spectra of mu-peroxodicobalt(III) complexes

    NASA Technical Reports Server (NTRS)

    Miskowski, Vincent M.

    1987-01-01

    Problems found in the determination of the electronic spectra of mu-peroxodicobalt(III) complexes are considered, and the common formation of different mu-peroxocomplexes upon oxygenation of Co(II)-ligand solutions is discussed. Three classes of spectra have been identified: (1) planar single bridged complexes; (2) nonplanar single-bridged complexes with a dihedral angle near 145 deg; and (3) dibridged mu-OH(-),O2(2-) complexes with a dihedral angle near 60 deg. All of the peroxide ligand-to-metal charge-transfer spectra are found to be consistent with a simple model that assumes a sinusoidal dependence of pi-asterisk O2(2-) energies and sigma-overlaps upon the dihedral angle.

  18. Complexation and molecular modeling studies of europium(III)-gallic acid-amino acid complexes.

    PubMed

    Taha, Mohamed; Khan, Imran; Coutinho, João A P

    2016-04-01

    With many metal-based drugs extensively used today in the treatment of cancer, attention has focused on the development of new coordination compounds with antitumor activity with europium(III) complexes recently introduced as novel anticancer drugs. The aim of this work is to design new Eu(III) complexes with gallic acid, an antioxida'nt phenolic compound. Gallic acid was chosen because it shows anticancer activity without harming health cells. As antioxidant, it helps to protect human cells against oxidative damage that implicated in DNA damage, cancer, and accelerated cell aging. In this work, the formation of binary and ternary complexes of Eu(III) with gallic acid, primary ligand, and amino acids alanine, leucine, isoleucine, and tryptophan was studied by glass electrode potentiometry in aqueous solution containing 0.1M NaNO3 at (298.2±0.1) K. Their overall stability constants were evaluated and the concentration distributions of the complex species in solution were calculated. The protonation constants of gallic acid and amino acids were also determined at our experimental conditions and compared with those predicted by using conductor-like screening model for realistic solvation (COSMO-RS) model. The geometries of Eu(III)-gallic acid complexes were characterized by the density functional theory (DFT). The spectroscopic UV-visible and photoluminescence measurements are carried out to confirm the formation of Eu(III)-gallic acid complexes in aqueous solutions. PMID:26827296

  19. The pro-oxidant chromium(VI) inhibits mitochondrial complex I, complex II, and aconitase in the bronchial epithelium: EPR markers for Fe-S proteins

    PubMed Central

    Myers, Charles R.; Antholine, William E.; Myers, Judith M.

    2010-01-01

    Hexavalent chromium [Cr(VI)] compounds (e.g. chromates) are strong oxidants that readily enter cells where they are reduced to reactive Cr species that also facilitate reactive oxygen species (ROS) generation. Recent studies demonstrated inhibition and oxidation of the thioredoxin system, with greater effects on mitochondrial thioredoxin (Trx2). This implies that Cr(VI)-induced oxidant stress may be especially directed at the mitochondria. Examination of other redox-sensitive mitochondrial functions showed that Cr(VI) treatments that cause Trx2 oxidation in human bronchial epithelial cells also result in pronounced and irreversible inhibition of aconitase, a TCA cycle enzyme that has an iron-sulfur (Fe-S) center that is labile with respect to certain oxidants. The activities of electron transport complexes I and II were also inhibited, whereas complex III was not. Electron paramagnetic resonance (EPR) studies of samples at liquid helium temperature (10 K) showed a strong signal at g = 1.94 that is consistent with the inhibition of electron flow through complexes I and/or II. A signal at g = 2.02 was also observed which is consistent with oxidation of the Fe-S center of aconitase. The g = 1.94 signal was particularly intense and remained after extracellular Cr(VI) was removed, whereas the g = 2.02 signal declined in intensity after Cr(VI) was removed. A similar inhibition of these activities and analogous EPR findings were noted in bovine airways treated ex vivo with Cr(VI). Overall, the data support the hypothesis that Cr(VI) exposure has deleterious effects on a number of redox-sensitive core mitochondrial proteins. The g = 1.94 signal could prove to be an important biomarker for oxidative damage resulting from Cr(VI) exposure. The EPR spectra simultaneously showed signals for Cr(V) and Cr(III) which verify Cr(VI) exposure and its intracellular reductive activation. PMID:20883776

  20. Solvolysis of the Tumor-Inhibiting Ru(III)-Complex trans-Tetrachlorobis(Indazole)Ruthenate(III).

    PubMed

    Pieper, T; Peti, W; Keppler, B K

    2000-01-01

    The ruthenium(III) complex Hlnd trans-[RuCl(4),(ind)(2)], with two trans-standing indazole (ind) ligands bound to ruthenium via nitrogen, shows remarkable activity in different tumor models in vitro and in vivo. The solvolysis of the complex trans-[RuCl(4),(ind)(2)](-) has been investigated by means of spectroscopic techniques (UV/vis, NMR)in different solvents. We investigated the indazolium as well as the sodium salt, the latter showing improved solubility in water. In aqueous acetonitrile and ethanol the solvolysis results in one main solvento complex. The hydrolysis of the complex is more complicated and depends on the pH of the solution as well as on the buffer system. PMID:18475949

  1. DISC1-dependent Regulation of Mitochondrial Dynamics Controls the Morphogenesis of Complex Neuronal Dendrites*

    PubMed Central

    Norkett, Rosalind; Modi, Souvik; Birsa, Nicol; Atkin, Talia A.; Ivankovic, Davor; Pathania, Manav; Trossbach, Svenja V.; Korth, Carsten; Hirst, Warren D.; Kittler, Josef T.

    2016-01-01

    The DISC1 protein is implicated in major mental illnesses including schizophrenia, depression, bipolar disorder, and autism. Aberrant mitochondrial dynamics are also associated with major mental illness. DISC1 plays a role in mitochondrial transport in neuronal axons, but its effects in dendrites have yet to be studied. Further, the mechanisms of this regulation and its role in neuronal development and brain function are poorly understood. Here we have demonstrated that DISC1 couples to the mitochondrial transport and fusion machinery via interaction with the outer mitochondrial membrane GTPase proteins Miro1 and Miro2, the TRAK1 and TRAK2 mitochondrial trafficking adaptors, and the mitochondrial fusion proteins (mitofusins). Using live cell imaging, we show that disruption of the DISC1-Miro-TRAK complex inhibits mitochondrial transport in neurons. We also show that the fusion protein generated from the originally described DISC1 translocation (DISC1-Boymaw) localizes to the mitochondria, where it similarly disrupts mitochondrial dynamics. We also show by super resolution microscopy that DISC1 is localized to endoplasmic reticulum contact sites and that the DISC1-Boymaw fusion protein decreases the endoplasmic reticulum-mitochondria contact area. Moreover, disruption of mitochondrial dynamics by targeting the DISC1-Miro-TRAK complex or upon expression of the DISC1-Boymaw fusion protein impairs the correct development of neuronal dendrites. Thus, DISC1 acts as an important regulator of mitochondrial dynamics in both axons and dendrites to mediate the transport, fusion, and cross-talk of these organelles, and pathological DISC1 isoforms disrupt this critical function leading to abnormal neuronal development. PMID:26553875

  2. DISC1-dependent Regulation of Mitochondrial Dynamics Controls the Morphogenesis of Complex Neuronal Dendrites.

    PubMed

    Norkett, Rosalind; Modi, Souvik; Birsa, Nicol; Atkin, Talia A; Ivankovic, Davor; Pathania, Manav; Trossbach, Svenja V; Korth, Carsten; Hirst, Warren D; Kittler, Josef T

    2016-01-01

    The DISC1 protein is implicated in major mental illnesses including schizophrenia, depression, bipolar disorder, and autism. Aberrant mitochondrial dynamics are also associated with major mental illness. DISC1 plays a role in mitochondrial transport in neuronal axons, but its effects in dendrites have yet to be studied. Further, the mechanisms of this regulation and its role in neuronal development and brain function are poorly understood. Here we have demonstrated that DISC1 couples to the mitochondrial transport and fusion machinery via interaction with the outer mitochondrial membrane GTPase proteins Miro1 and Miro2, the TRAK1 and TRAK2 mitochondrial trafficking adaptors, and the mitochondrial fusion proteins (mitofusins). Using live cell imaging, we show that disruption of the DISC1-Miro-TRAK complex inhibits mitochondrial transport in neurons. We also show that the fusion protein generated from the originally described DISC1 translocation (DISC1-Boymaw) localizes to the mitochondria, where it similarly disrupts mitochondrial dynamics. We also show by super resolution microscopy that DISC1 is localized to endoplasmic reticulum contact sites and that the DISC1-Boymaw fusion protein decreases the endoplasmic reticulum-mitochondria contact area. Moreover, disruption of mitochondrial dynamics by targeting the DISC1-Miro-TRAK complex or upon expression of the DISC1-Boymaw fusion protein impairs the correct development of neuronal dendrites. Thus, DISC1 acts as an important regulator of mitochondrial dynamics in both axons and dendrites to mediate the transport, fusion, and cross-talk of these organelles, and pathological DISC1 isoforms disrupt this critical function leading to abnormal neuronal development. PMID:26553875

  3. Nucleotide sequence analysis of the hypervariable region III of mitochondrial DNA in Thais.

    PubMed

    Thongngam, Punlop; Leewattanapasuk, Worraanong; Bhoopat, Tanin; Sangthong, Padchanee

    2016-07-01

    This study analyzed the nucleotide sequences of the hypervariable region III (HVRIII) of mitochondrial DNA in Thai individuals. Buccal swab samples were randomly obtained from 100 healthy, unrelated, adult (18-60 years old), volunteer donors living in Thailand. Eighteen different haplotypes were found, of which 11 haplotypes were unique. The most frequent haplotypes observed were 522D-523D. Nucleotide transition from Thymine (T) to Cytosine (C) at position 489 (43%) was the most frequent substitution. Nucleotide transversions were also observed at position 433 (Adenine (A) to C, 1%) and position 499 (Guanine (G) to C, 1%). Fifty-three samples presented nucleotide insertion and deletion of C and A (CA) at position 514-523. Insertion of 1AC (3%) and 2AC (2%) were observed. Deletion of 1CA (53%) and 2CA (2%) at position 514-523 were revealed. The deletion of T at position 459 was observed. The haplotype diversity, random match probability, and discrimination power were calculated to be 0.7770, 0.2308, and 0.7692, respectively. PMID:27107562

  4. C11orf83, a mitochondrial cardiolipin-binding protein involved in bc1 complex assembly and supercomplex stabilization.

    PubMed

    Desmurs, Marjorie; Foti, Michelangelo; Raemy, Etienne; Vaz, Frédéric Maxime; Martinou, Jean-Claude; Bairoch, Amos; Lane, Lydie

    2015-04-01

    Mammalian mitochondria may contain up to 1,500 different proteins, and many of them have neither been confidently identified nor characterized. In this study, we demonstrated that C11orf83, which was lacking experimental characterization, is a mitochondrial inner membrane protein facing the intermembrane space. This protein is specifically associated with the bc1 complex of the electron transport chain and involved in the early stages of its assembly by stabilizing the bc1 core complex. C11orf83 displays some overlapping functions with Cbp4p, a yeast bc1 complex assembly factor. Therefore, we suggest that C11orf83, now called UQCC3, is the functional human equivalent of Cbp4p. In addition, C11orf83 depletion in HeLa cells caused abnormal crista morphology, higher sensitivity to apoptosis, a decreased ATP level due to impaired respiration and subtle, but significant, changes in cardiolipin composition. We showed that C11orf83 binds to cardiolipin by its α-helices 2 and 3 and is involved in the stabilization of bc1 complex-containing supercomplexes, especially the III2/IV supercomplex. We also demonstrated that the OMA1 metalloprotease cleaves C11orf83 in response to mitochondrial depolarization, suggesting a role in the selection of cells with damaged mitochondria for their subsequent elimination by apoptosis, as previously described for OPA1. PMID:25605331

  5. C11orf83, a Mitochondrial Cardiolipin-Binding Protein Involved in bc1 Complex Assembly and Supercomplex Stabilization

    PubMed Central

    Foti, Michelangelo; Raemy, Etienne; Vaz, Frédéric Maxime; Martinou, Jean-Claude; Bairoch, Amos

    2015-01-01

    Mammalian mitochondria may contain up to 1,500 different proteins, and many of them have neither been confidently identified nor characterized. In this study, we demonstrated that C11orf83, which was lacking experimental characterization, is a mitochondrial inner membrane protein facing the intermembrane space. This protein is specifically associated with the bc1 complex of the electron transport chain and involved in the early stages of its assembly by stabilizing the bc1 core complex. C11orf83 displays some overlapping functions with Cbp4p, a yeast bc1 complex assembly factor. Therefore, we suggest that C11orf83, now called UQCC3, is the functional human equivalent of Cbp4p. In addition, C11orf83 depletion in HeLa cells caused abnormal crista morphology, higher sensitivity to apoptosis, a decreased ATP level due to impaired respiration and subtle, but significant, changes in cardiolipin composition. We showed that C11orf83 binds to cardiolipin by its α-helices 2 and 3 and is involved in the stabilization of bc1 complex-containing supercomplexes, especially the III2/IV supercomplex. We also demonstrated that the OMA1 metalloprotease cleaves C11orf83 in response to mitochondrial depolarization, suggesting a role in the selection of cells with damaged mitochondria for their subsequent elimination by apoptosis, as previously described for OPA1. PMID:25605331

  6. Parkinson disease-associated mutant VPS35 causes mitochondrial dysfunction by recycling DLP1 complexes

    PubMed Central

    Fujioka, Hisashi; Hoppel, Charles; Whone, Alan L.; Caldwell, Maeve A.; Cullen, Peter J.; Liu, Jun; Zhu, Xiongwei

    2015-01-01

    Mitochondrial dysfunction represents a critical step during the pathogenesis of Parkinson disease (PD) and increasing evidence suggests abnormal mitochondrial dynamics and quality control as important underlying mechanisms. The VPS35 gene, encoding a key component of the retromer complex, is the third autosomal-dominant gene associated with PD. However, how VPS35 mutations may lead to neurodegeneration remains unclear. Here we demonstrate that PD-associated VPS35 mutations caused mitochondrial fragmentation and cell death in cultured neurons in vitro, in mouse substantia nigra neurons in vivo, and in human fibroblasts from PD patient bearing the D620N mutation. VPS35-induced mitochondrial deficits and neuronal dysfunction could be prevented by inhibition of mitochondrial fission. VPS35 mutation caused increased interactions with DLP1 which enhanced mitochondrial DLP1 complex turnover via mitochondria-derived vesicles-dependent trafficking to lysosomes for degradation. Importantly, oxidative stress increased the VPS35–DLP1 interaction which was also increased in the brains of sporadic PD cases. These results revealed a novel cellular mechanism for the involvement of VPS35 in mitochondrial fission, dysregulation of which is likely involved in the pathogenesis of familial, and possibly sporadic, PD. PMID:26618722

  7. Investigating complex I deficiency in Purkinje cells and synapses in patients with mitochondrial disease

    PubMed Central

    Chrysostomou, Alexia; Grady, John P.; Laude, Alex; Taylor, Robert W.; Turnbull, Doug M.

    2015-01-01

    Aims Cerebellar ataxia is common in patients with mitochondrial disease, and despite previous neuropathological investigations demonstrating vulnerability of the olivocerebellar pathway in patients with mitochondrial disease, the exact neurodegenerative mechanisms are still not clear. We use quantitative quadruple immunofluorescence to enable precise quantification of mitochondrial respiratory chain protein expression in Purkinje cell bodies and their synaptic terminals in the dentate nucleus. Methods We investigated NADH dehydrogenase [ubiquinone] 1 alpha subcomplex subunit 13 protein expression in 12 clinically and genetically defined patients with mitochondrial disease and ataxia and 10 age‐matched controls. Molecular genetic analysis was performed to determine heteroplasmy levels of mutated mitochondrial DNA in Purkinje cell bodies and inhibitory synapses. Results Our data reveal that complex I deficiency is present in both Purkinje cell bodies and their inhibitory synapses which surround dentate nucleus neurons. Inhibitory synapses are fewer and enlarged in patients which could represent a compensatory mechanism. Mitochondrial DNA heteroplasmy demonstrated similarly high levels of mutated mitochondrial DNA in cell bodies and synapses. Conclusions This is the first study to use a validated quantitative immunofluorescence technique to determine complex I expression in neurons and presynaptic terminals, evaluating the distribution of respiratory chain deficiencies and assessing the degree of morphological abnormalities affecting synapses. Respiratory chain deficiencies detected in Purkinje cell bodies and their synapses and structural synaptic changes are likely to contribute to altered cerebellar circuitry and progression of ataxia. PMID:26337858

  8. Preparation and reactivity of macrocyclic rhodium(III) alkyl complexes

    SciTech Connect

    Carraher, Jack M.; Ellern, Arkady; Bakac, Andreja

    2013-09-21

    Macrocyclic rhodium(II) complexes LRh(H2O)(2+) (L = L-1 = cyclam and L-2 = meso-Me-6-cyclam) react with alkyl hydroperoxides RC(CH3)(2)OOH to generate the corresponding rhodium(III) alkyls L(H2O)RhR2+ (R = CH3, C2H5, PhCH2). Methyl and benzyl complexes can also be prepared by bimolecular group transfer from alkyl cobaloximes (dmgH)(2)(H2O) CoR and (dmgBF(2))(2)(H2O) CoR (R = CH3, PhCH2) to LRh(H2O)(2+). The new complexes were characterized by solution NMR and by crystal structure analysis. They exhibit great stability in aqueous solution at room temperature, but undergo efficient Rh-C bond cleavage upon photolysis. (C) 2013 Elsevier B.V. All rights reserved.

  9. Clueless, a protein required for mitochondrial function, interacts with the PINK1-Parkin complex in Drosophila

    PubMed Central

    Sen, Aditya; Kalvakuri, Sreehari; Bodmer, Rolf; Cox, Rachel T.

    2015-01-01

    ABSTRACT Loss of mitochondrial function often leads to neurodegeneration and is thought to be one of the underlying causes of neurodegenerative diseases such as Parkinson's disease (PD). However, the precise events linking mitochondrial dysfunction to neuronal death remain elusive. PTEN-induced putative kinase 1 (PINK1) and Parkin (Park), either of which, when mutated, are responsible for early-onset PD, mark individual mitochondria for destruction at the mitochondrial outer membrane. The specific molecular pathways that regulate signaling between the nucleus and mitochondria to sense mitochondrial dysfunction under normal physiological conditions are not well understood. Here, we show that Drosophila Clueless (Clu), a highly conserved protein required for normal mitochondrial function, can associate with Translocase of the outer membrane (TOM) 20, Porin and PINK1, and is thus located at the mitochondrial outer membrane. Previously, we found that clu genetically interacts with park in Drosophila female germ cells. Here, we show that clu also genetically interacts with PINK1, and our epistasis analysis places clu downstream of PINK1 and upstream of park. In addition, Clu forms a complex with PINK1 and Park, further supporting that Clu links mitochondrial function with the PINK1-Park pathway. Lack of Clu causes PINK1 and Park to interact with each other, and clu mutants have decreased mitochondrial protein levels, suggesting that Clu can act as a negative regulator of the PINK1-Park pathway. Taken together, these results suggest that Clu directly modulates mitochondrial function, and that Clu's function contributes to the PINK1-Park pathway of mitochondrial quality control. PMID:26035866

  10. Soluble, Prefibrillar α-Synuclein Oligomers Promote Complex I-dependent, Ca2+-induced Mitochondrial Dysfunction*

    PubMed Central

    Luth, Eric S.; Stavrovskaya, Irina G.; Bartels, Tim; Kristal, Bruce S.; Selkoe, Dennis J.

    2014-01-01

    α-Synuclein (αSyn) aggregation and mitochondrial dysfunction both contribute to the pathogenesis of Parkinson disease (PD). Although recent studies have suggested that mitochondrial association of αSyn may disrupt mitochondrial function, it is unclear what aggregation state of αSyn is most damaging to mitochondria and what conditions promote or inhibit the effect of toxic αSyn species. Because the neuronal populations most vulnerable in PD are characterized by large cytosolic Ca2+ oscillations that burden mitochondria, we examined mitochondrial Ca2+ stress in an in vitro system comprising isolated mitochondria and purified recombinant human αSyn in various aggregation states. Using fluorimetry to simultaneously measure four mitochondrial parameters, we observed that soluble, prefibrillar αSyn oligomers, but not monomeric or fibrillar αSyn, decreased the retention time of exogenously added Ca2+, promoted Ca2+-induced mitochondrial swelling and depolarization, and accelerated cytochrome c release. Inhibition of the permeability transition pore rescued these αSyn-induced changes in mitochondrial parameters. Interestingly, the mitotoxic effects of αSyn were specifically dependent upon both electron flow through complex I and mitochondrial uptake of exogenous Ca2+. Our results suggest that soluble prefibrillar αSyn oligomers recapitulate several mitochondrial phenotypes previously observed in animal and cell models of PD: complex I dysfunction, altered membrane potential, disrupted Ca2+ homeostasis, and enhanced cytochrome c release. These data reveal how the association of oligomeric αSyn with mitochondria can be detrimental to the function of cells with high Ca2+-handling requirements. PMID:24942732

  11. Lack of cytochrome c in Arabidopsis decreases stability of Complex IV and modifies redox metabolism without affecting Complexes I and III.

    PubMed

    Welchen, Elina; Hildebrandt, Tatjana M; Lewejohann, Dagmar; Gonzalez, Daniel H; Braun, Hans-Peter

    2012-07-01

    We studied the role of cytochrome c (CYTc), which mediates electron transfer between Complexes III and IV, in cellular events related with mitochondrial respiration, plant development and redox homeostasis. We analyzed single and double homozygous mutants in both CYTc-encoding genes from Arabidopsis: CYTC-1 and CYTC-2. While individual mutants were similar to wild-type, knock-out of both genes produced an arrest of embryo development, showing that CYTc function is essential at early stages of plant development. Mutants in which CYTc levels were extremely reduced respective to wild-type had smaller rosettes with a pronounced decrease in parenchymatic cell size and an overall delay in development. Mitochondria from these mutants had lower respiration rates and a relative increase in alternative respiration. Furthermore, the decrease in CYTc severely affected the activity and the amount of Complex IV, without affecting Complexes I and III. Reactive oxygen species levels were reduced in these mutants, which showed induction of genes encoding antioxidant enzymes. Ascorbic acid levels were not affected, suggesting that a small amount of CYTc is enough to support its normal synthesis. We postulate that, in addition to its role as an electron carrier between Complexes III and IV, CYTc influences Complex IV levels in plants, probably reflecting a role of this protein in Complex IV stability. This double function of CYTc most likely explains why it is essential for plant survival. PMID:22551905

  12. Mitochondrial myopathy, cardiomyopathy, and pontine signal changes in an adult patient with isolated complex II deficiency.

    PubMed

    Sonam, Kothari; Bindu, Parayil Sankaran; Taly, Arun B; Nalini, Atchayaram; Govindaraju, Chikkanna; Aravinda, Hanumanthapura R; Khan, Nahid Akthar; Thangaraj, Kumaraswamy; Gayathri, Narayanappa

    2014-12-01

    Mitochondrial disorders resulting from an isolated deficiency of complex II of the respiratory chain is rarely reported. The phenotypic spectrum associated with these disorders is heterogeneous and still expanding. This report describes a patient who presented with myopathy, dilated cardiomyopathy, and pontine signal changes on magnetic resonance imaging. Muscle biopsy showed total absence of succinate dehydrogenase on enzyme histochemistry, negative succinate dehydrogenase subunit A (SDHA) activity on immunohistochemistry, and ultrastructural evidence of mitochondrial aggregates of varying sizes confirming the diagnosis of complex II deficiency. A unique phenotype with complex II deficiency is reported. PMID:25415517

  13. The mitochondrial TOM complex modulates bax-induced apoptosis in Drosophila.

    PubMed

    Colin, J; Garibal, J; Mignotte, B; Guénal, I

    2009-02-20

    Bax is a pro-apoptotic member of the Bcl-2 family proteins involved in the release of apoptogenic factors from mitochondria to the cytosol. Recently, it has been shown both in mammals and yeast that Bax insertion in the mitochondrial outer membrane involves at least two distinct mechanisms, one of which uses the TOM complex. Here, we show that in Drosophila, heterozygous loss of function mutations of Tom22 or Tom70, two receptors of the TOM complex, attenuates bax-induced phenotypes in vivo. These results argue that the TOM complex may be used as a mitochondrial Bax receptor in Drosophila. PMID:19138672

  14. Molecular structure, photophysical and thermal properties of samarium (III) complexes

    NASA Astrophysics Data System (ADS)

    Kumar, Rajeev; Singh, Udai P.

    2008-03-01

    Some 8-coordinated samarium (III) complexes ( 1- 4) having bipy (2,2'-bipyridine), terpy (2,2':6',2″-terpyridine), phen (1,10-phenanthroline) and tp [hydrotris (pyrazol-1-yl) borate] as supporting ligands have been synthesized and structurally characterized by different techniques including X-ray crystallography. The X-ray studies demonstrated that the complexes 1, 2 and 4 crystallized in triclinic space group P1¯ with cell dimensions a = 8.5640(2) Å, b = 8.8696(2) Å, c = 15.8608(4) Å for 1; a = 7.2113(9) Å, b = 11.0737(14) Å, c = 13.6289(18) Å for 2; a = 12.440(3) Å, b = 12.874(3) Å, c = 17.822(4) Å for 4, whereas the complex 3 crystallized in the monoclinic space group P2 1/ c with cell dimensions a = 9.472(3) Å, b = 17.092(5) Å, c = 14.516(5) Å. The IR study suggested that the azide is coordinated in 1, 3-bridging mode in complex 4. The photophysical properties of above complexes have been studied with ultraviolet absorption and emission spectral studies. Thermogravimetric analyses suggested that all these complexes undergo the complete decomposition to form the thermally stable samarium oxide (Sm 2O 3).

  15. Polyamide preparation with pentaamine cobalt (III) complex catalyst

    SciTech Connect

    Wu, M.Y.M.; Ball, L.E.; Coffey, G.P.

    1987-11-17

    A process is described for preparing a polyamide containing amide groups as integral parts of the main polymer chain comprising polymerizing a polyamide forming system, chosen from (1) an alpha, beta-unsaturated carboxylic acid and ammonia, (2) an ammonium salt of an alpha, beta unsaturated carboxylic acid, (3) an alpha, beta-unsaturated nitrile and water, (4) an alpha, beta-unsaturated amine and ammonia, (5) or a beta-amino propionic acid or its alkyl derivatives, in contact with a catalyst comprising a pentaamine cobalt (III) complex.

  16. Exceptional Oxygen Sensing Properties of New Blue Light-Excitable Highly Luminescent Europium(III) and Gadolinium(III) Complexes

    PubMed Central

    Borisov, Sergey M.; Fischer, Roland; Saf, Robert; Klimant, Ingo

    2016-01-01

    New europium(III) and gadolinium(III) complexes bearing 8-hydroxyphenalenone antenna combine efficient absorption in the blue part of the spectrum and strong emission in polymers at room temperature. The Eu(III) complexes show characteristic red luminescence whereas the Gd(III) dyes are strongly phosphorescent. The luminescence quantum yields are about 20% for the Eu(III) complexes and 50% for the Gd(III) dyes. In contrast to most state-of-the-art Eu(III) complexes the new dyes are quenched very efficiently by molecular oxygen. The luminescence decay times of the Gd(III) complexes exceed 1 ms which ensures exceptional sensitivity even in polymers of moderate oxygen permeability. These sensors are particularly suitable for trace oxygen sensing and may be good substitutes for Pd(II) porphyrins. The photophysical and sensing properties can be tuned by varying the nature of the fourth ligand. The narrow-band emission of the Eu(III) allows efficient elimination of the background light and autofluorescence and is also very attractive for use e.g. in multi-analyte sensors. The highly photostable indicators incorporated in nanoparticles are promising for imaging applications. Due to the straightforward preparation and low cost of starting materials the new dyes represent a promising alternative to the state-of-the-art oxygen indicators particularly for such applications as e.g. food packaging. PMID:27158252

  17. MCUR1 Is a Scaffold Factor for the MCU Complex Function and Promotes Mitochondrial Bioenergetics.

    PubMed

    Tomar, Dhanendra; Dong, Zhiwei; Shanmughapriya, Santhanam; Koch, Diana A; Thomas, Toby; Hoffman, Nicholas E; Timbalia, Shrishiv A; Goldman, Samuel J; Breves, Sarah L; Corbally, Daniel P; Nemani, Neeharika; Fairweather, Joseph P; Cutri, Allison R; Zhang, Xueqian; Song, Jianliang; Jaña, Fabián; Huang, Jianhe; Barrero, Carlos; Rabinowitz, Joseph E; Luongo, Timothy S; Schumacher, Sarah M; Rockman, Michael E; Dietrich, Alexander; Merali, Salim; Caplan, Jeffrey; Stathopulos, Peter; Ahima, Rexford S; Cheung, Joseph Y; Houser, Steven R; Koch, Walter J; Patel, Vickas; Gohil, Vishal M; Elrod, John W; Rajan, Sudarsan; Madesh, Muniswamy

    2016-05-24

    Mitochondrial Ca(2+) Uniporter (MCU)-dependent mitochondrial Ca(2+) uptake is the primary mechanism for increasing matrix Ca(2+) in most cell types. However, a limited understanding of the MCU complex assembly impedes the comprehension of the precise mechanisms underlying MCU activity. Here, we report that mouse cardiomyocytes and endothelial cells lacking MCU regulator 1 (MCUR1) have severely impaired [Ca(2+)]m uptake and IMCU current. MCUR1 binds to MCU and EMRE and function as a scaffold factor. Our protein binding analyses identified the minimal, highly conserved regions of coiled-coil domain of both MCU and MCUR1 that are necessary for heterooligomeric complex formation. Loss of MCUR1 perturbed MCU heterooligomeric complex and functions as a scaffold factor for the assembly of MCU complex. Vascular endothelial deletion of MCU and MCUR1 impaired mitochondrial bioenergetics, cell proliferation, and migration but elicited autophagy. These studies establish the existence of a MCU complex that assembles at the mitochondrial integral membrane and regulates Ca(2+)-dependent mitochondrial metabolism. PMID:27184846

  18. The reducible complexity of a mitochondrial molecular machine

    PubMed Central

    Clements, Abigail; Bursac, Dejan; Gatsos, Xenia; Perry, Andrew J.; Civciristov, Srgjan; Celik, Nermin; Likic, Vladimir A.; Poggio, Sebastian; Jacobs-Wagner, Christine; Strugnell, Richard A.; Lithgow, Trevor

    2009-01-01

    Molecular machines drive essential biological processes, with the component parts of these machines each contributing a partial function or structural element. Mitochondria are organelles of eukaryotic cells, and depend for their biogenesis on a set of molecular machines for protein transport. How these molecular machines evolved is a fundamental question. Mitochondria were derived from an α-proteobacterial endosymbiont, and we identified in α-proteobacteria the component parts of a mitochondrial protein transport machine. In bacteria, the components are found in the inner membrane, topologically equivalent to the mitochondrial proteins. Although the bacterial proteins function in simple assemblies, relatively little mutation would be required to convert them to function as a protein transport machine. This analysis of protein transport provides a blueprint for the evolution of cellular machinery in general. PMID:19717453

  19. Preparation of new fluorophore lanthanide complexes-Cloisite nanohybrids using the tricationic Pr(III), Gd(III) and Dy(III) complexes with 9,10-phenanthrenequinone.

    PubMed

    Mallakpour, Shadpour; Behnamfar, Mohammad Taghi; Dinari, Mohammad; Hadadzadeh, Hassan

    2015-02-25

    New fluorophore lanthanide complexes-Cloisite (LCs-C) nanohybrids have been prepared by the intercalation reaction of Cloisite Na(+) with the tricationic lanthanide complexes (1-3), [M(PQ)3(DMF)2(H2O)2](3+) (M=Pr(III) (1), Gd(III) (2), and Dy(III) (3); PQ=9,10-phenanthrenequinone), in aqueous solutions. The X-ray diffraction analysis of the modified clays (LCs-C) showed an increase in the interlayer distance (d) as compared to the pure Cloisite Na(+). Field-emission scanning electron microscopy (FE-SEM) was used to study the morphology of the modified clays and the results were demonstrated a homogeneous morphology for the nanohybrids. The thermal behavior of the LCs-C nanohybrids was investigated using thermogravimetric analysis. Solid-state fluorescence properties of the LCs-C nanohybrids were also investigated. The results show that all tricationic complexes have a significant fluorescence at room temperature when the complexes are adsorbed onto Cloisite. PMID:25305612

  20. Steatotic livers are susceptible to normothermic ischemia-reperfusion injury from mitochondrial Complex-I dysfunction

    PubMed Central

    Chu, Michael JJ; Premkumar, Rakesh; Hickey, Anthony JR; Jiang, Yannan; Delahunt, Brett; Phillips, Anthony RJ; Bartlett, Adam SJR

    2016-01-01

    AIM: To assess the effects of ischemic preconditioning (IPC, 10-min ischemia/10-min reperfusion) on steatotic liver mitochondrial function after normothermic ischemia-reperfusion injury (IRI). METHODS: Sixty male Sprague-Dawley rats were fed 8-wk with either control chow or high-fat/high-sucrose diet inducing > 60% mixed steatosis. Three groups (n = 10/group) for each dietary state were tested: (1) the IRI group underwent 60 min partial hepatic ischemia and 4 h reperfusion; (2) the IPC group underwent IPC prior to same standard IRI; and (3) sham underwent the same surgery without IRI or IPC. Hepatic mitochondrial function was analyzed by oxygraphs. Mitochondrial Complex-I, Complex-II enzyme activity, serum alanine aminotransferase (ALT), and histological injury were measured. RESULTS: Steatotic-IRI livers had a greater increase in ALT (2476 ± 166 vs 1457 ± 103 IU/L, P < 0.01) and histological injury following IRI compared to the lean liver group. Steatotic-IRI demonstrated lower Complex-I activity at baseline [78.4 ± 2.5 vs 116.4 ± 6.0 nmol/(min.mg protein), P < 0.001] and following IRI [28.0 ± 6.2 vs 104.3 ± 12.6 nmol/(min.mg protein), P < 0.001]. Steatotic-IRI also demonstrated impaired Complex-I function post-IRI compared to the lean liver IRI group. Complex-II activity was unaffected by hepatic steatosis or IRI. Lean liver mitochondrial function was unchanged following IRI. IPC normalized ALT and histological injury in steatotic livers but had no effect on overall steatotic liver mitochondrial function or individual mitochondrial complex enzyme activities. CONCLUSION: Warm IRI impairs steatotic liver Complex-I activity and function. The protective effects of IPC in steatotic livers may not be mediated through mitochondria. PMID:27217699

  1. Myotonic dystrophy protein kinase (DMPK) prevents ROS-induced cell death by assembling a hexokinase II-Src complex on the mitochondrial surface

    PubMed Central

    Pantic, B; Trevisan, E; Citta, A; Rigobello, M P; Marin, O; Bernardi, P; Salvatori, S; Rasola, A

    2013-01-01

    The biological functions of myotonic dystrophy protein kinase (DMPK), a serine/threonine kinase whose gene mutations cause myotonic dystrophy type 1 (DM1), remain poorly understood. Several DMPK isoforms exist, and the long ones (DMPK-A/B/C/D) are associated with the mitochondria, where they exert unknown activities. We have studied the isoform A of DMPK, which we have found to be prevalently associated to the outer mitochondrial membrane. The kinase activity of mitochondrial DMPK protects cells from oxidative stress and from the ensuing opening of the mitochondrial permeability transition pore (PTP), which would otherwise irreversibly commit cells to death. We observe that DMPK (i) increases the mitochondrial localization of hexokinase II (HK II), (ii) forms a multimeric complex with HK II and with the active form of the tyrosine kinase Src, binding its SH3 domain and (iii) it is tyrosine-phosphorylated by Src. Both interaction among these proteins and tyrosine phosphorylation of DMPK are increased under oxidative stress, and Src inhibition selectively enhances death in DMPK-expressing cells after HK II detachment from the mitochondria. Down-modulation of DMPK abolishes the appearance of muscle markers in in vitro myogenesis, which is rescued by oxidant scavenging. Our data indicate that, together with HK II and Src, mitochondrial DMPK is part of a multimolecular complex endowed with antioxidant and pro-survival properties that could be relevant during the function and differentiation of muscle fibers. PMID:24136222

  2. 9,10-phenanthrenesemiquinone radical complexes of ruthenium(III), osmium(III) and rhodium(III) and redox series.

    PubMed

    Biswas, Manas Kumar; Patra, Sarat Chandra; Maity, Amarendra Nath; Ke, Shyue-Chu; Weyhermüller, Thomas; Ghosh, Prasanta

    2013-05-14

    Reactions of 9,10-phenanthrenequinone (PQ) in toluene with [M(II)(PPh3)3X2] at 298 K afford green complexes, trans-[M(PQ)(PPh3)2X2] (M = Ru, X = Cl, 1; M = Os, X = Br, 2) in moderate yields. Reaction of anhydrous RhCl3 with PQ and PPh3 in boiling ethanol affords the dark brown paramagnetic complex, cis-[Rh(PQ)(PPh3)2Cl2] (3) in good yields. Diffusion of iodine solution in n-hexane to the trans-[Os(PQ) (PPh3)2(CO)(Br)] solution in CH2Cl2 generates the crystals of trans-[Os(PQ)(PPh3)2(CO)(Br)](+)I3(-), (4(+))I3(-)), in lower yields. Single crystal X-ray structure determinations of 1·2toluene, 2·CH2Cl2 and 4(+)I3(-), UV-vis/NIR absorption spectra, EPR spectra of 3, electrochemical activities and DFT calculations on 1, 2, trans-[Ru(PQ)(PMe3)2Cl2] (1Me), trans-[Os(PQ)(PMe3)2Br2] (2Me), cis-[Rh(PQ)(PMe3)2Cl2] (3Me) and their oxidized and reduced analogues including trans-[Os(PQ)(PMe3)2(CO)(Br)](+) (4Me(+)) substantiated that 1-3 are the 9,10-phenanthrenesemiquinone radical (PQ(˙-)) complexes of ruthenium(III), osmium(III) and rhodium(III) and are defined as trans/cis-[M(III)(PQ(˙-))(PPh3)2X2] with a minor contribution of the resonance form trans/cis-[M(II)(PQ)(PPh3)2X2]. Two comparatively longer C-O (1.286(4) Å) and the shorter C-C lengths (1.415(7) Å) of the OO-chelate of 1·2toluene and 2·CH2Cl2 and the isotropic fluid solution EPR signal at g = 1.999 of 3 are consistent with the existence of the reduced PQ(˙-) ligand in 1-3 complexes. Anisotropic EPR spectra of the frozen glasses (g11 = g22 = 2.0046 and g33 = 1.9874) and solids (g11 = g22 = 2.005 and g33 = 1.987) instigate the contribution of the resonance form, cis-[Rh(II)(PQ)(PPh3)2Cl2] in 3. DFT calculations established that the closed shell singlet (CSS) solutions of 1Me and 2Me are unstable due to open shell singlet (OSS) perturbation. However, the broken symmetry (BS) (1,1) Ms = 0 solutions of 1Me and 2Me are respectively 22.6 and 24.2 kJ mole(-1) lower in energy and reproduced the experimental bond

  3. Luminescent chiral lanthanide(III) complexes as potential molecular probes

    PubMed Central

    Muller, Gilles

    2009-01-01

    This perspective gives an introduction into the design of luminescent lanthanide(III)-containing complexes possessing chiral properties and used to probe biological materials. The first part briefly describes general principles, focusing on the optical aspect (i.e. lanthanide luminescence, sensitization processes) of the most emissive trivalent lanthanide ions, europium and terbium, incorporated into molecular luminescent edifices. This is followed by a short discussion on the importance of chirality in the biological and pharmaceutical fields. The second part is devoted to the assessment of the chiroptical spectroscopic tools available (typically circular dichroism and circularly polarized luminescence) and the strategies used to introduce a chiral feature into luminescent lanthanide(III) complexes (chiral structure resulting from a chiral arrangement of the ligand molecules surrounding the luminescent center or presence of chiral centers in the ligand molecules). Finally, the last part illustrates these fundamental principles with recent selected examples of such chiral luminescent lanthanide-based compounds used as potential probes of biomolecular substrates. PMID:19885510

  4. A unique combination of rare mitochondrial ribosomal RNA variants affects the kinetics of complex I assembly.

    PubMed

    Porcelli, Anna Maria; Calvaruso, Maria Antonietta; Iommarini, Luisa; Kurelac, Ivana; Zuntini, Roberta; Ferrari, Simona; Gasparre, Giuseppe

    2016-06-01

    Mitochondrial DNA (mtDNA) mutations in respiratory complexes subunits contribute to a large spectrum of human diseases. Nonetheless, ribosomal RNA variants remain largely under-investigated from a functional point of view. We here report a unique combination of two rare mitochondrial rRNA variants detected by serendipity in a subject with chronic granulomatous disease and never reported to co-occur within the same mitochondrial haplotype. In silico prediction of the mitochondrial ribosomal structure showed a dramatic rearrangement of the rRNA secondary structure. Functional investigation of cybrids carrying this unique haplotype demonstrated that the co-occurrence of the two rRNA variants determines a slow-down of the mitochondrial protein synthesis, especially in cells with an elevated metabolic rate, which impairs the assembly kinetics of Complex I, induces a bioenergetic defect and stimulates reactive oxygen species production. In conclusion, our results point to a sub-pathogenic role for these two rare mitochondrial rRNA variants, when found in the unique combination here reported in a single individual. PMID:27102412

  5. Yeast Mitochondrial Interactosome Model: Metabolon Membrane Proteins Complex Involved in the Channeling of ADP/ATP

    PubMed Central

    Clémençon, Benjamin

    2012-01-01

    The existence of a mitochondrial interactosome (MI) has been currently well established in mammalian cells but the exact composition of this super-complex is not precisely known, and its organization seems to be different from that in yeast. One major difference is the absence of mitochondrial creatine kinase (MtCK) in yeast, unlike that described in the organization model of MI, especially in cardiac, skeletal muscle and brain cells. The aim of this review is to provide a detailed description of different partner proteins involved in the synergistic ADP/ATP transport across the mitochondrial membranes in the yeast Saccharomyces cerevisiae and to propose a new mitochondrial interactosome model. The ADP/ATP (Aacp) and inorganic phosphate (PiC) carriers as well as the VDAC (or mitochondrial porin) catalyze the import and export of ADP, ATP and Pi across the mitochondrial membranes. Aacp and PiC, which appear to be associated with the ATP synthase, consist of two nanomotors (F0, F1) under specific conditions and form ATP synthasome. Identification and characterization of such a complex were described for the first time by Pedersen and co-workers in 2003. PMID:22408429

  6. Mature DIABLO/Smac Is Produced by the IMP Protease Complex on the Mitochondrial Inner Membrane

    PubMed Central

    Burri, Lena; Strahm, Yvan; Hawkins, Christine J.; Gentle, Ian E.; Puryer, Michelle A.; Verhagen, Anne; Callus, Bernard; Vaux, David; Lithgow, Trevor

    2005-01-01

    DIABLO/Smac is a mitochondrial protein that can promote apoptosis by promoting the release and activation of caspases. To do so, DIABLO/Smac must first be processed by a mitochondrial protease and then released into the cytosol, and we show this in an intact cellular system. We propose that the precursor form of DIABLO/Smac enters the mitochondria through a stop-transfer pathway and is processed to its active form by the inner membrane peptidase (IMP) complex. Catalytic subunits of the mammalian IMP complex were identified based on sequence conservation and functional complementation, and the novel sequence motif RX5P in Imp1 and NX5S in Imp2 distinguish the two catalytic subunits. DIABLO/Smac is one of only a few specific proteins identified as substrates for the IMP complex in the mitochondrial intermembrane space. PMID:15814844

  7. Protein complexes in bacterial and yeast mitochondrial membranes differ in their sensitivity towards dissociation by SDS.

    PubMed

    Gubbens, Jacob; Slijper, Monique; de Kruijff, Ben; de Kroon, Anton I P M

    2008-12-01

    Previously, a 2D gel electrophoresis approach was developed for the Escherichia coli inner membrane, which detects membrane protein complexes that are stable in sodium dodecyl sulfate (SDS) at room temperature, and dissociate under the influence of trifluoroethanol [R. E. Spelbrink et al., J. Biol. Chem. 280 (2005), 28742-8]. Here, the method was applied to the evolutionarily related mitochondrial inner membrane that was isolated from the yeast Saccharomyces cerevisiae. Surprisingly, only very few proteins were found to be dissociated by trifluoroethanol of which Lpd1p, a component of multiple protein complexes localized in the mitochondrial matrix, is the most prominent. Usage of either milder or more stringent conditions did not yield any additional proteins that were released by fluorinated alcohols. This strongly suggests that membrane protein complexes in yeast are less stable in SDS solution than their E. coli counterparts, which might be due to the overall reduced hydrophobicity of mitochondrial transmembrane proteins. PMID:18817900

  8. Reactions of a chromium(III)-superoxo complex and nitric oxide that lead to the formation of chromium(IV)-oxo and chromium(III)-nitrito complexes.

    PubMed

    Yokoyama, Atsutoshi; Cho, Kyung-Bin; Karlin, Kenneth D; Nam, Wonwoo

    2013-10-01

    The reaction of an end-on Cr(III)-superoxo complex bearing a 14-membered tetraazamacrocyclic TMC ligand, [Cr(III)(14-TMC)(O2)(Cl)](+), with nitric oxide (NO) resulted in the generation of a stable Cr(IV)-oxo species, [Cr(IV)(14-TMC)(O)(Cl)](+), via the formation of a Cr(III)-peroxynitrite intermediate and homolytic O-O bond cleavage of the peroxynitrite ligand. Evidence for the latter comes from electron paramagnetic resonance spectroscopy, computational chemistry and the observation of phenol nitration chemistry. The Cr(IV)-oxo complex does not react with nitrogen dioxide (NO2), but reacts with NO to afford a Cr(III)-nitrito complex, [Cr(III)(14-TMC)(NO2)(Cl)](+). The Cr(IV)-oxo and Cr(III)-nitrito complexes were also characterized spectroscopically and/or structurally. PMID:24066924

  9. Structural insight into the TRIAP1/PRELI-like domain family of mitochondrial phospholipid transfer complexes

    PubMed Central

    Miliara, Xeni; Garnett, James A; Tatsuta, Takashi; Abid Ali, Ferdos; Baldie, Heather; Pérez-Dorado, Inmaculada; Simpson, Peter; Yague, Ernesto; Langer, Thomas; Matthews, Stephen

    2015-01-01

    The composition of the mitochondrial membrane is important for its architecture and proper function. Mitochondria depend on a tightly regulated supply of phospholipid via intra-mitochondrial synthesis and by direct import from the endoplasmic reticulum. The Ups1/PRELI-like family together with its mitochondrial chaperones (TRIAP1/Mdm35) represent a unique heterodimeric lipid transfer system that is evolutionary conserved from yeast to man. Work presented here provides new atomic resolution insight into the function of a human member of this system. Crystal structures of free TRIAP1 and the TRIAP1–SLMO1 complex reveal how the PRELI domain is chaperoned during import into the intermembrane mitochondrial space. The structural resemblance of PRELI-like domain of SLMO1 with that of mammalian phoshatidylinositol transfer proteins (PITPs) suggest that they share similar lipid transfer mechanisms, in which access to a buried phospholipid-binding cavity is regulated by conformationally adaptable loops. PMID:26071602

  10. Structural insight into the TRIAP1/PRELI-like domain family of mitochondrial phospholipid transfer complexes.

    PubMed

    Miliara, Xeni; Garnett, James A; Tatsuta, Takashi; Abid Ali, Ferdos; Baldie, Heather; Pérez-Dorado, Inmaculada; Simpson, Peter; Yague, Ernesto; Langer, Thomas; Matthews, Stephen

    2015-07-01

    The composition of the mitochondrial membrane is important for its architecture and proper function. Mitochondria depend on a tightly regulated supply of phospholipid via intra-mitochondrial synthesis and by direct import from the endoplasmic reticulum. The Ups1/PRELI-like family together with its mitochondrial chaperones (TRIAP1/Mdm35) represent a unique heterodimeric lipid transfer system that is evolutionary conserved from yeast to man. Work presented here provides new atomic resolution insight into the function of a human member of this system. Crystal structures of free TRIAP1 and the TRIAP1-SLMO1 complex reveal how the PRELI domain is chaperoned during import into the intermembrane mitochondrial space. The structural resemblance of PRELI-like domain of SLMO1 with that of mammalian phoshatidylinositol transfer proteins (PITPs) suggest that they share similar lipid transfer mechanisms, in which access to a buried phospholipid-binding cavity is regulated by conformationally adaptable loops. PMID:26071602

  11. Sparkle/AM1 Parameters for the Modeling of Samarium(III) and Promethium(III) Complexes.

    PubMed

    Freire, Ricardo O; da Costa, Nivan B; Rocha, Gerd B; Simas, Alfredo M

    2006-01-01

    The Sparkle/AM1 model is extended to samarium(III) and promethium(III) complexes. A set of 15 structures of high crystallographic quality (R factor < 0.05 Å), with ligands chosen to be representative of all samarium complexes in the Cambridge Crystallographic Database 2004, CSD, with nitrogen or oxygen directly bonded to the samarium ion, was used as a training set. In the validation procedure, we used a set of 42 other complexes, also of high crystallographic quality. The results show that this parametrization for the Sm(III) ion is similar in accuracy to the previous parametrizations for Eu(III), Gd(III), and Tb(III). On the other hand, promethium is an artificial radioactive element with no stable isotope. So far, there are no promethium complex crystallographic structures in CSD. To circumvent this, we confirmed our previous result that RHF/STO-3G/ECP, with the MWB effective core potential (ECP), appears to be the most efficient ab initio model chemistry in terms of coordination polyhedron crystallographic geometry predictions from isolated lanthanide complex ion calculations. We thus generated a set of 15 RHF/STO-3G/ECP promethium complex structures with ligands chosen to be representative of complexes available in the CSD for all other trivalent lanthanide cations, with nitrogen or oxygen directly bonded to the lanthanide ion. For the 42 samarium(III) complexes and 15 promethium(III) complexes considered, the Sparkle/AM1 unsigned mean error, for all interatomic distances between the Ln(III) ion and the ligand atoms of the first sphere of coordination, is 0.07 and 0.06 Å, respectively, a level of accuracy comparable to present day ab initio/ECP geometries, while being hundreds of times faster. PMID:26626380

  12. Effect of mitochondrial complex I inhibition on Fe-S cluster protein activity

    SciTech Connect

    Mena, Natalia P.; Bulteau, Anne Laure; Salazar, Julio; Hirsch, Etienne C.; Nunez, Marco T.

    2011-06-03

    Highlights: {yields} Mitochondrial complex I inhibition resulted in decreased activity of Fe-S containing enzymes mitochondrial aconitase and cytoplasmic aconitase and xanthine oxidase. {yields} Complex I inhibition resulted in the loss of Fe-S clusters in cytoplasmic aconitase and of glutamine phosphoribosyl pyrophosphate amidotransferase. {yields} Consistent with loss of cytoplasmic aconitase activity, an increase in iron regulatory protein 1 activity was found. {yields} Complex I inhibition resulted in an increase in the labile cytoplasmic iron pool. -- Abstract: Iron-sulfur (Fe-S) clusters are small inorganic cofactors formed by tetrahedral coordination of iron atoms with sulfur groups. Present in numerous proteins, these clusters are involved in key biological processes such as electron transfer, metabolic and regulatory processes, DNA synthesis and repair and protein structure stabilization. Fe-S clusters are synthesized mainly in the mitochondrion, where they are directly incorporated into mitochondrial Fe-S cluster-containing proteins or exported for cytoplasmic and nuclear cluster-protein assembly. In this study, we tested the hypothesis that inhibition of mitochondrial complex I by rotenone decreases Fe-S cluster synthesis and cluster content and activity of Fe-S cluster-containing enzymes. Inhibition of complex I resulted in decreased activity of three Fe-S cluster-containing enzymes: mitochondrial and cytosolic aconitases and xanthine oxidase. In addition, the Fe-S cluster content of glutamine phosphoribosyl pyrophosphate amidotransferase and mitochondrial aconitase was dramatically decreased. The reduction in cytosolic aconitase activity was associated with an increase in iron regulatory protein (IRP) mRNA binding activity and with an increase in the cytoplasmic labile iron pool. Since IRP activity post-transcriptionally regulates the expression of iron import proteins, Fe-S cluster inhibition may result in a false iron deficiency signal. Given that

  13. Synthesis of supramolecular iron (III) complexes by cluster aggregation

    NASA Astrophysics Data System (ADS)

    Seddon, Elisa Joy

    2000-12-01

    Biologically, iron is a ubiquitous and versatile metal, found in the active sites of proteins responsible for both oxygen and electron transport. Multinuclear iron-oxo proteins are either dinuclear, or contain many iron atoms; the [Fe2O] unit occurs in hemerythrin (Hr), ribonucleotide reductase, purple acid phosphatase (POP) and methane monooxygenase (MMO), whereas ferritin (Ft) can store up to 4500 iron atoms. Iron storage and transport are essential for protecting biological organisms from free iron, since free Fe(II) ions, will react with dioxygen to form destructive organic radicals, and free Fe(III) ions form insoluble iron hydroxide aggregates under physiological conditions. The tendency of iron to form molecular aggregates in systems containing water or alcohol, together with the fact that each iron atom possesses a large number of unpaired electrons (5 for high-spin FeIII) often results in products possessing large spin ground states (S). The current record-holder for iron is a Fe19 complex, with at least 33 unpaired electrons in the ground state (S = 33/2). Hence, iron is also important in the rapidly developing field of molecular magnetic materials. For these two reasons, the preparation of iron clusters with new topologies and properties has become a major goal of many synthetic inorganic groups, including our own. In this thesis work, synthetic and spectroscopic methods of inorganic coordination chemistry were used to achieve two different goals: firstly, to synthesize dinuclear iron complexes with the use of tetradentate ligands in order to study the magnetic interactions between the two metal centers; and secondly, to identify reactions and characterize the products whereby pre-formed iron oxide clusters undergo aggregation reactions to produce higher nuclearity products. The tetradentate ligands investigated were a bis-(beta-diketone) ligand L and a bis-bpy ligand L'. The reactions involving L and Fe(III) reagents produced complexes with a triple

  14. Pyridinophane platform for stable lanthanide(III) complexation.

    PubMed

    Castro, Goretti; Bastida, Rufina; Macías, Alejandro; Pérez-Lourido, Paulo; Platas-Iglesias, Carlos; Valencia, Laura

    2013-05-20

    A detailed investigation of the solid state and solution structures of lanthanide(III) complexes with the macrocyclic ligand 2,11,20-triaza[3.3.3](2,6)pyridinophane (TPP) is reported. The solid state structures of 14 different Ln(3+) complexes have been determined using X-ray crystallography. The ligand is coordinating to the Ln(3+) ion by using its six nitrogen atoms, while nitrate or triflate anions and water molecules complete the metal coordination environments. The structure of the complexes in solution has been investigated by (1)H and (13)C NMR spectroscopy, as well as by DFT calculations (TPSSh model) performed in aqueous solution. The structures obtained from these calculations for the complexes with the lightest Ln(3+) ions (La-Sm) are in very good agreement with those determined by the analysis of the Ln(3+)-induced paramagnetic shifts. A structural change occurs across the lanthanide series at Sm(3+); the complexes of the large Ln(3+) ions (La-Nd) are chiral due to the nonplanar conformation of the macrocycle, and present effective C3v symmetries in solution as a consequence of a fast interconversion of two enantiomeric forms with C3 symmetry. The activation free energy for this enantiomerization process, as estimated by using DFT calculations, amounts to 33.0 kJ·mol(-1). The TPP ligand in the complexes of the heaviest Ln(3+) ions (Eu-Lu) presents a half-chair conformation, which results in C(s) symmetries in solution. PMID:23627284

  15. The Silver Complexes of Porphyrins, Corroles, and Carbaporphyrins: Silver in the Oxidation States II and III

    ERIC Educational Resources Information Center

    Bruckner, Christian

    2004-01-01

    Studies in relation to the silver complexes of porphyrins, corroles and carbaporphyrins are presented especially with relation to silver in the oxidation states II and III. It is seen that the Ag(sub III) complex was electrochemically readily and reversibly reduced to the corresponding Ag(sub II) complex, thus indicating that the complex could be…

  16. Heteronuclear Ir(III)-Ln(III) Luminescent Complexes: Small-Molecule Probes for Dual Modal Imaging and Oxygen Sensing.

    PubMed

    Jana, Atanu; Crowston, Bethany J; Shewring, Jonathan R; McKenzie, Luke K; Bryant, Helen E; Botchway, Stanley W; Ward, Andrew D; Amoroso, Angelo J; Baggaley, Elizabeth; Ward, Michael D

    2016-06-01

    Luminescent, mixed metal d-f complexes have the potential to be used for dual (magnetic resonance imaging (MRI) and luminescence) in vivo imaging. Here, we present dinuclear and trinuclear d-f complexes, comprising a rigid framework linking a luminescent Ir center to one (Ir·Ln) or two (Ir·Ln2) lanthanide metal centers (where Ln = Eu(III) and Gd(III), respectively). A range of physical, spectroscopic, and imaging-based properties including relaxivity arising from the Gd(III) units and the occurrence of Ir(III) → Eu(III) photoinduced energy-transfer are presented. The rigidity imposed by the ligand facilitates high relaxivities for the Gd(III) complexes, while the luminescence from the Ir(III) and Eu(III) centers provide luminescence imaging capabilities. Dinuclear (Ir·Ln) complexes performed best in cellular studies, exhibiting good solubility in aqueous solutions, low toxicity after 4 and 18 h, respectively, and punctate lysosomal staining. We also demonstrate the first example of oxygen sensing in fixed cells using the dyad Ir·Gd, via two-photon phosphorescence lifetime imaging (PLIM). PMID:27219675

  17. Injury and differentiation following inhibition of mitochondrial respiratory chain complex IV in rat oligodendrocytes

    PubMed Central

    Ziabreva, Iryna; Campbell, Graham; Rist, Julia; Zambonin, Jessica; Rorbach, Joanna; Wydro, Mateusz M; Lassmann, Hans; Franklin, Robin J M; Mahad, Don

    2010-01-01

    Oligodendrocyte lineage cells are susceptible to a variety of insults including hypoxia, excitotoxicity, and reactive oxygen species. Demyelination is a well-recognized feature of several CNS disorders including multiple sclerosis, white matter strokes, progressive multifocal leukoencephalopathy, and disorders due to mitochondrial DNA mutations. Although mitochondria have been implicated in the demise of oligodendrocyte lineage cells, the consequences of mitochondrial respiratory chain defects have not been examined. We determine the in vitro impact of established inhibitors of mitochondrial respiratory chain complex IV or cytochrome c oxidase on oligodendrocyte progenitor cells (OPCs) and mature oligodendrocytes as well as on differentiation capacity of OPCs from P0 rat. Injury to mature oligodendrocytes following complex IV inhibition was significantly greater than to OPCs, judged by cell detachment and mitochondrial membrane potential (MMP) changes, although viability of cells that remained attached was not compromised. Active mitochondria were abundant in processes of differentiated oligodendrocytes and MMP was significantly greater in differentiated oligodendrocytes than OPCs. MMP dissipated following complex IV inhibition in oligodendrocytes. Furthermore, complex IV inhibition impaired process formation within oligodendrocyte lineage cells. Injury to and impaired process formation of oligodendrocytes following complex IV inhibition has potentially important implications for the pathogenesis and repair of CNS myelin disorders. © 2010 Wiley-Liss, Inc. PMID:20665559

  18. Mono- and bis-tolylterpyridine iridium(III) complexes

    SciTech Connect

    Hinkle, Lindsay M.; Young, Jr., Victor G.; Mann, Kent R.

    2012-01-20

    The first structure report of trichlorido[4'-(p-tolyl)-2,2':6',2{double_prime}-terpyridine]iridium(III) dimethyl sulfoxide solvate, [IrCl{sub 3}(C{sub 22}H{sub 17}N{sub 3})] {center_dot} C{sub 2}H{sub 6}OS, (I), is presented, along with a higher-symmetry setting of previously reported bis[4'-(p-tolyl)-2,2':6',2{double_prime}-terpyridine]iridium(III) tris(hexafluoridophosphate) acetonitrile disolvate, [Ir(C{sub 22}H{sub 17}N{sub 3})2](PF{sub 6}){sub 3} {center_dot} 2C{sub 2}H{sub 3}N, (II) [Yoshikawa, Yamabe, Kanehisa, Kai, Takashima & Tsukahara (2007). Eur. J. Inorg. Chem. pp. 1911-1919]. For (I), the data were collected with synchrotron radiation and the dimethyl sulfoxide solvent molecule is disordered over three positions, one of which is an inversion center. The previously reported structure of (II) is presented in the more appropriate C2/c space group. The iridium complex and one PF{sub 6}{sup -} anion lie on twofold axes in this structure, making half of the molecule unique.

  19. Characterization of the structure and DNA complexity of mung bean mitochondrial nucleoids.

    PubMed

    Lo, Yih-Shan; Hsiao, Lin-June; Cheng, Ning; Litvinchuk, Alexandra; Dai, Hwa

    2011-03-01

    Electron microscopic images of mitochondrial nucleoids isolated from mung bean seedlings revealed a relatively homogeneous population of particles, each consisting of a chromatin-like structure associated with a membrane component. Association of F-actin with mitochondrial nucleoids was also observed. The mitochondrial nucleoid structure identified in situ showed heterogeneous genomic organization. After pulsed-field gel electrophoresis (PFGE), a large proportion of the mitochondrial nucleoid DNA remained in the well, whereas the rest migrated as a 50-200 kb smear zone. This PFGE migration pattern was not affected by high salt, topoisomerase I or latrunculin B treatments; however, the mobility of a fraction of the fast-moving DNA decreased conspicuously following an in-gel ethidium-enhanced UV-irradiation treatment, suggesting that molecules with intricately compact structures were present in the 50-200 kb region. Approximately 70% of the mitochondrial nucleoid DNA molecules examined via electron microscopy were open circles, supercoils, complex forms, and linear molecules with interspersed sigma-shaped structures and/or loops. Increased sensitivity of mtDNA to DNase I was found after mitochondrial nucleoids were pretreated with high salt. This result indicates that some loosely bound or peripheral DNA binding proteins protected the mtDNA from DNase I degradation. PMID:21347700

  20. Activation of Mitofusin2 by Smad2-RIN1 Complex during Mitochondrial Fusion.

    PubMed

    Kumar, Sanjay; Pan, Christopher C; Shah, Nirav; Wheeler, Sarah E; Hoyt, Kari R; Hempel, Nadine; Mythreye, Karthikeyan; Lee, Nam Y

    2016-05-19

    Smads are nuclear-shuttling transcriptional mediators of transforming growth factor-β (TGF-β) signaling. Although their essential nuclear roles in gene regulation during development and carcinogenesis are well established, whether they have important cytoplasmic functions remains unclear. Here we report that Smad2 is a critical determinant of mitochondrial dynamics. We identified mitofusin2 (MFN2) and Rab and Ras Interactor 1 (RIN1) as new Smad2 binding partners required for mitochondrial fusion. Unlike TGF-β-induced Smad2/3 transcriptional responses underlying mitochondrial fragmentation and apoptosis, inactive cytoplasmic Smad2 rapidly promotes mitochondrial fusion by recruiting RIN1 into a complex with MFN2. We demonstrate that Smad2 is a key scaffold, allowing RIN1 to act as a GTP exchange factor for MFN2-GTPase activation to promote mitochondrial ATP synthesis and suppress superoxide production. These results reveal functional implications between Smads and mitochondrial dysfunction in cancer and metabolic and neurodegenerative disorders. PMID:27184078

  1. Mitochondrial respiratory chain complex IV deficiency complicated with chronic intestinal pseudo-obstruction in a neonate.

    PubMed

    Hashimura, Yuya; Morioka, Ichiro; Hisamatsu, Chieko; Yokoyama, Naoki; Taniguchi-Ikeda, Mariko; Yokozaki, Hiroshi; Murayama, Kei; Ohtake, Akira; Itoh, Kyoko; Takeshima, Yasuhiro; Iijima, Kazumoto

    2016-07-01

    A female infant born at 36 weeks gestational age with birthweight 2135 g, and who developed respiratory disorder, hyperlactacidemia and hypertrophic cardiomyopathy after birth, was admitted to hospital at 3 days of age. After admission, bilious emesis, abdominal distention, and passage disorder of the gastrointestinal tract were resistant to various drugs. Exploratory laparotomy was performed at 93 days of age, but no organic lesions were identified and normal Meissner/Auerbach nerve plexus was confirmed, which led to a clinical diagnosis of chronic intestinal pseudo-obstruction (CIPO). She was diagnosed with mitochondrial respiratory chain complex IV deficiency on histopathology of the abdominal rectus muscle and enzyme activity measurement. This is the first report of a neonate with mitochondrial respiratory chain complex deficiency with intractable CIPO. CIPO can occur in neonates with mitochondrial respiratory chain disorder, necessitating differential diagnosis from Hirschsprung disease. PMID:27264907

  2. EMPTY PERICARP16 is required for mitochondrial nad2 intron 4 cis-splicing, complex I assembly and seed development in maize.

    PubMed

    Xiu, Zhihui; Sun, Feng; Shen, Yun; Zhang, Xiaoyan; Jiang, Ruicheng; Bonnard, Géraldine; Zhang, Jianhua; Tan, Bao-Cai

    2016-02-01

    In higher plants, chloroplast and mitochondrial transcripts contain a number of group II introns that need to be precisely spliced before translation into functional proteins. However, the mechanism of splicing and the factors involved in this process are not well understood. By analysing a seed mutant in maize, we report here the identification of Empty pericarp16 (Emp16) that is required for splicing of nad2 intron 4 in mitochondria. Disruption of Emp16 function causes developmental arrest in the embryo and endosperm, giving rise to an empty pericarp phenotype in maize. Differentiation of the basal endosperm transfer layer cells is severely affected. Molecular cloning indicates that Emp16 encodes a P-type pentatricopeptide repeat (PPR) protein with 11 PPR motifs and is localized in the mitochondrion. Transcript analysis revealed that mitochondrial nad2 intron 4 splicing is abolished in the emp16 mutants, leading to severely reduced assembly and activity of complex I. In response, the mutant dramatically increases the accumulation of mitochondrial complex III and the expression of alternative oxidase AOX2. These results imply that EMP16 is specifically required for mitochondrial nad2 intron 4 cis-splicing and is essential for complex I assembly and embryogenesis and development endosperm in maize. PMID:26764126

  3. Preparation and reactivity of macrocyclic rhodium(III) alkyl complexes

    SciTech Connect

    Carraher, Jack M.; Ellern, Arkady; Bakac, Andreja

    2013-09-21

    We found that the macrocyclic rhodium(II) complexes LRh(H2O)2+ (L = L1 = cyclam and L2 = meso-Me-6-cyclam) react with alkyl hydroperoxides RC(CH3)2OOH to generate the corresponding rhodium(III) alkyls L(H2O)RhR2+ (R = CH3, C2H5, PhCH2). Methyl and benzyl complexes can also be prepared by bimolecular group transfer from alkyl cobaloximes (dmgH)2(H2O) CoR and (dmgBF2)2(H2O) CoR (R = CH3, PhCH2) to LRh(H2O)2+. Moreover, the new complexes were characterized by solution NMR and by crystal structure analysis. They exhibit great stability in aqueous solution at room temperature, but undergo efficient Rh-C bond cleavage upon photolysis.

  4. Hydroxo sulfate complexes of iron (III) in solution.

    PubMed

    Ciavatta, Liberato; De Tommaso, Gaetano; Iuliano, Mauro

    2002-01-01

    The ternary Fe (III)-OH(-)-SO4(2-) complexes have been investigated at 25 degrees C in 3 M NaClO4 by potentiometric titration with glass electrode. The metal and sulfate concentrations ranged from 2.5 x 10(-3) to 0.03 M and from 5.10(-3) to 0.060 M, respectively. [H+] was decreased from 0.05 M to incipient precipitation of basic sulfate which occured at log[H+] between -2.3 and -2.5 depending on the concentration of the metal. For the interpretation of the data stability constants of HSO4(-), of binary hydroxo complexes (FeOH2+, Fe(OH)2+, Fe2(OH)2(4+), Fe3(OH)4(5+), Fe3(OH)5(4+)) and of sulfate complexes (FeSO4+, FeHSO4(2+), Fe(SO4)2-) were assumed from independent sources. The data are consistent with the presence of FeOHSO4, log beta 1-11 = -0.49 +/- 0.03. Equilibrium constants are defined as beta pqr for pFe3+ +qH+ +rSO4(2-) [symbol: see text] FepHq(SO4)r3p+q-2r. No substantial better fit could be found by adding a second mixed complex. Only a slightly smaller agreement factor resulted introducing as minor ternary complex Fe3(OH)6(SO4)3(3-) with log beta 3-63 = -5.8 +/- 0.5. Its evidence, however, cannot be considered conclusive. PMID:12185749

  5. MITOCHONDRIAL DISEASES PART III: THERAPEUTIC INTERVENTIONS IN MOUSE MODELS OF OXPHOS DEFICIENCIES

    PubMed Central

    Peralta, Susana; Torraco, Alessandra; Iommarini, Luisa; Diaz, Francisca

    2015-01-01

    Mitochondrial defects are the cause of numerous disorders affecting the oxidative phosphorylation system (OXPHOS) in humans leading predominantly to neurological and muscular degeneration. The molecular origin, manifestations, and progression of mitochondrial diseases have a broad spectrum, which makes very challenging to find a globally effective therapy. The study of the molecular mechanisms underlying the mitochondrial dysfunction indicates that there is a wide range of pathways, enzymes and molecules that could be potentially targeted for therapeutic purpose. Therefore, focusing on the pathology of the disease is essential to design new treatments. In this review, we will summarize and discuss the different therapeutic interventions tested in some mouse models of mitochondrial diseases laying emphasis on the molecular mechanisms of action and their potential applications. PMID:25638392

  6. Enigmatic Presence of Mitochondrial Complex I in Trypanosoma brucei Bloodstream Forms

    PubMed Central

    Surve, Sachin; Heestand, Meredith; Panicucci, Brian

    2012-01-01

    The presence of mitochondrial respiratory complex I in the pathogenic bloodstream stages of Trypanosoma brucei has been vigorously debated: increased expression of mitochondrially encoded functional complex I mRNAs is countered by low levels of enzymatic activity that show marginal inhibition by the specific inhibitor rotenone. We now show that epitope-tagged versions of multiple complex I subunits assemble into α and β subcomplexes in the bloodstream stage and that these subcomplexes require the mitochondrial genome for their assembly. Despite the presence of these large (740- and 855-kDa) multisubunit complexes, the electron transport activity of complex I is not essential under experimental conditions since null mutants of two core genes (NUBM and NUKM) showed no growth defect in vitro or in mouse infection. Furthermore, the null mutants showed no decrease in NADH:ubiquinone oxidoreductase activity, suggesting that the observed activity is not contributed by complex I. This work conclusively shows that despite the synthesis and assembly of subunit proteins, the enzymatic function of the largest respiratory complex is neither significant nor important in the bloodstream stage. This situation appears to be in striking contrast to that for the other respiratory complexes in this parasite, where physical presence in a life-cycle stage always indicates functional significance. PMID:22158713

  7. QIL1 is a novel mitochondrial protein required for MICOS complex stability and cristae morphology

    PubMed Central

    Guarani, Virginia; McNeill, Elizabeth M; Paulo, Joao A; Huttlin, Edward L; Fröhlich, Florian; Gygi, Steven P; Van Vactor, David; Harper, J Wade

    2015-01-01

    The mitochondrial contact site and cristae junction (CJ) organizing system (MICOS) dynamically regulate mitochondrial membrane architecture. Through systematic proteomic analysis of human MICOS, we identified QIL1 (C19orf70) as a novel conserved MICOS subunit. QIL1 depletion disrupted CJ structure in cultured human cells and in Drosophila muscle and neuronal cells in vivo. In human cells, mitochondrial disruption correlated with impaired respiration. Moreover, increased mitochondrial fragmentation was observed upon QIL1 depletion in flies. Using quantitative proteomics, we show that loss of QIL1 resulted in MICOS disassembly with the accumulation of a MIC60-MIC19-MIC25 sub-complex and degradation of MIC10, MIC26, and MIC27. Additionally, we demonstrated that in QIL1-depleted cells, overexpressed MIC10 fails to significantly restore its interaction with other MICOS subunits and SAMM50. Collectively, our work uncovers a previously unrecognized subunit of the MICOS complex, necessary for CJ integrity, cristae morphology, and mitochondrial function and provides a resource for further analysis of MICOS architecture. DOI: http://dx.doi.org/10.7554/eLife.06265.001 PMID:25997101

  8. Trichomonas hydrogenosomes contain the NADH dehydrogenase module of mitochondrial complex I.

    PubMed

    Hrdy, Ivan; Hirt, Robert P; Dolezal, Pavel; Bardonová, Lucie; Foster, Peter G; Tachezy, Jan; Embley, T Martin

    2004-12-01

    Hydrogenosomes are double-membraned ATP-producing and hydrogen-producing organelles of diverse anaerobic eukaryotes. In some versions of endosymbiotic theory they are suggested to be homologues of mitochondria, but alternative views suggest they arose from an anaerobic bacterium that was distinct from the mitochondrial endosymbiont. Here we show that the 51-kDa and 24-kDa subunits of the NADH dehydrogenase module in complex I, the first step in the mitochondrial respiratory chain, are active in hydrogenosomes of Trichomonas vaginalis. Like mitochondrial NADH dehydrogenase, the purified Trichomonas enzyme can reduce a variety of electron carriers including ubiquinone, but unlike the mitochondrial enzyme it can also reduce ferredoxin, the electron carrier used for hydrogen production. The presence of NADH dehydrogenase solves the long-standing conundrum of how hydrogenosomes regenerate NAD+ after malate oxidation. Phylogenetic analyses show that the Trichomonas 51-kDa homologue shares common ancestry with the mitochondrial enzyme. Recruitment of complex I subunits into a H2-producing pathway provides evidence that mitochondria and hydrogenosomes are aerobic and anaerobic homologues of the same endosymbiotically derived organelle. PMID:15577909

  9. Loss of the mitochondrial protein-only ribonuclease P complex causes aberrant tRNA processing and lethality in Drosophila.

    PubMed

    Sen, Aditya; Karasik, Agnes; Shanmuganathan, Aranganathan; Mirkovic, Elena; Koutmos, Markos; Cox, Rachel T

    2016-07-27

    Proteins encoded by mitochondrial DNA are translated using mitochondrially encoded tRNAs and rRNAs. As with nuclear encoded tRNAs, mitochondrial tRNAs must be processed to become fully functional. The mitochondrial form of ribonuclease P (mt:RNase P) is responsible for 5'-end maturation and is comprised of three proteins; mitochondrial RNase P protein (MRPP) 1 and 2 together with proteinaceous RNase P (PRORP). However, its mechanism and impact on development is not yet known. Using homology searches, we have identified the three proteins composing Drosophila mt:RNase P: Mulder (PRORP), Scully (MRPP2) and Roswell (MRPP1). Here, we show that each protein is essential and localizes with mitochondria. Furthermore, reducing levels of each causes mitochondrial deficits, which appear to be due at least in part to defective mitochondrial tRNA processing. Overexpressing two members of the complex, Mulder and Roswell, is also lethal, and in the case of Mulder, causes abnormal mitochondrial morphology. These data are the first evidence that defective mt:RNase P causes mitochondrial dysfunction, lethality and aberrant mitochondrial tRNA processing in vivo, underscoring its physiological importance. This in vivo mt:RNase P model will advance our understanding of how loss of mitochondrial tRNA processing causes tissue failure, an important aspect of human mitochondrial disease. PMID:27131785

  10. Folate Deficiency Triggered Apoptosis of Synoviocytes: Role of Overproduction of Reactive Oxygen Species Generated via NADPH Oxidase/Mitochondrial Complex II and Calcium Perturbation.

    PubMed

    Hsu, Hung-Chih; Chang, Wen-Ming; Wu, Jin-Yi; Huang, Chin-Chin; Lu, Fung-Jou; Chuang, Yi-Wen; Chang, Pey-Jium; Chen, Kai-Hua; Hong, Chang-Zern; Yeh, Rang-Hui; Liu, Tsan-Zon; Chen, Ching-Hsein

    2016-01-01

    Despite a plethora of literature has documented that osteoarthritis (OA) is veritably associated with oxidative stress-mediated chondrocyte death and matrix degradation, yet the possible involvement of synoviocyte abnormality as causative factor of OA has not been thoroughly investigated. For this reason, we conduct the current studies to insight into how synoviocytes could respond to an episode of folate-deprived (FD) condition. First, when HIG-82 synoviocytes were cultivated under FD condition, a time-dependent growth impediment was observed and the demise of these cells was demonstrated to be apoptotic in nature mediated through FD-evoked overproduction of reactive oxygen species (ROS) and drastically released of cytosolic calcium (Ca2+) concentrations. Next, we uncovered that FD-evoked ROS overproduction could only be strongly suppressed by either mitochondrial complex II inhibitors (TTFA and carboxin) or NADPH oxidase (NOX) inhibitors (AEBSF and apocynin), but not by mitochondrial complex I inhibitor (rotenone) and mitochondrial complex III inhibitor (antimycin A). Interestingly, this selective inhibition of FD-evoked ROS by mitochondrial complex II and NOX inhibitors was found to correlate excellently with the suppression of cytosolic Ca2+ release and reduced the magnitude of the apoptotic TUNEL-positive cells. Taken together, we present the first evidence here that FD-triggered ROS overproduction in synoviocytes is originated from mitochondrial complex II and NOX. Both elevated ROS in tandem with cytosolic Ca2+ overload serve as final arbitrators for apoptotic lethality of synoviocytes cultivated under FD condition. Thus, folate supplementation may be beneficial to patients with OA. PMID:26771387

  11. Folate Deficiency Triggered Apoptosis of Synoviocytes: Role of Overproduction of Reactive Oxygen Species Generated via NADPH Oxidase/Mitochondrial Complex II and Calcium Perturbation

    PubMed Central

    Wu, Jin-Yi; Huang, Chin-Chin; Lu, Fung-Jou; Chuang, Yi-Wen; Chang, Pey-Jium; Chen, Kai-Hua; Hong, Chang-Zern; Yeh, Rang-Hui; Liu, Tsan-Zon; Chen, Ching-Hsein

    2016-01-01

    Despite a plethora of literature has documented that osteoarthritis (OA) is veritably associated with oxidative stress-mediated chondrocyte death and matrix degradation, yet the possible involvement of synoviocyte abnormality as causative factor of OA has not been thoroughly investigated. For this reason, we conduct the current studies to insight into how synoviocytes could respond to an episode of folate-deprived (FD) condition. First, when HIG-82 synoviocytes were cultivated under FD condition, a time-dependent growth impediment was observed and the demise of these cells was demonstrated to be apoptotic in nature mediated through FD-evoked overproduction of reactive oxygen species (ROS) and drastically released of cytosolic calcium (Ca2+) concentrations. Next, we uncovered that FD-evoked ROS overproduction could only be strongly suppressed by either mitochondrial complex II inhibitors (TTFA and carboxin) or NADPH oxidase (NOX) inhibitors (AEBSF and apocynin), but not by mitochondrial complex I inhibitor (rotenone) and mitochondrial complex III inhibitor (antimycin A). Interestingly, this selective inhibition of FD-evoked ROS by mitochondrial complex II and NOX inhibitors was found to correlate excellently with the suppression of cytosolic Ca2+ release and reduced the magnitude of the apoptotic TUNEL-positive cells. Taken together, we present the first evidence here that FD-triggered ROS overproduction in synoviocytes is originated from mitochondrial complex II and NOX. Both elevated ROS in tandem with cytosolic Ca2+ overload serve as final arbitrators for apoptotic lethality of synoviocytes cultivated under FD condition. Thus, folate supplementation may be beneficial to patients with OA. PMID:26771387

  12. Mitochondrial gamma carbonic anhydrases are required for complex I assembly and plant reproductive development.

    PubMed

    Fromm, Steffanie; Braun, Hans-Peter; Peterhansel, Christoph

    2016-07-01

    Complex I of the mitochondrial electron transport chain (mETC) in plants contains an extra domain that is made up from proteins homologous to prokaryotic gamma-carbonic anhydrases (γCA). This domain has been suggested to participate in complex I assembly or to support transport of mitochondrial CO2 to the chloroplast. Here, we generated mutants lacking CA1 and CA2 - two out of three CA proteins in Arabidopsis thaliana. Double mutants were characterized at the developmental and physiological levels. Furthermore, the composition and activity of the mETC were determined, and mutated CA versions were used for complementation assays. Embryo development of double mutants was strongly delayed and seed development stopped before maturation. Mutant plants could only be rescued on sucrose media, showed severe stress symptoms and never produced viable seeds. By contrast, callus cultures were only slightly affected in growth. Complex I was undetectable in the double mutants, but complex II and complex IV were upregulated concomitant with increased oxygen consumption in mitochondrial respiration. Ectopic expression of inactive CA variants was sufficient to complement the mutant phenotype. Data indicate that CA proteins are structurally required for complex I assembly and that reproductive development is dependent on the presence of complex I. PMID:26889912

  13. Lipids of Sarcina lutea III. Composition of the Complex Lipids

    PubMed Central

    Huston, Charles K.; Albro, Phillip W.; Grindey, Gerald B.

    1965-01-01

    Huston, Charles K. (Fort Detrick, Frederick, Md.), Phillip W. Albro, and Gerald B. Grindey. Lipids of Sarcina lutea. III. Composition of the complex lipids. J. Bacteriol. 89:768–775. 1965.—The complex lipids from a strain of Sarcina lutea were isolated and separated into fractions on diethylaminoethyl cellulose acetate and silicic acid columns. These fractions were monitored in several thin-layer chromatography systems. The various lipid types were characterized by their behavior in thin-layer systems and by an analysis of their hydrolysis products. The fatty acid composition of the column fractions was determined by gas-liquid chromatography. A number of components (13) were separated by thin-layer chromatography and characterized. The major components were polyglycerol phosphatide (17.0%), lipoamino acids (15.1%), phosphatidyl glycerol (13.8%), and an incompletely characterized substance (15.0%). Minor constituents included phosphatidyl inositol (5.5%), phosphatidic acid (4.2%), phosphatidyl serine (2.0%), and phosphatidyl choline (1.0%). No phosphatidyl ethanolamine was observed. PMID:14273659

  14. Deficiency of the iron-sulfur clusters of mitochondrial reduced nicotinamide-adenine dinucleotide-ubiquinone oxidoreductase (complex I) in an infant with congenital lactic acidosis.

    PubMed

    Moreadith, R W; Batshaw, M L; Ohnishi, T; Kerr, D; Knox, B; Jackson, D; Hruban, R; Olson, J; Reynafarje, B; Lehninger, A L

    1984-09-01

    We report the case of an infant with hypoglycemia, progressive lactic acidosis, an increased serum lactate/pyruvate ratio, and elevated plasma alanine, who had a moderate to profound decrease in the ability of mitochondria from four organs to oxidize pyruvate, malate plus glutamate, citrate, and other NAD+-linked respiratory substrates. The capacity to oxidize the flavin adenine dinucleotide-linked substrate, succinate, was normal. The most pronounced deficiency was in skeletal muscle, the least in kidney mitochondria. Enzymatic assays on isolated mitochondria ruled out defects in complexes II, III, and IV of the respiratory chain. Further studies showed that the defect was localized in the inner membrane mitochondrial NADH-ubiquinone oxidoreductase (complex I). When ferricyanide was used as an artificial electron acceptor, complex I activity was normal, indicating that electrons from NADH could reduce the flavin mononucleotide cofactor. However, electron paramagnetic resonance spectroscopy performed on liver submitochondrial particles showed an almost total loss of the iron-sulfur clusters characteristic of complex I, whereas normal signals were noted for other mitochondrial iron-sulfur clusters. This infant is presented as the first reported case of congenital lactic acidosis caused by a deficiency of the iron-sulfur clusters of complex I of the mitochondrial electron transport chain. PMID:6432847

  15. Complexation of Nd(III) with tetraborate ion and its effect on actinide (III) solubility in WIPP brine

    SciTech Connect

    Borkowski, Marian; Richmann, Michael K; Reed, Donald T; Yongliang, Xiong

    2010-01-01

    The potential importance of tetraborate complexation on lanthanide(III) and actinide(III) solubility is recognized in the literature but a systematic study of f-element complexation has not been performed. In neodymium solubility studies in WIPP brines, the carbonate complexation effect is not observed since tetraborate ions form a moderately strong complex with neodymium(III). The existence of these tetraborate complexes was established for low and high ionic strength solutions. Changes in neodymium(III) concentrations in undersaturation experiments were used to determine the neodymium with tetraborate stability constants as a function of NaCl ionic strength. As very low Nd(III) concentrations have to be measured, it was necessary to use an extraction pre-concentration step combined with ICP-MS analysis to extend the detection limit by a factor of 50. The determined Nd(III) with borate stability constants at infinite dilution and 25 C are equal to log {beta}{sub 1} = 4.55 {+-} 0.06 using the SIT approach, equal to log {beta}{sub 1} = 4.99 {+-} 0.30 using the Pitzer approach, with an apparent log {beta}{sub 1} = 4.06 {+-} 0.15 (in molal units) at I = 5.6 m NaCl. Pitzer ion-interaction parameters for neodymium with tetraborate and SIT interaction coefficients were also determined and reported.

  16. Differential inhibition of mitochondrial respiratory complexes by inhalation of combustion smoke and carbon monoxide, in vivo, in the rat brain.

    PubMed

    Lee, Heung M; Hallberg, Lance M; Greeley, George H; Englander, Ella W

    2010-08-01

    Combustion smoke contains gases and particulates, which act via hypoxia and cytotoxicity producing mechanisms to injure cells and tissues. While carbon monoxide (CO) is the major toxicant in smoke, its toxicity is exacerbated in the presence of other compounds. Here, we examined modulations of mitochondrial and cytosolic energy metabolism by inhalation of combustion smoke versus CO, in vivo, in the rat brain. Measurements revealed reduced activities of respiratory chain (RC) complexes, with greater inhibition by smoke than equivalent CO in ambient air. In the case of RC complex IV, inhibition by CO and smoke was similar--suggesting that complex IV inhibition is primarily by the action of CO. In contrast, inhibition of complexes I and III was greater by smoke. Increases in cytosolic lactate dehydrogenase and pyruvate kinase activities accompanied inhibition of RC complexes, likely reflecting compensatory increases in cytosolic energy production. Together, the data provide new insights into the mechanisms of smoke inhalation-induced perturbations of brain energetics, which impact neuronal function and contribute to the development of neuropathologies in survivors of exposures to CO and combustion smoke. PMID:20429857

  17. Iridium(III) Anthraquinone Complexes as Two-Photon Phosphorescence Probes for Mitochondria Imaging and Tracking under Hypoxia.

    PubMed

    Sun, Lingli; Chen, Yu; Kuang, Shi; Li, Guanying; Guan, Ruilin; Liu, Jiangping; Ji, Liangnian; Chao, Hui

    2016-06-20

    In the present study, four mitochondria-specific and two-photon phosphorescence iridium(III) complexes, Ir1-Ir4, were developed for mitochondria imaging in hypoxic tumor cells. The iridium(III) complex has two anthraquinone groups that are hypoxia-sensitive moieties. The phosphorescence of the iridium(III) complex was quenched by the functions of the intramolecular quinone unit, and it was restored through two-electron bioreduction under hypoxia. When the probes were reduced by reductase to hydroquinone derivative products under hypoxia, a significant enhancement in phosphorescence intensity was observed under one- (λ=405 nm) and two-photon (λ=720 nm) excitation, with a two-photon absorption cross section of 76-153 GM at λ=720 nm. More importantly, these probes possessed excellent specificity for mitochondria, which allowed imaging and tracking of the mitochondrial morphological changes in a hypoxic environment over a long period of time. Moreover, the probes can visualize hypoxic mitochondria in 3D multicellular spheroids and living zebrafish through two-photon phosphorescence imaging. PMID:27145442

  18. A Triangular Iron(III) Complex Potentially Relevant to Iron(III)-Binding Sites in Ferreascidin.

    PubMed

    Bill, E; Krebs, C; Winter, M; Gerdan, M; Trautwein, A X; Flörke, U; Haupt, H J; Chaudhuri, P

    1997-02-01

    An asymmetric triangular Fe(III) complex has been synthesized by an unusual Fe(II) -promoted activation of salicylaldoxime. Formation of the ligand 2-(bis(salicylideneamino)methyl)phenol in situ is believed to occur through the reductive deoximation of salicylaldoxime by ferrous ions. The trinuclear ferric complex has been characterized on the basis of elemental analysis, IR, variable-temperature magnetic susceptibility, and EPR and Mössbauer spectroscopies. The molecular structure established by X-ray diffraction consists of a trinuclear structure with a [Fe3 (μ3 -O)(μ2 -OPh)](6+) core. Two iron ions are in a distorted octahedral environment having FeN2 O4 coordination spheres, and the five-coordinated third iron ion, with an FeNO4 coordination sphere, is in a trigonal bipyramidal environment. The magnetic susceptibility measurements revealed an St = 5/2 ground state with the antiparallel exchange interactions J = - 34.3 cm(-1) , J' = - 4.7 cm(-1) , and D = - 0.90 cm(-1) . The EPR results are consistent with a ground state of S = 5/2 together with a negative D5/2 value. The Mössbauer isomer shifts together with the quadrupole splitting also provide evidence for the high-spin state of the three ferric sites. Magnetic Mössbauer spectra lead to the conclusion that the internal magnetic fields possibly lie in the plane of the three ferric ions. PMID:24022947

  19. Eukaryotic LYR Proteins Interact with Mitochondrial Protein Complexes.

    PubMed

    Angerer, Heike

    2015-01-01

    In eukaryotic cells, mitochondria host ancient essential bioenergetic and biosynthetic pathways. LYR (leucine/tyrosine/arginine) motif proteins (LYRMs) of the Complex1_LYR-like superfamily interact with protein complexes of bacterial origin. Many LYR proteins function as extra subunits (LYRM3 and LYRM6) or novel assembly factors (LYRM7, LYRM8, ACN9 and FMC1) of the oxidative phosphorylation (OXPHOS) core complexes. Structural insights into complex I accessory subunits LYRM6 and LYRM3 have been provided by analyses of EM and X-ray structures of complex I from bovine and the yeast Yarrowia lipolytica, respectively. Combined structural and biochemical studies revealed that LYRM6 resides at the matrix arm close to the ubiquinone reduction site. For LYRM3, a position at the distal proton-pumping membrane arm facing the matrix space is suggested. Both LYRMs are supposed to anchor an acyl-carrier protein (ACPM) independently to complex I. The function of this duplicated protein interaction of ACPM with respiratory complex I is still unknown. Analysis of protein-protein interaction screens, genetic analyses and predicted multi-domain LYRMs offer further clues on an interaction network and adaptor-like function of LYR proteins in mitochondria. PMID:25686363

  20. Inhibition of mitochondrial complex II affects dopamine metabolism and decreases its uptake into striatal synaptosomes.

    PubMed

    Cakała, Magdalena; Drabik, Jacek; Kaźmierczak, Anna; Kopczuk, Dorota; Adamczyk, Agata

    2006-01-01

    The mitochondrial toxin, 3-nitropropionic acid (3-NP), is a specific inhibitor of succinate dehydrogenase, complex II in the mitochondrial respiratory chain. The aim of our study was to determine the relationship between inhibition of mitochondrial complex II and dopamine (DA) metabolism and its transport into rat striatal synaptosomes after exposure to 3-NP. The study was carried out using spectrophotometric, radiochemical and HPLC methods. Our data showed that inhibition of succinate dehydrogenase by intraperitoneal (i.p.) injection of 3-NP (cumulated dose 100 mg/kg in 4 days) significantly affected DA metabolism, leading to the accumulation of its metabolites, 3,4-dihydroxylphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the rat striatum. These experimental conditions had no effect on free radical dependent lipid peroxidation in the brain. In vitro experiments revealed that DA and DOPAC significantly decrease lipid peroxidation in the brain homogenate. Moreover, 3-NP significantly inhibited [3H]DA uptake into striatal synaptosomes by specific dopamine transporter (DAT). The scavengers of superoxide radical (O2-) Tempol and Trolox had no effect on DAT function, but the nitric oxide synthase (NOS) inhibitor N w-nitro-L-arginine (100 microM) prevented 3-NP-evoked DAT down-regulation. In summary, our results indicate that inhibition of mitochondrial complex II by 3-NP enhances DA degradation and decreases its uptake into synaptosomes. It is suggested that NO and energy failure are responsible for alteration of the dopaminergic system in the striatum. PMID:17183449

  1. The mitochondrial receptor complex: Mom22 is essential for cell viability and directly interacts with preproteins.

    PubMed Central

    Hönlinger, A; Kübrich, M; Moczko, M; Gärtner, F; Mallet, L; Bussereau, F; Eckerskorn, C; Lottspeich, F; Dietmeier, K; Jacquet, M

    1995-01-01

    A multisubunit complex in the mitochondrial outer membrane is responsible for targeting and membrane translocation of nuclear-encoded preproteins. This receptor complex contains two import receptors, a general insertion pore and the protein Mom22. It was unknown if Mom22 directly interacts with preproteins, and two views existed about the possible functions of Mom22: a central role in transfer of preproteins from both receptors to the general insertion pore or a more limited function dependent on the presence of the receptor Mom19. For this report, we identified and cloned Saccharomyces cerevisiae MOM22 and investigated whether it plays a direct role in targeting of preproteins. A preprotein accumulated at the mitochondrial outer membrane was cross-linked to Mom22. The cross-linking depended on the import stage of the preprotein. Overexpression of Mom22 suppressed the respiratory defect of yeast cells lacking Mom19 and increased preprotein import into mom19 delta mitochondria, demonstrating that Mom22 can function independently of Mom19. Overexpression of Mom22 even suppressed the lethal phenotype of a double deletion of the two import receptors known so far (mom19 delta mom72 delta). Deletion of the MOM22 gene was lethal for yeast cells, identifying Mom22 as one of the few mitochondrial membrane proteins essential for fermentative growth. These results suggest that Mom22 plays an essential role in the mitochondrial receptor complex. It directly interacts with preproteins in transit and can perform receptor-like activities. PMID:7760834

  2. 1,2,4-Diazaphospholide complexes of lanthanum(iii), cerium(iii), neodymium(iii), praseodymium(iii), and samarium(iii): synthesis, X-ray structural characterization, and magnetic susceptibility studies.

    PubMed

    Zhao, Minggang; Wang, Lixia; Li, Pangpang; Ma, Jianping; Zheng, Wenjun

    2016-07-01

    A few heteroleptic, charge-separated heterobimetallic, and polymeric alkali metalate complexes of 1,2,4-diazaphospholide lanthanum(iii), cerium(iii), neodymium(iii), praseodymium(iii), and samarium(iii) were simply prepared via the metathesis reaction of MCl3 (THF)m (m = 1-2) and K[3,5-R2dp] ([3,5-R2dp](-) = 3,5-di-substituent-1,2,4-diazaphospholide; R = tBu, Ph) in a varied ratio (1 : 3, 1 : 4, and 1 : 5, respectively) at room temperature in tetrahydrofuran. All the complexes were fully characterized by (1)H, (13)C{(1)H}, (31)P{(1)H}, IR, and X-ray single crystal diffraction analysis despite their paramagnetism (excluding La(iii) complexes). The structures of the complexes were found to feature varied coordination modes. The magnetic properties of several compounds were studied by magnetic susceptibility, and the complexes presented the magnetic moments close to or lower than the theoretical values for the free ions in the trivalent oxidation states (Pr(3+), Nd(3+)). PMID:27326667

  3. The mitochondrial complex I of trypanosomatids--an overview of current knowledge.

    PubMed

    Duarte, Margarida; Tomás, Ana M

    2014-08-01

    The contribution of trypanosomatid mitochondrial complex I for energy transduction has long been debated. Herein, we summarize current knowledge on the composition and relevance of this enzyme. Bioinformatic and proteomic analyses allowed the identification of many conserved and trypanosomatid-specific subunits of NADH:ubiquinone oxidoreductase, revealing a multifunctional enzyme capable of performing bioenergetic activities and possibly, also of functioning in fatty acid metabolism. A multimeric structure organized in 5 domains of more than 2 MDa is predicted, in contrast to the 1 MDa described for mammalian complex I. The relevance of mitochondrial complex I within the Trypanosomatidae family is quite diverse with its NADH oxidation activity being dispensable for both procyclic and bloodstream Trypanosoma brucei, whereas in Phytomonas serpens the enzyme is the only respiratory complex able to sustain membrane potential. Aside from complex I, trypanosomatid mitochondria contain a type II NADH dehydrogenase and a NADH-dependent fumarate reductase as alternative electron entry points into the respiratory chain and thus, some trypanosomatids may have bypassed the need for complex I. The involvement of each of these enzymes in the maintenance of the mitochondrial redox balance in trypanosomatids is still an open question and requires further investigation. PMID:24961227

  4. How does the TOM complex mediate insertion of precursor proteins into the mitochondrial outer membrane?

    PubMed Central

    Rapaport, Doron

    2005-01-01

    A multisubunit translocase of the outer mitochondrial membrane (TOM complex) mediates both the import of mitochondrial precursor proteins into the internal compartments of the organelle and the insertion of proteins residing in the mitochondrial outer membrane. The proposed β-barrel structure of Tom40, the pore-forming component of the translocase, raises the question of how the apparent uninterrupted β-barrel topology can be compatible with a role of Tom40 in releasing membrane proteins into the lipid core of the bilayer. In this review, I discuss insertion mechanisms of proteins into the outer membrane and present alternative models based on the opening of a multisubunit β-barrel TOM structure or on the interaction of outer membrane precursors with the outer face of the Tom40 β-barrel structure. PMID:16260501

  5. Synthesis, characterization, molecular docking and DNA binding studies of Al(III), Ga(III) and In(III) water-soluble complexes

    NASA Astrophysics Data System (ADS)

    Shorkaei, Mohammad Ranjkesh; Asadi, Zahra; Asadi, Mozaffar

    2016-04-01

    In this work three new water-soluble aluminum(III), gallium(III) and indium(III) Schiff base complexes; Na2[M(L)NO3]; where L denotes; N,N'-bis(5-sulfosalicyliden)-1,2-phenylendiamin (salsophen) were synthesized and characterized by UV-vis, 1HNMR, FT-IR spectroscopy, thermal gravimetry (TG) and elemental analysis. To study the biological preference with the molecular target DNA, interaction of these complexes with DNA have been explored by employing various biophysical methods including absorption spectra, fluorescence spectra, cyclic voltammetry and viscosity measurement. The Kb values at 298 K were found to be 1.17 × 104 for Al(III), 1.35 × 104 for Ga(III) and 1.64 × 104 M-1 for In(III) complexes, respectively. These results suggesting the greater binding propensity of In(III) complexes. Additionally molecular docking was carried out to ascertain the mode of action towards the molecular target DNA.

  6. Complex mitochondrial DNA rearrangements in individual cells from patients with sporadic inclusion body myositis.

    PubMed

    Rygiel, Karolina A; Tuppen, Helen A; Grady, John P; Vincent, Amy; Blakely, Emma L; Reeve, Amy K; Taylor, Robert W; Picard, Martin; Miller, James; Turnbull, Doug M

    2016-06-20

    Mitochondrial DNA (mtDNA) rearrangements are an important cause of mitochondrial disease and age related mitochondrial dysfunction in tissues including brain and skeletal muscle. It is known that different mtDNA deletions accumulate in single cells, but the detailed nature of these rearrangements is still unknown. To evaluate this we used a complementary set of sensitive assays to explore the mtDNA rearrangements in individual cells from patients with sporadic inclusion body myositis, a late-onset inflammatory myopathy with prominent mitochondrial changes. We identified large-scale mtDNA deletions in individual muscle fibres with 20% of cytochrome c oxidase-deficient myofibres accumulating two or more mtDNA deletions. The majority of deletions removed only the major arc but ∼10% of all deletions extended into the minor arc removing the origin of light strand replication (OL) and a variable number of genes. Some mtDNA molecules contained two deletion sites. Additionally, we found evidence of mitochondrial genome duplications allowing replication and clonal expansion of these complex rearranged molecules. The extended spectrum of mtDNA rearrangements in single cells provides insight into the process of clonal expansion which is fundamental to our understanding of the role of mtDNA mutations in ageing and disease. PMID:27131788

  7. Complex mitochondrial DNA rearrangements in individual cells from patients with sporadic inclusion body myositis

    PubMed Central

    Rygiel, Karolina A.; Tuppen, Helen A.; Grady, John P.; Vincent, Amy; Blakely, Emma L.; Reeve, Amy K.; Taylor, Robert W.; Picard, Martin; Miller, James; Turnbull, Doug M.

    2016-01-01

    Mitochondrial DNA (mtDNA) rearrangements are an important cause of mitochondrial disease and age related mitochondrial dysfunction in tissues including brain and skeletal muscle. It is known that different mtDNA deletions accumulate in single cells, but the detailed nature of these rearrangements is still unknown. To evaluate this we used a complementary set of sensitive assays to explore the mtDNA rearrangements in individual cells from patients with sporadic inclusion body myositis, a late-onset inflammatory myopathy with prominent mitochondrial changes. We identified large-scale mtDNA deletions in individual muscle fibres with 20% of cytochrome c oxidase-deficient myofibres accumulating two or more mtDNA deletions. The majority of deletions removed only the major arc but ∼10% of all deletions extended into the minor arc removing the origin of light strand replication (OL) and a variable number of genes. Some mtDNA molecules contained two deletion sites. Additionally, we found evidence of mitochondrial genome duplications allowing replication and clonal expansion of these complex rearranged molecules. The extended spectrum of mtDNA rearrangements in single cells provides insight into the process of clonal expansion which is fundamental to our understanding of the role of mtDNA mutations in ageing and disease. PMID:27131788

  8. Highly luminescent charge-neutral europium(iii) and terbium(iii) complexes with tridentate nitrogen ligands.

    PubMed

    Senthil Kumar, Kuppusamy; Schäfer, Bernhard; Lebedkin, Sergei; Karmazin, Lydia; Kappes, Manfred M; Ruben, Mario

    2015-09-21

    We report on the synthesis of tridentate-nitrogen pyrazole-pyridine-tetrazole (L(1)H) and pyrazole-pyridine-triazole (L(2)H) ligands and their complexation with lanthanides (Ln = Gd(iii), Eu(iii) and Tb(iii)) resulting in stable, charge-neutral complexes Ln(L(1))3 and Ln(L(2))3, respectively. X-ray crystallographic analysis of the complexes with L(1) ligands revealed tricapped trigonal coordination geometry around the lanthanide ions. All complexes show bright photoluminescence (PL) in the solid state, indicating efficient sensitization of the lanthanide emission via the triplet states of the ligands. In particular, the terbium complexes show high PL quantum yields of 65 and 59% for L(1) and L(2), respectively. Lower PL efficiencies of the europium complexes (7.5 and 9%, respectively) are attributed to large energy gaps between the triplet states of the ligands and accepting levels of Eu(iii). The triplet state energy can be reduced by introducing an electron withdrawing (EW) group at the 4 position of the pyridine ring. Such substitution of L(1)H with a carboxylic ester (COOMe) EW group leads to a europium complex with increased PL quantum yield of 31%. A comparatively efficient PL of the complexes dissolved in ethanol indicates that the lanthanide ions are shielded against nonradiative deactivation via solvent molecules. PMID:26245980

  9. Activation of Mitochondrial Complex II-Dependent Respiration Is Beneficial for α-Synucleinopathies.

    PubMed

    Fröhlich, Christina; Zschiebsch, Katja; Gröger, Victoria; Paarmann, Kristin; Steffen, Johannes; Thurm, Christoph; Schropp, Eva-Maria; Brüning, Thomas; Gellerich, Frank; Radloff, Martin; Schwabe, Rainer; Lachmann, Ingolf; Krohn, Markus; Ibrahim, Saleh; Pahnke, Jens

    2016-09-01

    Parkinson's disease and dementia with Lewy bodies are major challenges in research and clinical medicine world-wide and contribute to the most common neurodegenerative disorders. Previously, specific mitochondrial polymorphisms have been found to enhance clearance of amyloid-β from the brain of APP-transgenic mice leading to beneficial clinical outcome. It has been discussed whether specific mitochondrial alterations contribute to disease progression or even prevent toxic peptide deposition, as seen in many neurodegenerative diseases. Here, we investigated α-synuclein-transgenic C57BL/6J mice with the A30P mutation, and a novel A30P C57BL/6J mouse model with three mitochondrial DNA polymorphisms in the ND3, COX3 and mtRNA(Arg) genes, as found in the inbred NOD/LtJ mouse strain. We were able to detect that the new model has increased mitochondrial complex II-respiration which occurs in parallel to neuronal loss and improved motor performance, although it exhibits higher amounts of high molecular weight species of α-synuclein. High molecular weight aggregates of different peptides are controversially discussed in the light of neurodegeneration. A favourable hypothesis states that high molecular weight species are protective and of minor importance for the pathogenesis of neurodegenerative disorders as compared to the extreme neurotoxic monomers and oligomers. Summarising, our results point to a potentially protective and beneficial effect of specific mitochondrial polymorphisms which cause improved mitochondrial complex II-respiration in α-synucleinopathies, an effect that could be exploited further for pharmaceutical interventions. PMID:26319560

  10. Complexation of trivalent cations (Al(III), Cr(III), Fe(III)) with two phosphonic acids in the pH range of fresh waters.

    PubMed

    Lacour, S; Deluchat, V; Bollinger, J C; Bernard Serpaud

    1998-08-01

    The complex formation constants of two phosphonic acids, HEDP and ATMP, with three trivalent metallic cations, Al(III), Cr(III) and Fe(III), have been determined by acid-base titration at 25 degrees C and constant ionic strength (0.1 mol l(-1), KNO(3)), using Martell and Motekaitis' computer programs. Species distribution curves showed that all three cations are in complex form in the pH range of fresh waters (5-9). The study of different cation/ligand ratios proved that both ligands mainly form anionic soluble complexes for systems having an excess of ligand-as protonated and unprotonated forms and especially ternary complexes with HEDP. For higher metal concentrations (excess of cation), weakly soluble species of HEDP and ATMP were formed with Al(III) and Cr(III). Two insoluble complexes with ATMP have been identified by SEM/EDAX as AlH(3)X((s)) and Cr(2)X((s)). Regarding Fe(III) species, Fe(OH)(3(s)) precipitate seems to predominate in solution. PMID:18967224

  11. Hypersensitivity to oxygen and shortened lifespan in a Drosophila mitochondrial complex II mutant.

    PubMed

    Walker, David W; Hájek, Petr; Muffat, Julien; Knoepfle, Dan; Cornelison, Stephanie; Attardi, Giuseppe; Benzer, Seymour

    2006-10-31

    Oxidative stress is implicated as a major cause of aging and age-related diseases, such as Parkinson's and Alzheimer's, as well as ischemia-reperfusion injury in stroke. The mitochondrial electron transport chain is the principal source of reactive oxygen species within cells. Despite considerable medical interest, the molecular mechanisms that regulate reactive oxygen species formation within the mitochondrion remain poorly understood. Here, we report the isolation and characterization of a Drosophila mutant with a defect in subunit b of succinate dehydrogenase (SDH; mitochondrial complex II). The sdhB mutant is hypersensitive to oxygen and displays hallmarks of a progeroid syndrome, including early-onset mortality and age-related behavioral decay. Pathological analysis of the flight muscle, which is amongst the most highly energetic tissues in the animal kingdom, reveals structural abnormalities in the mitochondria. Biochemical analysis shows that, in the mutant, there is a complex II-specific respiratory defect and impaired complex II-mediated electron transport, although the other respiratory complexes remain functionally intact. The complex II defect is associated with an increased level of mitochondrial hydrogen peroxide production, suggesting a possible mechanism for the observed sensitivity to elevated oxygen concentration and the decreased lifespan of the mutant fly. PMID:17056719

  12. New yellow-emitting phosphorescent cyclometalated iridium(III) complex

    NASA Astrophysics Data System (ADS)

    Ivanov, P.; Tomova, R.; Petrova, P.; Stanimirov, S.; Petkov, I.

    2012-12-01

    We have synthesized a new yellow iridium complex Iridium(III) bis[2-phenylbenzothiazolato-N,C2']-(1-phenylicosane-1,3-dionate) (bt)2Ir(bsm), based on the benzothiazole derivative. The synthesized molecule was identified by 1H NMR and elemental analysis. The UV-Visible absorption and photoluminescence (PL) spectra of (bt)Ir2(bsm) in CH2Cl2 solution were found at 273 nm and 559 nm, respectively. The complex was used as a dopant into a hole-transporting layer (HTL) in a multilayered organic light emitting device (OLED) structure: ITO/doped-HTL/EL/ETL/M. ITO was a transparent anode of In2O3:SnO2, M- a metallic Al cathode, HTL- 4,4'-bis(9H-carbazol-9-yl)biphenyl (CBP) incorporated in poly(N-vinylcarbazole) (PVK) matrix, EL- electroluminescent layer of bis(8-hydroxy-2-methylquinoline)-(4-phenylphenoxy)aluminum (BAlq) and ETL- electron-transporting layer of tris(8-hydroxyquinolinato)aluminum (Alq3). The electroluminescent (EL) spectra of OLEDs were basically the sum of the emissions of BAlq at 496 nm and the emission of (bt)2Ir(bsm) at 559 nm. With increasing (bt)2Ir(bsm) concentration, the relative electroluminescent intensity of greenish-blue emission (at 496 nm) decreased, while the yellow (at 559 nm) - increased and CIE coordinates of the device shifted from (0.21, 0.33) at 0 wt % to (0.40, 0.48) at 8 wt % of the dopant. It was found that OLED with 0.5 wt % (bt)2Ir(bsm) had the best performance and stable color chromaticity at various voltages.

  13. Sepsis-induced brain mitochondrial dysfunction is associated with altered mitochondrial Src and PTP1B levels.

    PubMed

    Lyu, Juanjuan; Zheng, Guilang; Chen, Zhijiang; Wang, Bin; Tao, Shaohua; Xiang, Dan; Xie, Meiyan; Huang, Jinda; Liu, Cui; Zeng, Qiyi

    2015-09-16

    Sepsis-induced brain dysfunction (SIBD) is often the first manifestation of sepsis, and its pathogenesis is associated with mitochondrial dysfunction. In this study, we investigated the roles of the tyrosine kinase Src and protein tyrosine phosphatase 1B (PTP1B) in brain mitochondrial dysfunction using a rat model of lipopolysaccharide (LPS)-induced sepsis. We found that there was a gradual and significant increase of PTP1B levels in the rat brain after sepsis induction. In contrast, brain Src levels were reduced in parallel with the PTP1B increase. Sepsis led to significantly reduced tyrosine phosphorylation of mitochondrial oxidative phosphorylation (OXPHOS) complexes I, II and III. Pretreatment of mitochondrial proteins with active PTP1B significantly inhibited complexes I and III activities in vitro, whereas Src enhanced complexes I, II, and III activities. PTP1B and Src were each co-immunoprecipitated with OXPHOS complexes I and III, suggesting direct interactions between both proteins and complexes I and III. Src also directly interacted with complex II. Furthermore, pretreatment of mitochondrial proteins with active PTP1B resulted in overproduction of reactive oxygen species and decreased mitochondrial membrane potential. Pretreatment with active Src produced the opposite effect. These results suggest that brain mitochondrial dysfunction following LPS-induced sepsis in rats is partly attributed to PTP1B and Src mediated decrease in mitochondrial protein tyrosine phosphorylation. PMID:25998537

  14. Contribution of dopamine to mitochondrial complex I inhibition and dopaminergic deficits caused by methylenedioxymethamphetamine in mice.

    PubMed

    Barros-Miñones, L; Goñi-Allo, B; Suquia, V; Beitia, G; Aguirre, N; Puerta, E

    2015-06-01

    Methylenedioxymethamphetamine (MDMA) causes a persistent loss of dopaminergic cell bodies in the substantia nigra of mice. Current evidence indicates that MDMA-induced neurotoxicity is mediated by oxidative stress probably due to the inhibition of mitochondrial complex I activity. In this study we investigated the contribution of dopamine (DA) to such effects. For this, we modulated the dopaminergic system of mice at the synthesis, uptake or metabolism levels. Striatal mitochondrial complex I activity was decreased 1 h after MDMA; an effect not observed in the striatum of DA depleted mice or in the hippocampus, a dopamine spare region. The DA precursor, L-dopa, caused a significant reduction of mitochondrial complex I activity by itself and exacerbated the dopaminergic deficits when combined with systemic MDMA. By contrast, no damage was observed when L-dopa was combined with intrastriatal injections of MDMA. On the other hand, dopamine uptake blockade using GBR 12909, inhibited both, the acute inhibition of complex I activity and the long-term dopaminergic toxicity caused by MDMA. Moreover, the inhibition of DA metabolism with the monoamine oxidase (MAO) inhibitor, pargyline, afforded a significant protection against MDMA-induced complex I inhibition and neurotoxicity. Taken together, these findings point to the formation of hydrogen peroxide subsequent to DA metabolism by MAO, rather than a direct DA-mediated mitochondrial complex I inhibition, and the contribution of a peripheral metabolite of MDMA, as the key steps in the chain of biochemical events leading to DA neurotoxicity caused by MDMA in mice. PMID:25666033

  15. Differential susceptibility of mitochondrial complex II to inhibition by oxaloacetate in brain and heart.

    PubMed

    Stepanova, Anna; Shurubor, Yevgeniya; Valsecchi, Federica; Manfredi, Giovanni; Galkin, Alexander

    2016-09-01

    Mitochondrial Complex II is a key mitochondrial enzyme connecting the tricarboxylic acid (TCA) cycle and the electron transport chain. Studies of complex II are clinically important since new roles for this enzyme have recently emerged in cell signalling, cancer biology, immune response and neurodegeneration. Oxaloacetate (OAA) is an intermediate of the TCA cycle and at the same time is an inhibitor of complex II with high affinity (Kd~10(-8)M). Whether or not OAA inhibition of complex II is a physiologically relevant process is a significant, but still controversial topic. We found that complex II from mouse heart and brain tissue has similar affinity to OAA and that only a fraction of the enzyme in isolated mitochondrial membranes (30.2±6.0% and 56.4±5.6% in the heart and brain, respectively) is in the free, active form. Since OAA could bind to complex II during isolation, we established a novel approach to deplete OAA in the homogenates at the early stages of isolation. In heart, this treatment significantly increased the fraction of free enzyme, indicating that OAA binds to complex II during isolation. In brain the OAA-depleting system did not significantly change the amount of free enzyme, indicating that a large fraction of complex II is already in the OAA-bound inactive form. Furthermore, short-term ischemia resulted in a dramatic decline of OAA in tissues, but it did not change the amount of free complex II. Our data show that in brain OAA is an endogenous effector of complex II, potentially capable of modulating the activity of the enzyme. PMID:27287543

  16. Activation of Type I and III Interferon Response by Mitochondrial and Peroxisomal MAVS and Inhibition by Hepatitis C Virus.

    PubMed

    Bender, Silke; Reuter, Antje; Eberle, Florian; Einhorn, Evelyne; Binder, Marco; Bartenschlager, Ralf

    2015-11-01

    Sensing viruses by pattern recognition receptors (PRR) triggers the innate immune system of the host cell and activates immune signaling cascades such as the RIG-I/IRF3 pathway. Mitochondrial antiviral-signaling protein (MAVS, also known as IPS-1, Cardif, and VISA) is the crucial adaptor protein of this pathway localized on mitochondria, peroxisomes and mitochondria-associated membranes of the endoplasmic reticulum. Activation of MAVS leads to the production of type I and type III interferons (IFN) as well as IFN stimulated genes (ISGs). To refine the role of MAVS subcellular localization for the induction of type I and III IFN responses in hepatocytes and its counteraction by the hepatitis C virus (HCV), we generated various functional and genetic knock-out cell systems that were reconstituted to express mitochondrial (mito) or peroxisomal (pex) MAVS, exclusively. Upon infection with diverse RNA viruses we found that cells exclusively expressing pexMAVS mounted sustained expression of type I and III IFNs to levels comparable to cells exclusively expressing mitoMAVS. To determine whether viral counteraction of MAVS is affected by its subcellular localization we employed infection of cells with HCV, a major causative agent of chronic liver disease with a high propensity to establish persistence. This virus efficiently cleaves MAVS via a viral protease residing in its nonstructural protein 3 (NS3) and this strategy is thought to contribute to the high persistence of this virus. We found that both mito- and pexMAVS were efficiently cleaved by NS3 and this cleavage was required to suppress activation of the IFN response. Taken together, our findings indicate comparable activation of the IFN response by pex- and mitoMAVS in hepatocytes and efficient counteraction of both MAVS species by the HCV NS3 protease. PMID:26588843

  17. Activation of Type I and III Interferon Response by Mitochondrial and Peroxisomal MAVS and Inhibition by Hepatitis C Virus

    PubMed Central

    Bender, Silke; Reuter, Antje; Eberle, Florian; Einhorn, Evelyne; Binder, Marco; Bartenschlager, Ralf

    2015-01-01

    Sensing viruses by pattern recognition receptors (PRR) triggers the innate immune system of the host cell and activates immune signaling cascades such as the RIG-I/IRF3 pathway. Mitochondrial antiviral-signaling protein (MAVS, also known as IPS-1, Cardif, and VISA) is the crucial adaptor protein of this pathway localized on mitochondria, peroxisomes and mitochondria-associated membranes of the endoplasmic reticulum. Activation of MAVS leads to the production of type I and type III interferons (IFN) as well as IFN stimulated genes (ISGs). To refine the role of MAVS subcellular localization for the induction of type I and III IFN responses in hepatocytes and its counteraction by the hepatitis C virus (HCV), we generated various functional and genetic knock-out cell systems that were reconstituted to express mitochondrial (mito) or peroxisomal (pex) MAVS, exclusively. Upon infection with diverse RNA viruses we found that cells exclusively expressing pexMAVS mounted sustained expression of type I and III IFNs to levels comparable to cells exclusively expressing mitoMAVS. To determine whether viral counteraction of MAVS is affected by its subcellular localization we employed infection of cells with HCV, a major causative agent of chronic liver disease with a high propensity to establish persistence. This virus efficiently cleaves MAVS via a viral protease residing in its nonstructural protein 3 (NS3) and this strategy is thought to contribute to the high persistence of this virus. We found that both mito- and pexMAVS were efficiently cleaved by NS3 and this cleavage was required to suppress activation of the IFN response. Taken together, our findings indicate comparable activation of the IFN response by pex- and mitoMAVS in hepatocytes and efficient counteraction of both MAVS species by the HCV NS3 protease. PMID:26588843

  18. Characterisation of the active/de-active transition of mitochondrial complex I☆

    PubMed Central

    Babot, Marion; Birch, Amanda; Labarbuta, Paola; Galkin, Alexander

    2014-01-01

    Oxidation of NADH in the mitochondrial matrix of aerobic cells is catalysed by mitochondrial complex I. The regulation of this mitochondrial enzyme is not completely understood. An interesting characteristic of complex I from some organisms is the ability to adopt two distinct states: the so-called catalytically active (A) and the de-active, dormant state (D). The A-form in situ can undergo de-activation when the activity of the respiratory chain is limited (i.e. in the absence of oxygen). The mechanisms and driving force behind the A/D transition of the enzyme are currently unknown, but several subunits are most likely involved in the conformational rearrangements: the accessory subunit 39 kDa (NDUFA9) and the mitochondrially encoded subunits, ND3 and ND1. These three subunits are located in the region of the quinone binding site. The A/D transition could represent an intrinsic mechanism which provides a fast response of the mitochondrial respiratory chain to oxygen deprivation. The physiological role of the accumulation of the D-form in anoxia is most probably to protect mitochondria from ROS generation due to the rapid burst of respiration following reoxygenation. The de-activation rate varies in different tissues and can be modulated by the temperature, the presence of free fatty acids and divalent cations, the NAD+/NADH ratio in the matrix, the presence of nitric oxide and oxygen availability. Cysteine-39 of the ND3 subunit, exposed in the D-form, is susceptible to covalent modification by nitrosothiols, ROS and RNS. The D-form in situ could react with natural effectors in mitochondria or with pharmacological agents. Therefore the modulation of the re-activation rate of complex I could be a way to ameliorate the ischaemia/reperfusion damage. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference. Guest Editors: Manuela Pereira and Miguel Teixeira. PMID:24569053

  19. Relationship between residual feed intake and lymphocyte mitochondrial complex protein concentration and ratio in crossbred steers.

    PubMed

    Davis, M P; Brooks, M A; Kerley, M S

    2016-04-01

    Rate of oxygen uptake by muscle mitochondria and respiratory chain protein concentrations differed between high- and low-residual feed intake (RFI) animals. The hypothesis of this research was that complex I (CI), II (CII), and III (CIII) mitochondria protein concentrations in lymphocyte (blood) mitochondria were related to the RFI phenotype of beef steers. Daily feed intake (ADFI) was individually recorded for 92 Hereford-crossbreed steers over 63 d using GrowSafe individual feed intake system. Predicted ADFI was calculated as the regression of ADFI on ADG and midtest BW. Difference between ADFI and predicted ADFI was RFI. Lymphocytes were isolated from low-RFI (-1.32 ± 0.11 kg/d; = 10) and high-RFI (1.34 ± 0.18 kg/d; = 8) steers. Immunocapture of CI, CII, and CIII proteins from the lymphocyte was done using MitoProfile CI, CII, and CIII immunocapture kits (MitoSciences Inc., Eugene, OR). Protein concentrations of CI, CII, and CIII and total protein were quantified using bicinchoninic acid colorimetric procedures. Low-RFI steers consumed 30% less ( = 0.0004) feed and had a 40% improvement ( < 0.0001) in feed efficiency compared with high-RFI steers with similar growth ( = 0.78) and weight measurements ( > 0.65). High- and low-RFI steers did not differ in CI ( = 0.22), CII ( = 0.69), and CIII ( = 0.59) protein concentrations. The protein concentration ratios for CI to CII ( = 0.03) were 20% higher and the ratios of CI to CIII ( = 0.01) were 30% higher, but the ratios of CII to CIII ( = 0.89) did not differ when comparing low-RFI steers with high-RFI steers. The similar magnitude difference in feed intake, feed efficiency measurements, and CI-to-CIII ratio between RFI phenotypes provides a plausible explanation for differences between the phenotypes. We also concluded that mitochondria isolated from lymphocytes could be used to study respiratory chain differences among differing RFI phenotypes. Further research is needed to determine if lymphocyte mitochondrial

  20. Disrupting mitochondrial-nuclear coevolution affects OXPHOS complex I integrity and impacts human health.

    PubMed

    Gershoni, Moran; Levin, Liron; Ovadia, Ofer; Toiw, Yasmin; Shani, Naama; Dadon, Sara; Barzilai, Nir; Bergman, Aviv; Atzmon, Gil; Wainstein, Julio; Tsur, Anat; Nijtmans, Leo; Glaser, Benjamin; Mishmar, Dan

    2014-10-01

    The mutation rate of the mitochondrial DNA (mtDNA), which is higher by an order of magnitude as compared with the nuclear genome, enforces tight mitonuclear coevolution to maintain mitochondrial activities. Interruption of such coevolution plays a role in interpopulation hybrid breakdown, speciation events, and disease susceptibility. Previously, we found an elevated amino acid replacement rate and positive selection in the nuclear DNA-encoded oxidative phosphorylation (OXPHOS) complex I subunit NDUFC2, a phenomenon important for the direct interaction of NDUFC2 with the mtDNA-encoded complex I subunit ND4. This finding underlines the importance of mitonuclear coevolution to physical interactions between mtDNA and nuclear DNA-encoded factors. Nevertheless, it remains unclear whether this interaction is important for the stability and activity of complex I. Here, we show that siRNA silencing of NDUFC2 reduced growth of human D-407 retinal pigment epithelial cells, significantly diminished mitochondrial membrane potential, and interfered with complex I integrity. Moreover, site-directed mutagenesis of a positively selected amino acid in NDUFC2 significantly interfered with the interaction of NDUFC2 with its mtDNA-encoded partner ND4. Finally, we show that a genotype combination involving this amino acid (NDUFC2 residue 46) and the mtDNA haplogroup HV likely altered susceptibility to type 2 diabetes mellitus in Ashkenazi Jews. Therefore, mitonuclear coevolution is important for maintaining mitonuclear factor interactions, OXPHOS, and for human health. PMID:25245408

  1. Inhibitory Effects of Amorphigenin on the Mitochondrial Complex I of Culex pipiens pallens Coquillett (Diptera: Culicidae)

    PubMed Central

    Ji, Mingshan; Liang, Yaping; Gu, Zumin; Li, Xiuwei

    2015-01-01

    Previous studies in our laboratory found that the extract from seeds of Amorpha fruticosa in the Leguminosae family had lethal effects against mosquito larvae, and an insecticidal compound amorphigenin was isolated. In this study, the inhibitory effects of amorphigenin against the mitochondrial complex I of Culex pipiens pallens (Diptera: Culicidae) were investigated and compared with that of rotenone. The results showed that amorphigenin and rotenone can decrease the mitochondrial complex I activity both in vivo and in vitro as the in vivo IC50 values (the inhibitor concentrations leading to 50% of the enzyme activity lost) were determined to be 2.4329 and 2.5232 μmol/L, respectively, while the in vitro IC50 values were 2.8592 and 3.1375 μmol/L, respectively. Both amorphigenin and rotenone were shown to be reversible and mixed-I type inhibitors of the mitochondrial complex I of Cx. pipiens pallens, indicating that amorphigenin and rotenone inhibited the enzyme activity not only by binding with the free enzyme but also with the enzyme-substrate complex, and the values of KI and KIS for amorphigenin were determined to be 20.58 and 87.55 μM, respectively, while the values for rotenone were 14.04 and 69.23 μM, respectively. PMID:26307964

  2. Mitochondrial Complex 1 Inhibition Increases 4-Repeat Isoform Tau by SRSF2 Upregulation

    PubMed Central

    De Andrade, Anderson; Höglinger, Günter

    2014-01-01

    Progressive Supranuclear Palsy (PSP) is a neurodegenerative disorder characterised by intracellular aggregation of the microtubule-associated protein tau. The tau protein exists in 6 predominant isoforms. Depending on alternative splicing of exon 10, three of these isoforms have four microtubule-binding repeat domains (4R), whilst the others only have three (3R). In PSP there is an excess of the 4R tau isoforms, which are thought to contribute significantly to the pathological process. The cause of this 4R increase is so far unknown. Several lines of evidence link mitochondrial complex I inhibition to the pathogenesis of PSP. We demonstrate here for the first time that annonacin and MPP+, two prototypical mitochondrial complex I inhibitors, increase the 4R isoforms of tau in human neurons. We show that the splicing factor SRSF2 is necessary to increase 4R tau with complex I inhibition. We also found SRSF2, as well as another tau splicing factor, TRA2B, to be increased in brains of PSP patients. Thereby, we provide new evidence that mitochondrial complex I inhibition may contribute as an upstream event to the pathogenesis of PSP and suggest that splicing factors may represent an attractive therapeutic target to intervene in the disease process. PMID:25402454

  3. Thiocyanato Chromium (III) Complexes: Separation by Paper Electrophoresis and Estimate of Stability Constants

    ERIC Educational Resources Information Center

    Larsen, Erik; Eriksen, J.

    1975-01-01

    Describes an experiment wherein the student can demonstrate the existence of all the thiocyanato chromium complexes, estimate the stepwise formation constants, demonstrate the robustness of chromium III complexes, and show the principles of paper electrophoresis. (GS)

  4. Light induced catalytic intramolecular hydrofunctionalization of allylphenols mediated by porphyrin rhodium(iii) complexes.

    PubMed

    Liu, Xu; Wang, Zikuan; Fu, Xuefeng

    2016-09-14

    Catalytic intramolecular hydrofunctionalization of allylphenols to heterocyclic compounds mediated by rhodium(iii) porphyrin complexes was described. The Wacker-type intermediate β-heterocyclic alkyl rhodium complex was independently synthesized and crystallized. PMID:27482840

  5. 1,2,4-Diazaphospholide complexes of yttrium(iii), dysprosium(iii), erbium(iii), and europium(ii,iii): synthesis, X-ray structural characterization, and EPR analysis.

    PubMed

    Wang, Yongli; Guo, Wenzhen; Liu, Dongling; Yang, Ying; Zheng, Wenjun

    2016-01-21

    Several structurally characterized heteroleptic, charge-separated heterobimetallic, and polymeric alkali metal ate complexes of 1,2,4-diazaphospholide Y(iii), Dy(iii), Er(iii), Eu(iii), and Eu(ii) were prepared via the reaction of MCl3 and K[3,5-R2dp] in varied ratios at 200-220 °C (M = Y, Dy, Er, Eu; R = tBu, Ph). PMID:26666366

  6. Fluorescence enhancement of rare earth Tb(III) by Tm(III) in benzyl benzoylmethyl sulphoxide complexes.

    PubMed

    Li, Wen-Xian; Chai, Wen-Juan; Liu, Yu; Li, Ying-Jie; Ren, Tie; Zhang, Jing; Ao, Bo-Yang

    2012-01-01

    A series of rare earth complexes [(Tb(x) Tm(y))L5 (ClO4)2](ClO4)·3H(2) O (x:y = 1.000:0.000, 0.999:0.001, 0.995:0.005, 0.990:0.010, 0.950:0.050, 0.900:0.100, 0.800:0.200, 0.700:0.300; L = C(6) H5 CH2 SOCH2 COC6 H5) (Tb(III) luminescence ion; Tm(III) doped inert ion) were synthesized and characterized by elemental analysis, infrared spectra (IR) and (1) H-NMR. The photophysical properties of these complexes were studied in detail using ultraviolet absorption spectra, fluorescent spectra and lifetimes. The fluorescence spectra of complexes indicated that the fluorescence emission intensity was significantly enhanced by Tm(III). The complexes showed the best luminescence properties when the mole ratio Tb(III):Tm(III) was 0.990:0.010. The fluorescence intensity could be increased to 390%. Additionally, phosphorescence spectra and the luminescence mechanisms are discussed. PMID:22114050

  7. Changes of haematic parameters, redox status and mitochondrial complex activity in the heart and liver of broilers fed with different density diets under low ambient temperature.

    PubMed

    Peng, Y Z; Wang, Y W; Ning, D; Guo, Y M

    2013-08-01

    This experiment was conducted to investigate the influence of dietary nutrient density on haematic parameters, oxidative status and mitochondrial complex activity in the heart and liver of broilers under low ambient temperature. Eight-day-old male ROSS-308 chickens were randomly divided into two treatments fed with normal (control) and high metabolizable energy (ME) and crude protein density (H) diets. A high nutrient density diet increased body weight gain and reduced the feed conversation ratio during the first 3 weeks. Increased ascites-related mortality (weeks 4 to 6), right ventricle/total ventricle (week 6), blood haemoglobin (weeks 2 and 4) and mean corpuscular haemoglobin (week 2) were observed in treatment H. Levels of malonaldehyde and protein carbonylation were increased at week 4, and activities of glutathione peroxidase at week 4 and CuZn superoxide dismutase and catalase at week 6 were decreased in the heart; only malonaldehyde (week 6) was increased in the liver in treatment H. Relative mRNA expression of hypoxia inducible factor-1 (heart) was increased and heme oxygenase-1 (heart and liver) was decreased at week 4 in broilers fed with high ME and protein diet. Activities of mitochondrial complex III and IV (week 6) in the heart, and complex I (week 6) and complex III and IV (week 4) in the liver were decreased in treatment H. In conclusion, high levels of dietary ME and protein resulted in oxidative stress and high incidence of ascites in broilers under low ambient temperature. Heart dysfunction was primarily attributed to ascites development, in which oxidative injury and inhibition of mitochondrial complex activity were involved. PMID:23721102

  8. Luminescent and triboluminescent properties of europium(III) complex with cinnamic acid

    NASA Astrophysics Data System (ADS)

    Kalinovskaya, I. V.; Mirochnik, A. G.; Nagornyi, I. G.

    2014-10-01

    An intensely emitting crystalline europium(III) complex with cinnamic acid [Eu(Cin)3] n and exhibiting triboluminescent properties is synthesized. It is established that the measured photo- and triboluminescence spectra are identical for the above polymeric non-centrosymmetric complex and are determined by the characteristic f-f luminescence of the europium(III) ion.

  9. Reversible piezochromic behavior of two new cationic iridium(III) complexes.

    PubMed

    Shan, Guo-Gang; Li, Hai-Bin; Cao, Hong-Tao; Zhu, Dong-Xia; Li, Peng; Su, Zhong-Min; Liao, Yi

    2012-02-14

    We demonstrate that two new cationic Ir(III) complexes exhibit an interesting piezochromism, and their emission color can be smartly switched by grinding and heating. This is the first example that the Ir(III) complexes display piezochromic phosphorescence. PMID:22237981

  10. Phosphorescent Imaging of Living Cells Using a Cyclometalated Iridium(III) Complex

    PubMed Central

    Ma, Dik-Lung; Zhong, Hai-Jing; Fu, Wai-Chung; Chan, Daniel Shiu-Hin; Kwan, Hiu-Yee; Fong, Wang-Fun; Chung, Lai-Hon; Wong, Chun-Yuen; Leung, Chung-Hang

    2013-01-01

    A cell permeable cyclometalated iridium(III) complex has been developed as a phosphorescent probe for cell imaging. The iridium(III) solvato complex [Ir(phq)2(H2O]2)] preferentially stains the cytoplasm of both live and dead cells with a bright luminescence. PMID:23457478

  11. Inhibition of Mitochondrial Complex II by the Anticancer Agent Lonidamine.

    PubMed

    Guo, Lili; Shestov, Alexander A; Worth, Andrew J; Nath, Kavindra; Nelson, David S; Leeper, Dennis B; Glickson, Jerry D; Blair, Ian A

    2016-01-01

    The antitumor agent lonidamine (LND; 1-(2,4-dichlorobenzyl)-1H-indazole-3-carboxylic acid) is known to interfere with energy-yielding processes in cancer cells. However, the effect of LND on central energy metabolism has never been fully characterized. In this study, we report that a significant amount of succinate is accumulated in LND-treated cells. LND inhibits the formation of fumarate and malate and suppresses succinate-induced respiration of isolated mitochondria. Utilizing biochemical assays, we determined that LND inhibits the succinate-ubiquinone reductase activity of respiratory complex II without fully blocking succinate dehydrogenase activity. LND also induces cellular reactive oxygen species through complex II, which reduced the viability of the DB-1 melanoma cell line. The ability of LND to promote cell death was potentiated by its suppression of the pentose phosphate pathway, which resulted in inhibition of NADPH and glutathione generation. Using stable isotope tracers in combination with isotopologue analysis, we showed that LND increased glutaminolysis but decreased reductive carboxylation of glutamine-derived α-ketoglutarate. Our findings on the previously uncharacterized effects of LND may provide potential combinational therapeutic approaches for targeting cancer metabolism. PMID:26521302

  12. Inhibition of Mitochondrial Complex II by the Anticancer Agent Lonidamine*

    PubMed Central

    Guo, Lili; Shestov, Alexander A.; Worth, Andrew J.; Nath, Kavindra; Nelson, David S.; Leeper, Dennis B.; Glickson, Jerry D.; Blair, Ian A.

    2016-01-01

    The antitumor agent lonidamine (LND; 1-(2,4-dichlorobenzyl)-1H-indazole-3-carboxylic acid) is known to interfere with energy-yielding processes in cancer cells. However, the effect of LND on central energy metabolism has never been fully characterized. In this study, we report that a significant amount of succinate is accumulated in LND-treated cells. LND inhibits the formation of fumarate and malate and suppresses succinate-induced respiration of isolated mitochondria. Utilizing biochemical assays, we determined that LND inhibits the succinate-ubiquinone reductase activity of respiratory complex II without fully blocking succinate dehydrogenase activity. LND also induces cellular reactive oxygen species through complex II, which reduced the viability of the DB-1 melanoma cell line. The ability of LND to promote cell death was potentiated by its suppression of the pentose phosphate pathway, which resulted in inhibition of NADPH and glutathione generation. Using stable isotope tracers in combination with isotopologue analysis, we showed that LND increased glutaminolysis but decreased reductive carboxylation of glutamine-derived α-ketoglutarate. Our findings on the previously uncharacterized effects of LND may provide potential combinational therapeutic approaches for targeting cancer metabolism. PMID:26521302

  13. Assignment of the gene for the core protein II (UQCRC2) subunit of the mitochondrial cytochrome bc[sub 1] complex to human chromosome 16p12

    SciTech Connect

    Duncan, A.M.V. Kingston General Hospital ); Ozawa, Takayuki; Suzuki, Hiroshi ); Rozen, R. Montreal Children's Hospital )

    1993-11-01

    The mammalian cytochrome be[sub 1] complex (complex III) of the mitochondrial respiratory chain catalyzes electron transfer from ubiquinol to cytochrome c. The complex consists of 10-11 subunits: Core proteins I and II, cytochromes b and c[sub 1], the Rieske iron-sulfur protein, the ubiquinone-binding protein, the hinge protein, and 3-4 subunits of low molecular weight. Cytochrome b is encoded by the mitochondrial genome; the other subunits are encoded by nuclear genes. Both the human cytochrome c[sub 1] and the human ubiquinone-binding protein subunits have been assigned to chromosome 8 by somatic cell hybrid mapping. In this study, the authors used in situ hybridization to map core protein II. In situ hybridization to BrdU-synchronized peripheral blood lymphocytes was performed using the method of Harper and Saunders. Chromosomes were stained with a modified fluorescence, 0.25% Wright's stain procedure. The positions of silver grains directly over or touching well-banded metaphase chromosomes were mapped to an ISCN idiogram. The analysis of the distribution of 200 silver grams following in situ hybridization revealed a significant clustering of grains in the p12 region of chromosome 16. The assignment of the core II subunit to human chromosome 16p12 confirms that it is encoded by the nuclear, rather than the mitochondrial, genome. The identification of a single strong hybridization signal is indicative of one locus with no pseudogenes. 6 refs., 1 fig.

  14. Mitochondrial disease associated with complex I (NADH-CoQ oxidoreductase) deficiency.

    PubMed

    Scheffler, Immo E

    2015-05-01

    Mitochondrial diseases due to a reduced capacity for oxidative phosphorylation were first identified more than 20 years ago, and their incidence is now recognized to be quite significant. In a large proportion of cases the problem can be traced to a complex I (NADH-CoQ oxidoreductase) deficiency (Phenotype MIM #252010). Because the complex consists of 44 subunits, there are many potential targets for pathogenic mutations, both on the nuclear and mitochondrial genomes. Surprisingly, however, almost half of the complex I deficiencies are due to defects in as yet unidentified genes that encode proteins other than the structural proteins of the complex. This review attempts to summarize what we know about the molecular basis of complex I deficiencies: mutations in the known structural genes, and mutations in an increasing number of genes encoding "assembly factors", that is, proteins required for the biogenesis of a functional complex I that are not found in the final complex I. More such genes must be identified before definitive genetic counselling can be applied in all cases of affected families. PMID:25224827

  15. Biological and protein-binding studies of newly synthesized polymer-cobalt(III) complexes.

    PubMed

    Vignesh, G; Pradeep, I; Arunachalam, S; Vignesh, S; Arthur James, R; Arun, R; Premkumar, K

    2016-03-01

    The polymer-cobalt(III) complexes, [Co(bpy)(dien)BPEI]Cl3 · 4H2O (bpy = 2,2'-bipyridine, dien = diethylentriamine, BPEI = branched polyethyleneimine) were synthesized and characterized. The interaction of these complexes with human serum albumin (HSA) and bovine serum albumin (BSA) was investigated under physiological conditions using various physico-chemical techniques. The results reveal that the fluorescence quenching of serum albumins by polymer-cobalt(III) complexes took place through static quenching. The binding of these complexes changed the molecular conformation of the protein considerably. The polymer-cobalt(III) complex with x = 0.365 shows antimicrobial activity against several human pathogens. This complex also induces cytotoxicity against MCF-7 through apoptotic induction. However, further studies are needed to decipher the molecular mode of action of polymer-cobalt(III) complex and for its possible utilization in anticancer therapy. PMID:26278128

  16. Complexation of Am(III) and Nd(III) by 1,10-Phenanthroline-2,9-Dicarboxylic Acid

    SciTech Connect

    Ogden, Mark D.; Sinkov, Sergey I.; Nilsson, Mikael; Lumetta, Gregg J.; Hancock, Robert D.; Nash, Ken L.

    2013-01-01

    The complexant 1,10-phenanthroline-2,9-dicarboxylic acid (PDA) is a planar tetradentate ligand that is more preorganized for metal complexation than its unconstrained analogue ethylendiiminodiacetic acid (EDDA). Furthermore, the backbone nitrogen atoms of PDA are aromatic, hence are softer than the aliphatic amines of EDDA. It has been hypothesized that PDA will selectively bond to trivalent actinides over lanthanides. In this report, the results of spectrophotometric studies of the complexation of Nd(III) and Am(III) by PDA are reported. Because the complexes are moderately stable, it was necessary to conduct these titrations using competitive equilibrium methods, competitive cation omplexing between PDA and diethylenetriaminepentaacetic acid, and competition between ligand protonation and complex formation. Stability constants and ligand protonation constants were determined at 0.1 mol/L ionic strength and at 0.5 mol/L ionic strength nitrate media at 21 ± 1 C. The stability constants are lower than those predicted from first principles and speciation calculations indicate that Am(III) selectivity over Nd(III) is less than that exhibited by 1,10-phenanthroline.

  17. Mitochondrial Ca2+ influx targets cardiolipin to disintegrate respiratory chain complex II for cell death induction

    PubMed Central

    Hwang, M-S; Schwall, C T; Pazarentzos, E; Datler, C; Alder, N N; Grimm, S

    2014-01-01

    Massive Ca2+ influx into mitochondria is critically involved in cell death induction but it is unknown how this activates the organelle for cell destruction. Using multiple approaches including subcellular fractionation, FRET in intact cells, and in vitro reconstitutions, we show that mitochondrial Ca2+ influx prompts complex II of the respiratory chain to disintegrate, thereby releasing an enzymatically competent sub-complex that generates excessive reactive oxygen species (ROS) for cell death induction. This Ca2+-dependent dissociation of complex II is also observed in model membrane systems, but not when cardiolipin is replaced with a lipid devoid of Ca2+ binding. Cardiolipin is known to associate with complex II and upon Ca2+ binding coalesces into separate homotypic clusters. When complex II is deprived of this lipid, it disintegrates for ROS formation and cell death. Our results reveal Ca2+ binding to cardiolipin for complex II disintegration as a pivotal step for oxidative stress and cell death induction. PMID:24948011

  18. Ischemic A/D transition of mitochondrial complex I and its role in ROS generation.

    PubMed

    Dröse, Stefan; Stepanova, Anna; Galkin, Alexander

    2016-07-01

    Mitochondrial complex I (NADH:ubiquinone oxidoreductase) is a key enzyme in cellular energy metabolism and provides approximately 40% of the proton-motive force that is utilized during mitochondrial ATP production. The dysregulation of complex I function--either genetically, pharmacologically, or metabolically induced--has severe pathophysiological consequences that often involve an imbalance in the production of reactive oxygen species (ROS). Slow transition of the active (A) enzyme to the deactive, dormant (D) form takes place during ischemia in metabolically active organs such as the heart and brain. The reactivation of complex I occurs upon reoxygenation of ischemic tissue, a process that is usually accompanied by an increase in cellular ROS production. Complex I in the D-form serves as a protective mechanism preventing the oxidative burst upon reperfusion. Conversely, however, the D-form is more vulnerable to oxidative/nitrosative damage. Understanding the so-called active/deactive (A/D) transition may contribute to the development of new therapeutic interventions for conditions like stroke, cardiac infarction, and other ischemia-associated pathologies. In this review, we summarize current knowledge on the mechanism of A/D transition of mitochondrial complex I considering recently available structural data and site-specific labeling experiments. In addition, this review discusses in detail the impact of the A/D transition on ROS production by complex I and the S-nitrosation of a critical cysteine residue of subunit ND3 as a strategy to prevent oxidative damage and tissue damage during ischemia-reperfusion injury. This article is part of a Special Issue entitled Respiratory complex I, edited by Volker Zickermann and Ulrich Brandt. PMID:26777588

  19. Chlorogenic acid ameliorates intestinal mitochondrial injury by increasing antioxidant effects and activity of respiratory complexes.

    PubMed

    Zhou, Yan; Zhou, Lili; Ruan, Zheng; Mi, Shumei; Jiang, Min; Li, Xiaolan; Wu, Xin; Deng, Zeyuan; Yin, Yulong

    2016-05-01

    Dietary polyphenols are thought to be beneficial for human health by acting as antioxidants. Chlorogenic acid (CGA) is abundant in plant-based foods as an ester of caffeic acid and quinic acid. In this study, we investigated the effects of CGA on mitochondrial protection. Our results demonstrated that pretreatment with CGA ameliorated the intestinal mitochondrial injury induced by H2O2; membrane potential was increased, mitochondrial swelling, levels of reactive oxygen species, contents of 8-hydroxy-2-deoxyguanosine, and cytochrome c released were decreased. The beneficial effects of CGA were accompanied by an increase in antioxidant and respiratory-chain complex I, IV, and V activities. In trinitrobenzene-sulfonic acid-induced colitic rats indicated that CGA supplementation improved mitochondria ultrastructure and decreased mitochondrial injury. Our results suggest a promising role for CGA as a mitochondria-targeted antioxidant in combating intestinal oxidative injury. Daily intake of diets containing CGA, such as coffee and honeysuckle, may be useful for prevention of intestinal diseases. PMID:26824685

  20. Liver proteomic response to hypertriglyceridemia in human-apolipoprotein C-III transgenic mice at cellular and mitochondrial compartment levels

    PubMed Central

    2014-01-01

    Background Hypertriglyceridemia (HTG) is defined as a triglyceride (TG) plasma level exceeding 150 mg/dl and is tightly associated with atherosclerosis, metabolic syndrome, obesity, diabetes and acute pancreatitis. The present study was undertaken to investigate the mitochondrial, sub-mitochondrial and cellular proteomic impact of hypertriglyceridemia in the hepatocytes of hypertriglyceridemic transgenic mice (overexpressing the human apolipoproteinC-III). Methods Quantitative proteomics (2D-DIGE) analysis was carried out on both “low-expressor” (LE) and “high-expressor” (HE) mice, respectively exhibiting moderate and severe HTG, to characterize the effect of the TG plasma level on the proteomic response. Results The mitoproteome analysis has revealed a large-scale phenomenon in transgenic mice, i.e. a general down-regulation of matricial proteins and up-regulation of inner membrane proteins. These data also demonstrate that the magnitude of proteomic changes strongly depends on the TG plasma level. Our different analyses indicate that, in HE mice, the capacity of several metabolic pathways is altered to promote the availability of acetyl-CoA, glycerol-3-phosphate, ATP and NADPH for TG de novo biosynthesis. The up-regulation of several cytosolic ROS detoxifying enzymes has also been observed, suggesting that the cytoplasm of HTG mice is subjected to oxidative stress. Moreover, our results suggest that iron over-accumulation takes place in the cytosol of HE mice hepatocytes and may contribute to enhance oxidative stress and to promote cellular proliferation. Conclusions These results indicate that the metabolic response to HTG in human apolipoprotein C-III overexpressing mice may support a high TG production rate and that the cytosol of hepatocytes is subjected to an important oxidative stress, probably as a result of FFA over-accumulation, iron overload and enhanced activity of some ROS-producing catabolic enzymes. PMID:25047818

  1. Isoniazid-induced cell death is precipitated by underlying mitochondrial complex I dysfunction in mouse hepatocytes.

    PubMed

    Lee, Kang Kwang; Fujimoto, Kazunori; Zhang, Carmen; Schwall, Christine T; Alder, Nathan N; Pinkert, Carl A; Krueger, Winfried; Rasmussen, Theodore; Boelsterli, Urs A

    2013-12-01

    Isoniazid (INH) is an antituberculosis drug that has been associated with idiosyncratic liver injury in susceptible patients. The underlying mechanisms are still unclear, but there is growing evidence that INH and/or its major metabolite, hydrazine, may interfere with mitochondrial function. However, hepatic mitochondria have a large reserve capacity, and minor disruption of energy homeostasis does not necessarily induce cell death. We explored whether pharmacologic or genetic impairment of mitochondrial complex I may amplify mitochondrial dysfunction and precipitate INH-induced hepatocellular injury. We found that INH (≤ 3000 μM) did not induce cell injury in cultured mouse hepatocytes, although it decreased hepatocellular respiration and ATP levels in a concentration-dependent fashion. However, coexposure of hepatocytes to INH and nontoxic concentrations of the complex I inhibitors rotenone (3 μM) or piericidin A (30 nM) resulted in massive ATP depletion and cell death. Although both rotenone and piericidin A increased MitoSox-reactive fluorescence, Mito-TEMPO or N-acetylcysteine did not attenuate the extent of cytotoxicity. However, preincubation of cells with the acylamidase inhibitor bis-p-nitrophenol phosphate provided protection from hepatocyte injury induced by rotenone/INH (but not rotenone/hydrazine), suggesting that hydrazine was the cell-damaging species. Indeed, we found that hydrazine directly inhibited the activity of solubilized complex II. Hepatocytes isolated from mutant Ndufs4(+/-) mice, although featuring moderately lower protein expression levels of this complex I subunit in liver mitochondria, exhibited unchanged hepatic complex I activity and were therefore not sensitized to INH. These data indicate that underlying inhibition of complex I, which alone is not acutely toxic, can trigger INH-induced hepatocellular injury. PMID:23911619

  2. Effects of low-level laser therapy on mitochondrial respiration and nitrosyl complex content.

    PubMed

    Buravlev, Evgeny A; Zhidkova, Tatyana V; Vladimirov, Yury A; Osipov, Anatoly N

    2014-11-01

    Among the photochemical reactions responsible for therapeutic effects of low-power laser radiation, the photolysis of nitrosyl iron complexes of iron-containing proteins is of primary importance. The purpose of the present study was to compare the effects of blue laser radiation on the respiration rate and photolysis of nitrosyl complexes of iron-sulfur clusters (NO-FeS) in mitochondria, subjected to NO as well as the possibility of NO transfer from NO-FeS to hemoglobin. It was shown that mitochondrial respiration in State 3 (V3) and State 4 (V4), according to Chance, dramatically decreased in the presence of 3 mM NO, but laser radiation (λ = 442 nm, 30 J/cm(2)) restored the respiration rates virtually to the initial level. At the same time, electron paramagnetic resonance (EPR) spectra showed that laser irradiation decomposed nitrosyl complexes produced by the addition of NO to mitochondria. EPR signal of nitrosyl complexes of FeS-clusters, formed in the presence of 3 mM NO, was maximal in hypoxic mitochondria, and disappeared in a dose-dependent manner, almost completely at the irradiation dose 120 J/cm(2). EPR measurements showed that the addition of lysed erythrocytes to mitochondria decreased the amount of nitrosyl complexes in iron-sulfur clusters and produced the accumulation of NO-hemoglobin. On the other hand, the addition of lysed erythrocytes to mitochondria, preincubated with nitric oxide, restored mitochondrial respiration rates V3 and V4 to initial levels. We may conclude that there are two possible ways to destroy FeS nitrosyl complexes in mitochondria and recover mitochondrial respiration inhibited by NO: laser irradiation and ample supply of the compounds with high affinity to nitric oxide, including hemoglobin. PMID:24858235

  3. Molecular Gold Wire from Mixed-Valent Au(I/III) Complexes.

    PubMed

    Böge, Matthias; Heck, Jürgen

    2016-05-10

    Crystals of mixed-valent Au complexes have been grown from solutions of cyclohexanecarbonitrile and a stoichiometric amount of gold(I) and gold(III) chloride. The purely obtained compound was characterized as bis(cyclohexanecarbonitrile)gold(I) tetrachloridoaurate(III). The crystal packing of the mixed valent Au(I/III) compound demonstrates a columnar arrangement of the gold(I) and gold(III) atoms. The new structure displays the shortest unsupported gold(I)-gold(III) interactions with the sub-van der Waals distance of 324-325 pm, which is assumed as an aurophilic bonding interaction. PMID:27032070

  4. Ethanol oxidation by imidorhenium(V) complexes: formation of amidorhenium(III) complexes.

    PubMed

    Suing, A L; Dewan, C R; White, P S; Thorp, H H

    2000-12-25

    The reaction of Re(NC6H4R)Cl3(PPh3)2 (R = H, 4-Cl, 4-OMe) with 1,2-bis(diphenylphosphino)ethane (dppe) is investigated in refluxing ethanol. The reaction produces two major products, Re(NC6H4R)Cl(dppe)(2)2+ (R = H, 1-H; R = Cl, 1-Cl; R = OMe, 1-OMe) and the rhenium(III) species Re(NHC6H4R)Cl(dppe)2+ (R = H, 2-H; R = Cl, 2-Cl). Complexes 1-H (orthorhombic, Pcab, a = 22.3075(10) A, b = 23.1271(10) A, c = 23.3584(10) A, Z = 8), 1-Cl (triclinic, P1, a = 11.9403(6) A, b = 14.6673(8) A, c = 17.2664(9) A, alpha = 92.019(1) degrees, beta = 97.379(1) degrees, gamma = 90.134(1) degrees, Z = 2), and 1-OMe (triclinic, P1, a = 11.340(3) A, b = 13.134(4) A, c = 13.3796(25) A, alpha = 102.370(20) degrees, beta = 107.688(17) degrees, gamma = 114.408(20) degrees, Z = 1) are crystallographically characterized and show an average Re-N bond length (1.71 A) typical of imidorhenium(V) complexes. There is a small systematic decrease in the Re-N bond length on going from Cl to H to OMe. Complex 2-Cl (monoclinic, Cc, a = 24.2381(11) A, b = 13.4504(6) A, c = 17.466(8) A, beta = 97.06900(0) degrees, Z = 4) is also crystallographically characterized and shows a Re-N bond length (1.98 A) suggestive of amidorhenium(III). The rhenium(III) complexes exhibit unusual proton NMR spectra where all of the resonances are found at expected locations except those for the amido protons, which are at 37.8 ppm for 2-Cl and 37.3 ppm for 1-H. The phosphorus resonances are also unremarkable, but the 13C spectrum of 2-Cl shows a significantly shifted resonance at 177.3 ppm, which is assigned to the ipso carbon of the phenylamido ligand. The extraordinary shifts of the amido hydrogen and ipso carbon are attributed to second-order magnetism that is strongly focused along the axially compressed amido axis. The reducing equivalents for the formation of the Re(III) product are provided by oxidation of the ethanol solvent, which produces acetal and acetaldehyde in amounts as much as 30 equiv based on the quantity of

  5. Depletion of the "gamma-type carbonic anhydrase-like" subunits of complex I affects central mitochondrial metabolism in Arabidopsis thaliana.

    PubMed

    Fromm, Steffanie; Göing, Jennifer; Lorenz, Christin; Peterhänsel, Christoph; Braun, Hans-Peter

    2016-01-01

    "Gamma-type carbonic anhydrase-like" (CAL) proteins form part of complex I in plants. Together with "gamma carbonic anhydrase" (CA) proteins they form an extra domain which is attached to the membrane arm of complex I on its matrix exposed side. In Arabidopsis two CAL and three CA proteins are present, termed CAL1, CAL2, CA1, CA2 and CA3. It has been proposed that the carbonic anhydrase domain of complex I is involved in a process mediating efficient recycling of mitochondrial CO2 for photosynthetic carbon fixation which is especially important during growth conditions causing increased photorespiration. Depletion of CAL proteins has been shown to significantly affect plant development and photomorphogenesis. To better understand CAL function in plants we here investigated effects of CAL depletion on the mitochondrial compartment. In mutant lines and cell cultures complex I amount was reduced by 90-95% but levels of complexes III and V were unchanged. At the same time, some of the CA transcripts were less abundant. Proteome analysis of CAL depleted cells revealed significant reduction of complex I subunits as well as proteins associated with photorespiration, but increased amounts of proteins participating in amino acid catabolism and stress response reactions. Developmental delay of the mutants was slightly alleviated if plants were cultivated at high CO2. Profiling of selected metabolites revealed defined changes in intermediates of the citric acid cycle and amino acid catabolism. It is concluded that CAL proteins are essential for complex I assembly and that CAL depletion specifically affects central mitochondrial metabolism. PMID:26482706

  6. The structure of the avian mitochondrial cytochrome bc(sub 1) complex

    SciTech Connect

    Berry, Edward A.; Huang, Li-Shar; Zhang, Zhaolei; Kim, Sung-Hou

    1999-05-12

    There are now four structures of vertebrate mitochondrial bc1 complexes available in the protein databases, and structures from yeast and bacterial sources are expected soon. This review summarizes the new information with emphasis on the avian cytochrome bc1 complex (PDB entries 1BCC and 3BCC). The Rieske ironsulfur protein is mobile, and this has been proposed to be important for catalysis. The binding sites for quinone have been located based on structures containing inhibitors and, in the case of the quinone reduction site Qi, the quinone itself.

  7. Quantitative Mapping of Reversible Mitochondrial Complex I Cysteine Oxidation in a Parkinson Disease Mouse Model*

    PubMed Central

    Danielson, Steven R.; Held, Jason M.; Oo, May; Riley, Rebeccah; Gibson, Bradford W.; Andersen, Julie K.

    2011-01-01

    Differential cysteine oxidation within mitochondrial Complex I has been quantified in an in vivo oxidative stress model of Parkinson disease. We developed a strategy that incorporates rapid and efficient immunoaffinity purification of Complex I followed by differential alkylation and quantitative detection using sensitive mass spectrometry techniques. This method allowed us to quantify the reversible cysteine oxidation status of 34 distinct cysteine residues out of a total 130 present in murine Complex I. Six Complex I cysteine residues were found to display an increase in oxidation relative to controls in brains from mice undergoing in vivo glutathione depletion. Three of these residues were found to reside within iron-sulfur clusters of Complex I, suggesting that their redox state may affect electron transport function. PMID:21196577

  8. Inhibition of Beta-Amyloid Fibrillation by Luminescent Iridium(III) Complex Probes

    PubMed Central

    Lu, Lihua; Zhong, Hai-Jing; Wang, Modi; Ho, See-Lok; Li, Hung-Wing; Leung, Chung-Hang; Ma, Dik-Lung

    2015-01-01

    We report herein the application of kinetically inert luminescent iridium(III) complexes as dual inhibitors and probes of beta-amyloid fibrillogenesis. These iridium(III) complexes inhibited Aβ1–40 peptide aggregation in vitro, and protected against Aβ-induced cytotoxicity in neuronal cells. Furthermore, the complexes differentiated between the aggregated and unaggregated forms of Aβ1–40 peptide on the basis of their emission response. PMID:26419607

  9. Evidence of iron(III)-oxalato complex formation in aqueous solution from x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Magini, Mauro

    1981-02-01

    An aqueous solution of ferric ammonium oxalate has been examined to provide direct experimental evidence of complex formation between iron(III) and a typical organic complexing ligand. The radial distribution function as well as analysis of the structure function lead to the conclusion that the dominant species present in solution is the trioxalato-iron(III) complex in which each oxalate ion occupies two corners of a distorted octahedron around the Fe 3+ ions.

  10. Inhibition of Beta-Amyloid Fibrillation by Luminescent Iridium(III) Complex Probes

    NASA Astrophysics Data System (ADS)

    Lu, Lihua; Zhong, Hai-Jing; Wang, Modi; Ho, See-Lok; Li, Hung-Wing; Leung, Chung-Hang; Ma, Dik-Lung

    2015-09-01

    We report herein the application of kinetically inert luminescent iridium(III) complexes as dual inhibitors and probes of beta-amyloid fibrillogenesis. These iridium(III) complexes inhibited Aβ1-40 peptide aggregation in vitro, and protected against Aβ-induced cytotoxicity in neuronal cells. Furthermore, the complexes differentiated between the aggregated and unaggregated forms of Aβ1-40 peptide on the basis of their emission response.

  11. Voltage-Dependent Regulation of Complex II Energized Mitochondrial Oxygen Flux.

    PubMed

    Bai, Fan; Fink, Brian D; Yu, Liping; Sivitz, William I

    2016-01-01

    Oxygen consumption by isolated mitochondria is generally measured during state 4 respiration (no ATP production) or state 3 (maximal ATP production at high ADP availability). However, mitochondria in vivo do not function at either extreme. Here we used ADP recycling methodology to assess muscle mitochondrial function over intermediate clamped ADP concentrations. In so doing, we uncovered a previously unrecognized biphasic respiratory pattern wherein O2 flux on the complex II substrate, succinate, initially increased and peaked over low clamped ADP concentrations then decreased markedly at higher clamped concentrations. Mechanistic studies revealed no evidence that the observed changes in O2 flux were due to altered opening or function of the mitochondrial permeability transition pore or to changes in reactive oxygen. Based on metabolite and functional metabolic data, we propose a multifactorial mechanism that consists of coordinate changes that follow from reduced membrane potential (as the ADP concentration in increased). These changes include altered directional electron flow, altered NADH/NAD+ redox cycling, metabolite exit, and OAA inhibition of succinate dehydrogenase. In summary, we report a previously unrecognized pattern for complex II energized O2 flux. Moreover, our findings suggest that the ADP recycling approach might be more widely adapted for mitochondrial studies. PMID:27153112

  12. The Mitochondrial Unfoldase-Peptidase Complex ClpXP Controls Bioenergetics Stress and Metastasis.

    PubMed

    Seo, Jae Ho; Rivadeneira, Dayana B; Caino, M Cecilia; Chae, Young Chan; Speicher, David W; Tang, Hsin-Yao; Vaira, Valentina; Bosari, Silvano; Palleschi, Alessandro; Rampini, Paolo; Kossenkov, Andrew V; Languino, Lucia R; Altieri, Dario C

    2016-07-01

    Mitochondria must buffer the risk of proteotoxic stress to preserve bioenergetics, but the role of these mechanisms in disease is poorly understood. Using a proteomics screen, we now show that the mitochondrial unfoldase-peptidase complex ClpXP associates with the oncoprotein survivin and the respiratory chain Complex II subunit succinate dehydrogenase B (SDHB) in mitochondria of tumor cells. Knockdown of ClpXP subunits ClpP or ClpX induces the accumulation of misfolded SDHB, impairing oxidative phosphorylation and ATP production while activating "stress" signals of 5' adenosine monophosphate-activated protein kinase (AMPK) phosphorylation and autophagy. Deregulated mitochondrial respiration induced by ClpXP targeting causes oxidative stress, which in turn reduces tumor cell proliferation, suppresses cell motility, and abolishes metastatic dissemination in vivo. ClpP is universally overexpressed in primary and metastatic human cancer, correlating with shortened patient survival. Therefore, tumors exploit ClpXP-directed proteostasis to maintain mitochondrial bioenergetics, buffer oxidative stress, and enable metastatic competence. This pathway may provide a "drugable" therapeutic target in cancer. PMID:27389535

  13. Voltage-Dependent Regulation of Complex II Energized Mitochondrial Oxygen Flux

    PubMed Central

    Bai, Fan; Fink, Brian D.; Yu, Liping; Sivitz, William I.

    2016-01-01

    Oxygen consumption by isolated mitochondria is generally measured during state 4 respiration (no ATP production) or state 3 (maximal ATP production at high ADP availability). However, mitochondria in vivo do not function at either extreme. Here we used ADP recycling methodology to assess muscle mitochondrial function over intermediate clamped ADP concentrations. In so doing, we uncovered a previously unrecognized biphasic respiratory pattern wherein O2 flux on the complex II substrate, succinate, initially increased and peaked over low clamped ADP concentrations then decreased markedly at higher clamped concentrations. Mechanistic studies revealed no evidence that the observed changes in O2 flux were due to altered opening or function of the mitochondrial permeability transition pore or to changes in reactive oxygen. Based on metabolite and functional metabolic data, we propose a multifactorial mechanism that consists of coordinate changes that follow from reduced membrane potential (as the ADP concentration in increased). These changes include altered directional electron flow, altered NADH/NAD+ redox cycling, metabolite exit, and OAA inhibition of succinate dehydrogenase. In summary, we report a previously unrecognized pattern for complex II energized O2 flux. Moreover, our findings suggest that the ADP recycling approach might be more widely adapted for mitochondrial studies. PMID:27153112

  14. The Mitochondrial Unfoldase-Peptidase Complex ClpXP Controls Bioenergetics Stress and Metastasis

    PubMed Central

    Seo, Jae Ho; Rivadeneira, Dayana B.; Caino, M. Cecilia; Chae, Young Chan; Speicher, David W.; Vaira, Valentina; Bosari, Silvano; Rampini, Paolo; Kossenkov, Andrew V.; Languino, Lucia R.; Altieri, Dario C.

    2016-01-01

    Mitochondria must buffer the risk of proteotoxic stress to preserve bioenergetics, but the role of these mechanisms in disease is poorly understood. Using a proteomics screen, we now show that the mitochondrial unfoldase-peptidase complex ClpXP associates with the oncoprotein survivin and the respiratory chain Complex II subunit succinate dehydrogenase B (SDHB) in mitochondria of tumor cells. Knockdown of ClpXP subunits ClpP or ClpX induces the accumulation of misfolded SDHB, impairing oxidative phosphorylation and ATP production while activating “stress” signals of 5′ adenosine monophosphate-activated protein kinase (AMPK) phosphorylation and autophagy. Deregulated mitochondrial respiration induced by ClpXP targeting causes oxidative stress, which in turn reduces tumor cell proliferation, suppresses cell motility, and abolishes metastatic dissemination in vivo. ClpP is universally overexpressed in primary and metastatic human cancer, correlating with shortened patient survival. Therefore, tumors exploit ClpXP-directed proteostasis to maintain mitochondrial bioenergetics, buffer oxidative stress, and enable metastatic competence. This pathway may provide a “drugable” therapeutic target in cancer. PMID:27389535

  15. Interaction of Pseudomonas fluorescens with Eu(III) and Ce(IV) - Desferrioxamine Complexes

    NASA Astrophysics Data System (ADS)

    Yoshida, T.; Ozaki, T.; Ohnuki, T.; Francis, A.

    2002-12-01

    Naturally occurring chelating agents-, such as siderophores, are able to form complexes with actinides and enhance their solubility and mobility in the environment. Adsorption and/or biodegradation of chelated actinides by microorganisms are important processes which regulate their mobility in the natural environment. In this study, association of Eu(III), Ce(IV), and Fe(III) - desferrioxamine B (DFO) complexes with aerobic bacterium, Pseudomonas fluorescens (ATCC 55241), was investigated-, Eu(III) and Ce(IV) were used as analogues to trivalent and tetravalent actinides, respectively. When 20 μM of 1:1 Eu(III) - and Ce(IV) - DFO complexes were incubated with P. fluorescens in 0.1 M Tris-HCl buffer (pH = 7.3), the metals were removed from solution, with no change in DFO in solution. With decreasing metal/DFO molar ratio from 1 to 0.01, the accumulation of Eu(III) and Ce(IV) by P. fluorescens decreased. Kinetics study showed that accumulation of Eu(III) reached the maximum within 30 minutes, and then it decreased slightly with time. On the other hand, Ce(IV) accumulation proceeded in a parabolic process where the kinetics was slower than that of Eu(III) accumulation. In comparison to Eu(III) and Ce(IV), the removal of Fe(III) added as a DFO complex by P. fluorescens was not observed. The formation constants (log K) of Eu(III) - DFO and Fe(III) - DFO are reported to be 15 and 30.6, respectively. These results suggest that Eu(III) - DFO complex was dissociated in the presence of bacteria cells and was readily biosorbed.

  16. Recessive germline SDHA and SDHB mutations causing leukodystrophy and isolated mitochondrial complex II deficiency

    PubMed Central

    Alston, Charlotte L; Davison, James E; Meloni, Francesca; van der Westhuizen, Francois H; He, Langping; Hornig-Do, Hue-Tran; Peet, Andrew C; Gissen, Paul; Goffrini, Paola; Ferrero, Ileana; Wassmer, Evangeline; McFarland, Robert; Taylor, Robert W

    2012-01-01

    Background Isolated complex II deficiency is a rare form of mitochondrial disease, accounting for approximately 2% of all respiratory chain deficiency diagnoses. The succinate dehydrogenase (SDH) genes (SDHA, SDHB, SDHC and SDHD) are autosomally-encoded and transcribe the conjugated heterotetramers of complex II via the action of two known assembly factors (SDHAF1 and SDHAF2). Only a handful of reports describe inherited SDH gene defects as a cause of paediatric mitochondrial disease, involving either SDHA (Leigh syndrome, cardiomyopathy) or SDHAF1 (infantile leukoencephalopathy). However, all four SDH genes, together with SDHAF2, have known tumour suppressor functions, with numerous germline and somatic mutations reported in association with hereditary cancer syndromes, including paraganglioma and pheochromocytoma. Methods and results Here, we report the clinical and molecular investigations of two patients with histochemical and biochemical evidence of a severe, isolated complex II deficiency due to novel SDH gene mutations; the first patient presented with cardiomyopathy and leukodystrophy due to compound heterozygous p.Thr508Ile and p.Ser509Leu SDHA mutations, while the second patient presented with hypotonia and leukodystrophy with elevated brain succinate demonstrated by MR spectroscopy due to a novel, homozygous p.Asp48Val SDHB mutation. Western blotting and BN-PAGE studies confirmed decreased steady-state levels of the relevant SDH subunits and impairment of complex II assembly. Evidence from yeast complementation studies provided additional support for pathogenicity of the SDHB mutation. Conclusions Our report represents the first example of SDHB mutation as a cause of inherited mitochondrial respiratory chain disease and extends the SDHA mutation spectrum in patients with isolated complex II deficiency. PMID:22972948

  17. The resistance of electron-transport chain Fe-S clusters to oxidative damage during the reaction of peroxynitrite with mitochondrial complex II and rat-heart pericardium.

    PubMed

    Pearce, Linda L; Martinez-Bosch, Sandra; Manzano, Elisenda Lopez; Winnica, Daniel E; Epperly, Michael W; Peterson, Jim

    2009-05-01

    The effects of peroxynitrite and nitric oxide on the iron-sulfur clusters in complex II (succinate dehydrogenase) isolated from bovine heart have been studied primarily by EPR spectroscopy and no measurable damage to the constitutive 2Fe-2S, 3Fe-4S, or 4Fe-4S clusters was observed. The enzyme can be repeatedly oxidized with a slight excess of peroxynitrite and then quantitatively re-reduced with succinate. When added in large excess, peroxynitrite reacted with at least one tyrosine in each subunit of complex II to form 3-nitrotyrosines, but activity was barely compromised. Examination of rat-heart pericardium subjected to conditions leading to peroxynitrite production showed a small inhibition of complex II (16%) and a greater inhibition of aconitase (77%). In addition, experiments performed with excesses of sodium citrate and sodium succinate on rat-heart pericardium indicated that the "g approximately 2.01" EPR signal observed immediately following the beginning of conditions modeling oxidative/nitrosative stress, could be a consequence of both reversible oxidation of the constitutive 3Fe-4S cluster in complex II and degradation of the 4Fe-4S cluster in aconitase. However, the net signal envelope, which becomes apparent in less than 1min following the start of oxidative/nitrosative conditions, is dominated by the component arising from complex II. Taking into account the findings of a previous study concerning complexes I and III (L.L. Pearce, A.J. Kanai, M.W. Epperly, J. Peterson, Nitrosative stress results in irreversible inhibition of purified mitochondrial complexes I and III without modification of cofactors, Nitric Oxide 13 (2005) 254-263) it is now apparent that, with the exception of the cofactor in aconitase, mammalian (mitochondrial) iron-sulfur clusters are surprisingly resistant to degradation stemming from oxidative/nitrosative stress. PMID:19118636

  18. Complexity of Compensatory Effects in Nrf1 Knockdown: Linking Undeveloped Anxiety-Like Behavior to Prevented Mitochondrial Dysfunction and Oxidative Stress.

    PubMed

    Khalifeh, Solmaz; Oryan, Shahrbanoo; Khodagholi, Fariba; Digaleh, Hadi; Shaerzadeh, Fatemeh; Maghsoudi, Nader; Zarrindast, Mohammad-Reza

    2016-05-01

    Anxiety-related disorders are complex illnesses that underlying molecular mechanisms need to be understood. Mitochondria stand as an important link between energy metabolism, oxidative stress, and anxiety. The nuclear factor, erythroid-derived 2,-like 1(Nrf1) is a member of the cap "n" collar subfamily of basic region leucine zipper transcription factors and plays the major role in regulating the adaptive response to oxidants and electrophiles within the cell. Here, we injected small interfering RNA (siRNA) targeting Nrf1 in dorsal third ventricle of adult male albino Wistar rats and subsequently examined the effect of this silencing on anxiety-related behavior. We also evaluated apoptotic markers and mitochondrial biogenesis factors, along with electron transport chain activity in three brain regions: hippocampus, amygdala, and prefrontal cortex. Our data revealed that in the group that received Nrf1-siRNA, anxiety-related behavior did not show any significant changes compared to the control group. Caspase-3 did not increase in Nrf1-siRNA-injected rats even though Bax/Bcl2 ratio markedly elevated in Nrf1-knockdown rats in all three mentioned regions compared to control rats. Also, Nrf1 silencing of complex I and II-III did not alter, generally. In addition, Nrf1-knockdown affected mitochondrial biogenesis markers. The level of peroxisome proliferator-activated receptor gamma coactivator-1α and cytochrome-c increased, which indicates a possible role for mitochondrial biogenesis in anxiety. PMID:26202310

  19. A mitofusin-dependent docking ring complex triggers mitochondrial fusion in vitro

    PubMed Central

    Brandt, Tobias; Cavellini, Laetitia; Kühlbrandt, Werner; Cohen, Mickaël M

    2016-01-01

    Fusion of mitochondrial outer membranes is crucial for proper organelle function and involves large GTPases called mitofusins. The discrete steps that allow mitochondria to attach to one another and merge their outer membranes are unknown. By combining an in vitro mitochondrial fusion assay with electron cryo-tomography (cryo-ET), we visualize the junction between attached mitochondria isolated from Saccharomyces cerevisiae and observe complexes that mediate this attachment. We find that cycles of GTP hydrolysis induce progressive formation of a docking ring structure around extended areas of contact. Further GTP hydrolysis triggers local outer membrane fusion at the periphery of the contact region. These findings unravel key features of mitofusin-dependent fusion of outer membranes and constitute an important advance in our understanding of how mitochondria connect and merge. DOI: http://dx.doi.org/10.7554/eLife.14618.001 PMID:27253069

  20. Arrested development of the myxozoan parasite, Myxobolus cerebralis, in certain populations of mitochondrial 16S lineage III Tubifex tubifex.

    PubMed

    Baxa, D V; Kelley, G O; Mukkatira, K S; Beauchamp, K A; Rasmussen, C; Hedrick, R P

    2008-01-01

    Laboratory populations of Tubifex tubifex from mitochondrial (mt)16S ribosomal DNA (rDNA) lineage III were generated from single cocoons of adult worms releasing the triactinomyxon stages (TAMs) of the myxozoan parasite, Myxobolus cerebralis. Subsequent worm populations from these cocoons, referred to as clonal lines, were tested for susceptibility to infection with the myxospore stages of M. cerebralis. Development and release of TAMs occurred in five clonal lines, while four clonal lines showed immature parasitic forms that were not expelled from the worm (non-TAM producers). Oligochaetes from TAM- and non-TAM-producing clonal lines were confirmed as lineage III based on mt16S rDNA and internal transcribed spacer region 1 (ITS1) sequences, but these genes did not differentiate these phenotypes. In contrast, random amplified polymorphic DNA analyses of genomic DNA demonstrated unique banding patterns that distinguished the phenotypes. Cohabitation of parasite-exposed TAM- and non-TAM-producing phenotypes showed an overall decrease in expected TAM production compared to the same exposure dose of the TAM-producing phenotype without cohabitation. These studies suggest that differences in susceptibility to parasite infection can occur in genetically similar T. tubifex populations, and their coexistence may affect overall M. cerebralis production, a factor that may influence the severity of whirling disease in wild trout populations. PMID:17891544

  1. Arrested development of the myxozoan parasite, Myxobolus cerebralis, in certain populations of mitochondrial 16S lineage III Tubifex tubifex

    USGS Publications Warehouse

    Baxa, D.V.; Kelley, G.O.; Mukkatira, K.S.; Beauchamp, K.A.; Rasmussen, C.; Hedrick, R.P.

    2008-01-01

    Laboratory populations of Tubifex tubifex from mitochondrial (mt)16S ribosomal DNA (rDNA) lineage III were generated from single cocoons of adult worms releasing the triactinomyxon stages (TAMs) of the myxozoan parasite, Myxobolus cerebralis. Subsequent worm populations from these cocoons, referred to as clonal lines, were tested for susceptibility to infection with the myxospore stages of M. cerebralis. Development and release of TAMs occurred in five clonal lines, while four clonal lines showed immature parasitic forms that were not expelled from the worm (non-TAM producers). Oligochaetes from TAM- and non-TAM-producing clonal lines were confirmed as lineage III based on mt16S rDNA and internal transcribed spacer region 1 (ITS1) sequences, but these genes did not differentiate these phenotypes. In contrast, random amplified polymorphic DNA analyses of genomic DNA demonstrated unique banding patterns that distinguished the phenotypes. Cohabitation of parasite-exposed TAM- and non-TAM-producing phenotypes showed an overall decrease in expected TAM production compared to the same exposure dose of the TAM-producing phenotype without cohabitation. These studies suggest that differences in susceptibility to parasite infection can occur in genetically similar T. tubifex populations, and their coexistence may affect overall M. cerebralis production, a factor that may influence the severity of whirling disease in wild trout populations. ?? 2007 Springer-Verlag.

  2. Synthesis of tyrosine-involved corrole Cu(III), Mn(IV), and Mn(III) complexes as biomimetic models of oxygen evolving complex in photosystem II

    NASA Astrophysics Data System (ADS)

    Xia, M.; Gao, Y.

    2014-12-01

    Boc-protected tyrosine-attached corrole ligand on the " ortho" position compound 3, its corresponding copper (III) 4a, manganese (IV) 4b, and manganese (III) 4c complexes have been designed and synthesized based on the structures of active-centers of related biological systems. 1H NMR and electronic absorption spectra of these metal complexes are investigated. The crystal structure of 4a displays the relative position of TyrOH unit to the high valent metal center. Electrochemistry investigations display the possibilities of intramolecular electron or energy transfer between TyrOH group and metal corrole group.

  3. MITOCHONDRIAL DISEASES PART I: MOUSE MODELS OF OXPHOS DEFICIENCIES CAUSED BY DEFECTS ON RESPIRATORY COMPLEX SUBUNITS OR ASSEMBLY FACTORS

    PubMed Central

    Torraco, Alessandra; Peralta, Susana; Iommarini, Luisa; Diaz, Francisca

    2015-01-01

    Mitochondrial disorders are the most common inborn errors of metabolism affecting the oxidative phosphorylation system (OXPHOS). Because the poor knowledge of the pathogenic mechanisms, a cure for these disorders is still unavailable and all the treatments currently in use are supportive more than curative. Therefore, in the past decade a great variety of mouse models have been developed to assess the in vivo function of several mitochondrial proteins involved in human diseases. Due to the genetic and physiological similarity to humans, mice represent reliable models to study the pathogenic mechanisms of mitochondrial disorders and are precious to test new therapeutic approaches. Here we summarize the features of several mouse models of mitochondrial diseases directly related to defects in subunits of the OXPHOS complexes or in assembly factors. We discuss how these models recapitulate many human conditions and how they have contributed to the understanding of mitochondrial function in health and disease. PMID:25660179

  4. Neodymium(III) Complexation by Amino-Carbohydrates via a Ligand-Controlled Hydrolysis Mechanism

    SciTech Connect

    Levitskaia, Tatiana G.; Chen, Yongsheng; Fulton, John L.; Sinkov, Sergey I.

    2011-07-28

    Chelation of neodymium-III Nd(III) by D-glucosamine (DGA) and chitosan was investigated in solution at near-physiological pH and ionic strength. This research demonstrates the first example of the lanthanide ion heteroleptic hydroxo-carbohydrate complex in solution. It was demonstrated that DGA and chitosan suppressed formation of polynuclear Nd(III) species at elevated pH.

  5. Synthesis, structure and luminescence studies of Eu(III), Tb(III), Sm(III), Dy(III) cationic complexes with acetylacetone and bis(5-(pyridine-2-yl)-1,2,4-triazol-3-yl)propane☆

    PubMed Central

    Gusev, Alexey N.; Hasegawa, Miki; Shimizu, Tomohito; Fukawa, Tomonori; Sakurai, Shoya; Nishchymenko, Galyna A.; Shul’gin, Victor F.; Meshkova, Svetlana B.; Linert, Wolfgang

    2013-01-01

    Studies concerning synthesis, structure and luminescence of eight-coordinate Eu, Tb, Sm and Dy complexes of the type [Ln(acac)2(L)]Cl (Hacac = pentanedione-2,4 and L = bis(5-(pyridine-2-yl)-1,2,4-triazol-3-yl)propane) are reported in detail. The obtained complexes were investigated by various means including elemental- and thermogravimetric analysis, IR- and electron transition spectroscopy. The structure of the Tb complex was determined by single-crystal X-ray crystallography: Tb is eight-coordinate, and L acting only as a tetradentate chelate together with two bidentate acac ligands. Photophysical studies of the complexes were carried out. The Tb(III) and Eu(III) complexes show strong emissions both in solid state and solution. The intensity of the luminescence of Dy(III) and Sm(III) are relatively weak. The factors determining the intensity of the photoluminescence are discussed. PMID:24068839

  6. Cardioprotection by S-nitrosation of a cysteine switch on mitochondrial complex I

    PubMed Central

    Chouchani, Edward T; Methner, Carmen; Nadtochiy, Sergiy M; Logan, Angela; Pell, Victoria R; Ding, Shujing; James, Andrew M; Cochemé, Helena M; Reinhold, Johannes; Lilley, Kathryn S; Partridge, Linda; Fearnley, Ian M; Robinson, Alan J; Hartley, Richard C; Smith, Robin A J; Krieg, Thomas; Brookes, Paul S; Murphy, Michael P

    2014-01-01

    Oxidative damage from elevated production of reactive oxygen species (ROS) contributes to ischemia-reperfusion injury in myocardial infarction and stroke. The mechanism by which the increase in ROS occurs is not known, and it is unclear how this increase can be prevented. A wide variety of nitric oxide donors and S-nitrosating agents protect the ischemic myocardium from infarction, but the responsible mechanisms are unclear1–6. Here we used a mitochondria-selective S-nitrosating agent, MitoSNO, to determine how mitochondrial S-nitrosation at the reperfusion phase of myocardial infarction is cardioprotective in vivo in mice. We found that protection is due to the S-nitrosation of mitochondrial complex I, which is the entry point for electrons from NADH into the respiratory chain. Reversible S-nitrosation of complex I slows the reactivation of mitochondria during the crucial first minutes of the reperfusion of ischemic tissue, thereby decreasing ROS production, oxidative damage and tissue necrosis. Inhibition of complex I is afforded by the selective S-nitrosation of Cys39 on the ND3 subunit, which becomes susceptible to modification only after ischemia. Our results identify rapid complex I reactivation as a central pathological feature of ischemia-reperfusion injury and show that preventing this reactivation by modification of a cysteine switch is a robust cardioprotective mechanism and hence a rational therapeutic strategy. PMID:23708290

  7. Mitochondrial oxidative phosphorylation complexes exist in the sarcolemma of skeletal muscle

    PubMed Central

    Lee, Hyun; Kim, Seung-Hyeob; Lee, Jae-Seon; Yang, Yun-Hee; Nam, Jwa-Min; Kim, Bong-Woo; Ko, Young-Gyu

    2016-01-01

    Although proteomic analyses have revealed the presence of mitochondrial oxidative phosphorylation (OXPHOS) proteins in the plasma membrane, there have been no in-depth evaluations of the presence or function of OXPHOS I-V in the plasma membrane. Here, we demonstrate the in situ localization of OXPHOS I-V complexes to the sarcolemma of skeletal muscle by immunofluorescence and immunohistochemistry. A portion of the OXPHOS I-V complex proteins was not co-stained with MitoTracker but co-localized with caveolin-3 in the sarcolemma of mouse gastrocnemius. Mitochondrial matrix-facing OXPHOS complex subunits were ectopically expressed in the sarcolemma of the non-permeabilized muscle fibers and C2C12 myotubes. The sarcolemmal localization of cytochrome c was also observed from mouse gastrocnemius muscles and C2C12 myotubes, as determined by confocal and total internal resonance fluorescence (TIRF) microscopy. Based on these data, we conclude that a portion of OXPHOS complexes is localized in the sarcolemma of skeletal muscle and may have non-canonical functions. [BMB Reports 2016; 49(2): 116-121] PMID:26645635

  8. Production of new amilorides as potent inhibitors of mitochondrial respiratory complex I.

    PubMed

    Murai, Masatoshi; Habu, Sayako; Murakami, Sonomi; Ito, Takeshi; Miyoshi, Hideto

    2015-01-01

    Amilorides, well-known inhibitors of Na(+)/H(+) antiporters, have also shown to inhibit bacterial and mitochondrial NADH-quinone oxidoreductase (complex I). Since the membrane subunits ND2, ND4, and ND5 of bovine mitochondrial complex I are homologous to Na(+)/H(+) antiporters, amilorides have been thought to bind to any or all of the antiporter-like subunits; however, there is no direct experimental evidence in support of this notion. Photoaffinity labeling is a powerful technique to identify the binding site of amilorides in bovine complex I. Commercially available amilorides such as 5-(N-ethyl-N-isopropyl)amiloride are not suitable as design templates to synthesize photoreactive amilorides because of their low binding affinities to bovine complex I. Thereby, we attempted to modify the structures of commercially available amilorides in order to obtain more potent derivatives. We successfully produced two photoreactive amilorides (PRA1 and PRA2) with a photolabile azido group at opposite ends of the molecule. PMID:25731956

  9. RSC Chromatin-Remodeling Complex Is Important for Mitochondrial Function in Saccharomyces cerevisiae

    PubMed Central

    Imamura, Yuko; Yu, Feifei; Nakamura, Misaki; Chihara, Yuhki; Okane, Kyo; Sato, Masahiro; Kanai, Muneyoshi; Hamada, Ryoko; Ueno, Masaru; Yukawa, Masashi; Tsuchiya, Eiko

    2015-01-01

    RSC (Remodel the Structure of Chromatin) is an ATP-dependent chromatin remodeling complex essential for the growth of Saccharomyces cerevisiae. RSC exists as two distinct isoforms that share core subunits including the ATPase subunit Nps1/Sth1 but contain either Rsc1or Rsc2. Using the synthetic genetic array (SGA) of the non-essential null mutation method, we screened for mutations exhibiting synthetic growth defects in combination with the temperature-sensitive mutant, nps1-105, and found connections between mitochondrial function and RSC. rsc mutants, including rsc1Δ, rsc2Δ, and nps1-13, another temperature-sensitive nps1 mutant, exhibited defective respiratory growth; in addition, rsc2Δ and nps1-13 contained aggregated mitochondria. The rsc2Δ phenotypes were relieved by RSC1 overexpression, indicating that the isoforms play a redundant role in respiratory growth. Genome-wide expression analysis in nps1-13 under respiratory conditions suggested that RSC regulates the transcription of some target genes of the HAP complex, a transcriptional activator of respiratory gene expression. Nps1 physically interacted with Hap4, the transcriptional activator moiety of the HAP complex, and overexpression of HAP4 alleviated respiratory defects in nps1-13, suggesting that RSC plays pivotal roles in mitochondrial gene expression and shares a set of target genes with the HAP complex. PMID:26086550

  10. Complexation of Curium(III) with DTPA at 10–70 °C: Comparison with Eu(III)–DTPA in Thermodynamics, Luminescence, and Coordination Modes

    SciTech Connect

    Tian, Guoxin; Zhang, Zhiyong; Martin, Leigh R.; Rao, Linfeng

    2015-02-16

    Separation of trivalent actinides (An(III)) from trivalent lanthanides (Ln(III)) is a challenging task because of their nearly identical chemical properties. Diethylenetriaminepentaacetate (DTPA), a key reagent used in the TALSPEAK process that effectively separates An(III) from Ln(III), is believed to play a critical role in the An(III)/Ln(III) separation. However, the underlying principles for the separation based on the difference in the complexation of DTPA with An(III) and Ln(III) remain unclear. In this work, the complexation of DTPA with Cm(III) at 10-70 ºC was investigated by spectrophotometry, luminescence spectroscopy, and microcalorimetry, in conjunction with computational methods. The binding strength, the enthalpy of complexation, the coordination modes, and the luminescence properties are compared between the Cm(III)-DTPA and Eu(III)-DTPA systems. The experimental and computational data have demonstrated that the difference between Cm(III) and Eu(III) in the binding strength with DTPA can be attributed to the stronger covalence bonding between Cm(III) and the nitrogen donors of DTPA.

  11. PINK1 loss-of-function mutations affect mitochondrial complex I activity via NdufA10 ubiquinone uncoupling.

    PubMed

    Morais, Vanessa A; Haddad, Dominik; Craessaerts, Katleen; De Bock, Pieter-Jan; Swerts, Jef; Vilain, Sven; Aerts, Liesbeth; Overbergh, Lut; Grünewald, Anne; Seibler, Philip; Klein, Christine; Gevaert, Kris; Verstreken, Patrik; De Strooper, Bart

    2014-04-11

    Under resting conditions, Pink1 knockout cells and cells derived from patients with PINK1 mutations display a loss of mitochondrial complex I reductive activity, causing a decrease in the mitochondrial membrane potential. Analyzing the phosphoproteome of complex I in liver and brain from Pink1(-/-) mice, we found specific loss of phosphorylation of serine-250 in complex I subunit NdufA10. Phosphorylation of serine-250 was needed for ubiquinone reduction by complex I. Phosphomimetic NdufA10 reversed Pink1 deficits in mouse knockout cells and rescued mitochondrial depolarization and synaptic transmission defects in pink(B9)-null mutant Drosophila. Complex I deficits and adenosine triphosphate synthesis were also rescued in cells derived from PINK1 patients. Thus, this evolutionary conserved pathway may contribute to the pathogenic cascade that eventually leads to Parkinson's disease in patients with PINK1 mutations. PMID:24652937

  12. Complexation Effect on Redox Potential of Iron(III)-Iron(II) Couple: A Simple Potentiometric Experiment

    ERIC Educational Resources Information Center

    Rizvi, Masood Ahmad; Syed, Raashid Maqsood; Khan, Badruddin

    2011-01-01

    A titration curve with multiple inflection points results when a mixture of two or more reducing agents with sufficiently different reduction potentials are titrated. In this experiment iron(II) complexes are combined into a mixture of reducing agents and are oxidized to the corresponding iron(III) complexes. As all of the complexes involve the…

  13. Resveratrol attenuates oxidative stress in mitochondrial Complex I deficiency: Involvement of SIRT3.

    PubMed

    Mathieu, Lise; Costa, Alexandra Lopes; Le Bachelier, Carole; Slama, Abdelhamid; Lebre, Anne-Sophie; Taylor, Robert W; Bastin, Jean; Djouadi, Fatima

    2016-07-01

    The pathophysiological mechanisms underlying Complex I (CI) deficiencies are understood only partially which severely limits the treatment of this common, devastating, mitochondrial disorder. Recently, we have shown that resveratrol (RSV), a natural polyphenol, has beneficial effects on CI deficiency of nuclear origin. Here, we demonstrate that RSV is able to correct the biochemical defect in oxygen consumption in five of thirteen CI-deficient patient cell lines. Other beneficial effects of RSV include a decrease of total intracellular ROS and the up-regulation of the expression of mitochondrial superoxide dismutase (SOD2) protein, a key antioxidant defense enzyme. The molecular mechanisms leading to the up-regulation of SOD2 protein expression by RSV require the estrogen receptor (ER) and the estrogen-related receptor alpha (ERRα). Although RSV increases the level of SOD2 protein in patients' fibroblasts, the enzyme activity is not increased, in contrast to normal fibroblasts. This led us to hypothesize that SOD2 enzyme activity is regulated post-translationally. This regulation involves SIRT3, a mitochondrial NAD(+)-dependent deacetylase and is critically dependent on NAD(+) levels. Taken together, our data show that the metabolic effects of RSV combined with its antioxidant capacities makes RSV particularly interesting as a candidate molecule for the therapy of CI deficiencies. PMID:27126960

  14. AtFtsH4 perturbs the mitochondrial respiratory chain complexes and auxin homeostasis in Arabidopsis.

    PubMed

    Zhang, Shengchun; ZHang, Daowei; Yang, Chengwei

    2014-07-25

    Mitochondrial AtFtsH4 protease is one of four inner membrane-bound FtsH proteases in Arabidopsis. We found that the loss of AtFtsH4 regulates Arabidopsis development and architecture by mediating the peroxidase-dependent interplay between hydrogen peroxide (H 2O 2) and auxin homeostasis. These morphological changes were correlated with elevated levels of both hydrogen peroxide and peroxidases, which suggested that ftsh4-4 plant was related to the oxidative stress, and that the architecture was caused by the auxin homeostasis perturbation. This view was supported by the expression levels of several auxin signaling genes and auxin binding and transport genes were decreased significantly in ftsh4-4 plants. Taken together, our data published in the May issue of Molecular Plant suggests a link between the lack of AtFtsH4 protease, oxidative stress,s and auxin homeostasis to regulate plant growth and development. However, the detail molecular mechanisms of AtFtSH4 regulating oxidation stress and auxin homeostasis is unclear. Here, we present evidence that the high level accumulated of H 2O 2 in ftsh4-4 may correlates with the decreased mitochondrial respiration genes. We also showed that the decreased auxin level and auxin transport may caused by the inhibition of mitochondrial respiratory chain complexes. PMID:25061946

  15. Mitochondrial Complex I Deficiency Increases Protein Acetylation and Accelerates Heart Failure

    PubMed Central

    Karamanlidis, Georgios; Lee, Chi Fung; Garcia-Menendez, Lorena; Kolwicz, Stephen C.; Suthammarak, Wichit; Gong, Guohua; Sedensky, Margaret M.; Morgan, Philip G.; Wang, Wang; Tian, Rong

    2013-01-01

    Summary Mitochondrial respiratory dysfunction is linked to the pathogenesis of multiple diseases including heart failure but the specific mechanisms for this link remain largely elusive. We modeled the impairment of mitochondrial respiration by inactivation of the Ndufs4 gene, a protein critical for Complex I (C-I) assembly, in the mouse heart (cKO). While C-I supported respiration decreased by >40%, the cKO mice maintained normal cardiac function in vivo and high-energy phosphate content in isolated perfused hearts. However, the cKO mice developed accelerated heart failure after pressure overload or repeated pregnancy. Decreased NAD+/NADH ratio by C-I deficiency inhibited Sirt3 activity, leading to increase in protein acetylation, and sensitization of the permeability transition in mitochondria (mPTP). NAD+ precursor supplementation to cKO mice partially normalized the NAD+/NADH ratio, protein acetylation and mPTP sensitivity. These findings describe a mechanism connecting mitochondrial dysfunction to the susceptibility to diseases and propose a potential therapeutic target. PMID:23931755

  16. Benzaldehyde Thiosemicarbazone Derived from Limonene Complexed with Copper Induced Mitochondrial Dysfunction in Leishmania amazonensis

    PubMed Central

    Britta, Elizandra Aparecida; Barbosa Silva, Ana Paula; Ueda-Nakamura, Tânia; Dias-Filho, Benedito Prado; Silva, Cleuza Conceição; Sernaglia, Rosana Lázara; Nakamura, Celso Vataru

    2012-01-01

    Background Leishmaniasis is a major health problem that affects more than 12 million people. Treatment presents several problems, including high toxicity and many adverse effects, leading to the discontinuation of treatment and emergence of resistant strains. Methodology/Principal Findings We evaluated the in vitro antileishmanial activity of benzaldehyde thiosemicarbazone derived from limonene complexed with copper, termed BenzCo, against Leishmania amazonensis. BenzCo inhibited the growth of the promastigote and axenic amastigote forms, with IC50 concentrations of 3.8 and 9.5 µM, respectively, with 72 h of incubation. Intracellular amastigotes were inhibited by the compound, with an IC50 of 10.7 µM. BenzCo altered the shape, size, and ultrastructure of the parasites. Mitochondrial membrane depolarization was observed in protozoa treated with BenzCo but caused no alterations in the plasma membrane. Additionally, BenzCo induced lipoperoxidation and the production of mitochondrial superoxide anion radicals in promastigotes and axenic amastigotes of Leishmania amazonensis. Conclusion/Significance Our studies indicated that the antileishmania activity of BenzCo might be associated with mitochondrial dysfunction and oxidative damage, leading to parasite death. PMID:22870222

  17. The Mitochondrial Genome of Soybean Reveals Complex Genome Structures and Gene Evolution at Intercellular and Phylogenetic Levels

    PubMed Central

    Chang, Shengxin; Wang, Yankun; Lu, Jiangjie; Gai, Junyi; Li, Jijie; Chu, Pu; Guan, Rongzhan; Zhao, Tuanjie

    2013-01-01

    Determining mitochondrial genomes is important for elucidating vital activities of seed plants. Mitochondrial genomes are specific to each plant species because of their variable size, complex structures and patterns of gene losses and gains during evolution. This complexity has made research on the soybean mitochondrial genome difficult compared with its nuclear and chloroplast genomes. The present study helps to solve a 30-year mystery regarding the most complex mitochondrial genome structure, showing that pairwise rearrangements among the many large repeats may produce an enriched molecular pool of 760 circles in seed plants. The soybean mitochondrial genome harbors 58 genes of known function in addition to 52 predicted open reading frames of unknown function. The genome contains sequences of multiple identifiable origins, including 6.8 kb and 7.1 kb DNA fragments that have been transferred from the nuclear and chloroplast genomes, respectively, and some horizontal DNA transfers. The soybean mitochondrial genome has lost 16 genes, including nine protein-coding genes and seven tRNA genes; however, it has acquired five chloroplast-derived genes during evolution. Four tRNA genes, common among the three genomes, are derived from the chloroplast. Sizeable DNA transfers to the nucleus, with pericentromeric regions as hotspots, are observed, including DNA transfers of 125.0 kb and 151.6 kb identified unambiguously from the soybean mitochondrial and chloroplast genomes, respectively. The soybean nuclear genome has acquired five genes from its mitochondrial genome. These results provide biological insights into the mitochondrial genome of seed plants, and are especially helpful for deciphering vital activities in soybean. PMID:23431381

  18. Development of a C3-symmetric benzohydroxamate tripod: Trimetallic complexation with Fe(III), Cr(III) and Al(III)

    NASA Astrophysics Data System (ADS)

    Baral, Minati; Gupta, Amit; Kanungo, B. K.

    2016-06-01

    The design, synthesis and physicochemical characterization of a C3-symmetry Benzene-1,3,5-tricarbonylhydroxamate tripod, noted here as BTHA, are described. The chelator was built from a benzene as an anchor, symmetrically extended by three hydroxamate as ligating moieties, each bearing O, O donor sites. A combination of absorption spectrophotometry, potentiometry and theoretical investigations are used to explore the complexation behavior of the ligand with some trivalent metal ions: Fe(III), Cr(III), and Al(III). Three protonation constants were calculated for the ligand in a pH range of 2-11 in a highly aqueous medium (9:1 H2O: DMSO). A high rigidity in the molecular structure restricts the formation of 1:1 (M/L) metal encapsulation but shows a high binding efficiency for a 3:1 metal ligand stoichiometry giving formation constant (in β unit) 28.73, 26.13 and 19.69 for [M3L]; Mdbnd Fe(III), Al(III) and Cr(III) respectively, and may be considered as an efficient Fe-carrier. The spectrophotometric study reveals of interesting electronic transitions occurred during the complexation. BTHA exhibits a peak at 238 nm in acidic pH and with the increase of pH, a new peak appeared at 270 nm. A substantial shifting in both of the peaks in presence of the metal ions implicates a s coordination between ligand and metal ions. Moreover, complexation of BTHA with iron shows three distinct colors, violet, reddish orange and yellow in different pH, enables the ligand to be considered for the use as colorimetric sensor.

  19. Development of a C3-symmetric benzohydroxamate tripod: Trimetallic complexation with Fe(III), Cr(III) and Al(III).

    PubMed

    Baral, Minati; Gupta, Amit; Kanungo, B K

    2016-06-01

    The design, synthesis and physicochemical characterization of a C3-symmetry Benzene-1,3,5-tricarbonylhydroxamate tripod, noted here as BTHA, are described. The chelator was built from a benzene as an anchor, symmetrically extended by three hydroxamate as ligating moieties, each bearing O, O donor sites. A combination of absorption spectrophotometry, potentiometry and theoretical investigations are used to explore the complexation behavior of the ligand with some trivalent metal ions: Fe(III), Cr(III), and Al(III). Three protonation constants were calculated for the ligand in a pH range of 2-11 in a highly aqueous medium (9:1 H2O: DMSO). A high rigidity in the molecular structure restricts the formation of 1:1 (M/L) metal encapsulation but shows a high binding efficiency for a 3:1 metal ligand stoichiometry giving formation constant (in β unit) 28.73, 26.13 and 19.69 for [M3L]; MFe(III), Al(III) and Cr(III) respectively, and may be considered as an efficient Fe-carrier. The spectrophotometric study reveals of interesting electronic transitions occurred during the complexation. BTHA exhibits a peak at 238nm in acidic pH and with the increase of pH, a new peak appeared at 270nm. A substantial shifting in both of the peaks in presence of the metal ions implicates a s coordination between ligand and metal ions. Moreover, complexation of BTHA with iron shows three distinct colors, violet, reddish orange and yellow in different pH, enables the ligand to be considered for the use as colorimetric sensor. PMID:26970809

  20. 21 CFR 176.160 - Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Chromium (Cr III) complex of N-ethyl-N... § 176.160 Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine. The chromium... by weight of the chromium (Cr III) complex of heptadecylfluoro-octane sulfonic acid may be...

  1. 21 CFR 176.160 - Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Chromium (Cr III) complex of N-ethyl-N... Substances for Use Only as Components of Paper and Paperboard § 176.160 Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine. The chromium (Cr III) complex of N-ethyl -...

  2. Inhibition of mitochondrial complex I by various non-steroidal anti-inflammatory drugs and its protection by quercetin via a coenzyme Q-like action.

    PubMed

    Sandoval-Acuña, Cristian; Lopez-Alarcón, Camilo; Aliaga, Margarita E; Speisky, Hernán

    2012-07-30

    Mitochondrial dysfunction plays a major role in the development of oxidative stress and cytotoxicity induced by non-steroidal anti-inflammatory drugs (NSAIDs). A major objective of the present study was to investigate whether in vitro the NSAIDs, aspirin, indomethacin, diclofenac, piroxicam and ibuprofen, which feature different chemical structures, are able to inhibit mitochondrial complex I. All NSAIDs were effective inhibitors when added both, directly to mitochondria isolated from rat duodenum epithelium (50 μM) or to Caco-2 cells (250 μM). In the former system, complex I inhibition was concentration-dependent and susceptible to competition and reversion by the addition of coenzyme Q (32.5-520 μM). Based on reports suggesting a potential gastro-protective activity of quercetin, the ability of this flavonoid to protect isolated mitochondria against NSAIDs-induced complex I inhibition was evaluated. Low micromolar concentrations of quercetin (1-20 μM) protected against such inhibition, in a concentration dependent manner. In the case of aspirin, quercetin (5 μM) increased the IC50 by 10-fold. In addition, the present study shows that quercetin (5-10 μM) can behave as a "coenzyme Q-mimetic" molecule, allowing a normal electron flow along the whole electron transporting chain (complexes I, II, III and IV). The exposed findings reveal that complex I inhibition is a common deleterious effect of NSAIDs at the mitochondrial level, and that such effect is, for all tested agents, susceptible to be prevented by quercetin. Data provided here supports the contention that the protective action of quercetin resides on its, here for first time-shown, ability to behave as a coenzyme Q-like molecule. PMID:22652335

  3. ND3, ND1 and 39 kDa subunits are more exposed in the de-active form of bovine mitochondrial complex I

    PubMed Central

    Babot, Marion; Labarbuta, Paola; Birch, Amanda; Kee, Sara; Fuszard, Matthew; Botting, Catherine H.; Wittig, Ilka; Heide, Heinrich; Galkin, Alexander

    2014-01-01

    An intriguing feature of mitochondrial complex I from several species is the so-called A/D transition, whereby the idle enzyme spontaneously converts from the active (A) form to the de-active (D) form. The A/D transition plays an important role in tissue response to the lack of oxygen and hypoxic deactivation of the enzyme is one of the key regulatory events that occur in mitochondria during ischaemia. We demonstrate for the first time that the A/D conformational change of complex I does not affect the macromolecular organisation of supercomplexes in vitro as revealed by two types of native electrophoresis. Cysteine 39 of the mitochondrially-encoded ND3 subunit is known to become exposed upon de-activation. Here we show that even if complex I is a constituent of the I + III2 + IV (S1) supercomplex, cysteine 39 is accessible for chemical modification in only the D-form. Using lysine-specific fluorescent labelling and a DIGE-like approach we further identified two new subunits involved in structural rearrangements during the A/D transition: ND1 (MT-ND1) and 39 kDa (NDUFA9). These results clearly show that structural rearrangements during de-activation of complex I include several subunits located at the junction between hydrophilic and hydrophobic domains, in the region of the quinone binding site. De-activation of mitochondrial complex I results in concerted structural rearrangement of membrane subunits which leads to the disruption of the sealed quinone chamber required for catalytic turnover. PMID:24560811

  4. Depleted energy charge and increased pulmonary endothelial permeability induced by mitochondrial complex I inhibition are mitigated by coenzyme Q1 in the isolated perfused rat lung.

    PubMed

    Bongard, Robert D; Yan, Ke; Hoffmann, Raymond G; Audi, Said H; Zhang, Xiao; Lindemer, Brian J; Townsley, Mary I; Merker, Marilyn P

    2013-12-01

    Mitochondrial dysfunction is associated with various forms of lung injury and disease that also involve alterations in pulmonary endothelial permeability, but the relationship, if any, between the two is not well understood. This question was addressed by perfusing isolated intact rat lung with a buffered physiological saline solution in the absence or presence of the mitochondrial complex I inhibitor rotenone (20 μM). Compared to control, rotenone depressed whole lung tissue ATP from 5.66 ± 0.46 (SEM) to 2.34 ± 0.15 µmol · g(-1) dry lung, with concomitant increases in the ADP:ATP and AMP:ATP ratios. Rotenone also increased lung perfusate lactate (from 12.36 ± 1.64 to 38.62 ± 3.14 µmol · 15 min(-1) perfusion · g(-1) dry lung) and the lactate:pyruvate ratio, but had no detectable impact on lung tissue GSH:GSSG redox status. The amphipathic quinone coenzyme Q1 (CoQ1; 50 μM) mitigated the impact of rotenone on the adenine nucleotide balance, wherein mitigation was blocked by NAD(P)H-quinone oxidoreductase 1 or mitochondrial complex III inhibitors. In separate studies, rotenone increased the pulmonary vascular endothelial filtration coefficient (Kf) from 0.043 ± 0.010 to 0.156 ± 0.037 ml · min(-1) · cm H2O(-1) · g(-1) dry lung, and CoQ1 protected against the effect of rotenone on Kf. A second complex I inhibitor, piericidin A, qualitatively reproduced the impact of rotenone on Kf and the lactate:pyruvate ratio. Taken together, the observations imply that pulmonary endothelial barrier integrity depends on mitochondrial bioenergetics as reflected in lung tissue ATP levels and that compensatory activation of whole lung glycolysis cannot protect against pulmonary endothelial hyperpermeability in response to mitochondrial blockade. The study further suggests that low-molecular-weight amphipathic quinones may have therapeutic utility in protecting lung barrier function in mitochondrial insufficiency. PMID:23912160

  5. Depleted energy charge and increased pulmonary endothelial permeability induced by mitochondrial complex I inhibition are mitigated by coenzyme Q1 in the isolated perfused rat lung

    PubMed Central

    Bongard, Robert D.; Yan, Ke; Hoffmann, Raymond G.; Audi, Said H.; Zhang, Xiao; Lindemer, Brian J.; Townsley, Mary I.; Merker, Marilyn P.

    2013-01-01

    Mitochondrial dysfunction is associated with various forms of lung injury and disease that also involve alterations in pulmonary endothelial permeability, but the relationship, if any, between the two is not well understood. This question was addressed by perfusing the isolated intact rat lung with a buffered physiological saline solution in the absence or presence of the mitochondrial complex I inhibitor rotenone (20 uM). As compared to control, rotenone depressed whole lung tissue ATP from 5.66 ± 0.46 (SEM) to 2.34 ± 0.15 (SEM) μmol·gram−1 dry lung, with concomitant increases in the ADP:ATP and AMP:ATP ratios. Rotenone also increased lung perfusate lactate (from 12.36 ± 1.64 (SEM) to 38.62 ± 3.14 μmol·15 min−1 perfusion·gm−1 dry lung) and the lactate:pyruvate ratio, but had no detectable impact on lung tissue GSH:GSSG redox status. The amphipathic quinone, coenzyme Q1 (CoQ1; 50 μM) mitigated the impact of rotenone on the adenine nucleotide balance, wherein mitigation was blocked by NAD(P)H:quinone oxidoreductase 1 (NQO1) or mitochondrial complex III inhibitors. In separate studies, rotenone increased the pulmonary vascular endothelial filtration coefficient (Kf) from 0.043 ± 0.010 (SEM) to 0.156 ± 0.037 (SEM) ml·min−1·cm H2O−1·gm−1 dry lung weight, and CoQ1 protected against the effect of rotenone on Kf. A second complex I inhibitor, piericidin A, qualitatively reproduced the impact of rotenone on Kf and the lactate/pyruvate ratio. Taken together, the observations imply that pulmonary endothelial barrier integrity depends on mitochondrial bioenergetics as reflected in lung tissue ATP levels and that compensatory activation of whole lung glycolysis cannot protect against pulmonary endothelial hyperpermeability in response to mitochondrial blockade. The study further suggests that low molecular weight amphipathic quinones may have therapeutic utility in protecting lung barrier function in mitochondrial insufficiency. PMID:23912160

  6. Crystallization and structure determination of a symmetrical 'football' complex of the mammalian mitochondrial Hsp60-Hsp10 chaperonins.

    PubMed

    Nisemblat, Shahar; Parnas, Avital; Yaniv, Oren; Azem, Abdussalam; Frolow, Felix

    2014-01-01

    The mitochondrial Hsp60-Hsp10 complex assists the folding of various proteins impelled by ATP hydrolysis, similar to the bacterial chaperonins GroEL and GroES. The near-atomic structural details of the mitochondrial chaperonins are not known, despite the fact that almost two decades have passed since the structures of the bacterial chaperonins became available. Here, the crystallization procedure, diffraction experiments and structure determination by molecular replacement of the mammalian mitochondrial chaperonin HSP60 (E321K mutant) and its co-chaperonin Hsp10 are reported. PMID:24419632

  7. Identification of an iridium(III) complex with anti-bacterial and anti-cancer activity

    PubMed Central

    Lu, Lihua; Liu, Li-Juan; Chao, Wei-chieh; Zhong, Hai-Jing; Wang, Modi; Chen, Xiu-Ping; Lu, Jin-Jian; Li, Ruei-nian; Ma, Dik-Lung; Leung, Chung-Hang

    2015-01-01

    Group 9 transition metal complexes have been widely explored as therapeutic agents due to their unique geometry, their propensity to undergo ligand exchanges with biomolecules and their diverse steric and electronic properties. These metal complexes can offer distinct modes of action in living organisms compared to carbon-based molecules. In this study, we investigated the antimicrobial and anti-proliferative abilities of a series of cyclometallated iridium(III) complexes. The iridium(III) complex 1 inhibited the growth of S. aureus with MIC and MBC values of 3.60 and 7.19 μM, respectively, indicating its potent bactericidal activity. Moreover, complex 1 also exhibited cytotoxicity against a number of cancer cell lines, with particular potency against ovarian, cervical and melanoma cells. This cyclometallated iridium(III) complex is the first example of a substitutionally-inert, Group 9 organometallic compound utilized as a direct and selective inhibitor of S. aureus. PMID:26416333

  8. Insight into the flagella type III export revealed by the complex structure of the type III ATPase and its regulator.

    PubMed

    Imada, Katsumi; Minamino, Tohru; Uchida, Yumiko; Kinoshita, Miki; Namba, Keiichi

    2016-03-29

    FliI and FliJ form the FliI6FliJ ATPase complex of the bacterial flagellar export apparatus, a member of the type III secretion system. The FliI6FliJ complex is structurally similar to the α3β3γ complex of F1-ATPase. The FliH homodimer binds to FliI to connect the ATPase complex to the flagellar base, but the details are unknown. Here we report the structure of the homodimer of a C-terminal fragment of FliH (FliHC2) in complex with FliI. FliHC2 shows an unusually asymmetric homodimeric structure that markedly resembles the peripheral stalk of the A/V-type ATPases. The FliHC2-FliI hexamer model reveals that the C-terminal domains of the FliI ATPase face the cell membrane in a way similar to the F/A/V-type ATPases. We discuss the mechanism of flagellar ATPase complex formation and a common origin shared by the type III secretion system and the F/A/V-type ATPases. PMID:26984495

  9. NDUFA12L mitochondrial complex-I assembly factor: Implications for taupathies

    PubMed Central

    Salama, Mohamed; Mohamed, Wael M.Y.

    2015-01-01

    There is a strong correlation between taupathies and the development and progression of neurodegenerative disorders. Abnormal tau becomes hyperphosphorylated and dissociated from microtubules with the aggregation of intracellular tau aggregates within the patient's brain. The current review is divided into two broad sections. In the first section we discuss the molecular biology and the clinicopathologic features of taupathies. While in the second section we discuss the relationship between mitochondrial complex-I and taupathies. Polymorphism in NDUFA12L may be a crucial factor for development of neurodegenerative taupathies. Thus NDUFA12L screening may be an early biomarker for identifying risk groups for such disorders. PMID:26937358

  10. Human Mitochondrial Transcription Initiation Complexes Have Similar Topology on the Light and Heavy Strand Promoters.

    PubMed

    Morozov, Yaroslav I; Temiakov, Dmitry

    2016-06-24

    Transcription is a highly regulated process in all domains of life. In human mitochondria, transcription of the circular genome involves only two promoters, called light strand promoter (LSP) and heavy strand promoter (HSP), located in the opposite DNA strands. Initiation of transcription occurs upon sequential assembly of an initiation complex that includes mitochondrial RNA polymerase (mtRNAP) and the initiation factors mitochondrial transcription factor A (TFAM) and TFB2M. It has been recently suggested that the transcription initiation factor TFAM binds to HSP and LSP in opposite directions, implying that the mechanisms of transcription initiation are drastically dissimilar at these promoters. In contrast, we found that binding of TFAM to HSP and the subsequent recruitment of mtRNAP results in a pre-initiation complex that is remarkably similar in topology and properties to that formed at the LSP promoter. Our data suggest that assembly of the pre-initiation complexes on LSP and HSP brings these transcription units in close proximity, providing an opportunity for regulatory proteins to simultaneously control transcription initiation in both mtDNA strands. PMID:27226527

  11. Neurofibromatosis Type 1: A Novel NF1 Mutation Associated with Mitochondrial Complex I Deficiency

    PubMed Central

    Isidoro, Lara; Rocha, Dalila

    2014-01-01

    Background. Neurofibromatosis type 1 is a multisystemic, progressive disease, with an estimated incidence of 1/3500-2500. Mitochondrial diseases are generally multisystemic and may be present at any age, and the global prevalence is 1/8500. The diagnosis of these disorders is complex because of its clinical and genetic heterogeneity. Case Report. We present a rare case of the association of these two different genetic diseases, in which a heterozygous missense mutation in the NF1 gene was identified which had not yet been described (p.M1149 V). Additionally, the patient is suspected of carrying an unspecified mutation causing respiratory chain complex I deficiency. Clinical presentation included hypotonia, global development delay, reduced growth rate, progressive microcephaly, and numerous café-au-lait spots. Discussion. To the best of our knowledge this is the first report of complex I deficiency in a patient with neurofibromatosis type 1. It is very important to maintain a high index of suspicion for the diagnosis of mitochondrial disorders. In this patient, both the laboratory screening and muscle histology were normal and only the biochemical study of muscle allowed us to confirm the diagnosis. PMID:24711935

  12. Synthesis, spectroscopic characterization and antibacterial studies of lanthanide(III) Schiff base complexes containing N, O donor atoms

    NASA Astrophysics Data System (ADS)

    Lekha, L.; Raja, K. Kanmani; Rajagopal, G.; Easwaramoorthy, D.

    2014-01-01

    A series of six Ln(III) Schiff base complexes, Pr(III), Sm(III), Gd(III), Tb(III), Er(III) and Yb(III), were synthesized using sodium salt of Schiff base, 2-[(5-bromo-2-hydroxy-benzylidene)-amino]-3-hydroxy-propionic acid, derived from L-serine and 5-bromosalicylaldehyde. These complexes having general formula [Ln(L)(NO3)2(H2O)]·NO3 were characterized by elemental analysis, conductivity measurements, UV-Vis, FT-IR, mass spectrometry and fluorescence studies. Elemental analysis and conductivity measurements suggest the complexes have a 1:1 stoichiometry. From the spectral studies it has been concluded that Ln(III) complexes display eight coordination. The Schiff base and its Ln(III) metal complexes have also been screened for their antibacterial activities by Agar diffusion method.

  13. Study of holmium (III) and yttrium(III) with DOTA complexes as candidates for radiopharmaceutical use

    NASA Astrophysics Data System (ADS)

    Ernestová, M.; Jedináková-Křížová, V.

    2003-01-01

    Reaction conditions for complexation of radionuclides with DOTA were studied using thinlayer chromatography (TLC), paper chromatography (PC) and potentiometry. It was found that all of the studied complexes can reach very high radiochemical yield about 95%. Optimal conditions for obtaining such high radiochemical yields are as follows: pH higher than 4 and the excess of chelating agent must be minimally 3∶1. Potentiometric study showed that the formation of complexes is characterised by very slow kinetics.

  14. Novel Luminescent Probe Based on a Terbium(III) Complex for Hemoglobin Determination

    NASA Astrophysics Data System (ADS)

    Yegorova, A. V.; Leonenko, I. I.; Aleksandrova, D. I.; Scrypynets, Yu. V.; Antonovich, V. P.; Ukrainets, I. V.

    2014-09-01

    We have studied the spectral luminescent properties of Tb(III) and Eu(III) complexes with a number of novel derivatives of oxoquinoline-3-carboxylic acid amides (L1-L5 ). We have observed quenching of the luminescence of 1:1 Tb(III)-L1-5 complexes by hemoglobin (Hb), which is explained by resonance energy transfer of electronic excitation from the donor (Tb(III)-L1-5 ) to the acceptor (Hb). Using the novel luminescent probe Tb(III)-L1, we have developed a method for determining Hb in human blood. The calibration Stern-Volmer plot is linear in the Hb concentration range 0.6-36.0 μg/mL, detection limit 0.2 μg/mL (3·10-9 mol/L).

  15. Dipyrrinphenol-Mn(III) complex: synthesis, electrochemistry, spectroscopic characterisation and reactivity.

    PubMed

    El Ghachtouli, Sanae; Wójcik, Karolina; Copey, Laurent; Szydlo, Florence; Framery, Eric; Goux-Henry, Catherine; Billon, Laurianne; Charlot, Marie-France; Guillot, Régis; Andrioletti, Bruno; Aukauloo, Ally

    2011-09-28

    Herein, we report the manganese complex with a novel trianionic ligand, the pentafluorophenyldipyrrinphenol ligand DPPH(3). The X-ray crystal structure reveals that the Mn(III) complex exists in a dimeric form in the solid state. Electrochemical studies indicate two quasi-reversible one electron oxidation processes. EPR data on the one electron oxidised species in solution support the formation of a monuclear Mn complex with an S = 3/2 spin system. Preliminary studies towards epoxidation reactions were tested in the presence of iodosylbenzene (PhIO) and are in favour of an oxygen-atom-transfer (OAT) reaction catalyzed by the Mn(III) complex. PMID:21842061

  16. A mononuclear nonheme iron(III)-superoxo complex: Crystallographic and spectroscopic characterization and reactivities

    PubMed Central

    Hong, Seungwoo; Sutherlin, Kyle D.; Park, Jiyoung; Kwon, Eunji; Siegler, Maxime A.; Solomon, Edward I.; Nam, Wonwoo

    2016-01-01

    Mononuclear nonheme iron(III)-superoxo species (FeIII-O2−•) have been implicated as key intermediates in the catalytic cycles of dioxygen activation by nonheme iron enzymes. Although nonheme iron(III)-superoxo species have been trapped and characterized spectroscopically in enzymatic and biomimetic reactions, no structural information has yet been obtained. Here we report for the first time the isolation, spectroscopic characterization, and crystal structure of a mononuclear side-on (η2) iron(III)-superoxo complex with a tetraamido macrocyclic ligand (TAML), [FeIII (TAML) (O2)]2− (1). The nonheme iron(III)-superoxo species undergoes both electrophilic and nucleophilic oxidation reactions as well as O2-transfer between metal complexes. In the O2-transfer reaction, 1 transfers the bound O2 unit to a manganese(III) analogue, resulting in the formation of a manganese(IV)-peroxo complex, [MnIV(TAML)(O2)]2− (2); 2 is characterized structurally and spectroscopically as a mononuclear side-on (η2) manganese(IV)-peroxo complex. The difference in the redox distribution between the metal ions and O2 in 1 and 2 is rationalized using density functional theory calculations. PMID:25510711

  17. Effects of reactive Mn(III)-oxalate complexes on structurally intact plant cell walls

    NASA Astrophysics Data System (ADS)

    Summering, J. A.; Keiluweit, M.; Goni, M. A.; Nico, P. S.; Kleber, M.

    2011-12-01

    Lignin components in the in plant litter are commonly assumed to have longer residence times in soil than many other compounds, which are supposedly, more easily degradable. The supposed resistance of lignin compounds to decomposition is generally attributed to the complex chain of biochemical steps required to create footholds in the non-porous structure of ligno-cellulose in cell walls. Interestingly, Mn(III) complexes have shown the ability to degrade ligno-cellulose. Mn(III) chelated by ligands such as oxalate are soluble oxidizers with a high affinity for lignin structures. Here we determined (i) the formation and decay kinetics of the Mn(III)-oxalate complexes in aqueous solution and (ii) the effects that these complexes have on intact ligno-cellulose. UV/vis spectroscopy and iodometric titrations confirmed the transient nature of Mn(III)-oxalate complexes with decay rates being in the order of hours. Zinnia elegans tracheary elements - a model ligno-cellulose substrate - were treated with Mn(III)-oxalate complexes in a newly developed flow-through reactor. Soluble decomposition products released during the treatment were analyzed by GC/MS and the degree of cell integrity was measured by cell counts, pre- and post-treatment counts indicate a decrease in intact Zinnia elegans as a result of Mn(III)-treatment. GC/MS results showed the release of a multitude of solubilized lignin breakdown products from plant cell walls. We conclude that Mn(III)-oxalate complexes have the ability to lyse intact plant cells and solubilize lignin. Lignin decomposition may thus be seen as resource dependent, with Mn(III) a powerful resource that should be abundant in terrestrial characterized by frequent redox fluctuations.

  18. Cr(III), Fe(III) and Co(III) complexes of tetradentate (ONNO) Schiff base ligands: Synthesis, characterization, properties and biological activity

    NASA Astrophysics Data System (ADS)

    Keskioğlu, Eren; Gündüzalp, Ayla Balaban; Çete, Servet; Hamurcu, Fatma; Erk, Birgül

    2008-08-01

    A series of metal complexes were synthesized from equimolar amounts of Schiff bases: 1,4-bis[3-(2-hydroxy-1-naphthaldimine)propyl]piperazine (bappnaf) and 1,8-bis[3-(2-hydroxy-1-naphthaldimine)- p-menthane (damnaf) with metal chlorides. All of synthesized compounds were characterized by elemental analyses, spectral (UV-vis, IR, 1H- 13C NMR, LC-MS) and thermal (TGA-DTA) methods, magnetic and conductance measurements. Schiff base complexes supposed in tetragonal geometry have the general formula [M(bappnaf or damnaf)]Cl· nH 2O, where M = Cr(III), Co(III) and n = 2, 3. But also Fe(III) complexes have octahedral geometry by the coordination of two water molecules and the formula is [Fe(bappnaf or damnaf)(H 2O) 2]Cl. The changes in the selected vibration bands in FT-IR indicate that Schiff bases behave as (ONNO) tetradentate ligands and coordinate to metal ions from two phenolic oxygen atoms and two azomethine nitrogen atoms. Conductance measurements suggest 1:1 electrolytic nature of the metal complexes. The synthesized compounds except bappnaf ligand have the antimicrobial activity against the bacteria: Escherichia coli (ATCC 11230), Yersinia enterocolitica (ATCC 1501), Bacillus magaterium (RSKK 5117), Bacillus subtilis (RSKK 244), Bacillus cereus (RSKK 863) and the fungi: Candida albicans (ATCC 10239). These results have been considerably interest in piperazine derivatives due to their significant applications in antimicrobial studies.

  19. Spectral characterization of iron(III) complexes of 2-benzoylpyridine N(4)-substituted thiosemicarbazones

    NASA Astrophysics Data System (ADS)

    Joseph, Marthakutty; Sreekanth, Anandaram; Suni, V.; Kurup, M. R. Prathapachandra

    2006-06-01

    Three iron(III) complexes (1-3) of 2-benzoylpyridine N(4)-phenyl thiosemicarbazone (HL 1) and one iron(III) complex (4) of 2-benzoylpyridine N(4)-cyclohexyl thiosemicarbazone (HL 2) were synthesized and characterized by means of different physicochemical techniques viz., molar conductivity measurements, magnetic susceptibility studies and electronic, infrared and EPR spectral studies. The analytical data and the molar conductance measurements of the complexes reveal that two molecules of the ligand and the anion are coordinated to the metal atom in all the four complexes. The magnetic moments of the complexes suggest that they are of low spin. From the infrared spectra of the ligands and the complexes it is confirmed that the ligands coordinate to iron(III) as an anion coordinating via the azomethine nitrogen, pyridyl nitrogen, and the thiolate sulphur. The EPR spectra of the complexes in the polycrystalline state at 298 and 110 K and in DMF solution at 110 K were recorded and all the spectra show three g values indicating that these complexes have rhombic distortion. All the iron(III) complexes in DMF solution at 110 K have similar anisotropic spectra with almost the same gav values, indicating that the bonding in all the complexes is similar and is unaffected by the coordination of the anion.

  20. Death-associated protein kinase as a sensor of mitochondrial membrane potential: role of lysosome in mitochondrial toxin-induced cell death.

    PubMed

    Shang, Tiesong; Joseph, Joy; Hillard, Cecilia J; Kalyanaraman, B

    2005-10-14

    We have investigated here the mechanism of dephosphorylation and activation of death-associated protein kinase (DAPK) and the role of lysosome in neuroblastoma cells (SH-SY5Y) treated with mitochondrial toxins, such as MPP(+) and rotenone. Mitochondrial respiratory chain inhibitors and uncouplers decreased mitochondrial membrane potential leading to DAPK dephosphorylation and activation. The class III phosphoinositide 3-kinase inhibitors attenuated DAPK dephosphorylation induced by mitochondrial toxins. Complex I inhibition by mitochondrial toxins (e.g. MPP(+)) resulted in mitochondrial swelling and lysosome reduction. Inhibition of class III phosphoinositide 3-kinase attenuated MPP(+)-induced lysosome reduction and cell death. The role of DAPK as a sensor of mitochondrial membrane potential in mitochondrial diseases was addressed. PMID:16085644

  1. Preparation and characterization of a microcrystalline non-heme FeIII(OOH) complex powder: EPR reinvestigation of FeIII(OOH) complexes-improvement of the perturbation equations for the g tensor of low-spin FeIII.

    PubMed

    Martinho, Marlène; Dorlet, Pierre; Rivière, Eric; Thibon, Aurore; Ribal, Caroline; Banse, Frédéric; Girerd, Jean-Jacques

    2008-01-01

    The first example of a microcrystalline powder of a synthetic low-spin (LS) mononuclear Fe(III)(OOH) intermediate has been obtained by the precipitation of the [Fe(III)(L(5) (2))(OOH)](2+) complex at low temperature. The high purity of this thermally unstable powder is revealed by magnetic susceptibility measurements. EPR studies on this complex, in the solid state and also in frozen solution, are reported and reveal the coexistence of two related Fe(III)(OOH) species in both states. We also present a theoretical analysis of the g tensor for LS Fe(III) complexes, based on new perturbation equations. These simple equations provide distortion-energy parameters that are in good agreement with those obtained by a full-diagonalization calculation. PMID:18240118

  2. The pH dependence of Am(III) complexation with acetate: an EXAFS study.

    PubMed

    Fröhlich, Daniel R; Skerencak-Frech, Andrej; Bauer, Nicole; Rossberg, André; Panak, Petra J

    2015-01-01

    The complexation of acetate with Am(III) is studied as a function of the pH (1-6) by extended X-ray absorption fine-structure (EXAFS) spectroscopy. The molecular structure of the Am(III)-acetate complexes (coordination numbers, oxygen and carbon distances) is determined from the raw k(3)-weighted Am LIII-edge EXAFS spectra. The results show a continuous shift of Am(III) speciation with increasing pH value towards the complexed species. Furthermore, it is verified that acetate coordinates in a bidentate coordination mode to Am(III) (Am-C distance: 2.82 ± 0.03 Å). The EXAFS data are analyzed by iterative transformation factor analysis to further verify the chemical speciation, which is calculated on the basis of thermodynamic constants, and the used structural model. The experimental results are in very good agreement with the thermodynamic modelling. PMID:25537594

  3. “Scanning mutagenesis” of the amino acid sequences flanking phosphorylation site 1 of the mitochondrial pyruvate dehydrogenase complex

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The mitochondrial pyruvate dehydrogenase complex is regulated by reversible seryl-phosphorylation of the E1alpha subunit by a dedicated, intrinsic kinase. The phospho-complex is reactivated when dephosphorylated by an intrinsic PP2C-type protein phosphatase. Both the position of the phosphorylated...

  4. Solvation structure and thermodynamics for Pr(III), Nd(III) and Dy(III) complexes in ionic liquids evaluated by Raman spectroscopy and DFT calculation

    NASA Astrophysics Data System (ADS)

    Kuribara, Keita; Matsumiya, Masahiko; Tsunashima, Katsuhiko

    2016-12-01

    The coordination states of trivalent praseodymium, neodymium, and dysprosium complexes in the ionic liquid, triethyl-n-pentylphosphonium bis(trifluoromethyl-sulfonyl) amide ([P2225][TFSA]) were investigated by Raman spectroscopy. The effect of the concentration of rare earth ions on the Raman spectra was investigated, ranging from 0.23 to 0.45 mol kg-1 of Pr(III), Nd(III), and Dy(III) in [P2225][TFSA]. Based on a conventional analysis, the solvation numbers, n, of Pr(III), Nd(III), and Dy(III) in [P2225][TFSA] were determined to be 4.99, 5.01, and 5.00 at 298 K and 5.04, 5.06, and 5.07 at 373 K, respectively. Thermodynamic properties such as ΔisoG, ΔisoH, and ΔisoS for the isomerism of [TFSA]- from trans- to cis-coordinated isomer in the bulk and the first solvation sphere of the central RE3+ (RE = Pr, Nd, and Dy) cation in [P2225][TFSA] were evaluated from the temperature dependence of the Raman bands, measured at temperatures ranging from 298 to 398 K. Regarding the bulk properties, ΔisoG(bulk), ΔisoH(bulk), and TΔisoS(bulk) at 298 K were found to be -1.06, 6.86, and 7.92 kJ mol-1, respectively. The trans-[TFSA]- was a dominant contributor to the enthalpy, as shown by the positive value of ΔisoH(bulk). The value of TΔisoS(bulk) was slightly larger than that of ΔisoH(bulk), and cis-[TFSA]- was, therefore, entropy-controlled in [P2225][TFSA]. In contrast, in the first solvation sphere of the RE3+ cation, ΔisoH(RE) became remarkably negative, suggesting that cis-[TFSA]- isomers were stabilized by enthalpic contributions. Furthermore, ΔisoH(RE) contributed to the remarkable decrease in ΔisoG(RE), and this result clearly indicates that cis-[TFSA]- conformers bound to RE3+ cations are the preferred coordination state of [RE(III)(cis-TFSA)5]2- in [P2225][TFSA]. Moreover, optimized geometries and binding energies of [Pr(III)(cis-TFSA)5]2-, [Nd(III)(cis-TFSA)5]2-, and [Dy(III)(cis-TFSA)5]2- clusters were also investigated by DFT calculations using the ADF

  5. Integrity of the core mitochondrial RNA-binding complex 1 is vital for trypanosome RNA editing.

    PubMed

    Huang, Zhenqiu; Faktorová, Drahomíra; Křížová, Adéla; Kafková, Lucie; Read, Laurie K; Lukeš, Julius; Hashimi, Hassan

    2015-12-01

    Trypanosoma brucei is the causative agent of the human and veterinarian diseases African sleeping sickness and nagana. A majority of its mitochondrial-encoded transcripts undergo RNA editing, an essential process of post-transcriptional uridine insertion and deletion to produce translatable mRNA. Besides the well-characterized RNA editing core complex, the mitochondrial RNA-binding 1 (MRB1) complex is one of the key players. It comprises a core complex of about six proteins, guide RNA-associated proteins (GAPs) 1/2, which form a heterotetramer that binds and stabilizes gRNAs, plus MRB5390, MRB3010, and MRB11870, which play roles in initial stages of RNA editing, presumably guided by the first gRNA:mRNA duplex in the case of the latter two proteins. To better understand all functions of the MRB1 complex, we performed a functional analysis of the MRB8620 core subunit, the only one not characterized so far. Here we show that MRB8620 plays a role in RNA editing in both procyclic and bloodstream stages of T. brucei, which reside in the tsetse fly vector and mammalian circulatory system, respectively. While RNAi silencing of MRB8620 does not affect procyclic T. brucei fitness when grown in glucose-containing media, it is somewhat compromised in cells grown in the absence of this carbon source. MRB8620 is crucial for integrity of the MRB1 core, such as its association with GAP1/2, which presumably acts to deliver gRNAs to this complex. In contrast, GAP1/2 is not required for the fabrication of the MRB1 core. Disruption of the MRB1 core assembly is followed by the accumulation of mRNAs associated with GAP1/2. PMID:26447184

  6. Mitochondrial respiratory chain Complexes I and IV are impaired by β-amyloid via direct interaction and through Complex I-dependent ROS production, respectively.

    PubMed

    Bobba, A; Amadoro, G; Valenti, D; Corsetti, V; Lassandro, R; Atlante, A

    2013-07-01

    Here we investigate the effect of β-amyloid on mitochondrial respiratory function, i.e. mitochondrial oxygen consumption and membrane potential generation as well as the individual activities of both the mitochondrial Complexes I-IV, that compose mitochondrial electron transport chain, and the ATP synthase, by using homogenate from cerebellar granule cells, treated with low concentrations of β-amyloid, and Alzheimer synaptic-enriched brain samples. We found that β-amyloid caused both a selective defect in Complex I activity associated with an increase (5 fold) of intracellular reactive oxygen species and an impairment of Complex IV likely due to membrane lipid peroxidation. In addition, a 130% increase of the GSSG/GSH ratio was measured in Alzheimer brains with respect to age-matched controls. Knowing the mechanisms of action of β-amyloid could allow to mitigate or even to interrupt the toxic cascade that leads a cell to death. The results of this study represent an important innovation because they offer the possibility to act at mitochondrial level and on specific sites to protect cells, for example by preventing the interaction of β-amyloid with the identified targets, by stabilizing or by restoring mitochondrial function or by interfering with the energy metabolism. PMID:23562762

  7. Cytosolic DNA triggers mitochondrial apoptosis via DNA damage signaling proteins independently of AIM2 and RNA polymerase III.

    PubMed

    Wenzel, Michael; Wunderlich, Michael; Besch, Robert; Poeck, Hendrik; Willms, Simone; Schwantes, Astrid; Kremer, Melanie; Sutter, Gerd; Endres, Stefan; Schmidt, Andreas; Rothenfusser, Simon

    2012-01-01

    A key host response to limit microbial spread is the induction of cell death when foreign nucleic acids are sensed within infected cells. In mouse macrophages, transfected DNA or infection with modified vaccinia virus Ankara (MVA) can trigger cell death via the absent in melanoma 2 (AIM2) inflammasome. In this article, we show that nonmyeloid human cell types lacking a functional AIM2 inflammasome still die in response to cytosolic delivery of different DNAs or infection with MVA. This cell death induced by foreign DNA is independent of caspase-8 and carries features of mitochondrial apoptosis: dependence on BAX, APAF-1, and caspase-9. Although it does not require the IFN pathway known to be triggered by infection with MVA or transfected DNA via polymerase III and retinoid acid-induced gene I-like helicases, it shows a strong dependence on components of the DNA damage signaling pathway: cytosolic delivery of DNA or infection with MVA leads to phosphorylation of p53 (serines 15 and 46) and autophosphorylation of ataxia telangiectasia mutated (ATM); depleting p53 or ATM with small interfering RNA or inhibiting the ATM/ATM-related kinase family by caffeine strongly reduces apoptosis. Taken together, our findings suggest that a pathway activating DNA damage signaling plays an important independent role in detecting intracellular foreign DNA, thereby complementing the induction of IFN and activation of the AIM2 inflammasome. PMID:22140256

  8. Astrocyte-Specific Overexpression of Nrf2 Protects Striatal Neurons from Mitochondrial Complex II Inhibition

    PubMed Central

    Calkins, Marcus J.; Vargas, Marcelo R.; Johnson, Delinda A.; Johnson, Jeffrey A.

    2010-01-01

    Nuclear factor E2-related factor 2 (Nrf2) is a transcription factor that is known to regulate a variety of cytoprotective genes through the antioxidant response element (ARE). This endogenous response is one of the major pathways by which cells are protected from xenobiotic or innate oxidative insults. Furthermore, in neural systems, astrocyte-specific activation of Nrf2 is known to protect neurons. In previous work, our laboratory found that Nrf2 protects from intrastriatal injections of the mitochondrial complex II inhibitor malonate. Here, we extend these results to show that multiple methods of astrocyte-specific Nrf2 overexpression provide protection from neurotoxicity in vivo. GFAP-Nrf2 transgenic mice are significantly more resistant to malonate lesioning. This outcome is associated with an increased basal resistance, but more so, an enhanced Nrf2 response to lesioning that attenuated the ensuing neurotoxicity. Furthermore, striatal transplantation of neuroprogenitor cells overexpressing Nrf2 that differentiate into astrocytes after grafting also significantly reduced malonate toxicity. Overall, these data establish that enhanced astrocytic Nrf2 response and Nrf2 preconditioning are both sufficient to protect from acute lesions from mitochondrial complex II inhibition. PMID:20211941

  9. Molecular Modeling Analysis of the Inhibition of Mitochondrial Cytochrome BC1 Complex Activity by Tocol Derivatives

    NASA Astrophysics Data System (ADS)

    Singh, Awantika; Hauer-Jensen, Martin; Compadre, Cesar M.; Kumar, K. Sree

    2011-06-01

    The biological functions of vitamin E related compounds have been of interest in biomedical research for several decades. Among those compounds, α-, β-, δ-, and γ-tocopherols and their oxidation products, α-, β-, δ-, γ-tocopherylquinone and their analogs α-TQo, γ-TQo, TMC20 and TMC40 were recently shown to inhibit the mitochondrial cytochrome bc1 complex. In this investigation the effects of the structural variation on the inhibition of the mitochondrial cytochrome bc1 complex were analyzed using Comparative Molecular Field Analysis (CoMFA). CoMFA performed using steric and electrostatic molecular fields produced a very good correlation. The best CoMFA models were obtained using the manual alignment of 12 compounds with 5 components (q2 = 0.589, SPRESS = 0.515, r2 = 0.992, s = 0.068 and F value = 156.520). The resulting contour maps produced by the best CoMFA model were helpful in identifying the structural features required for the biological activity of compounds under study. These results would be helpful for predicting the activity of new compounds, and they could be used for guiding the design, synthesis and development of new and more effective agents.

  10. Electrical properties of nanofibers and structural characterization of DNA-Au(III) complexes.

    PubMed

    Kwon, Young-Wan; Lee, Chang Hoon; Jin, Jung-Il; Hwang, Jong Seung; Hwang, Sung Woo

    2014-05-23

    In order to realize deoxyribonucleic acid (DNA)-based molecular electronics, chemical modifications of DNA are needed to improve electrical conductivity. We developed a novel method utilizing the incorporation of Au(III) ions into DNA bases to alter their electronic properties. When Au(III) ions were incorporated proportionally into DNA bases, conductance increased up to an Au(III) content of 0.42 Au(III) ion/nucleotide. Surprisingly, electron paramagnetic resonance signals of Au(II) ions were detected at g ∼1.98, and the calculated spin number of Au(II) ions ranged from ∼10(13) to ∼10(15). The structural deformation of the DNA helix occurred when complexed with Au(III); simultaneously, the conductance of DNA-Au(III) complexes decreased when the content of Au(III) was higher than 0.42 atom/nucleotide. This observation implies that the maintenance of helical structure in the Au(III) doped state of DNA molecules is very important to the enhancement of the carrier mobility of DNA. PMID:24786616

  11. Complete Mitochondrial Complex I Deficiency Induces an Up-Regulation of Respiratory Fluxes That Is Abolished by Traces of Functional Complex I.

    PubMed

    Kühn, Kristina; Obata, Toshihiro; Feher, Kristen; Bock, Ralph; Fernie, Alisdair R; Meyer, Etienne H

    2015-08-01

    Complex I (NADH:ubiquinone oxidoreductase) is central to cellular NAD(+) recycling and accounts for approximately 40% of mitochondrial ATP production. To understand how complex I function impacts respiration and plant development, we isolated Arabidopsis (Arabidopsis thaliana) lines that lack complex I activity due to the absence of the catalytic subunit NDUFV1 (for NADH:ubiquinone oxidoreductase flavoprotein1) and compared these plants with ndufs4 (for NADH:ubiquinone oxidoreductase Fe-S protein4) mutants possessing trace amounts of complex I. Unlike ndufs4 plants, ndufv1 lines were largely unable to establish seedlings in the absence of externally supplied sucrose. Measurements of mitochondrial respiration and ATP synthesis revealed that compared with ndufv1, the complex I amounts retained by ndufs4 did not increase mitochondrial respiration and oxidative phosphorylation capacities. No major differences were seen in the mitochondrial proteomes, cellular metabolomes, or transcriptomes between ndufv1 and ndufs4. The analysis of fluxes through the respiratory pathway revealed that in ndufv1, fluxes through glycolysis and the tricarboxylic acid cycle were dramatically increased compared with ndufs4, which showed near wild-type-like fluxes. This indicates that the strong growth defects seen for plants lacking complex I originate from a switch in the metabolic mode of mitochondria and an up-regulation of respiratory fluxes. Partial reversion of these phenotypes when traces of active complex I are present suggests that complex I is essential for plant development and likely acts as a negative regulator of respiratory fluxes. PMID:26134164

  12. Complete Mitochondrial Complex I Deficiency Induces an Up-Regulation of Respiratory Fluxes That Is Abolished by Traces of Functional Complex I1[OPEN

    PubMed Central

    Kühn, Kristina; Obata, Toshihiro; Feher, Kristen; Bock, Ralph; Fernie, Alisdair R.; Meyer, Etienne H.

    2015-01-01

    Complex I (NADH:ubiquinone oxidoreductase) is central to cellular NAD+ recycling and accounts for approximately 40% of mitochondrial ATP production. To understand how complex I function impacts respiration and plant development, we isolated Arabidopsis (Arabidopsis thaliana) lines that lack complex I activity due to the absence of the catalytic subunit NDUFV1 (for NADH:ubiquinone oxidoreductase flavoprotein1) and compared these plants with ndufs4 (for NADH:ubiquinone oxidoreductase Fe-S protein4) mutants possessing trace amounts of complex I. Unlike ndufs4 plants, ndufv1 lines were largely unable to establish seedlings in the absence of externally supplied sucrose. Measurements of mitochondrial respiration and ATP synthesis revealed that compared with ndufv1, the complex I amounts retained by ndufs4 did not increase mitochondrial respiration and oxidative phosphorylation capacities. No major differences were seen in the mitochondrial proteomes, cellular metabolomes, or transcriptomes between ndufv1 and ndufs4. The analysis of fluxes through the respiratory pathway revealed that in ndufv1, fluxes through glycolysis and the tricarboxylic acid cycle were dramatically increased compared with ndufs4, which showed near wild-type-like fluxes. This indicates that the strong growth defects seen for plants lacking complex I originate from a switch in the metabolic mode of mitochondria and an up-regulation of respiratory fluxes. Partial reversion of these phenotypes when traces of active complex I are present suggests that complex I is essential for plant development and likely acts as a negative regulator of respiratory fluxes. PMID:26134164

  13. Preparation of manganese(II), chromium(III) and ferric(III) oxides nanoparticles in situ metal citraconate complexes frameworks

    NASA Astrophysics Data System (ADS)

    Refat, Moamen S.

    2014-12-01

    The new reactions of some divalent and trivalent transition metal ions (Mn(II), Cr(III), and Fe(III)) with citraconic acid has been studied. The obtained results indicate the formation of citraconic acid compounds with molar ratio of metal to citraconic acid of 2:2 or 2:3 with general formulas Mn2(C5H4O4)2 or M2(C5H4O4)3ṡnH2O where n = 6 for Cr, and Fe(III). The thermal decomposition of the crystalline solid complexes was investigated. The IR spectra of citraconate suggested that the carboxylic groups are bidentatically bridging and chelating. In the course of decomposition the complexes are dehydrated and then decompose either directly to oxides in only one step or with intermediate formation of oxocarbonates. This proposal dealing the preparation of MnO2, Fe2O3 and Cr2O3 nanoparticles. The crystalline structure of oxide products were checked by X-ray powder diffraction (XRD), and the morphology of particles by scanning electron microscopy (SEM).

  14. Preparation of manganese(II), chromium(III) and ferric(III) oxides nanoparticles in situ metal citraconate complexes frameworks.

    PubMed

    Refat, Moamen S

    2014-12-10

    The new reactions of some divalent and trivalent transition metal ions (Mn(II), Cr(III), and Fe(III)) with citraconic acid has been studied. The obtained results indicate the formation of citraconic acid compounds with molar ratio of metal to citraconic acid of 2:2 or 2:3 with general formulas Mn2(C5H4O4)2 or M2(C5H4O4)3⋅nH2O where n=6 for Cr, and Fe(III). The thermal decomposition of the crystalline solid complexes was investigated. The IR spectra of citraconate suggested that the carboxylic groups are bidentatically bridging and chelating. In the course of decomposition the complexes are dehydrated and then decompose either directly to oxides in only one step or with intermediate formation of oxocarbonates. This proposal dealing the preparation of MnO2, Fe2O3 and Cr2O3 nanoparticles. The crystalline structure of oxide products were checked by X-ray powder diffraction (XRD), and the morphology of particles by scanning electron microscopy (SEM). PMID:24952090

  15. Organometallic rhodium(III) and iridium(III) cyclopentadienyl complexes with curcumin and bisdemethoxycurcumin co-ligands.

    PubMed

    Pettinari, Riccardo; Marchetti, Fabio; Pettinari, Claudio; Condello, Francesca; Petrini, Agnese; Scopelliti, Rosario; Riedel, Tina; Dyson, Paul J

    2015-12-21

    A series of half-sandwich cyclopentadienyl rhodium(III) and iridium(III) complexes of the type [Cp*M(curc/bdcurc)Cl] and [Cp*M(curc/bdcurc)(PTA)][SO3CF3], in which Cp* = pentamethylcyclopentadienyl, curcH = curcumin and bdcurcH = bisdemethoxycurcumin as O^O-chelating ligands, and PTA = 1,3,5-triaza-7-phosphaadamantane, is described. The X-ray crystal structures of three of the complexes, i.e. [Cp*Rh(curc)(PTA)][SO3CF3] (5), [Cp*Rh(bdcurc)(PTA)][SO3CF3] (6) and [Cp*Ir(bdcurc)(PTA)][SO3CF3] (8), confirm the expected "piano-stool" geometry. With the exception of 5, the complexes are stable under pseudo-physiological conditions and are moderately cytotoxic to human ovarian carcinoma (A2780 and A2780cisR) cells and also to non-tumorigenic human embryonic kidney (HEK293) cells, but lack the cancer cell selectivity observed for related arene ruthenium(II) complexes. PMID:26548708

  16. Complexation Studies of Bidentate Heterocyclic N-Donor Ligands with Nd(III) and Am(III)

    SciTech Connect

    Ogden, Mark; Hoch, Courtney L.; Sinkov, Sergey I.; Meier, Patrick; Lumetta, Gregg J.; Nash, Kenneth L.

    2011-11-28

    A new bidentate nitrogen donor complexing agent that combines pyridine and triazole functional groups, 2-((4-phenyl-1H-1,2,3-triazol-1-yl)methyl)pyridine (PTMP), has been synthesized. The strength of its complexes with trivalent americium (Am3+) and neodymium (Nd3+) in anhydrous methanol has been evaluated using spectrophotometric techniques. The purpose of this investigation is to assess this ligand (as representative of a class of similarly structured species) as a possible model compound for the challenging separation of trivalent actinides from lanthanides. This separation, important in the development of advanced nuclear fuel cycles, is best achieved through the agency of multidentate chelating agents containing some number of nitrogen or sulfur donor groups. To evaluate the relative strength of the bidentate complexes, the derived constants are compared to those of the same metal ions with 2,2*-bipyridyl (bipy), 1,10-phenanthroline (phen), and 2-pyridin-2-yl-1H-benzimidazole (PBIm). At issue is the relative affinity of the triazole moiety for trivalent f element ions. For all ligands, the derived stability constants are higher for Am3+ than Nd3+. In the case of Am3+ complexes with phen and PBIm, the presence of 1:2 (AmL2) species is indicated. Possible separations are suggested based on the relative stability and stoichiometry of the Am3+ and Nd3+ complexes. It can be noted that the 1,2,3-triazolyl group imparts a potentially useful selectivity for trivalent actinides (An(III)) over trivalent lanthanides (Ln(III)), though the attainment of higher complex stoichiometries in actinide compared with lanthanide complexes may be an important driver for developing successful separations.

  17. Internal switches modulating electron tunneling currents in respiratory complex III.

    PubMed

    Hagras, Muhammad A; Stuchebrukhov, Alexei A

    2016-06-01

    In different X-ray crystal structures of bc1 complex, some of the key residues of electron tunneling pathways are observed in different conformations; here we examine their relative importance in modulating electron transfer and propose their possible gating function in the Q-cycle. The study includes inter-monomeric electron transfer; here we provide atomistic details of the reaction, and discuss the possible roles of inter-monomeric electronic communication in bc(1) complex. Binding of natural ligands or inhibitors leads to local conformational changes which propagate through protein and control the conformation of key residues involved in the electron tunneling pathways. Aromatic-aromatic interactions are highly utilized in the communication network since the key residues are aromatic in nature. The calculations show that there is a substantial change of the electron transfer rates between different redox pairs depending on the different conformations acquired by the key residues of the complex. PMID:26874053

  18. A multisubunit complex of outer and inner mitochondrial membrane protein translocases stabilized in vivo by translocation intermediates.

    PubMed

    Schülke, N; Sepuri, N B; Gordon, D M; Saxena, S; Dancis, A; Pain, D

    1999-08-01

    Translocation of nuclear encoded preproteins into the mitochondrial matrix requires the coordinated action of two translocases: one (Tom) located in the outer mitochondrial membrane and the other (Tim) located in the inner membrane. These translocases reversibly cooperate during protein import. We have previously constructed a chimeric precursor (pPGPrA) consisting of an authentic mitochondrial precursor at the N terminus (Delta(1)-pyrroline-5-carboxylate dehydrogenase, pPut) linked, through glutathione S-transferase, to protein A. When pPGPrA is expressed in yeast, it becomes irreversibly arrested during translocation across the outer and inner mitochondrial membranes. Consequently, the two membranes of mitochondria become progressively "zippered" together, forming long stretches in which they are in close contact (Schülke, N., Sepuri, N. B. V., and Pain, D. (1997) Proc. Natl. Acad. Sci. U. S. A. 94, 7314-7319). We now demonstrate that trapped PGPrA intermediates hold the import channels stably together and inhibit mitochondrial protein import and cell growth. Using IgG-Sepharose affinity chromatography of solubilized zippered membranes, we have isolated a multisubunit complex that contains all Tom and Tim components known to be essential for import of matrix-targeted proteins, namely Tom40, Tom22, Tim17, Tim23, Tim44, and matrix-localized Hsp70. Further characterization of this complex may shed light on structural features of the complete mitochondrial import machinery. PMID:10428870

  19. Sensitization of visible and NIR emitting lanthanide(III) ions in noncentrosymmetric complexes of hexafluoroacetylacetone and unsubstituted monodentate pyrazole.

    PubMed

    Ahmed, Zubair; Iftikhar, K

    2013-11-01

    A series of highly volatile eight-coordinate air and moisture stable lanthanide complexes of the type [Ln(hfaa)3(L)2] (Ln = Pr (1), Nd (2), Eu (3), Gd (4), Tb (5), Dy (6), Ho (7), Er (8), Tm (9), and Yb (10); hfaa = anion of hexafluoroacetylacetone and L = pyrazole) have been synthesized and characterized by elemental analysis, IR, ESI-MS(+), and NMR studies. Single-crystal X-ray structures have been determined for the Eu(III) and Dy(III) complexes. These complexes crystallize in the monoclinic space group P2(1)/c. The lanthanide ion in each of these complexes is eight-coordinate with six oxygen atoms from three hfaa and two N-atoms from two pyrazole units, forming a coordination polyhedron best describable as a distorted square antiprism. The NMR spectra reveal that both the pyrazole units remain attached to the metal in solution and the β-diketonate and pyrazole protons are shifted in opposite directions in the case of paramagnetic complexes. The lanthanide-induced chemical shifts are dipolar in nature. The hypersensitive transitions of Nd(III), Ho(III), and Er(III) are sensitive to the environment (solvent), which is reflected by the oscillator strength and band shape of these transitions. The band shape due to the hypersensitive transition of Nd(III) in noncoordinating chloroform and dichloromethane is similar to those of the typical eight-coordinate Nd(III) β-diketonate complexes. The quantum yield and lifetime of Pr(III), Eu(III), Tb(III), Dy(III), and Tm(III) in visible and Pr(III), Nd(III), Dy(III), Ho(III), Er(III) Tm(III), and Yb(III) in the NIR region are sizable. The environment around these metal ions is asymmetric, which leads to increased radiative rates and luminescence efficiencies. The quantum yield of the complexes reveal that ligand-to-metal energy transfer follows the order Eu(III) > Tb(III) ≫ Pr(III) > Dy(III) > Tm(III). Both ligands (hfaa and pyrazole) are good sensitizers for all the visible and NIR emitters effectively, except for Tb(III

  20. Mechanisms of cell death pathway activation following drug-induced inhibition of mitochondrial complex I

    PubMed Central

    Imaizumi, Naoki; Kwang Lee, Kang; Zhang, Carmen; Boelsterli, Urs A.

    2015-01-01

    Respiratory complex I inhibition by drugs and other chemicals has been implicated as a frequent mode of mitochondria-mediated cell injury. However, the exact mechanisms leading to the activation of cell death pathways are incompletely understood. This study was designed to explore the relative contributions to cell injury of three distinct consequences of complex I inhibition, i.e., impairment of ATP biosynthesis, increased formation of superoxide and, hence, peroxynitrite, and inhibition of the mitochondrial protein deacetylase, Sirt3, due to imbalance of the NADH/NAD+ ratio. We used the antiviral drug efavirenz (EFV) to model drug-induced complex I inhibition. Exposure of cultured mouse hepatocytes to EFV resulted in a rapid onset of cell injury, featuring a no-effect level at 30 µM EFV and submaximal effects at 50 µM EFV. EFV caused a concentration-dependent decrease in cellular ATP levels. Furthermore, EFV resulted in increased formation of peroxynitrite and oxidation of mitochondrial protein thiols, including cyclophilin D (CypD). This was prevented by the superoxide scavenger, Fe-TCP, or the peroxynitrite decomposition catalyst, Fe-TMPyP. Both ferroporphyrins completely protected from EFV-induced cell injury, suggesting that peroxynitrite contributed to the cell injury. Finally, EFV increased the NADH/NAD+ ratio, inhibited Sirt3 activity, and led to hyperacetylated lysine residues, including those in CypD. However, hepatocytes isolated from Sirt3-null mice were protected against 40 µM EFV as compared to their wild-type controls. In conclusion, these data are compatible with the concept that chemical inhibition of complex I activates multiple pathways leading to cell injury; among these, peroxynitrite formation may be the most critical. PMID:25625582

  1. EXAFS studies of americium (III)-benzimidazole complex in ethanol.

    PubMed

    Yaita, T; Tachimori, S; Edelstein, N M; Bucher, J J; Rao, L; Shuh, D K; Allen, P G

    2001-03-01

    The local structures of Am, Nd and Er-Benzimidazole (Biz) in solution were determined by EXAFS. The BIZ molecule coordinated to Am and Nd through two nitrogen atoms in a bidentate fashion. Two nitrogen atoms of BIZ ligated to Am and Nd with the bond distances R(Am-n) N=2.63A and R(Nd-N) = 2.65 A, respectively. The total coordination number of the Am BIZ complexes (at a molar ratio of metal ion to ligand of 1:20) was approximately 10 but that of Nd BIZ complex was approximately 9. PMID:11512888

  2. Synthesis and characterization of a new Inonotus obliquus polysaccharide-iron(III) complex.

    PubMed

    Wang, Jia; Chen, Haixia; Wang, Yanwei; Xing, Lisha

    2015-04-01

    A new Inonotus obliquus polysaccharide-iron(III) complex (IOPS-iron) was synthesized and characterized. The preparation conditions of IOPS-iron(III) were optimized and the physicochemical properties were characterized by physicochemical methods, scanning electron microscopy (SEM), electron paramagnetic resonance (EPR) spectroscopy, fourier transform infrared (FTIR) spectroscopy, circular dichroism (CD) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy, respectively. The highest iron content of IOPS-iron(III) complex (19.40%) was obtained at the conditions: the ratio of IOPS and FeCl3 • 6H2O was 3:5 (w/w), the pH value of alkali solution was 10, the reaction temperature was 30 °C and the reaction time was 6h. The iron(III) was shown to be bound through the binding sites of the polysaccharide IOPS and it could form spatially separated iron centers on the polysaccharide backbone. IOPS-iron(III) complex was found to have good digestive availability and antioxidant activities in the in vitro assays, which suggested the IOPS-iron(III) complex might be used as a new iron supplement candidate. PMID:25643995

  3. NIR-FT-Raman spectroscopic studies of hexammine and pentammine chromium(III) complexes

    NASA Astrophysics Data System (ADS)

    Chen, Yuying; Christensen, Daniel H.; Sørensen, Georg O.; Nielsen, Ole Faurskov; Jacobsen, Claus J. H.; Hyldtoft, Jens

    1994-03-01

    The NIR-FT-Raman spectra are presented for the hexammine [Cr(NH 3) 6]X 3 (where X = Br -, NO -3), pentamminechloro [Cr(NH 3) 5Cl]X 2 (where X = Cl -, ClO -4), and pentammineaqua [Cr(NH 3) 5(H 2O)]X 3 (where X = ClO -4, CF 3SO -3) chromium(III) complexes. The NIR-FT-Raman spectra, with an excitation wavelength of 1064 nm, were obtained at room temperature without problems from the strongly colored samples, which often cause problems with excitation by lasers in the visible region. All the Raman frequencies observed from the complexes have been assigned to the skeleton vibrational region from 100 to 600 cm -1. The symmetry and the general valence force constants for the bonds chromium(III)nitrogen, chromium(III)oxygen and chromium(III)chloro have been obtained. The nature of the metalligand bond between chromium(III) ammine complexes has been compared with recent results obtained for similar cobalt(III) ammine complexes.

  4. A novel photo-responsive europium(iii) complex for advanced anti-counterfeiting and encryption.

    PubMed

    Mei, Jin-Feng; Lv, Zhong-Peng; Lai, Jian-Cheng; Jia, Xiao-Yong; Li, Cheng-Hui; Zuo, Jing-Lin; You, Xiao-Zeng

    2016-04-01

    A novel europium(iii) complex simultaneously exhibiting photocolorimetric and photofluorometric behavior was obtained. Multiple distinguishable identities can be obtained and reversibly modulated using light as external stimuli. With this novel photo-responsive complex, double encryption and advanced anti-counterfeiting were realized. PMID:26961725

  5. Characterization of lanthanide(III) DOTP complexes: Thermodynamics, protonation, and coordination to alkali metal ions

    SciTech Connect

    Sherry, A.D.; Ren, J.; Huskens, J.

    1996-07-31

    The chemical and thermodynamic characterization of Lanthanide(III) DOTP complexes was performed. Spectrophotometry, potentiometry, osmometry, and NMR spectroscopy were used in this characterization. Stability constants, protonation equilibria, and interactions of the complexes with alkali metal ions were measured and summarized.

  6. Luminescent characteristics of some mesogenic tris(β-diketonate) europium(III) complexes with Lewis bases

    NASA Astrophysics Data System (ADS)

    Romanova, K. A.; Datskevich, N. P.; Taidakov, I. V.; Vitukhnovskii, A. G.; Galyametdinov, Yu. G.

    2013-12-01

    Luminescent properties of liquid-crystalline tris(β-diketonate) europium(III) complexes with Lewis bases (substituted 2,2'-bipyridine and 1,10-phenantroline) are investigated. Absolute and relative quantum yields and lifetimes are determined. Absorption, excitation, and emission spectra of the complexes are investigated.

  7. Characterization of Hydrogen Complex Formation in III-V Semiconductors

    SciTech Connect

    Williams, Michael D

    2006-09-28

    Atomic hydrogen has been found to react with some impurity species in semiconductors. Hydrogenation is a methodology for the introduction of atomic hydrogen into the semiconductor for the express purpose of forming complexes within the material. Efforts to develop hydrogenation as an isolation technique for AlGaAs and Si based devices failed to demonstrate its commercial viability. This was due in large measure to the low activation energies of the formed complexes. Recent studies of dopant passivation in long wavelength (0.98 - 1.55m) materials suggested that for the appropriate choice of dopants much higher activation energies can be obtained. This effort studied the formation of these complexes in InP, This material is extensively used in optoelectronics, i.e., lasers, modulators and detectors. The experimental techniques were general to the extent that the results can be applied to other areas such as sensor technology, photovoltaics and to other material systems. The activation energies for the complexes have been determined and are reported in the scientific literature. The hydrogenation process has been shown by us to have a profound effect on the electronic structure of the materials and was thoroughly investigated. The information obtained will be useful in assessing the long term reliability of device structures fabricated using this phenomenon and in determining new device functionalities.

  8. Plane Transformations in a Complex Setting III: Similarities

    ERIC Educational Resources Information Center

    Dana-Picard, Thierry

    2009-01-01

    This is the third part of a study of plane transformations described in a complex setting. After the study of homotheties, translations, rotations and reflections, we proceed now to the study of plane similarities, either direct or inverse. Their group theoretical properties are described, and their action on classical geometrical objects is…

  9. A general access to organogold(iii) complexes by oxidative addition of diazonium salts.

    PubMed

    Huang, Long; Rominger, Frank; Rudolph, Matthias; Hashmi, A Stephen K

    2016-05-11

    At room temperature under mild photochemical conditions, namely irradiation with a simple blue light LED, gold(i) chloro complexes of both phosphane and carbene ligands in combination with aryldiazonium salts afford arylgold(iii) complexes. With chelating P,N-ligands cationic six- or five-membered chelate complexes were isolated in the form of salts with weakly coordinating counter anions that were brought in from the diazonium salt. With monodentate P ligands or N-heterocyclic carbene ligands and diazonium chlorides neutral arylgold(iii) dichloro complexes were obtained. The coordination geometry was determined by X-ray crystal structure analyses of representative compounds, a cis arrangement of the aryl and the phosphane ligand at the square planar gold(iii) center is observed. PMID:27094217

  10. GSK3 inactivation is involved in mitochondrial complex IV defect in transforming growth factor (TGF) {beta}1-induced senescence

    SciTech Connect

    Byun, Hae-Ok; Jung, Hyun-Jung; Seo, Yong-Hak; Lee, Young-Kyoung; Hwang, Sung-Chul; Seong Hwang, Eun; Yoon, Gyesoon

    2012-09-10

    Transforming growth factor {beta}1 (TGF {beta}1) induces Mv1Lu cell senescence by persistently producing mitochondrial reactive oxygen species (ROS) through decreased complex IV activity. Here, we investigated the molecular mechanism underlying the effect of TGF {beta}1 on mitochondrial complex IV activity. TGF {beta}1 progressively phosphorylated the negative regulatory sites of both glycogen synthase kinase 3 (GSK3) {alpha} and {beta}, corresponding well to the intracellular ROS generation profile. Pre-treatment of N-acetyl cysteine, an antioxidant, did not alter this GSK3 phosphorylation (inactivation), whereas pharmacological inhibition of GSK3 by SB415286 significantly increased mitochondrial ROS, implying that GSK3 phosphorylation is an upstream event of the ROS generation. GSK3 inhibition by SB415286 decreased complex IV activity and cellular O{sub 2} consumption rate and eventually induced senescence of Mv1Lu cell. Similar results were obtained with siRNA-mediated knockdown of GSK3. Moreover, we found that GSK3 not only exists in cytosol but also in mitochondria of Mv1Lu cell and the mitochondrial GSK3 binds complex IV subunit 6b which has no electron carrier and is topologically located in the mitochondrial intermembrane space. Involvement of subunit 6b in controlling complex IV activity and overall respiration rate was proved with siRNA-mediated knockdown of subunit 6b. Finally, TGF {beta}1 treatment decreased the binding of the subunit 6b to GSK3 and subunit 6b phosphorylation. Taken together, our results suggest that GSK3 inactivation is importantly involved in TGF {beta}1-induced complex IV defects through decreasing phosphorylation of the subunit 6b, thereby contributing to senescence-associated mitochondrial ROS generation.

  11. Formation of Soluble Organo-Chromium(III) Complexes after Chromate Reduction in the Presence of Cellular Organics

    SciTech Connect

    Puzon, Geoffrey J.; Roberts, Arthur G.; Kramer, David M.; Xun, Luying

    2005-04-01

    Microbial reduction of hexavalent chromium [Cr(VI)] to trivalent chromium [Cr(III)] has been investigated as a method for bioremediation of Cr(VI) contaminated environments. The produced Cr(III) is thought to be insoluble Cr(OH)3; however, recent reports suggested a more complex fate of Cr(III). A bacterial enzyme system, using NADH as the reductant, converts Cr(VI) to a soluble NAD+-Cr(III) complex, and cytochrome c-mediated Cr(VI) reduction produces cytochrome c-Cr(III) adducts. In this study, Cr(VI) reduction in the presence of cellular organic metabolites formed both soluble and insoluble organo-Cr(III) end-products. Several soluble end-products were characterized by absorbance spectroscopy and electron paramagnetic resonance spectrometry as organo-Cr(III) complexes, similar to the known ascorbate-Cr(III) complex. The complexes remained soluble and stable upon dialysis against distilled H2O and over a broad pH range. The ready formation of stable organo-Cr(III) complexes suggests that organo-Cr(III) complexes are rather common, likely representing an integral part of the natural cycling of chromium. Finally, thus, organo-Cr(III) complexes may account for the mobile form of Cr(III) detected in the environment.

  12. Epistatic interactions modulate the evolution of mammalian mitochondrial respiratory complex components

    PubMed Central

    Azevedo, Luísa; Carneiro, João; van Asch, Barbara; Moleirinho, Ana; Pereira, Filipe; Amorim, António

    2009-01-01

    Background The deleterious effect of a mutation can be reverted by a second-site interacting residue. This is an epistatic compensatory process explaining why mutations that are deleterious in some species are tolerated in phylogenetically related lineages, rendering evident that those mutations are, by all means, only deleterious in the species-specific context. Although an extensive and refined theoretical framework on compensatory evolution does exist, the supporting evidence remains limited, especially for protein models. In this current study, we focused on the molecular mechanism underlying the epistatic compensatory process in mammalian mitochondrial OXPHOS proteins using a combination of in-depth structural and sequence analyses. Results Modeled human structures were used in this study to predict the structural impairment and recovery of deleterious mutations alone and combined with an interacting compensatory partner, respectively. In two cases, COI and COIII, intramolecular interactions between spatially linked residues restore the folding pattern impaired by the deleterious mutation. In a third case, intermolecular contact between mitochondrial CYB and nuclear CYT1 encoded components of the cytochrome bc1 complex are likely to restore protein binding. Moreover, we observed different modes of compensatory evolution that have resulted in either a quasi-simultaneous occurrence of a mutation and corresponding compensatory partner, or in independent occurrences of mutations in distinct lineages that were always preceded by the compensatory site. Conclusion Epistatic interactions between individual replacements involving deleterious mutations seems to follow a parsimonious model of evolution in which genomes hold pre-compensating states that subsequently tolerate deleterious mutations. This phenomenon is likely to have been constraining the variability at coevolving sites and shaping the interaction between the mitochondrial and the nuclear genome. PMID

  13. Synthesis, characterization and DNA-binding studies on La(III) and Ce(III) complexes containing ligand of N-phenyl-2-pyridinecarboxamide

    NASA Astrophysics Data System (ADS)

    He, Xin-Qian; Lin, Qiu-Yue; Hu, Rui-Ding; Lu, Xiao-Hong

    2007-09-01

    La(III) and Ce(III) complexes containing ligand of N-phenyl-2-pyridinecarboxamide (HL) were synthesized and characterized by elemental analyses, conductivity measurement, IR spectra and thermal analysis. The general formulas of the complexes were [Ln(HL) 3(H 2O) 2](NO 3) 3·2H 2O [Ln = La(III), Ce(III)]. The results indicated that the oxygen of carbonyl and the nitrogen of pyridyl coordinated to Ln(III), and there were also two water molecules taking part in coordination. Ln(III) and HL formed 1:3 chelate complexes and the coordination number was eight. The interaction between the complexes and DNA was studied by means of UV-vis spectra, fluorescence spectra, SERS spectra and agarose gel electrophoresis. The results showed that complexes can bind to DNA. The binding ability decreased in following order: La(III) complex, Ce(III) complex, and HL. The interaction modes between DNA and the three compounds were found to be mainly intercalative.

  14. (Porphyrinato)bis(phthalocyaninato)dilanthanide(III) complexes presenting a sandwich triple-decker-like structure

    SciTech Connect

    Moussavi, M.; De Cian, A.; Fischer, J.; Weiss, R.

    1986-06-18

    Bis(phthalocyaninato)lanthanide(III) derivatives presenting a sandwich-type structure have been known for many years. These complexes are still intensively studied due to their semi-conductor and electrochromic properties. The synthesis and properties of bis(porphyrinato) and tris(porphyrinato)lanthanide(III) derivatives have also been reported. X-ray structural studies have shown that bis(porphyrinato) complexes have geometries that are similar to those displayed by the LnPc/sub 2/ complexes (Ln = lanthanide; Pc = phthalocyanine) whereas the tris(porphyrinato) derivatives present structures in which two lanthanide(III) metal cations are sandwiched between three macrocyclic rings in triple-decker-like geometry. Structural, magnetic, and spectroscopic properties of the green form of lutetium(III) bis(phthalocyanate) have shown that this complex is in a nonprotonated, one-electron-oxidized ligand form, Ln (Pc/sup 2 -/) (Pc..pi..). In such a molecule, the unpaired spin could be either located on one phthalocyanine ring or delocalized over both rings. In order to force the localization of the unpaired spin on one ring, the authors have tried to synthesize a dissymmetric mixed-ligand, porphyrin (Por) phthalocyanine (Pc), lanthanide sandwich Ln(Por)(Pc). However, under the conditions used, the authors obtained dilanthanide sandwich-triple-decker-like complexes. (Por(Ln)Pc(Ln)Pc) in which the two metal cations are sandwiched between three macrocyclic rings. They report the synthesis and spectral properties of such derivatives obtained with Ln = Nd(III), Eu(III), and Gd(III) and with meso-tetrakis(4-methoxyphenyl) porphyrin (H/sub 2/T(4-OCH/sub 3/)PP) and phthalocyanine (H/sub 2/Pc). The X-ray structure of the neodymim complex is also reported.

  15. A spectrophotometric study of Am(III) complexation with nitrate in aqueous solution at elevated temperatures.

    PubMed

    Tian, Guoxin; Shuh, David K

    2014-10-21

    The complexation of americium(iii) with nitrate was studied at temperatures from 10 to 85 °C in 1 M HNO3-HClO4 by spectrophotometry. The 1 : 1 complex species, AmNO3(2+), was identified and the stability constants were calculated from the absorption spectra recorded for titrations at several temperatures. Specific ion interaction theory (SIT) was used for ionic strength corrections to obtain the stability constants of AmNO3(2+) at infinite dilution and variable temperatures. The absorption spectra of Am(iii) in diluted HClO4 were also reviewed, and the molar absorptivity of Am(iii) at around 503 nm and 813 nm was re-calibrated by titrations with standardized DTPA solutions to determine the concentration of Am(iii). PMID:24999760

  16. Synthesis, spectral and electrochemical studies of binuclear Ru(III) complexes containing dithiosemicarbazone ligand

    NASA Astrophysics Data System (ADS)

    Kanchana Devi, A.; Ramesh, R.

    2014-01-01

    Synthesis of several new octahedral binuclear ruthenium(III) complexes of the general composition [(EPh3)2(X)Ru-L-Ru(X)(EPh3)2] containing benzene dithiosemicarbazone ligands (where E = P or As; X = Cl or Br; L = binucleating ligands) is presented. All the complexes have been fully characterized by elemental analysis, FT-IR, UV-vis and EPR spectroscopy together with magnetic susceptibility measurements. IR study shows that the dithiosemicarbazone ligands behave as dianionic tridentate ligands coordinating through the oxygen atom of the deprotonated phenolic group, nitrogen atom of the azomethine group and thiolate sulphur. In DMF solution, all the complexes exhibit intense d-d transition and ligand-to-metal charge transfer (LMCT) transition in the visible region. The magnetic moment values of the complexes are in the range 1.78-1.82 BM, which reveals the presence of one unpaired electron on each metal ion. The EPR spectra of the liquid samples at LNT show the presence of three different 'g' values (gx ≠ gy ≠ gz) indicate a rhombic distortion around the ruthenium ion. All the complexes exhibit two quasi-reversible one electron oxidation responses (RuIII-RuIII/RuIII-RuIV; RuIII-RuIV/RuIV-RuIV) within the E1/2 range of 0.61-0.74 V and 0.93-0.98 V respectively, versus Ag/AgCl.

  17. Visible-light sensitized luminescent europium(III)-β-diketonate complexes: bioprobes for cellular imaging.

    PubMed

    Reddy, M L P; Divya, V; Pavithran, Rani

    2013-11-21

    Visible-light sensitized luminescent europium(III) molecular materials are of considerable importance because their outstanding photophysical properties make them well suited as labels in fluorescence-based bioassays and low-voltage driven pure red-emitters in optoelectronic technology. One challenge in this field is development of visible-light sensitizing ligands that can form highly emissive europium(III) complexes with sufficient stability and aqueous solubility for practical applications. Indeed, some of the recent reports have demonstrated that the excitation-window can be shifted to longer-wavelengths in europium(III)-β-diketonate complexes by appropriate molecular engineering and suitably expanded π-conjugation in the complex molecules. In this review, attention is focused on the latest innovations in the syntheses and photophysical properties of visible-light sensitized europium(III)-β-diketonate complexes and their application as bioprobes for cellular imaging. Furthermore, luminescent nanomaterials derived from long-wavelength sensitized europium(III)-β-diketonate complexes and their application in life sciences are also highlighted. PMID:24076753

  18. Luminescent Iridium(III) Complex Labeled DNA for Graphene Oxide-Based Biosensors.

    PubMed

    Zhao, Qingcheng; Zhou, Yuyang; Li, Yingying; Gu, Wei; Zhang, Qi; Liu, Jian

    2016-02-01

    There has been growing interest in utilizing highly photostable iridium(III) complexes as new luminescent probes for biotechnology and life science. Herein, iridium(III) complex with carboxyl group was synthesized and activated with N-hydroxysuccinimide, followed by tagging to the amino terminate of single-stranded DNA (ssDNA). The Ir-ssDNA probe was further combined with graphene oxide (GO) nanosheets to develop a GO-based biosensor for target ssDNA detection. The quenching efficiency of GO, and the photostability of iridium(III) complex and GO-Ir-ssDNA biosensor, were also investigated. On the basis of the high luminescence quenching efficiency of GO toward iridium(III) complex, the GO-Ir-ssDNA biosensor exhibited minimal background signals, while strong emission was observed when Ir-ssDNA desorbed from GO nanosheets and formed a double helix with the specific target, leading to a high signal-to-background ratio. Moreover, it was found that luminescent intensities of iridium(III) complex and GO-Ir-ssDNA biosensor were around 15 and 3 times higher than those of the traditional carboxyl fluorescein (FAM) dye and the GO-FAM-ssDNA biosensor after UV irradiation, respectively. Our study suggested the sensitive and selective Ir-ssDNA probe was suitable for the development of highly photostable GO-based detection platforms, showing promise for application beyond the OLED (organic light emitting diode) area. PMID:26753824

  19. Toxic variability and radiation potentiation by Rh(III) complexes in Salmonella typhimurium cells

    SciTech Connect

    Richmond, R.C.; O'Hara, J.; Picker, D.H.; Douple, E.B.

    1986-12-01

    Stationary-phase cells of Salmonella typhimurium were irradiated in phosphate-buffered saline in the presence of rhodium complexes to test for the potentiation of radiation-induced cell killing. Eleven Rh complexes, two Rh(I) and nine Rh(III), were tested. Seven Rh(III) complexes were found to be radiation potentiators; six potentiate only under hypoxic conditions, and one potentiates under both hypoxic and oxic conditions. Four of these seven Rh(III) complexes demonstrate potentiation that is 2 to 13 times greater than the sensitization caused by oxygen. Irradiating cells in Ham's F-12 culture medium rather than in phosphate-buffered saline eliminates this latter hypoxic radiation potentiation. None of the seven Rh(III) radiation potentiators are directly toxic to cells. However, four complexes were tested for hypoxic radiation-induced cytocidal toxicity, and three were found to be toxic after irradiation. The efficiency of this toxicity is not sufficient to account for the observed radiation potentiation. It is suggested that both reductive and oxidative free radical events are involved in the spectrum of Rh(III) potentiation observed.

  20. Synthesis, spectral and electrochemical studies of binuclear Ru(III) complexes containing dithiosemicarbazone ligand.

    PubMed

    Kanchana Devi, A; Ramesh, R

    2014-01-01

    Synthesis of several new octahedral binuclear ruthenium(III) complexes of the general composition [(EPh3)2(X)Ru-L-Ru(X)(EPh3)2] containing benzene dithiosemicarbazone ligands (where E=P or As; X=Cl or Br; L=binucleating ligands) is presented. All the complexes have been fully characterized by elemental analysis, FT-IR, UV-vis and EPR spectroscopy together with magnetic susceptibility measurements. IR study shows that the dithiosemicarbazone ligands behave as dianionic tridentate ligands coordinating through the oxygen atom of the deprotonated phenolic group, nitrogen atom of the azomethine group and thiolate sulphur. In DMF solution, all the complexes exhibit intense d-d transition and ligand-to-metal charge transfer (LMCT) transition in the visible region. The magnetic moment values of the complexes are in the range 1.78-1.82 BM, which reveals the presence of one unpaired electron on each metal ion. The EPR spectra of the liquid samples at LNT show the presence of three different 'g' values (gx≠gy≠gz) indicate a rhombic distortion around the ruthenium ion. All the complexes exhibit two quasi-reversible one electron oxidation responses (Ru(III)-Ru(III)/Ru(III)-Ru(IV); Ru(III)-Ru(IV)/Ru(IV)-Ru(IV)) within the E1/2 range of 0.61-0.74 V and 0.93-0.98 V respectively, versus Ag/AgCl. PMID:23988528

  1. [Tl(III)(dota)](-): An Extraordinarily Robust Macrocyclic Complex.

    PubMed

    Fodor, Tamás; Bányai, István; Bényei, Attila; Platas-Iglesias, Carlos; Purgel, Mihály; Horváth, Gábor L; Zékány, László; Tircsó, Gyula; Tóth, Imre

    2015-06-01

    The X-ray structure of {C(NH2)3}[Tl(dota)]·H2O shows that the Tl(3+) ion is deeply buried in the macrocyclic cavity of the dota(4-) ligand (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate) with average Tl-N and Tl-O distances of 2.464 and 2.365 Å, respectively. The metal ion is directly coordinated to the eight donor atoms of the ligand, which results in a twisted square antiprismatic (TSAP') coordination around Tl(3+). A multinuclear (1)H, (13)C, and (205)Tl NMR study combined with DFT calculations confirmed the TSAP' structure of the complex in aqueous solution, which exists as the Λ(λλλλ)/Δ(δδδδ) enantiomeric pair. (205)Tl NMR spectroscopy allowed the protonation constant associated with the protonation of the complex according to [Tl(dota)](-) + H(+) ⇆ [Tl(Hdota)] to be determined, which turned out to be pK(H)Tl(dota) = 1.4 ± 0.1. [Tl(dota)](-) does not react with Br(-), even when using an excess of the anion, but it forms a weak mixed complex with cyanide, [Tl(dota)](-) + CN(-) ⇆ [Tl(dota)(CN)](2-), with an equilibrium constant of Kmix = 6.0 ± 0.8. The dissociation of the [Tl(dota)](-) complex was determined by UV-vis spectrophotometry under acidic conditions using a large excess of Br(-), and it was found to follow proton-assisted kinetics and to take place very slowly (∼10 days), even in 1 M HClO4, with the estimated half-life of the process being in the 10(9) h range at neutral pH. The solution dynamics of [Tl(dota)](-) were investigated using (13)C NMR spectroscopy and DFT calculations. The (13)C NMR spectra recorded at low temperature (272 K) point to C4 symmetry of the complex in solution, which averages to C4v as the temperature increases. This dynamic behavior was attributed to the Λ(λλλλ) ↔ Δ(δδδδ) enantiomerization process, which involves both the inversion of the macrocyclic unit and the rotation of the pendant arms. According to our calculations, the arm-rotation process limits the Λ(λλλλ) ↔

  2. Mutations in NDUFB11, Encoding a Complex I Component of the Mitochondrial Respiratory Chain, Cause Microphthalmia with Linear Skin Defects Syndrome

    PubMed Central

    van Rahden, Vanessa A.; Fernandez-Vizarra, Erika; Alawi, Malik; Brand, Kristina; Fellmann, Florence; Horn, Denise; Zeviani, Massimo; Kutsche, Kerstin

    2015-01-01

    Microphthalmia with linear skin defects (MLS) syndrome is an X-linked male-lethal disorder also known as MIDAS (microphthalmia, dermal aplasia, and sclerocornea). Additional clinical features include neurological and cardiac abnormalities. MLS syndrome is genetically heterogeneous given that heterozygous mutations in HCCS or COX7B have been identified in MLS-affected females. Both genes encode proteins involved in the structure and function of complexes III and IV, which form the terminal segment of the mitochondrial respiratory chain (MRC). However, not all individuals with MLS syndrome carry a mutation in either HCCS or COX7B. The majority of MLS-affected females have severe skewing of X chromosome inactivation, suggesting that mutations in HCCS, COX7B, and other as-yet-unidentified X-linked gene(s) cause selective loss of cells in which the mutated X chromosome is active. By applying whole-exome sequencing and filtering for X-chromosomal variants, we identified a de novo nonsense mutation in NDUFB11 (Xp11.23) in one female individual and a heterozygous 1-bp deletion in a second individual, her asymptomatic mother, and an affected aborted fetus of the subject’s mother. NDUFB11 encodes one of 30 poorly characterized supernumerary subunits of NADH:ubiquinone oxidoreductase, known as complex I (cI), the first and largest enzyme of the MRC. By shRNA-mediated NDUFB11 knockdown in HeLa cells, we demonstrate that NDUFB11 is essential for cI assembly and activity as well as cell growth and survival. These results demonstrate that X-linked genetic defects leading to the complete inactivation of complex I, III, or IV underlie MLS syndrome. Our data reveal an unexpected role of cI dysfunction in a developmental phenotype, further underscoring the existence of a group of mitochondrial diseases associated with neurocutaneous manifestations. PMID:25772934

  3. Changes in the mitochondrial proteome during the anoxia to air transition in rice focus around cytochrome-containing respiratory complexes.

    PubMed

    Millar, A Harvey; Trend, Alice E; Heazlewood, Joshua L

    2004-09-17

    The ability of rice seedlings to grow from dry seed under anoxia provides a rare opportunity in a multicellular eukaryote to study the stages of mitochondrial biogenesis triggered by oxygen availability. The function and proteome of rice mitochondria synthesized under 6 days of anoxia following 1 day of air adaptation have been compared with mitochondria isolated from 7-day aerobically grown rice seedlings. Rice coleoptiles grown under anoxia, and the mitochondria isolated from them respired very slowly compared with air-adapted and air-grown seedlings. Immunodetection of key mitochondrial protein markers, isoelectric focusing electrophoresis followed by SDS-PAGE to make soluble mitochondria proteome maps, and shotgun sequencing of mitochondrial proteins by liquid chromatography-tandem mass spectrometry all revealed similar patterns of the major function categories of mitochondrial proteins from both anoxic and air-adapted samples. Activity analysis showed respiratory oxidases markedly increased in activity during the air adaptation of seedlings. Blue-native electrophoresis followed by SDS-PAGE of mitochondrial membrane proteins clearly showed the very low abundance of assembled b/c complex and cytochrome c(1) oxidase complex in the mitochondrial membrane in anoxic samples and the dramatic increase in the abundance of these complexes on air adaptation. Total heme content, cytochrome absorbance spectra, and the electron carrier, cytochrome c, also increased markedly on air adaptation. These results likely reflect limited heme synthesis for cytochrome assembly in the absence of oxygen and represent a discrete and reversible blockage of full mitochondrial biogenesis in this anoxia-tolerant species. PMID:15258153

  4. Intramolecular deactivation processes in complexes of salicylic acid or glycolic acid with Eu(III)

    NASA Astrophysics Data System (ADS)

    Kuke, S.; Marmodée, B.; Eidner, S.; Schilde, U.; Kumke, M. U.

    2010-04-01

    The complexation of Eu(III) by 2-hydroxy benzoic acid (2HB) or glycolic acid (GL) was investigated using steady-state and time-resolved laser spectroscopy. Experiments were carried out in H 2O as well as in D 2O in the temperature range of 80KIII) luminescence spectra and luminescence decay times were evaluated with respect to the temperature dependence of (i) the luminescence decay time τ, (ii) the energy of the D→F transition, (iii) the width of the D→F transition, and (iv) the asymmetry ratio calculated from the luminescence intensities of the D→F and D→F transition, respectively. The differences in ligand-related luminescence quenching are discussed. Based on the temperature dependence of the luminescence decay times an activation energy for the ligand-specific non-radiative deactivation in Eu(III)-2HB or Eu(III)-GL complexes was determined. It is stressed that ligand-specific quenching processes (other than OH quenching induced by water molecules) need to be determined and considered in detail, in order to extract speciation-relevant information from luminescence data (e.g., estimation of the number of water molecules nO in the first coordination sphere of Eu(III)). In case of 2HB, conclusions drawn from the evaluation of the Eu(III) luminescence are compared with results of a X-ray structure analysis.

  5. Single molecule magnet behaviour in a rare trinuclear {Cr(III)Dy} methoxo-bridged complex.

    PubMed

    Car, Pierre-Emmanuel; Favre, Annaïck; Caneschi, Andrea; Sessoli, Roberta

    2015-09-28

    The reaction of the chromium(iii) chloride tetrahydrofuran complex with the dipivaloylmethane ligand, the lanthanide alcoholic salt DyCl3·CH3OH and the 1,1,1-tris(hydroxymethyl)-ethane ligand resulted in the formation of a new trinuclear chromium-dysprosium complex. Magnetic investigations revealed that the new 3d-4f complex exhibits single molecule magnet behaviour. PMID:26282265

  6. Aqueous complexation of citrate with neodymium(III) and americium(III): a study by potentiometry, absorption spectrophotometry, microcalorimetry, and XAFS.

    PubMed

    Brown, M Alex; Kropf, A Jeremy; Paulenova, Alena; Gelis, Artem V

    2014-05-01

    The aqueous complexation of Nd(III) and Am(III) with anions of citrate was studied by potentiometry, absorption spectrophotometry, microcalorimetry, and X-ray absorption fine structure (XAFS). Using potentiometric titration data fitting the metal-ligand (L) complexes that were identified for Nd(III) were NdHL, NdL, NdHL2, and NdL2; a review of trivalent metal-citrate complexes is also included. Stability constants for these complexes were calculated from potentiometric and spectrophotometric titrations. Microcalorimetric results concluded that the entropy term of complex formation is much more dominant than the enthalpy. XAFS results showed a dependence in the Debye-Waller factor that indicated Nd(iii)-citrate complexation over the pH range of 1.56-6.12. PMID:24619154

  7. Thermodynamic and Spectroscopic Studies of Lanthanides(III) Complexation with Polyamines in Dimethyl Sulfoxide

    SciTech Connect

    Di Bernardo, Plinio; Zanonato, Pier Luigi; Melchior, Andrea; Portanova, Roberto; Tolazzi, Marilena; Choppin, Gregory R.; Wang, Zheming

    2008-01-01

    The thermodynamic parameters of complexation of Ln(III) cations with tris(2-aminoethyl)amine (tren) and tetraethylenepentamine (tetren) were determined in dimethyl sulfoxide (DMSO) by potentiometry and calorimetry. The excitation and emission spectra and luminescence decay constants of Eu3+ and Tb3+ complexed by tren and tetren, as well as those of the same lanthanides(III) complexed with diethylenetriamine (dien) and triethylenetetramine (trien), were also obtained in the same solvent. The combination of thermodynamic and spectroscopic data showed that, in the 1:1 complexes, all nitrogens of the ligands bound to the lanthanides except in the case of tren, in which only pendant N bound. For the larger ligands (trien, tren, tetren) in the higher complexes (ML2), there was less complete binding by available donors, presumably due to steric crowding. FT-IR studies were carried out in an acetonitrile/DMSO mixture, suitably chosen in order to follow the changes in the primary solvation sphere of lanthanide(III) due to complexation of amine ligands. Results show that the mean number of molecules of DMSO removed from the inner coordination sphere of lanthanides(III) is lower than ligand denticity and that the coordination number of the metal ions increases with amine complexation from ~8 to ~10. Independently of the number and structure of the amines, linear trends, similar for all lanthanides, were obtained by plotting the values of ΔGj°, ΔHj° and TΔSj° for the complexation of ethylenediamine (en), dien, trien, tren and tetren as a function of the number of amine metal-coordinated nitrogen atoms. The main factors on which the thermodynamic functions of lanthanide(III) complexation reactions in DMSO depend are discussed.

  8. Characterization of the apoLp-III/LPS complex: insight in the mode of binding interaction

    PubMed Central

    Oztug, Merve; Martinon, Daisy; Weers, Paul M.M.

    2012-01-01

    Apolipoproteins are able to associate with lipopolysaccharides (LPS), potentially providing protection against septic shock. To gain insight in the molecular details of this binding interaction, apolipophorin III (apoLp-III) from Galleria mellonella was used as a model. The binding of apoLp-III to LPS was optimal around 37–40 °C, close to the LPS phase transition temperature. ApoLp-III formed complexes with LPS from E. coli (serotype O55:B5) with a diameter of 24 nm, a molecular weight of ~390 kDa, containing four molecules of apoLp-III and 24 molecules of LPS. The LPS-bound form of the protein was substantially more resistant to guanidine-induced denaturation compared to unbound protein. The denaturation profile displayed a multiphase character with a steep drop in secondary structure between 0–1 M guanidine, and a slower decrease above 1 M guanidine HCl. In contrast, apoLp-III bound to detoxified LPS was only slightly more resistant to guanidine HCl induced denaturation compared to unbound protein. Analysis of size-exclusion FPLC elution profiles of mixtures of apoLp-III with LPS or detoxified LPS indicated a much weaker binding interaction with detoxified LPS compared to intact LPS. These results indicate that apoLp-III initially interacts with exposed carbohydrate regions, but that the lipid A region is required for a more stable LPS binding interaction. PMID:22779761

  9. Chromophore-Assisted Light Inactivation of Mitochondrial Electron Transport Chain Complex II in Caenorhabditis elegans

    PubMed Central

    Wojtovich, Andrew P.; Wei, Alicia Y.; Sherman, Teresa A.; Foster, Thomas H.; Nehrke, Keith

    2016-01-01

    Mitochondria play critical roles in meeting cellular energy demand, in cell death, and in reactive oxygen species (ROS) and stress signaling. Most Caenorhabditis elegans loss-of-function (lf) mutants in nuclear-encoded components of the respiratory chain are non-viable, emphasizing the importance of respiratory function. Chromophore-Assisted Light Inactivation (CALI) using genetically-encoded photosensitizers provides an opportunity to determine how individual respiratory chain components contribute to physiology following acute lf. As proof-of-concept, we expressed the ‘singlet oxygen generator’ miniSOG as a fusion with the SDHC subunit of respiratory complex II, encoded by mev-1 in C. elegans, using Mos1-mediated Single Copy Insertion. The resulting mev-1::miniSOG transgene complemented mev-1 mutant phenotypes in kn1 missense and tm1081(lf) deletion mutants. Complex II activity was inactivated by blue light in mitochondria from strains expressing active miniSOG fusions, but not those from inactive fusions. Moreover, light-inducible phenotypes in vivo demonstrated that complex II activity is important under conditions of high energy demand, and that specific cell types are uniquely susceptible to loss of complex II. In conclusion, miniSOG-mediated CALI is a novel genetic platform for acute inactivation of respiratory chain components. Spatio-temporally controlled ROS generation will expand our understanding of how the respiratory chain and mitochondrial ROS influence whole organism physiology. PMID:27440050

  10. Dynamics of Human Mitochondrial Complex I Assembly: Implications for Neurodegenerative Diseases.

    PubMed

    Giachin, Gabriele; Bouverot, Romain; Acajjaoui, Samira; Pantalone, Serena; Soler-López, Montserrat

    2016-01-01

    Neurons are extremely energy demanding cells and highly dependent on the mitochondrial oxidative phosphorylation (OXPHOS) system. Mitochondria generate the energetic potential via the respiratory complexes I to IV, which constitute the electron transport chain (ETC), together with complex V. These redox reactions release energy in the form of ATP and also generate reactive oxygen species (ROS) that are involved in cell signaling but can eventually lead to oxidative stress. Complex I (CI or NADH:ubiquinone oxidoreductase) is the largest ETC enzyme, containing 44 subunits and the main contributor to ROS production. In recent years, the structure of the CI has become available and has provided new insights into CI assembly. A number of chaperones have been identified in the assembly and stability of the mature holo-CI, although they are not part of its final structure. Interestingly, CI dysfunction is the most common OXPHOS disorder in humans and defects in the CI assembly process are often observed. However, the dynamics of the events leading to CI biogenesis remain elusive, which precludes our understanding of how ETC malfunctioning affects neuronal integrity. Here, we review the current knowledge of the structural features of CI and its assembly factors and the potential role of CI misassembly in human disorders such as Complex I Deficiencies or Alzheimer's and Parkinson's diseases. PMID:27597947

  11. Chromophore-Assisted Light Inactivation of Mitochondrial Electron Transport Chain Complex II in Caenorhabditis elegans.

    PubMed

    Wojtovich, Andrew P; Wei, Alicia Y; Sherman, Teresa A; Foster, Thomas H; Nehrke, Keith

    2016-01-01

    Mitochondria play critical roles in meeting cellular energy demand, in cell death, and in reactive oxygen species (ROS) and stress signaling. Most Caenorhabditis elegans loss-of-function (lf) mutants in nuclear-encoded components of the respiratory chain are non-viable, emphasizing the importance of respiratory function. Chromophore-Assisted Light Inactivation (CALI) using genetically-encoded photosensitizers provides an opportunity to determine how individual respiratory chain components contribute to physiology following acute lf. As proof-of-concept, we expressed the 'singlet oxygen generator' miniSOG as a fusion with the SDHC subunit of respiratory complex II, encoded by mev-1 in C. elegans, using Mos1-mediated Single Copy Insertion. The resulting mev-1::miniSOG transgene complemented mev-1 mutant phenotypes in kn1 missense and tm1081(lf) deletion mutants. Complex II activity was inactivated by blue light in mitochondria from strains expressing active miniSOG fusions, but not those from inactive fusions. Moreover, light-inducible phenotypes in vivo demonstrated that complex II activity is important under conditions of high energy demand, and that specific cell types are uniquely susceptible to loss of complex II. In conclusion, miniSOG-mediated CALI is a novel genetic platform for acute inactivation of respiratory chain components. Spatio-temporally controlled ROS generation will expand our understanding of how the respiratory chain and mitochondrial ROS influence whole organism physiology. PMID:27440050

  12. Apocytochrome c requires the TOM complex for translocation across the mitochondrial outer membrane.

    PubMed

    Diekert, K; de Kroon, A I; Ahting, U; Niggemeyer, B; Neupert, W; de Kruijff, B; Lill, R

    2001-10-15

    The import of proteins into the mitochondrial intermembrane space differs in various aspects from the classical import pathway into the matrix. Apocytochrome c defines one of several pathways known to reach the intermembrane space, yet the components and pathways involved in outer membrane translocation are poorly defined. Here, we report the reconstitution of the apocytochrome c import reaction using proteoliposomes harbouring purified components. Import specifically requires the protease-resistant part of the TOM complex and is driven by interactions of the apoprotein with internal parts of the complex (involving Tom40) and the 'trans-side receptor' cytochrome c haem lyase. Despite the necessity of TOM complex function, the translocation pathway of apocytochrome c does not overlap with that of presequence-containing preproteins. We conclude that the TOM complex is a universal preprotein translocase that mediates membrane passage of apocytochrome c and other preproteins along distinct pathways. Apocytochrome c may provide a paradigm for the import of other small proteins into the intermembrane space such as factors used in apoptosis and protection from stress. PMID:11598006

  13. Dynamics of Human Mitochondrial Complex I Assembly: Implications for Neurodegenerative Diseases

    PubMed Central

    Giachin, Gabriele; Bouverot, Romain; Acajjaoui, Samira; Pantalone, Serena; Soler-López, Montserrat

    2016-01-01

    Neurons are extremely energy demanding cells and highly dependent on the mitochondrial oxidative phosphorylation (OXPHOS) system. Mitochondria generate the energetic potential via the respiratory complexes I to IV, which constitute the electron transport chain (ETC), together with complex V. These redox reactions release energy in the form of ATP and also generate reactive oxygen species (ROS) that are involved in cell signaling but can eventually lead to oxidative stress. Complex I (CI or NADH:ubiquinone oxidoreductase) is the largest ETC enzyme, containing 44 subunits and the main contributor to ROS production. In recent years, the structure of the CI has become available and has provided new insights into CI assembly. A number of chaperones have been identified in the assembly and stability of the mature holo-CI, although they are not part of its final structure. Interestingly, CI dysfunction is the most common OXPHOS disorder in humans and defects in the CI assembly process are often observed. However, the dynamics of the events leading to CI biogenesis remain elusive, which precludes our understanding of how ETC malfunctioning affects neuronal integrity. Here, we review the current knowledge of the structural features of CI and its assembly factors and the potential role of CI misassembly in human disorders such as Complex I Deficiencies or Alzheimer's and Parkinson's diseases. PMID:27597947

  14. Localizing Perturbations of the Racemic Equilibria Involving Dipicolinate-Derived Lanthanide(III) Complexes.

    PubMed

    Nguyen, Brian T; Ingram, Andrew J; Muller, Gilles

    2016-04-01

    Helical D3 tris(4-amino-2,6-pyridine-dicarboxylate)terbium(III) and europium(III) complexes, which form a racemic equilibrium in aqueous solution, were prepared to study their secondary coordination sphere interactions with chiral amino acids. These interactions were probed using a combination of circularly polarized luminescence (CPL) and 13C NMR spectroscopy. The results indicate that, regardless of the interaction between the chiral molecule and the complex, without an accessible hydrogen-bond donor on the associating molecule, perturbation of the racemic equilibrium cannot occur. A generalized conclusion is established that indicates that the mechanism of chiral recognition by tris(dipicolinate)lanthanide(III) complexes is similar across a variety of analogous ligands. PMID:26935003

  15. Cellulose derivatives modified by sodium tellurate and a chromium(III) tellurate complex.

    PubMed

    Butler, Ian S; El-Sherbeny, Heba Allah M; Kenawy, Ibrahim; Mostafa, Sahar I

    2016-07-01

    A novel cellulose (Cell) derivative, sodium-tellurato (Cell-TeO(OH)4(ONa)/Cell-Cl), has been synthesized from the reaction of 6-chloro-6-deoxycellulose (Cell-Cl) with telluric acid in the presence of sodium hydroxide. The subsequent reaction of this polymeric material with chromium(III) in aqueous solution yields the [Cr(Cell-TeO3(OH)3/Cell-Cl)(Cell-TeO2(OH)4/Cell-Cl)(H2O)3] complex. The molecular structures and morphology of the new polymer and the Cr(III) complex have been examined using elemental analysis, solid-state (13)C NMR, UV-vis, XRD and FTIR spectroscopy, and SEM-EDX, TGA and magnetic measurements. The results are considered to be consistent with the formulations proposed. The deprotonation constants of the modified cellulose and the stability constant of the Cr(III) complex have been determined by pH-metric measurements. PMID:27037053

  16. Mössbauer study of peroxynitrito complex formation with FeIII-chelates

    NASA Astrophysics Data System (ADS)

    Homonnay, Zoltan; Buszlai, Peter; Nádor, Judit; Sharma, Virender K.; Kuzmann, Erno; Vértes, Attila

    2012-03-01

    The reaction of the μ-oxo-diiron(III)-L complex (L = EDTA, ethylene diamine tetraacetate, HEDTA, hydroxyethyl ethylene diamine triacetate, and CyDTA, cyclohexane diamine tetraacetate) with peroxynitrite in alkaline solution was studied by Mössbauer spectroscopy using rapid-freezing technique. These complexes yield an (L)FeIII( η 2-O2)^{3-} complex ion when they react with hydrogen peroxide and the formation of the peroxide adduct results in a deep purple coloration of the solution. The same color appears when the reaction occurs with peroxinitrite. Although spectrophotometry indicated some difference between the molar extinction coefficients of the peroxo and the peroxinitrito adducts, the Mössbauer parameters proved to be the same within experimental error. It is concluded that the peroxynitrite ion decomposes when reacting with FeIII(L) and the peroxo adduct forms.

  17. EglN2 associates with the NRF1-PGC1α complex and controls mitochondrial function in breast cancer.

    PubMed

    Zhang, Jing; Wang, Chengyang; Chen, Xi; Takada, Mamoru; Fan, Cheng; Zheng, Xingnan; Wen, Haitao; Liu, Yong; Wang, Chenguang; Pestell, Richard G; Aird, Katherine M; Kaelin, William G; Liu, Xiaole Shirley; Zhang, Qing

    2015-12-01

    The EglN2/PHD1 prolyl hydroxylase is an important oxygen sensor contributing to breast tumorigenesis. Emerging studies suggest that there is functional cross talk between oxygen sensing and mitochondrial function, both of which play an essential role for sustained tumor growth. However, the potential link between EglN2 and mitochondrial function remains largely undefined. Here, we show that EglN2 depletion decreases mitochondrial respiration in breast cancer under normoxia and hypoxia, which correlates with decreased mitochondrial DNA in a HIF1/2α-independent manner. Integrative analyses of gene expression profile and genomewide binding of EglN2 under hypoxic conditions reveal nuclear respiratory factor 1 (NRF1) motif enrichment in EglN2-activated genes, suggesting NRF1 as an EglN2 binding partner. Mechanistically, by forming an activator complex with PGC1α and NRF1 on chromatin, EglN2 promotes the transcription of ferridoxin reductase (FDXR) and maintains mitochondrial function. In addition, FDXR, as one of effectors for EglN2, contributes to breast tumorigenesis in vitro and in vivo. Our findings suggest that EglN2 regulates mitochondrial function in ERα-positive breast cancer. PMID:26492917

  18. Dietary Tocotrienol/γ-Cyclodextrin Complex Increases Mitochondrial Membrane Potential and ATP Concentrations in the Brains of Aged Mice

    PubMed Central

    Schloesser, Anke; Esatbeyoglu, Tuba; Piegholdt, Stefanie; Dose, Janina; Ikuta, Naoko; Okamoto, Hinako; Ishida, Yoshiyuki; Terao, Keiji; Matsugo, Seiichi; Rimbach, Gerald

    2015-01-01

    Brain aging is accompanied by a decrease in mitochondrial function. In vitro studies suggest that tocotrienols, including γ- and δ-tocotrienol (T3), may exhibit neuroprotective properties. However, little is known about the effect of dietary T3 on mitochondrial function in vivo. In this study, we monitored the effect of a dietary T3/γ-cyclodextrin complex (T3CD) on mitochondrial membrane potential and ATP levels in the brain of 21-month-old mice. Mice were fed either a control diet or a diet enriched with T3CD providing 100 mg T3 per kg diet for 6 months. Dietary T3CD significantly increased mitochondrial membrane potential and ATP levels compared to those of controls. The increase in MMP and ATP due to dietary T3CD was accompanied by an increase in the protein levels of the mitochondrial transcription factor A (TFAM). Furthermore, dietary T3CD slightly increased the mRNA levels of superoxide dismutase, γ-glutamyl cysteinyl synthetase, and heme oxygenase 1 in the brain. Overall, the present data suggest that T3CD increases TFAM, mitochondrial membrane potential, and ATP synthesis in the brains of aged mice. PMID:26301044

  19. A mitochondrial-focused genetic interaction map reveals a scaffold-like complex required for inner membrane organization in mitochondria

    PubMed Central

    Hoppins, Suzanne; Collins, Sean R.; Cassidy-Stone, Ann; Hummel, Eric; DeVay, Rachel M.; Lackner, Laura L.; Westermann, Benedikt; Schuldiner, Maya

    2011-01-01

    To broadly explore mitochondrial structure and function as well as the communication of mitochondria with other cellular pathways, we constructed a quantitative, high-density genetic interaction map (the MITO-MAP) in Saccharomyces cerevisiae. The MITO-MAP provides a comprehensive view of mitochondrial function including insights into the activity of uncharacterized mitochondrial proteins and the functional connection between mitochondria and the ER. The MITO-MAP also reveals a large inner membrane–associated complex, which we term MitOS for mitochondrial organizing structure, comprised of Fcj1/Mitofilin, a conserved inner membrane protein, and five additional components. MitOS physically and functionally interacts with both outer and inner membrane components and localizes to extended structures that wrap around the inner membrane. We show that MitOS acts in concert with ATP synthase dimers to organize the inner membrane and promote normal mitochondrial morphology. We propose that MitOS acts as a conserved mitochondrial skeletal structure that differentiates regions of the inner membrane to establish the normal internal architecture of mitochondria. PMID:21987634

  20. Analysis of complete mitochondrial DNA sequences of three members of the Montastraea annularis coral species complex (Cnidaria, Anthozoa, Scleractinia)

    NASA Astrophysics Data System (ADS)

    Fukami, Hironobu; Knowlton, Nancy

    2005-11-01

    Complete mitochondrial nucleotide sequences of two individuals each of Montastraea annularis, Montastraea faveolata, and Montastraea franksi were determined. Gene composition and order differed substantially from the sea anemone Metridium senile, but were identical to that of the phylogenetically distant coral genus Acropora. However, characteristics of the non-coding regions differed between the two scleractinian genera. Among members of the M. annularis complex, only 25 of 16,134 base pair positions were variable. Sixteen of these occurred in one colony of M. franksi, which (together with additional data) indicates the existence of multiple divergent mitochondrial lineages in this species. Overall, rates of evolution for these mitochondrial genomes were extremely slow (0.03 0.04% per million years based on the fossil record of the M. annularis complex). At higher taxonomic levels, patterns of genetic divergence and synonymous/nonsynonymous substitutions suggest non-neutral and unequal rates of evolution between the two lineages to which Montastraea and Acropora belong.

  1. Mitochondrial Cardiomyopathies

    PubMed Central

    El-Hattab, Ayman W.; Scaglia, Fernando

    2016-01-01

    Mitochondria are found in all nucleated human cells and perform various essential functions, including the generation of cellular energy. Mitochondria are under dual genome control. Only a small fraction of their proteins are encoded by mitochondrial DNA (mtDNA), whereas more than 99% of them are encoded by nuclear DNA (nDNA). Mutations in mtDNA or mitochondria-related nDNA genes result in mitochondrial dysfunction leading to insufficient energy production required to meet the needs for various organs, particularly those with high energy requirements, including the central nervous system, skeletal and cardiac muscles, kidneys, liver, and endocrine system. Because cardiac muscles are one of the high energy demanding tissues, cardiac involvement occurs in mitochondrial diseases with cardiomyopathies being one of the most frequent cardiac manifestations found in these disorders. Cardiomyopathy is estimated to occur in 20–40% of children with mitochondrial diseases. Mitochondrial cardiomyopathies can vary in severity from asymptomatic status to severe manifestations including heart failure, arrhythmias, and sudden cardiac death. Hypertrophic cardiomyopathy is the most common type; however, mitochondrial cardiomyopathies might also present as dilated, restrictive, left ventricular non-compaction, and histiocytoid cardiomyopathies. Cardiomyopathies are frequent manifestations of mitochondrial diseases associated with defects in electron transport chain complexes subunits and their assembly factors, mitochondrial transfer RNAs, ribosomal RNAs, ribosomal proteins, translation factors, mtDNA maintenance, and coenzyme Q10 synthesis. Other mitochondrial diseases with cardiomyopathies include Barth syndrome, Sengers syndrome, TMEM70-related mitochondrial complex V deficiency, and Friedreich ataxia. PMID:27504452

  2. Mitochondrial Cardiomyopathies.

    PubMed

    El-Hattab, Ayman W; Scaglia, Fernando

    2016-01-01

    Mitochondria are found in all nucleated human cells and perform various essential functions, including the generation of cellular energy. Mitochondria are under dual genome control. Only a small fraction of their proteins are encoded by mitochondrial DNA (mtDNA), whereas more than 99% of them are encoded by nuclear DNA (nDNA). Mutations in mtDNA or mitochondria-related nDNA genes result in mitochondrial dysfunction leading to insufficient energy production required to meet the needs for various organs, particularly those with high energy requirements, including the central nervous system, skeletal and cardiac muscles, kidneys, liver, and endocrine system. Because cardiac muscles are one of the high energy demanding tissues, cardiac involvement occurs in mitochondrial diseases with cardiomyopathies being one of the most frequent cardiac manifestations found in these disorders. Cardiomyopathy is estimated to occur in 20-40% of children with mitochondrial diseases. Mitochondrial cardiomyopathies can vary in severity from asymptomatic status to severe manifestations including heart failure, arrhythmias, and sudden cardiac death. Hypertrophic cardiomyopathy is the most common type; however, mitochondrial cardiomyopathies might also present as dilated, restrictive, left ventricular non-compaction, and histiocytoid cardiomyopathies. Cardiomyopathies are frequent manifestations of mitochondrial diseases associated with defects in electron transport chain complexes subunits and their assembly factors, mitochondrial transfer RNAs, ribosomal RNAs, ribosomal proteins, translation factors, mtDNA maintenance, and coenzyme Q10 synthesis. Other mitochondrial diseases with cardiomyopathies include Barth syndrome, Sengers syndrome, TMEM70-related mitochondrial complex V deficiency, and Friedreich ataxia. PMID:27504452

  3. Long-lived luminescent soft materials of hexanitratosamarate(III) complexes with orange visible emission.

    PubMed

    Tang, Ning; Zhao, Ying; He, Ling; Yuan, Wen-Li; Tao, Guo-Hong

    2015-05-21

    Sm(III)-based ionic liquids incorporating hexanitratosamarate(III) anions were obtained and fully characterized as novel Sm(III)-containing organic complexes. The structure of the ionic liquids was determined by single-crystal X-ray diffraction (1: monoclinic system C2/c space group with cell parameters: a = 19.5624(4) Å, b = 10.11895(18) Å, c = 33.2256(6) Å, β = 101.2912(18)°, Z = 8). The central Sm(III) ion is 12-coordinated by six bidentate nitrate ligands with twelve oxygen donors to form a [Sm(NO3)6](3-) anion. The low melting point, high thermostability and wide liquid range of these ionic liquids were determined in detail. All the complexes 1-5 display orange luminescence, rather than red luminescence as in most Sm(III)-containing organic complexes. Three characteristic monochromatic bands and an intense emission, derived from (4)G5/2→(6)HJ (J = 5/2, 7/2, and 9/2) intraconfigurational f-f transitions, were revealed. All these complexes exhibit long luminescence lifetimes. PMID:25860117

  4. Synthesis and properties of polynitrophenyltetrazolatocobalt(III) complexes

    SciTech Connect

    Fronabarger, J.; Johnson, R.; Fleming, W.

    1986-01-01

    The explosive 3,5-dinitrophenyltetrazolato complex (3,5-DNP) tends to propagate in the deflagration mode which suggests its use as a pressure cartridge charge. However, the existence of 3,5-DNP as a hydrate appears to result in variations of thermomechanical properties thus rendering it undesirable for component use. The 2,4-DNP and 2,4,6-TNP analogs were synthesized. These exist in the anhydrous form under normal conditions and underwent DDT in component configuration. This negated their use in pressure cartridge applications. Synthetic procedures have been developed for 5-(2,4-dinitrophenyl)tetrazole and 5-picryltetrazole as well as for the precursor 2,4-dinitro- and 2,4,6-trinitrobenzonitriles. 6 refs.

  5. Spectrophotometric studies of holmium(III) chloride-aluminum(III) chloride vapor complexes

    SciTech Connect

    Williams, C.W.; Hessler, J.P.; Peterson, E.J.

    1980-01-01

    The gas complexation reactions between LnCl/sub 3/ and Al/sub 2/Cl/sub 6/ to yield molecular species of the form LnCl/sub 3/ (Al/sub 2/Cl/sub 6/)/sub x/ have been studied for a number of years. The spectrophotometric technique has been used to deduce the thermodynamic properties of the molecular species. We have studied the HoCl/sub 3/ (Al/sub 2/Cl/sub 6/)/sub x/ system from 600 to 900/sup 0/K and at Al/sub 2/Cl/sub 6/ pressures between 1 and 7 atm. The Ho/sup 3 +/ hypersensitive transition between /sup 5/I/sub 8/ and /sup 5/G/sub 6/ at 456 nm has been used to measure the complex vapor densities as a function of pressure and temperature. A temperature-dependence of the optical absorption spectrum was observed in samples with a constant Ho/sup 3 +/ ion density. These data cannot be understood in terms of the generally used treatment of molar absorptivity, but requires the introduction of an effective oscillator strength. A temperature-dependent oscillator effect is also observed and this is interpeted as evidence for the presence of multiple species with differing oscillator strengths. The consequence of these observations for the determination of equilibrium constants for the different species will be discussed.

  6. Mechanism of oxidation of alkyl and superoxo complexes of chromium (III) by aquamanganese(III) ions

    SciTech Connect

    Jee, Joo-Eun; Pestovsky, Oleg; Hidayat, Irene; Szajna-Fuller; Bakac, Andreja

    2010-07-01

    The reaction between aqueous manganese(III) ions, Mn(H{sub 2}O){sub 6}{sup 3+}, and (H{sub 2}O){sub 5}CrOO{sup 2+} has a 1:1 stoichiometry and generates Cr(H{sub 2}O){sub 6}{sup 3+} and O{sub 2} as products. The mixed second-order rate constant exhibits an [H{sup +}] dependence that identifies the hexaaquamanganese ion as the reactive form at 0.5 {le} [H{sup +}] {le} 3.0 mol L{sup -1}, k{sub H} = 350 {+-} 10 (mol L{sup -1}){sup -1} s{sup -1}. The reactivity of (H{sub 2}O)5MnOH{sup 2+} is negligible under these conditions, most likely because the much lower reduction potential of this hydrolytic form results in unfavorable thermodynamics for the overall reaction. Mn(H{sub 2}O){sub 6}{sup 3+} also oxidizes a benzylchromium ion, (H{sub 2}O)5CrCH{sub 2}Ph{sup 2+}, with a rate constant k = 273 {+-} 13 (mol L{sup -1}){sup -1} s{sup -1} in 3.0 mol L{sup -1} HClO{sub 4}. The reaction has a 2:1 [Mn(H{sub 2}O){sub 6}{sup 3+}]/[(H{sub 2}O){sub 5}CrCH{sub 2}Ph{sup 2+}] stoichiometry and generates benzyl alcohol as the sole organic product. The data are consistent with oxidative homolysis which generates benzyl radicals followed by rapid oxidation of the radicals with the second equivalent of Mn(H{sub 2}O){sub 6}{sup 3+}. The unexpected similarity between the rate constants for the Mn(H{sub 2}O){sub 6}{sup 3+} oxidation of (H{sub 2}O){sub 5}CrOO{sup 2+} and (H{sub 2}O){sub 5}CrCH{sub 2}Ph{sup 2+} is discussed.

  7. Evidence of Positive Selection in Mitochondrial Complexes I and V of the African Elephant

    PubMed Central

    Finch, Tabitha M.; Zhao, Nan; Korkin, Dmitry; Frederick, Katy H.; Eggert, Lori S.

    2014-01-01

    As species evolve, they become adapted to their local environments. Detecting the genetic signature of selection and connecting that to the phenotype of the organism, however, is challenging. Here we report using an integrative approach that combines DNA sequencing with structural biology analyses to assess the effect of selection on residues in the mitochondrial DNA of the two species of African elephants. We detected evidence of positive selection acting on residues in complexes I and V, and we used homology protein structure modeling to assess the effect of the biochemical properties of the selected residues on the enzyme structure. Given the role these enzymes play in oxidative phosphorylation, we propose that the selected residues may contribute to the metabolic adaptation of forest and savanna elephants to their unique habitats. PMID:24695069

  8. Direct evidence of arsenic(III)-carbonate complexes obtained using electrochemical scanning tunneling microscopy.

    PubMed

    Han, Mei-Juan; Hao, Jumin; Christodoulatos, Christos; Korfiatis, George P; Wan, Li-Jun; Meng, Xiaoguang

    2007-05-15

    Electrochemical scanning tunneling microscopy (ECSTM), ion chromatography (IC), and electrospray ionization-mass spectrometry/mass spectrometry were applied to investigate the interactions between arsenite [As(III)] and carbonate and arsenate [As(V)] and carbonate. The chemical species in the single and binary component solutions of As(III), As(V), and carbonate were attached to a Au(111) surface and then imaged in a 0.1 M NaClO4 solution at the molecular level by ECSTM. The molecules formed highly ordered adlayers on the Au(111) surface. High-resolution STM images revealed the orientation and packing arrangement of the molecular adlayers. Matching the STM images with the molecular models constructed using the Hyperchem software package indicated that As(III) formed two types of complexes with carbonate, including As(OH)2CO3- and As(OH)3(HCO3-)2. No complexes were formed between As(V) and carbonate. IC chromatograms of the solutions revealed the emergence of the new peak only in the aged As(III)-carbonate solution. MS spectra showed the presence of a new peak at m/z 187 in the aged As(III)-carbonate solution. The results obtained with the three independent methods confirmed the formation of As(OH)2CO3-. The results also indicated that As(OH)3 could be associated with HCO3- through a hydrogen bond. The knowledge of the formation of the As(III) and carbonate complexes will improve the understanding of As(III) mobility in the environment and removal of As(III) in water treatment systems. PMID:17441685

  9. RNA-activated DNA cleavage by the Type III-B CRISPR-Cas effector complex.

    PubMed

    Estrella, Michael A; Kuo, Fang-Ting; Bailey, Scott

    2016-02-15

    The CRISPR (clustered regularly interspaced short palindromic repeat) system is an RNA-guided immune system that protects prokaryotes from invading genetic elements. This system represents an inheritable and adaptable immune system that is mediated by multisubunit effector complexes. In the Type III-B system, the Cmr effector complex has been found to cleave ssRNA in vitro. However, in vivo, it has been implicated in transcription-dependent DNA targeting. We show here that the Cmr complex from Thermotoga maritima can cleave an ssRNA target that is complementary to the CRISPR RNA. We also show that binding of a complementary ssRNA target activates an ssDNA-specific nuclease activity in the histidine-aspartate (HD) domain of the Cmr2 subunit of the complex. These data suggest a mechanism for transcription-coupled DNA targeting by the Cmr complex and provide a unifying mechanism for all Type III systems. PMID:26848046

  10. Mitochondrial dysfunction and organophosphorus compounds

    SciTech Connect

    Karami-Mohajeri, Somayyeh; Abdollahi, Mohammad

    2013-07-01

    Organophosphorous (OPs) pesticides are the most widely used pesticides in the agriculture and home. However, many acute or chronic poisoning reports about OPs have been published in the recent years. Mitochondria as a site of cellular oxygen consumption and energy production can be a target for OPs poisoning as a non-cholinergic mechanism of toxicity of OPs. In the present review, we have reviewed and criticized all the evidences about the mitochondrial dysfunctions as a mechanism of toxicity of OPs. For this purpose, all biochemical, molecular, and morphological data were retrieved from various studies. Some toxicities of OPs are arisen from dysfunction of mitochondrial oxidative phosphorylation through alteration of complexes I, II, III, IV and V activities and disruption of mitochondrial membrane. Reductions of adenosine triphosphate (ATP) synthesis or induction of its hydrolysis can impair the cellular energy. The OPs disrupt cellular and mitochondrial antioxidant defense, reactive oxygen species generation, and calcium uptake and promote oxidative and genotoxic damage triggering cell death via cytochrome C released from mitochondria and consequent activation of caspases. The mitochondrial dysfunction induced by OPs can be restored by use of antioxidants such as vitamin E and C, alpha-tocopherol, electron donors, and through increasing the cytosolic ATP level. However, to elucidate many aspect of mitochondrial toxicity of Ops, further studies should be performed. - Highlights: • As a non-cholinergic mechanism of toxicity, mitochondria is a target for OPs. • OPs affect action of complexes I, II, III, IV and V in the mitochondria. • OPs reduce mitochondrial ATP. • OPs promote oxidative and genotoxic damage via release of cytochrome C from mitochondria. • OP-induced mitochondrial dysfunction can be restored by increasing the cytosolic ATP.

  11. Differential requirement for the mitochondrial Hsp70-Tim44 complex in unfolding and translocation of preproteins.

    PubMed Central

    Voos, W; von Ahsen, O; Müller, H; Guiard, B; Rassow, J; Pfanner, N

    1996-01-01

    The mitochondrial heat shock protein Hsp70 is essential for import of nuclear-encoded proteins, involved in both unfolding and membrane translocation of preproteins. mtHsp70 interacts reversibly with Tim44 of the mitochondrial inner membrane, yet the role of this interaction is unknown. We analysed this role by using two yeast mutants of mtHsp70 that differentially influenced its interaction with Tim44. One mutant mtHsp70 (Ssc1-2p) efficiently bound preproteins, but did not show a detectable complex formation with Tim44; the mitochondria imported loosely folded preproteins with wild-type kinetics, yet were impaired in unfolding of preproteins. The other mutant Hsp70 (Ssc1-3p') bound both Tim44 and preproteins, but the mitochondria did not import folded polypeptides and were impaired in import of unfolded preproteins; Ssc1-3p' was defective in its ATPase domain and did not undergo a nucleotide-dependent conformational change, resulting in permanent binding to Tim44. The following conclusions are suggested. (i) The import of loosely folded polypeptides (translocase function of mtHsp70) does not depend on formation of a detectable Hsp70-Tim44 complex. Two explanations are possible: a trapping mechanism by soluble mtHsp70, or a weak/very transient interaction of Ssc1-2p with Tim44 that leads to a weak force generation sufficient for import of loosely folded, but not folded, polypeptides. (ii) Import of folded preproteins (unfoldase function of mtHsp70) involves a reversible nucleotide-dependent interaction of mtHsp70 with Tim44, including a conformational change in mtHsp70. This is consistent with a model that the dynamic interaction of mtHsp70 with Tim44 generates a pulling force on preproteins which supports unfolding during translocation. Images PMID:8654364

  12. Challenges in assignment of orbital populations in a high spin manganese(iii) complex.

    PubMed

    Fitzpatrick, A J; Stepanovic, S; Müller-Bunz, H; Gruden-Pavlović, M A; García-Fernández, P; Morgan, G G

    2016-04-12

    Magnetic, structural and computational data of four complex salts with the same mononuclear high spin octahedral Mn(iii) complex cation are reported. The manifestation of Jahn-Teller-like distortions in the Mn(iii) cation is dependent on the nature of the charge-balancing anion, with small anions yielding a planar elongation and large anions freezing out a preferential axial elongation along one of the amine-Mn-imine directions within that same plane. Modulation of the lattice by changing the charge balancing anion results in mixing of the orbital symmetry due to vibrational perturbation. PMID:26974518

  13. Direct interaction of mitochondrial targeting presequences with purified components of the TIM23 protein complex.

    PubMed

    Marom, Milit; Dayan, Dana; Demishtein-Zohary, Keren; Mokranjac, Dejana; Neupert, Walter; Azem, Abdussalam

    2011-12-23

    Precursor proteins that are imported from the cytosol into the matrix of mitochondria carry positively charged amphipathic presequences and cross the inner membrane with the help of vital components of the TIM23 complex. It is currently unclear which subunits of the TIM23 complex recognize and directly bind to presequences. Here we analyzed the binding of presequence peptides to purified components of the TIM23 complex. The interaction of three different presequences with purified soluble domains of yeast Tim50 (Tim50IMS), Tim23 (Tim23IMS), and full-length Tim44 was examined. Using chemical cross-linking and surface plasmon resonance we demonstrate, for the first time, the ability of purified Tim50IMS and Tim44 to interact directly with the yeast Hsp60 presequence. We also analyzed their interaction with presequences derived from precursors of yeast mitochondrial 70-kDa heat shock protein (mHsp70) and of bovine cytochrome P450SCC. Moreover, we characterized the nature of the interactions and determined their KDs. On the basis of our results, we suggest a mechanism of translocation where stronger interactions of the presequences on the trans side of the channel support the import of precursor proteins through TIM23 into the matrix. PMID:21969381

  14. Direct Interaction of Mitochondrial Targeting Presequences with Purified Components of the TIM23 Protein Complex*

    PubMed Central

    Marom, Milit; Dayan, Dana; Demishtein-Zohary, Keren; Mokranjac, Dejana; Neupert, Walter; Azem, Abdussalam

    2011-01-01

    Precursor proteins that are imported from the cytosol into the matrix of mitochondria carry positively charged amphipathic presequences and cross the inner membrane with the help of vital components of the TIM23 complex. It is currently unclear which subunits of the TIM23 complex recognize and directly bind to presequences. Here we analyzed the binding of presequence peptides to purified components of the TIM23 complex. The interaction of three different presequences with purified soluble domains of yeast Tim50 (Tim50IMS), Tim23 (Tim23IMS), and full-length Tim44 was examined. Using chemical cross-linking and surface plasmon resonance we demonstrate, for the first time, the ability of purified Tim50IMS and Tim44 to interact directly with the yeast Hsp60 presequence. We also analyzed their interaction with presequences derived from precursors of yeast mitochondrial 70-kDa heat shock protein (mHsp70) and of bovine cytochrome P450SCC. Moreover, we characterized the nature of the interactions and determined their KDs. On the basis of our results, we suggest a mechanism of translocation where stronger interactions of the presequences on the trans side of the channel support the import of precursor proteins through TIM23 into the matrix. PMID:21969381

  15. Mitochondrial protein import: recognition of internal import signals of BCS1 by the TOM complex.

    PubMed

    Stan, Tincuta; Brix, Jan; Schneider-Mergener, Jens; Pfanner, Nikolaus; Neupert, Walter; Rapaport, Doron

    2003-04-01

    BCS1, a component of the inner membrane of mitochondria, belongs to the group of proteins with internal, noncleavable import signals. Import and intramitochondrial sorting of BCS1 are encoded in the N-terminal 126 amino acid residues. Three sequence elements were identified in this region, namely, the transmembrane domain (amino acid residues 51 to 68), a presequence type helix (residues 69 to 83), and an import auxiliary region (residues 84 to 126). The transmembrane domain is not required for stable binding to the TOM complex. The Tom receptors (Tom70, Tom22 and Tom20), as determined by peptide scan analysis, interact with the presequence-like helix, yet the highest binding was to the third sequence element. We propose that the initial recognition of BCS1 precursor at the surface of the organelle mainly depends on the auxiliary region and does not require the transmembrane domain. This essential region represents a novel type of signal with targeting and sorting functions. It is recognized by all three known mitochondrial import receptors, demonstrating their capacity to decode various targeting signals. We suggest that the BCS1 precursor crosses the TOM complex as a loop structure and that once the precursor emerges from the TOM complex, all three structural elements are essential for the intramitochondrial sorting to the inner membrane. PMID:12640110

  16. An EXAFS spectroscopic study of Am(III) complexation with lactate.

    PubMed

    Fröhlich, Daniel R; Skerencak-Frech, Andrej; Kaplan, Ugras; Koke, Carsten; Rossberg, André; Panak, Petra J

    2015-11-01

    The pH dependence (1-7) of Am(III) complexation with lactate in aqueous solution is studied using extended X-ray absorption fine-structure (EXAFS) spectroscopy. Structural data (coordination numbers, Am--O and Am--C distances) of the formed Am(III)-lactate species are determined from the raw k(3)-weighted Am LIII-edge EXAFS spectra. Between pH 1 and pH 6, Am(III) speciation shifts continuously towards complexed species with increasing pH. At higher pH, the amount of complexed species decreases due to formation of hydroxo species. The coordination numbers and distances (3.41-3.43 Å) of the coordinating carbon atoms clearly point out that lactate is bound `side-on' to Am(III) through both the carboxylic and the α-hydroxy function of lactate. The experimentally determined coordination numbers are compared with speciation calculations on the basis of tabulated thermodynamic stability constants. Both EXAFS data and thermodynamic modelling are in very good agreement. The EXAFS spectra are also analyzed by iterative transformation factor analysis to further verify the determined Am(III) speciation and the used structural model. PMID:26524312

  17. [U(III) {N(SiMe2 tBu)2 }3 ]: a structurally authenticated trigonal planar actinide complex.

    PubMed

    Goodwin, Conrad A P; Tuna, Floriana; McInnes, Eric J L; Liddle, Stephen T; McMaster, Jonathan; Vitorica-Yrezabal, Inigo J; Mills, David P

    2014-11-01

    We report the synthesis and characterization of the uranium(III) triamide complex [U(III) (N**)3 ] [1, N**=N(SiMe2 tBu)2 (-) ]. Surprisingly, complex 1 exhibits a trigonal planar geometry in the solid state, which is unprecedented for three-coordinate actinide complexes that have exclusively adopted trigonal pyramidal geometries to date. The characterization data for [U(III) (N**)3 ] were compared with the prototypical trigonal pyramidal uranium(III) triamide complex [U(III) (N")3 ] (N"=N(SiMe3 )2 (-) ), and taken together with theoretical calculations it was concluded that pyramidalization results in net stabilization for [U(III) (N")3 ], but this can be overcome with very sterically demanding ligands, such as N**. The planarity of 1 leads to favorable magnetic dynamics, which may be considered in the future design of U(III) single-molecule magnets. PMID:25241882

  18. Three-Coordinate Terminal Imidoiron(III) Complexes: Structure, Spectroscopy, and Mechanism of Formation

    PubMed Central

    Cowley, Ryan E.; DeYonker, Nathan J.; Eckert, Nathan A.; Cundari, Thomas R.; DeBeer, Serena; Bill, Eckhard; Ottenwaelder, Xavier; Flaschenriem, Christine; Holland, Patrick L.

    2010-01-01

    Reaction of 1-adamantyl azide with iron(I) diketiminate precursors gives metastable but isolable imidoiron(III) complexes LFe=NAd (L = bulky β-diketiminate ligand; Ad = 1-adamantyl). This paper addresses: (1) the spectroscopic and structural characterization of the Fe=N multiple bond in these interesting three-coordinate iron imido complexes, and (2) the mechanism through which the imido complexes form. The iron(III) imido complexes have been examined by 1H NMR and EPR spectroscopies and temperature-dependent magnetic susceptibility (SQUID), and structurally characterized by crystallography and/or X-ray absorption (EXAFS) measurements. These data show that the imido complexes have quartet ground states and short (1.68 ± 0.01 Å) iron-nitrogen bonds. The formation of the imido complexes proceeds through unobserved iron–RN3 intermediates, which are indicated by QM/MM computations to be best described as iron(II) with an RN3 radical anion. The radical character on the organoazide bends its NNN linkage to enable easy N2 loss and imido complex formation. The product distribution between imidoiron(III) products and hexazene-bridged diiron(II) products is solvent-dependent, and the solvent dependence can be explained by coordination of certain solvents to the iron(I) precursor prior to interaction with the organoazide. PMID:20524625

  19. Mitochondrial fatty acid synthesis is required for normal mitochondrial morphology and function in Trypanosoma brucei

    PubMed Central

    Guler, Jennifer L.; Kriegova, Eva; Smith, Terry K.; Lukeš, Julius; Englund, Paul T.

    2013-01-01

    Summary Trypanosoma brucei use microsomal elongases for de novo synthesis of most of its fatty acids. In addition, this parasite utilizes an essential mitochondrial type II synthase for production of octanoate (a lipoic acid precursor) as well as longer fatty acids such as palmitate. Evidence from other organisms suggests that mitochondrially synthesized fatty acids are required for efficient respiration but the exact relationship remains unclear. In procyclic form trypanosomes, we also found that RNAi depletion of the mitochondrial acyl carrier protein, an important component of the fatty acid synthesis machinery, significantly reduces cytochrome-mediated respiration. This reduction was explained by RNAi-mediated inhibition of respiratory complexes II, III and IV, but not complex I. Other effects of RNAi, such as changes in mitochondrial morphology and alterations in membrane potential, raised the possibility of a change in mitochondrial membrane composition. Using mass spectrometry, we observed a decrease in total and mitochondrial phosphatidylinositol and mitochondrial phosphatidylethanolamine. Thus, we conclude that the mitochondrial synthase produces fatty acids needed for maintaining local phospholipid levels that are required for activity of respiratory complexes and preservation of mitochondrial morphology and function. PMID:18221265

  20. The globular cluster system of NGC 1316. III. Kinematic complexity

    NASA Astrophysics Data System (ADS)

    Richtler, T.; Hilker, M.; Kumar, B.; Bassino, L. P.; Gómez, M.; Dirsch, B.

    2014-09-01

    discernable out to 3' radius. The kinematic major axis of NGC 1316 is misaligned by about 10° with the photometric major axis, which might indicate a triaxial symmetry. A simple spherical model like that suggested by dynamical analyses of planetary nebulae also reproduces the velocity dispersions of the faint globular clusters. Conclusions: The central dark matter density of the present model resembles a giant elliptical galaxy. This contradicts population properties which indicate spiral galaxies as pre-merger components. Modified Newtonian dynamics (MOND) would provide a solution, but the kinematical complexity of NGC 1316 does not allow a really firm conclusion. However, NGC 1316 might anyway be a problem for a cold dark matter scenario, if the high dark matter density in the inner region is confirmed in future studies. Based on observations obtained with the VLT at ESO, Cerro Paranal, Chile under the programme 078.B-0856.Appendices are available in electronic form at http://www.aanda.org

  1. Synthesis and characterization of dopamine substitue tripodal trinuclear [(salen/salophen/salpropen)M] (Mdbnd Cr(III), Mn(III), Fe(III) ions) capped s-triazine complexes: Investigation of their thermal and magnetic properties

    NASA Astrophysics Data System (ADS)

    Uysal, Şaban; Koç, Ziya Erdem

    2016-04-01

    In this work, we aimed to synthesize and characterize a novel tridirectional ligand including three catechol groups and its novel tridirectional-trinuclear triazine core complexes. For this purpose, we used melamine (2,4,6-triamino-1,3,5-triazine) (MA) as starting material. 2,4,6-tris(4-carboxybenzimino)-1,3,5-triazine (II) was synthesized by the reaction of an equivalent melamine (I) and three equivalent 4-carboxybenzaldehyde. 4,4‧,4″-((1E,1‧E,1″E)-((1,3,5-triazine-2,4,6-triyl)tris(azanylylidene))tris(methanylylidene))tris(N-(3,4-dihydroxyphenethyl)benzamide) L (IV) was synthesized by the reaction of one equivalent (II) and three equivalent dopamine (3,4-dihydroxyphenethylamine) (DA) by using two different methods. (II, III, IV) and nine novel trinuclear Cr(III), Mn(III) and Fe(III) complexes of (IV) were characterized by means of elemental analyses, 1H NMR, FT-IR spectrometry, LC-MS (ESI+) and thermal analyses. The metal ratios of the prepared complexes were performed using Atomic Absorption Spectrophotometry (AAS). We also synthesized novel tridirectional-trinuclear systems and investigated their effects on magnetic behaviors of [salen, salophen, salpropen Cr(III)/Mn(III)/Fe(III)] capped complexes. The complexes were determined to be low-spin distorted octahedral Mn(III) and Fe(III), and distorted octahedral Cr(III) all bridged by catechol group.

  2. Ascochlorin is a novel, specific inhibitor of the mitochondrial cytochrome bc1 complex

    PubMed Central

    Berry, Edward A.; Huang, Li-shar; Lee, Dong-Woo; Daldal, Fevzi; Nagai, Kazuo; Minagawa, Nobuko

    2009-01-01

    Ascochlorin is an isoprenoid antibiotic that is produced by the phytopathogenic fungus Ascochyta viciae. Similar to ascofuranone, which specifically inhibits trypanosome alternative oxidase by acting at the ubiquinol binding domain, ascochlorin is also structurally related to ubiquinol. When added to the mitochondrial preparations isolated from rat liver, or the yeast Pichia (Hansenula) anomala, ascochlorin inhibited the electron transport via CoQ in a fashion comparable to antimycin A and stigmatellin, indicating that this antibiotic acted on the cytochrome bc1 complex. In contrast to ascochlorin, ascofuranone had much less inhibition on the same activities. On the one hand, like the Qi site inhibitors antimycin A and funiculosin, ascochlorin induced in H. anomala the expression of nuclear-encoded alternative oxidase gene much more strongly than the Qo site inhibitors tested. On the other hand, it suppressed the reduction of cytochrome b and the generation of superoxide anion in the presence of antimycin A3 in a fashion similar to the Qo site inhibitor myxothiazol. These results suggested that ascochlorin might act at both the Qi and the Qo sites of the fungal cytochrome bc1 complex. Indeed, the altered electron paramagnetic resonance (EPR) line shape of the Rieske iron-sulfur protein, and the light-induced time resolved cytochrome b and c reduction kinetics of Rhodobacter capsulatus cytochrome bc1 complex in the presence of ascochlorin demonstrated that this inhibitor can bind to both the Qo and Qi sites of the bacterial enzyme. Additional experiments using purified bovine cytochrome bc1 complex showed that ascochlorin inhibits reduction of cytochrome b by ubiquinone through both Qi and Qo sites. Moreover, crystal structure of chicken cytochrome bc1 complex treated with excess ascochlorin revealed clear electron densities that could be attributed to ascochlorin bound at both the Qi and Qo sites. Overall findings clearly show that ascochlorin is an unusual

  3. Mitochondrial Complex I Is a Global Regulator of Secondary Metabolism, Virulence and Azole Sensitivity in Fungi

    PubMed Central

    Bromley, Mike; Johns, Anna; Davies, Emma; Fraczek, Marcin; Mabey Gilsenan, Jane; Kurbatova, Natalya; Keays, Maria; Kapushesky, Misha; Gut, Marta; Gut, Ivo; Denning, David W.; Bowyer, Paul

    2016-01-01

    Recent estimates of the global burden of fungal disease suggest that that their incidence has been drastically underestimated and that mortality may rival that of malaria or tuberculosis. Azoles are the principal class of antifungal drug and the only available oral treatment for fungal disease. Recent occurrence and increase in azole resistance is a major concern worldwide. Known azole resistance mechanisms include over—expression of efflux pumps and mutation of the gene encoding the target protein cyp51a, however, for one of the most important fungal pathogens of humans, Aspergillus fumigatus, much of the observed azole resistance does not appear to involve such mechanisms. Here we present evidence that azole resistance in A. fumigatus can arise through mutation of components of mitochondrial complex I. Gene deletions of the 29.9KD subunit of this complex are azole resistant, less virulent and exhibit dysregulation of secondary metabolite gene clusters in a manner analogous to deletion mutants of the secondary metabolism regulator, LaeA. Additionally we observe that a mutation leading to an E180D amino acid change in the 29.9 KD subunit is strongly associated with clinical azole resistant A. fumigatus isolates. Evidence presented in this paper suggests that complex I may play a role in the hypoxic response and that one possible mechanism for cell death during azole treatment is a dysfunctional hypoxic response that may be restored by dysregulation of complex I. Both deletion of the 29.9 KD subunit of complex I and azole treatment alone profoundly change expression of gene clusters involved in secondary metabolism and immunotoxin production raising potential concerns about long term azole therapy. PMID:27438017

  4. Mitochondrial Complex I Is a Global Regulator of Secondary Metabolism, Virulence and Azole Sensitivity in Fungi.

    PubMed

    Bromley, Mike; Johns, Anna; Davies, Emma; Fraczek, Marcin; Mabey Gilsenan, Jane; Kurbatova, Natalya; Keays, Maria; Kapushesky, Misha; Gut, Marta; Gut, Ivo; Denning, David W; Bowyer, Paul

    2016-01-01

    Recent estimates of the global burden of fungal disease suggest that that their incidence has been drastically underestimated and that mortality may rival that of malaria or tuberculosis. Azoles are the principal class of antifungal drug and the only available oral treatment for fungal disease. Recent occurrence and increase in azole resistance is a major concern worldwide. Known azole resistance mechanisms include over-expression of efflux pumps and mutation of the gene encoding the target protein cyp51a, however, for one of the most important fungal pathogens of humans, Aspergillus fumigatus, much of the observed azole resistance does not appear to involve such mechanisms. Here we present evidence that azole resistance in A. fumigatus can arise through mutation of components of mitochondrial complex I. Gene deletions of the 29.9KD subunit of this complex are azole resistant, less virulent and exhibit dysregulation of secondary metabolite gene clusters in a manner analogous to deletion mutants of the secondary metabolism regulator, LaeA. Additionally we observe that a mutation leading to an E180D amino acid change in the 29.9 KD subunit is strongly associated with clinical azole resistant A. fumigatus isolates. Evidence presented in this paper suggests that complex I may play a role in the hypoxic response and that one possible mechanism for cell death during azole treatment is a dysfunctional hypoxic response that may be restored by dysregulation of complex I. Both deletion of the 29.9 KD subunit of complex I and azole treatment alone profoundly change expression of gene clusters involved in secondary metabolism and immunotoxin production raising potential concerns about long term azole therapy. PMID:27438017

  5. Luminescent Alkyne-Bearing Terbium(III) Complexes and Their Application to Bioorthogonal Protein Labeling.

    PubMed

    O'Malley, William I; Abdelkader, Elwy H; Aulsebrook, Margaret L; Rubbiani, Riccardo; Loh, Choy-Theng; Grace, Michael R; Spiccia, Leone; Gasser, Gilles; Otting, Gottfried; Tuck, Kellie L; Graham, Bim

    2016-02-15

    Two new bifunctional macrocyclic chelate ligands that form luminescent terbium(III) complexes featuring an alkyne group for conjugation to (bio)molecules via the Cu(I)-catalyzed "click" reaction were synthesized. Upon ligation, the complexes exhibit a significant luminescent enhancement when excited at the λ(max) of the "clicked" products. To demonstrate the utility of the complexes for luminescent labeling, they were conjugated in vitro to E. coli aspartate/glutamate-binding protein incorporating a genetically encoded p-azido-L-phenylalanine or p-(azidomethyl)-L-phenylalanine residue. The complexes may prove useful for time-gated assay applications. PMID:26821062

  6. Theoretical studies on the photophysical properties of some Iridium (III) complexes used for OLED

    NASA Astrophysics Data System (ADS)

    Urinda, Sharmistha; Das, Goutam; Pramanik, Anup; Sarkar, Pranab

    2016-09-01

    The structural and photophysical properties of four heteroleptic Iridium (III) complexes, based on 1-phenylpyrazole ligand, have been investigated theoretically. The effect of chemical substitution on the absorption and the emission spectra of the complexes has been studied and compared with the experimental data. We observe a significant structural change in the lowest triplet excited state as compared to the ground singlet state. We compute the emission wavelength of the complexes by considering the spin-orbit coupling. Using these understandings, we predict two new complexes having deeper blue emission which are supposed to be better efficient OLED materials.

  7. Reactions of Co(III)-nitrosyl complexes with superoxide and their mechanistic insights.

    PubMed

    Kumar, Pankaj; Lee, Yong-Min; Park, Young Jun; Siegler, Maxime A; Karlin, Kenneth D; Nam, Wonwoo

    2015-04-01

    New Co(III)-nitrosyl complexes bearing N-tetramethylated cyclam (TMC) ligands, [(12-TMC)Co(III)(NO)](2+) (1) and [(13-TMC)Co(III)(NO)](2+) (2), were synthesized via [(TMC)Co(II)(CH3CN)](2+) + NO(g) reactions. Spectroscopic and structural characterization showed that these compounds bind the nitrosyl moiety in a bent end-on fashion. Complexes 1 and 2 reacted with KO2/2.2.2-cryptand to produce [(12-TMC)Co(II)(NO2)](+) (3) and [(13-TMC)Co(II)(NO2)](+) (4), respectively; these possess O,O'-chelated nitrito ligands. Mechanistic studies using (18)O-labeled superoxide ((18)O2(•-)) showed that one O atom in the nitrito ligand is derived from superoxide and the O2 produced comes from the other superoxide O atom. Evidence supporting the formation of a Co-peroxynitrite intermediate is also presented. PMID:25793706

  8. Anticancer Activity of Organogallium(III) Complexes in Colon Cancer Cells.

    PubMed

    Kaluđerović, Milena R; Mojić, Marija; Gómez-Ruiz, Santiago; Mijatović, Sanja; Maksimović-Ivanić, Danijela

    2016-01-01

    In vitro antitumor activity of various organogallium(III) complexes (1-8) has been tested against CT26CL25, HCT116, SW480 colon cancer cell lines. CV and MTT assays were used to assess on the antiproliferative effect of investigated organogallium(III) complexes. From the investigated complexes, the most active was found to be tetranuclear compound 8 against CT26CL25 cells. Flow cytometric analysis of the CT26CL25 cells upon the treatment with 8 was performed in order to determine the role of apoptosis, caspase activation, autophagy and proliferation rate on the cell death caused with this compound. Results indicate cytotoxic potential of the tetranuclear complex 8 by inducing caspase independent apoptosis and blocking most of the cells before first division. PMID:26443026

  9. Synthesis and characterization of Mn(II), Au(III) and Zr(IV) hippurates complexes.

    PubMed

    Refat, Moamen S; El-Korashy, Sabry A; Ahmed, Ahmed S

    2008-09-01

    Mn(II), Au(III) and Zr(III) complexes with N-benzoylglycine (hippuric acid) (abbreviation hipH) were synthesized and characterized by elemental analysis, molar conductivity, magnetic measurements, spectral methods (mid-infrared, 1H NMR, mass, X-ray powder diffraction and UV/vis spectra) and simultaneous thermal analysis (TG and DTG) techniques. The molar conductance measurements proved that all hippuric acid complexes are non-electrolytes. The electronic spectra and magnetic susceptibility measurements were used to infer the structures. The IR spectra of the ligand and its complexes are used to identify the type of bonding. The kinetic thermodynamic parameters such as: E*, DeltaH*, DeltaS* and DeltaG* are estimated from the DTG curves. The free ligand and its complexes have been studied for their possible biological antifungal activity. PMID:17981497

  10. Near-Infrared Phosphorescent Iridium(III) Benzonorrole Complexes Possessing Pyridine-based Axial Ligands.

    PubMed

    Maurya, Yogesh Kumar; Ishikawa, Takahiro; Kawabe, Yasunori; Ishida, Masatoshi; Toganoh, Motoki; Mori, Shigeki; Yasutake, Yuhsuke; Fukatsu, Susumu; Furuta, Hiroyuki

    2016-06-20

    Novel near-infrared phosphorescent iridium(III) complexes based on benzo-annulated N-linked corrole analogue (termed as benzonorrole) were synthesized. The structures of the complexes revealed octahedral coordination geometries involving an organometallic iridium-carbon bond with two external axial ligands. Interestingly, the iridium(III) complex exhibits near-infrared phosphorescence at room temperature at wavelengths beyond 900 nm. The significant redshift of the emission, as compared to the corrole congener, is originated from the ligand-centered triplet character. The fine-tuning of the photophysical properties of the complexes was achieved by introducing electron-donating and electron-withdrawing substituents on the axial pyridine ligands. PMID:27249778

  11. Geometric and Electronic Structure of a Peroxomanganese(III) Complex Supported by a Scorpionate Ligand

    PubMed Central

    Colmer, Hannah E.; Geiger, Robert A.; Leto, Domenick F.; Wijeratne, Gayan B.; Day, Victor W.; Jackson, Timothy A.

    2014-01-01

    A monomeric MnII complex has been prepared with the facially-coordinating TpPh2 ligand, (TpPh2 = hydrotris(3,5-diphenylpyrazol-1-yl)borate). The X-ray crystal structure shows three coordinating solvent molecules resulting in a six-coordinate complex with Mn-ligand bond lengths that are consistent with a high-spin MnII ion. Treatment of this MnII complex with excess KO2 at room temperature resulted in the formation of a MnIII-O2 complex that is stable for several days at ambient conditions, allowing for the determination of the X-ray crystal structure of this intermediate. The electronic structure of this peroxomanganese(III) adduct was examined by using electronic absorption, electron paramagnetic resonance (EPR), low-temperature magnetic circular dichroism (MCD), and variable-temperature variable-field (VTVH) MCD spectroscopies. Density functional theory (DFT), time-dependent (TD)-DFT, and multireference ab initio CASSCF/NEVPT2 calculations were used to assign the electronic transitions and further investigate the electronic structure of the peroxomanganese(III) species. The lowest ligand-field transition in the electronic absorption spectrum of the MnIII-O2 complex exhibits a blue shift in energy compared to other previously characterized peroxomanganese(III) complexes that results from a large axial bond elongation, reducing the metal-ligand covalency and stabilizing the σ-antibonding Mn dz2 MO that is the donor MO for this transition. PMID:25312785

  12. X-ray Absorption Spectroscopy and Reactivity of Thiolate-Ligated FeIII-OOR Complexes

    PubMed Central

    Stasser, Jay; Namuswe, Frances; Kasper, Gary D.; Jiang, Yunbo; Krest, Courtney M.; Green, Michael T.; Penner-Hahn, James; Goldberg, David P.

    2010-01-01

    The reaction of a series of thiolate-ligated iron(II) complexes [FeII([15]aneN4)(SC6H5)]BF4 (1), [FeII([15]aneN4)(SC6H4-p-Cl)]BF4 (2), and [FeII([15]aneN4)(SC6H4-p-NO2)]BF4 (3) with alkylhydroperoxides at low temperature (−78 °C or −40 °C) leads to the metastable alkylperoxo-iron(III) species [FeIII([15]aneN4)(SC6H5)(OOtBu)]BF4 (1a), [FeIII([15]aneN4)(SC6H4-p-Cl)(OOtBu)]BF4 (2a), and [FeIII([15]aneN4)(SC6H4-p-NO2)(OOtBu)]BF4 (3a), respectively. X-ray absorption spectroscopic studies (XAS) were conducted on the FeIII-OOR complexes and their iron(II) precursors. The edge energy for the iron(II) complexes (~7118 eV) shifts to higher energy upon oxidation by ROOH, and the resulting edge energies for the FeIII-OOR species range from 7121 – 7125 eV and correlate with the nature of the thiolate donor. EXAFS analysis of the iron(II) complexes 1 – 3 in CH2Cl2 show that their solid state structures remain intact in solution. The EXAFS data on 1a – 3a confirm their proposed structures as mononuclear, 6-coordinate FeIII-OOR complexes with 4N and 1S donors completing the coordination sphere. The Fe-O bond distances obtained from EXAFS for 1a – 3a are 1.82 – 1.85 Å, significantly longer than other low-spin FeIII-OOR complexes. The Fe-O distances correlate with the nature of the thiolate donor, in agreement with the previous trends observed for ν(Fe-O) from resonance Raman (RR) spectroscopy, and supported by optimized geometries obtained from density functional theory (DFT) calculations. Reactivity and kinetic studies on 1a – 3a show an important influence of the thiolate donor. PMID:20839847

  13. Evidence of Mitochondrial Dysfunction within the Complex Genetic Etiology of Schizophrenia

    PubMed Central

    Hjelm, Brooke E.; Rollins, Brandi; Mamdani, Firoza; Lauterborn, Julie C.; Kirov, George; Lynch, Gary; Gall, Christine M.; Sequeira, Adolfo; Vawter, Marquis P.

    2015-01-01

    Genetic evidence has supported the hypothesis that schizophrenia (SZ) is a polygenic disorder caused by the disruption in function of several or many genes. The most common and reproducible cellular phenotype associated with SZ is a reduction in dendritic spines within the neocortex, suggesting alterations in dendritic architecture may cause aberrant cortical circuitry and SZ symptoms. Here, we review evidence supporting a multifactorial model of mitochondrial dysfunction in SZ etiology and discuss how these multiple paths to mitochondrial dysfunction may contribute to dendritic spine loss and/or underdevelopment in some SZ subjects. The pathophysiological role of mitochondrial dysfunction in SZ is based upon genomic analyses of both the mitochondrial genome and nuclear genes involved in mitochondrial function. Previous studies and preliminary data suggest SZ is associated with specific alleles and haplogroups of the mitochondrial genome, and also correlates with a reduction in mitochondrial copy number and an increase in synonymous and nonsynonymous substitutions of mitochondrial DNA. Mitochondrial dysfunction has also been widely implicated in SZ by genome-wide association, exome sequencing, altered gene expression, proteomics, microscopy analyses, and induced pluripotent stem cell studies. Together, these data support the hypothesis that SZ is a polygenic disorder with an enrichment of mitochondrial targets. PMID:26550561

  14. First structurally characterized mixed-halogen nickel(III) NCN-pincer complex

    NASA Astrophysics Data System (ADS)

    Kozhanov, Konstantin A.; Bubnov, Michael P.; Cherkasov, Vladimir K.; Fukin, Georgy K.; Vavilina, Nina N.; Efremova, Larisa Yu.; Abakumov, Gleb A.

    2009-03-01

    A square-pyramidal mixed-halogen nickel(III) NCN-pincer complex (PipeNCN)NiClBr (where PipeNCN = 2,6-bis(piperidinomethyl)phenyl) was structurally characterized. Bromine occupies apical position; pincer ligand and chlorine atom are in the basal plane. EPR detects that complex in solution exists as a mixture of two structural isomers with bromine or chlorine atoms in the top of pyramid.

  15. Enhanced photophysics from self-assembled cyclometalated Ir(iii) complexes in water.

    PubMed

    McGoorty, Michelle M; Khnayzer, Rony S; Castellano, Felix N

    2016-06-14

    Two water-soluble anionic cyclometalated Ir(iii) complexes, Ir(ppy)2BPS [] and Ir(F-mppy)2BPS [] have been synthesized and display clear evidence of self-assembly in water. Concentration-induced aggregation enhances the excited-state properties of both complexes, blue-shifting the photoluminescence emission energies as well as increasing the corresponding excited state lifetimes and quantum yields up to a factor of 5. PMID:27240481

  16. Synthesis and spectroscopic studies of iron (III) complex with a quinolone family member (pipemidic acid)

    NASA Astrophysics Data System (ADS)

    Skrzypek, D.; Szymanska, B.; Kovala-Demertzi, Dimitra; Wiecek, Joanna; Talik, E.; Demertzis, Mavroudis A.

    2006-12-01

    The interaction of iron (III) with pipemidic acid, Hpipem, afforded the complex [Fe (pipem) (HO)2 (H2O)]2. The new complex has been characterised by elemental analyses, infra-red, EPR and XPS spectroscopies. The monoanion, pipem, exhibits O, O ligation through the carbonyl and carboxylato oxygen atoms. Six coordinate dimer distorted octahedral configuration has been proposed for [Fe (pipem) (HO)2 (H2O)]2.

  17. Luminescent and triboluminescent properties of europium(III) hexafluoroacetylacetonate and trifluoroacetate complexes with triphenylphosphine oxide

    NASA Astrophysics Data System (ADS)

    Kalinovskaya, I. V.; Mirochnik, A. G.

    2014-03-01

    Crystalline and strongly luminescent complexes of europium hexafluoroacetylacetonate and trifluoroacetate with triphenylphosphine oxide of Eu(HFAA)3 · 2TPPO and [Eu(TFA)3 · 2TPPO(H2O)]2 composition are synthesized that demonstrating triboluminescent properties. It is established that the measured photoluminescence and triboluminescence spectra of these noncentrosymmetric complex compounds are identical, due to the characteristic f- f-luminescence of the europium(III) ion.

  18. Evidence for Physical Association of Mitochondrial Fatty Acid Oxidation and Oxidative Phosphorylation Complexes

    PubMed Central

    Wang, Yudong; Mohsen, Al-Walid; Mihalik, Stephanie J.; Goetzman, Eric S.; Vockley, Jerry

    2010-01-01

    Fatty acid β-oxidation (FAO) and oxidative phosphorylation (OXPHOS) are key pathways involved in cellular energetics. Reducing equivalents from FAO enter OXPHOS at the level of complexes I and III. Genetic disorders of FAO and OXPHOS are among the most frequent inborn errors of metabolism. Patients with deficiencies of either FAO or OXPHOS often show clinical and/or biochemical findings indicative of a disorder of the other pathway. In this study, the physical and functional interactions between these pathways were examined. Extracts of isolated rat liver mitochondria were subjected to blue native polyacrylamide gel electrophoresis (BNGE) to separate OXPHOS complexes and supercomplexes followed by Western blotting using antisera to various FAO enzymes. Extracts were also subjected to sucrose density centrifugation and fractions analyzed by BNGE or enzymatic assays. Several FAO enzymes co-migrated with OXPHOS supercomplexes in different patterns in the gels. When palmitoyl-CoA was added to the sucrose gradient fractions containing OXPHOS supercomplexes in the presence of potassium cyanide, cytochrome c was reduced. Cytochrome c reduction was completely blocked by myxothiazol (a complex III inhibitor) and 3-mercaptopropionate (an inhibitor of the first step of FAO), but was only partially inhibited by rotenone (a complex I inhibitor). Although palmitoyl-CoA and octanoyl-CoA provided reducing equivalents to OXPHOS-containing supercomplex fractions, no accumulation of their intermediates was detected. In contrast, short branched acyl-CoA substrates were not metabolized by OXPHOS-containing supercomplex fractions. These data provide evidence of a multifunctional FAO complex within mitochondria that is physically associated with OXPHOS supercomplexes and promotes metabolic channeling. PMID:20663895

  19. Synthesis and Base Hydrolysis of a Cobalt(III) Complex Coordinated by a Thioether Ligand

    ERIC Educational Resources Information Center

    Roecker, Lee

    2008-01-01

    A two-week laboratory experiment for students in advanced inorganic chemistry is described. Students prepare and characterize a cobalt(III) complex coordinated by a thioether ligand during the first week of the experiment and then study the kinetics of Co-S bond cleavage in basic solution during the second week. The synthetic portion of the…

  20. A spin-crossover ionic liquid from the cationic iron(III) Schiff base complex.

    PubMed

    Okuhata, Megumi; Funasako, Yusuke; Takahashi, Kazuyuki; Mochida, Tomoyuki

    2013-09-01

    A thermochromic magnetic ionic liquid containing a cationic iron(III) Schiff-base complex has been developed, whose color and magnetic moment change with temperature because of spin crossover in the liquid state. This spin-crossover behavior closely resembles that of a solid having the same cation. PMID:23872624

  1. Future Development Of The Flerov Laboratory Accelerator Complex (Project DRIBs-III)

    NASA Astrophysics Data System (ADS)

    Gulbekian, G. G.; Dmitriev, S. N.; Itkis, M. G.; Oganessian, Yu. Ts.; Popeko, A. G.

    2010-04-01

    Future development of the FLNR accelerator complex (project DRIBs-III) includes modernization of existing cyclotrons, construction of a new experimental hall, creation of a new high current cyclotron and of next generation experimental set-ups. Realization of the project is planned for 2010-2016.

  2. Eu(III) Complexes of Octadentate 1-Hydroxy-2-pyridinones: Stability and Improved Photophysical Performance

    SciTech Connect

    Moore, Evan G.; D'Aleo, Anthony; Xu, Jide; Raymond, Kenneth N.

    2009-05-29

    The luminescence properties of lanthanoid ions can be dramatically enhanced by coupling them to antenna ligands that absorb light in the UV-visible and then efficiently transfer the energy to the lanthanoid centre. The synthesis and the complexation of Ln{sup III} cations (Ln = Eu, Gd) for a ligand based on four 1-hydroxy-2-pyridinone (1,2-HOPO) chelators appended to a ligand backbone derived by linking two L-lysine units (3LI-bis-LYS) is described. This octadentate Eu{sup III} complex ([Eu(3LI-bis-LYS-1,2-HOPO)]{sup -}) has been evaluated in terms of its thermodynamic stability, UV-visible absorption and luminescence properties. For this complex, the conditional stability constant (pM) is 19.9, which is an order of magnitude higher than diethylenetriaminepentacetic acid at pH = 7.4. This Eu{sup III} complex also shows an almost two-fold increase in its luminescence quantum yield in aqueous solution (pH = 7.4) when compared with other octadentate ligands. Hence, despite a slight decrease of the molar absorption coefficient, a much higher brightness is obtained for [Eu(3LI-bis-LYS-1,2-HOPO)]{sup -}. This overall improvement was achieved by saturating the coordination sphere of the Eu{sup III} cation, yielding an increased metal-centred efficiency by excluding solvent water molecules from the metal's inner sphere.

  3. Negative results in phase III trials of complex interventions: cause for concern or just good science?

    PubMed

    Crawford, Mike J; Barnicot, Kirsten; Patterson, Sue; Gold, Christian

    2016-07-01

    Not all interventions that show promise in exploratory trials will be supported in phase III studies. But the high failure rate in recent trials of complex mental health interventions is a concern. Proper consideration of trial processes and greater use of adaptive trial designs could ensure better use of available resources. PMID:27369475

  4. Vibrational spectra of the Ga(III) complexes with oxine and clioquinol

    NASA Astrophysics Data System (ADS)

    Wagner, Claudia C.; González-Baró, Ana C.; Baran, Enrique J.

    2011-09-01

    The FTIR and FT-Raman spectra of the gallium(III) complexes of 8-hydroxyquinoline (oxine) and 5-chloro-7-iodo-8-hydroxyquinoline (clioquinol), were recorded and briefly discussed by comparison with the spectra of the uncoordinated ligands and with some related species.

  5. A gadolinium(iii) complex that shows room-temperature phosphorescence in the crystalline state.

    PubMed

    Nakai, Hidetaka; Kitagawa, Kazuhiro; Seo, Juncheol; Matsumoto, Takahiro; Ogo, Seiji

    2016-07-19

    This paper presents a gadolinium(iii) complex that shows blue phosphorescence in the crystalline state at room temperature under air atmosphere; color of the crystals can be changed to pale-green from blue by doping of 1-naphthol. PMID:27221814

  6. Synthesis and luminescence modulation of pyrazine-based gold(III) pincer complexes.

    PubMed

    Fernandez-Cestau, Julio; Bertrand, Benoît; Blaya, Maria; Jones, Garth A; Penfold, Thomas J; Bochmann, Manfred

    2015-12-01

    The first examples of pyrazine-based gold(III) pincer complexes are reported; their intense photoemissions can be modified by protonation, N-alkylation or metal ions, without the need for altering the ligand framework. Emissions shift from red (77 K) to blue (298 K) due to thermally activated delayed fluorescence (TADF). PMID:26425736

  7. Pharmacologic targeting of sirtuin and PPAR signaling improves longevity and mitochondrial physiology in respiratory chain complex I mutant Caenorhabditis elegans

    PubMed Central

    McCormack, Shana; Polyak, Erzsebet; Ostrovsky, Julian; Dingley, Stephen D.; Rao, Meera; Kwon, Young Joon; Xiao, Rui; Zhang, Zhe; Nakamaru-Ogiso, Eiko; Falk, Marni J.

    2015-01-01

    Mitochondrial respiratory chain (RC) diseases are highly morbid multi-systemic conditions for which few effective therapies exist. Given the essential role of sirtuin and PPAR signaling in mediating both mitochondrial physiology and the cellular response to metabolic stress in RC complex I (CI) disease, we postulated that drugs that alter these signaling pathways either directly (resveratrol for sirtuin, rosiglitazone for PPARγ, fenofibrate for PPARα), or indirectly by increasing NAD+ availability (nicotinic acid), might offer effective treatment strategies for primary RC disease. Integrated effects of targeting these cellular signaling pathways on animal lifespan and multi-dimensional in vivo parameters were studied in gas-1(fc21) relative to wild-type (N2 Bristol) worms. Specifically, animal lifespan, transcriptome profiles, mitochondrial oxidant burden, mitochondrial membrane potential, mitochondrial content, amino acid profiles, stable isotope-based intermediary metabolic flux, and total nematode NADH and NAD+ concentrations were compared. Shortened gas-1(fc21) mutant lifespan was rescued with either resveratrol or nicotinic acid, regardless of whether treatments were begun at the early larval stage or in young adulthood. Rosiglitazone administration beginning in young adult stage animals also rescued lifespan. All drug treatments reversed the most significant transcriptome alterations at the biochemical pathway level relative to untreated gas-1(fc21) animals. Interestingly, increased mitochondrial oxidant burden in gas-1(fc21) was reduced with nicotinic acid but exacerbated significantly by resveratrol and modestly by fenofibrate, with little change by rosiglitazone treatment. In contrast, the reduced mitochondrial membrane potential of mutant worms was further decreased by nicotinic acid but restored by either resveratrol, rosiglitazone, or fenofibrate. Using a novel HPLC assay, we discovered that gas-1(fc21) worms have significant deficiencies of NAD+ and

  8. Mitochondrial electron transport chain complexes, catalase and markers of oxidative stress in platelets of patients with severe aluminum phosphide poisoning.

    PubMed

    Anand, R; Sharma, D R; Verma, D; Bhalla, A; Gill, K D; Singh, S

    2013-08-01

    Aluminum phosphide (ALP), a widely used fumigant and rodenticide, leads to high mortality if ingested. Its toxicity is due to phosphine that is liberated when it comes in contact with moisture. The exact site or mechanism of action of phosphine is not known, although it is widely believed that it affects mitochondrial oxidative phosphorylation. Basic serum biochemical parameters, activity of mitochondrial complexes, antioxidant enzymes and parameters of oxidative stress were estimated in the platelets of 21 patients who developed severe poisoning following ALP ingestion. These parameters were compared with 32 healthy controls and with 22 patients with shock due to other causes (cardiogenic shock (11), septic shock (9) and hemorrhagic shock (2)). The serum levels of creatine kinase-muscle brain and lactate dehydrogenase were higher in patients poisoned with ALP, whereas a significant decrease was observed in the activities of mitochondrial complexes I, II and IV. The activity of catalase was lower but the activities of superoxide dismutase and glutathione peroxidase were unaffected in them. A significant increase in lipid peroxidation and protein carbonylation was observed, whereas total blood thiol levels were lower. In patients severely poisoned with ALP, not only cytochrome c oxidase but also other complexes are involved in mitochondrial electron transport, and enzymes are also inhibited. PMID:23821638

  9. Resveratrol Induces a Mitochondrial Complex I-dependent Increase in NADH Oxidation Responsible for Sirtuin Activation in Liver Cells*

    PubMed Central

    Desquiret-Dumas, Valérie; Gueguen, Naïg; Leman, Géraldine; Baron, Stéphanie; Nivet-Antoine, Valérie; Chupin, Stéphanie; Chevrollier, Arnaud; Vessières, Emilie; Ayer, Audrey; Ferré, Marc; Bonneau, Dominique; Henrion, Daniel; Reynier, Pascal; Procaccio, Vincent

    2013-01-01

    Resveratrol (RSV) has been shown to be involved in the regulation of energetic metabolism, generating increasing interest in therapeutic use. SIRT1 has been described as the main target of RSV. However, recent reports have challenged the hypothesis of its direct activation by RSV, and the signaling pathways remain elusive. Here, the effects of RSV on mitochondrial metabolism are detailed both in vivo and in vitro using murine and cellular models and isolated enzymes. We demonstrate that low RSV doses (1–5 μm) directly stimulate NADH dehydrogenases and, more specifically, mitochondrial complex I activity (EC50 ∼1 μm). In HepG2 cells, this complex I activation increases the mitochondrial NAD+/NADH ratio. This higher NAD+ level initiates a SIRT3-dependent increase in the mitochondrial substrate supply pathways (i.e. the tricarboxylic acid cycle and fatty acid oxidation). This effect is also seen in liver mitochondria of RSV-fed animals (50 mg/kg/day). We conclude that the increase in NADH oxidation by complex I is a crucial event for SIRT3 activation by RSV. Our results open up new perspectives in the understanding of the RSV signaling pathway and highlight the critical importance of RSV doses used for future clinical trials. PMID:24178296

  10. Mitochondrial lineage sorting in action – historical biogeography of the Hyles euphorbiae complex (Sphingidae, Lepidoptera) in Italy

    PubMed Central

    2013-01-01

    Background Mitochondrial genes are among the most commonly used markers in studies of species’ phylogeography and to draw conclusions about taxonomy. The Hyles euphorbiae complex (HEC) comprises six distinct mitochondrial lineages in the Mediterranean region, of which one exhibits a cryptic disjunct distribution. The predominant mitochondrial lineage in most of Europe, euphorbiae, is also present on Malta; however, it is nowadays strangely absent from Southern Italy and Sicily, where it is replaced by 'italica'. A separate biological entity in Italy is further corroborated by larval colour patterns with a congruent, confined suture zone along the Northern Apennines. By means of historic DNA extracted from museum specimens, we aimed to investigate the evolution of the mitochondrial demographic structure of the HEC in Italy and Malta throughout the Twentieth Century. Results At the beginning of the Twentieth Century, the European mainland lineages were also present at a moderate frequency in Southern Italy and Sicily. The proportion of 'italica' then steadily increased in this area from below 60 percent to near fixation in about 120 years. Thus, geographical sorting of mitochondrial lineages in the HEC was not as complete then as the current demography suggests. The pattern of an integral 'italica' core region and a disjunct euphorbiae distribution evolved very recently. To explain these strong demographic changes, we propose genetic drift due to anthropogenic habitat loss and fragmentation in combination with an impact from recent climate warming that favoured the spreading of the potentially better adapted 'italica' populations. Conclusions The pattern of geographically separated mitochondrial lineages is commonly interpreted as representing long term separated entities. However, our results indicate that such a pattern can emerge surprisingly quickly, even in a widespread and rather common taxon. We thus caution against drawing hasty taxonomic conclusions from

  11. Synthesis, characterization, and stability of iron (III) complex ions possessing phenanthroline-based ligands

    PubMed Central

    Rios, Andrew; Frias, Elma; Eichler, Jack F.

    2014-01-01

    It has previously been demonstrated that phenanthroline-based ligands used to make gold metallotherapuetics have the ability to exhibit cytotoxicity when not coordinated to the metal center. In an effort to help assess the mechanism by which these ligands may cause tumor cell death, iron binding and removal experiments have been considered. The close linkage between cell proliferation and intracellular iron concentrations suggest that iron deprivation strategies may be a mechanism involved in inhibiting tumor cell growth. With the creation of iron (III) phen complexes, the iron binding abilities of three polypyridal ligands [1,10-phenanthroline (phen), 2,9-dimethyl-1, 10-phenanthroline (methylphen), and 2,9-di-sec-butyl-1, 10-phenanthroline (sec-butylphen)] can be tested via a competition reaction with a known iron chelator. Therefore, iron (III) complexes possessing all three ligands were synthesized. Initial mass spectrometric and infrared absorption data indicate that iron (III) tetrachloride complex ions with protonated phen ligands (RphenH+) were formed: [phenH][FeCl4], [methylphenH][FeCl4], [sec-butylphenH][FeCl4]. UV-Vis spectroscopy was used to monitor the stability of the complex ions, and it was found that the sec-butylpheniron complex was more stable than the phen and methylphen analogues. This was based on the observation that free ligand was observed immediately upon the addition of EDTA to the [phenH][FeCl4] and [methylphenH] [FeCl4] complex ions. PMID:25379358

  12. Mononuclear ruthenium(III) complexes containing chelating thiosemicarbazones: Synthesis, characterization and catalytic property

    NASA Astrophysics Data System (ADS)

    Raja, N.; Ramesh, R.

    2010-02-01

    Mononuclear ruthenium(III) complexes of the type [RuX(EPh 3) 2(L)] (E = P or As; X = Cl or Br; L = dibasic terdentate dehydroacetic acid thiosemicarbazones) have been synthesized from the reaction of thiosemicarbazone ligands with ruthenium(III) precursors, [RuX 3(EPh 3) 3] (where E = P, X = Cl; E = As, X = Cl or Br) and [RuBr 3(PPh 3) 2(CH 3OH)] in benzene. The compositions of the complexes have been established by elemental analysis, magnetic susceptibility measurement, FT-IR, UV-vis and EPR spectral data. These complexes are paramagnetic and show intense d-d and charge transfer transitions in dichloromethane. The complexes show rhombic EPR spectra at LNT which are typical of low-spin distorted octahedral ruthenium(III) species. All the complexes are redox active and display an irreversible metal centered redox processes. Complex [RuCl(PPh 3) 2(DHA-PTSC)] ( 5) was used as catalyst for transfer hydrogenation of ketones in the presence of isopropanol/KOH and was found to be the active species.

  13. Synthesis, Physicochemical Properties, and Antimicrobial Studies of Iron (III) Complexes of Ciprofloxacin, Cloxacillin, and Amoxicillin

    PubMed Central

    Ajali, Uzoechi; Ukoha, Pius O.

    2014-01-01

    Iron (III) complexes of ciprofloxacin, amoxicillin, and cloxacillin were synthesized and their aqueous solubility profiles, relative stabilities, and antimicrobial properties were evaluated. The complexes showed improved aqueous solubility when compared to the corresponding ligands. Relative thermal and acid stabilities were determined spectrophotometrically and the results showed that the complexes have enhanced thermal and acid stabilities when compared to the pure ligands. Antimicrobial studies showed that the complexes have decreased activities against most of the tested microorganisms. Ciprofloxacin complex, however, showed almost the same activity as the corresponding ligand. Job's method of continuous variation suggested 1 : 2 metals to ligand stoichiometry for ciprofloxacin complex but 1 : 1 for cloxacillin complex. PMID:25505991

  14. The origin, composition, and reactivity of dissolved iron(III) complexes in coastal organic- and iron-rich sediments

    NASA Astrophysics Data System (ADS)

    Beckler, Jordon S.; Jones, Morris E.; Taillefert, Martial

    2015-03-01

    The redox chemistry and speciation of Fe in both solid and dissolved phases were characterized in the organic- and Fe-rich sediments of the Satilla River estuary in South-East Georgia (USA) on a series of four cruises between July 2007 and January 2008. Results indicate that dissolved Fe is present in relatively high concentration in the overlying waters at the freshwater end of the estuary and flocculates along the river as the salinity increases downstream. Soluble organic-Fe(III) complexes comprise the majority of dissolved Fe (<0.2 μm) in the suboxic pore waters of the upriver stations that are characterized by high concentrations of poorly crystalline Fe(III) (oxy)hydroxides. In contrast, SO42--reducing conditions downstream prevent the accumulation of organic-Fe(III) in the pore waters by titrating Fe from the sediment. Separation of dissolved Fe by size exclusion chromatography revealed that Fe(II) is complexed by organic ligands in the pore waters while the organic-Fe(III) complexes are either small or highly reactive with the column matrix. Finally, dissimilatory Fe(III) reduction, stimulated by inoculating anaerobic sediments with a Fe(III)-reducing bacterium (FeRB), Shewanella putrefaciens strain 200, increased production of soluble organic-Fe(III) complexes, and addition of reactive Fe(III) hydroxides accelerated the non-reductive dissolution of Fe(III) (oxy)hydroxides irrespective of the presence of exogenous FeRB. These findings suggest soluble organic-Fe(III) complexes in suboxic pore waters may be produced both as intermediates during the dissimilatory reduction of Fe(III) (oxy)hydroxides by Fe(III)-reducing microorganisms and during the oxidation of organic-Fe(II) complexes by Fe(III) (oxy)hydroxides. These soluble organic-Fe(III) complexes are stable in pore waters and may flux from the sediments to the continental shelf.

  15. Complete mitochondrial DNA genome of Bemisia tabaci cryptic pest species complex Asia I (Hemiptera: Aleyrodidae).

    PubMed

    Tay, W T; Elfekih, S; Court, L; Gordon, K H; De Barro, P J

    2016-01-01

    The complete length of the Asia I member of the Bemisia tabaci species complex mitochondrial DNA genome (mitogenome) is 15,210 bp (GenBank accession no. KJ778614) with an A-T biased nucleotide composition (A: 32.7%; T: 42.4%; G: 14.0%; C: 10.8%). The mitogenome consists of 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs), 2 ribosomal RNA (rRNAs) and a 467 bp putative control region which also includes the A+T rich repeat region. All PCGs have an ATA (n = 8) or ATG (n = 5) start codon. Gene synteny of Asia I is overall similar to B. afer and two other members of the B. tabaci species complex Mediterranean and New World 1, and contains the tRNA-Ser2 located between the Cytb and ND1 genes found in Mediterranean and New World 1, but which is absent in B. afer. The orientation of the tRNA-Arg in Asia I is on the "plus" strand and differed from Mediterranean which is found on the "minus" strand. The Asia I mitogenome size is currently ranked the second smallest after B. afer (14,968 bp) followed by New World 1 (15,322 bp) and Mediterranean (15,632 bp). PMID:24960562

  16. Characterization of the reaction of decoupling ubiquinone with bovine mitochondrial respiratory complex I.

    PubMed

    Masuya, Takahiro; Okuda, Kenji; Murai, Masatoshi; Miyoshi, Hideto

    2016-08-01

    We previously produced the unique ubiquinone QT ("decoupling" quinone), the catalytic reduction of which in NADH-quinone oxidoreduction with bovine heart mitochondrial NADH-ubiquinone oxidoreductase (complex I) is completely decoupled from proton translocation across the membrane domain. This feature is markedly distinct from those of typical short-chain quinones such as ubiquinone-1. To further characterize the features of the QT reaction with complex I, we herein synthesized three QT analogs, QT2-QT4, and characterized their electron transfer reactions. We found that all aspects of electron transfer (e.g. electron-accepting activity and membrane potential formation) vary significantly among these analogs. The features of QT2 as decoupling quinone were slightly superior to those of original QT. Based on these results, we conclude that the bound positions of QTs within the quinone binding cavity susceptibly change depending on their side-chain structures, and the positions, in turn, govern the behavior of QTs as electron acceptors. PMID:27140857

  17. Inhibitors of ROS production by the ubiquinone-binding site of mitochondrial complex I identified by chemical screening.

    PubMed

    Orr, Adam L; Ashok, Deepthi; Sarantos, Melissa R; Shi, Tong; Hughes, Robert E; Brand, Martin D

    2013-12-01

    Mitochondrial production of reactive oxygen species is often considered an unavoidable consequence of aerobic metabolism and currently cannot be manipulated without perturbing oxidative phosphorylation. Antioxidants are widely used to suppress effects of reactive oxygen species after formation, but they can never fully prevent immediate effects at the sites of production. To identify site-selective inhibitors of mitochondrial superoxide/H2O2 production that do not interfere with mitochondrial energy metabolism, we developed a robust small-molecule screen and secondary profiling strategy. We describe the discovery and characterization of a compound (N-cyclohexyl-4-(4-nitrophenoxy)benzenesulfonamide; CN-POBS) that selectively inhibits superoxide/H2O2 production from the ubiquinone-binding site of complex I (site I(Q)) with no effects on superoxide/H2O2 production from other sites or on oxidative phosphorylation. Structure/activity studies identified a core structure that is important for potency and selectivity for site I(Q). By employing CN-POBS in mitochondria respiring on NADH-generating substrates, we show that site I(Q) does not produce significant amounts of superoxide/H2O2 during forward electron transport on glutamate plus malate. Our screening platform promises to facilitate further discovery of direct modulators of mitochondrially derived oxidative damage and advance our ability to understand and manipulate mitochondrial reactive oxygen species production under both normal and pathological conditions. PMID:23994103

  18. Crystallization of Mitochondrial Respiratory Complex II fromChicken Heart: A Membrane-Protein Complex Diffracting to 2.0Angstrom

    SciTech Connect

    Huang, Li-shar; Borders, Toni M.; Shen, John T.; Wang, Chung-Jen; Berry, Edward A.

    2004-12-17

    Procedure is presented for preparation of diffraction-quality crystals of a vertebrate mitochondrial respiratory Complex II. The crystals have the potential to diffract to at least 2.0 Angstrom with optimization of post-crystal-growth treatment and cryoprotection. This should allow determination of the structure of this important and medically relevant membrane protein complex at near-atomic resolution and provide great detail of the mode of binding of substrates and inhibitors at the two substrate-binding sites.

  19. Cyclometalated Iridium(III) Complexes as AIE Phosphorescent Probes for Real-Time Monitoring of Mitophagy in Living Cells

    NASA Astrophysics Data System (ADS)

    Jin, Chengzhi; Liu, Jiangping; Chen, Yu; Guan, Ruilin; Ouyang, Cheng; Zhu, Yanjiao; Ji, Liangnian; Chao, Hui

    2016-02-01

    Mitophagy, which is a special autophagy that removes damaging mitochondria to maintain sufficient healthy mitochondria, provides an alternative path for addressing dysfunctional mitochondria and avoiding cellular death. In the present study, by coupling the triphenylamine group with 2-phenylimidazo[4,5-f][1,10]phenanthroline derivatives, we synthesized five Ir(III) complexes with an AIE property that are expected to fulfill requirements for real-time monitoring of mitophagy. Ir1-Ir5 were exploited to image mitochondria with a short incubation time by confocal microscopy and inductive coupled plasma-mass spectrometry (ICP-MS). Due to aggregation-induced emission (AIE), Ir1-Ir5 exhibited excellent photostability compared to MitoTracker Green (MTG). Moreover, Ir1-Ir5 manifested satisfactory photostability in the mitochondrial physiological pH range. In addition, the uptake mechanism of Ir1 was investigated using confocal microscopy and flow cytometry analysis. Finally, using both Ir1 and LysoTracker Green, we were able to achieve real-time monitoring of mitophagy.

  20. Cyclometalated Iridium(III) Complexes as AIE Phosphorescent Probes for Real-Time Monitoring of Mitophagy in Living Cells

    PubMed Central

    Jin, Chengzhi; Liu, Jiangping; Chen, Yu; Guan, Ruilin; Ouyang, Cheng; Zhu, Yanjiao; Ji, Liangnian; Chao, Hui

    2016-01-01

    Mitophagy, which is a special autophagy that removes damaging mitochondria to maintain sufficient healthy mitochondria, provides an alternative path for addressing dysfunctional mitochondria and avoiding cellular death. In the present study, by coupling the triphenylamine group with 2-phenylimidazo[4,5-f][1,10]phenanthroline derivatives, we synthesized five Ir(III) complexes with an AIE property that are expected to fulfill requirements for real-time monitoring of mitophagy. Ir1-Ir5 were exploited to image mitochondria with a short incubation time by confocal microscopy and inductive coupled plasma–mass spectrometry (ICP-MS). Due to aggregation-induced emission (AIE), Ir1-Ir5 exhibited excellent photostability compared to MitoTracker Green (MTG). Moreover, Ir1-Ir5 manifested satisfactory photostability in the mitochondrial physiological pH range. In addition, the uptake mechanism of Ir1 was investigated using confocal microscopy and flow cytometry analysis. Finally, using both Ir1 and LysoTracker Green, we were able to achieve real-time monitoring of mitophagy. PMID:26907559

  1. Mitochondrially targeted Endonuclease III has a powerful anti-infarct effect in an in vivo rat model of myocardial ischemia/reperfusion.

    PubMed

    Yang, Xi-Ming; Cui, Lin; White, James; Kuck, Jamie; Ruchko, Mykhaylo V; Wilson, Glenn L; Alexeyev, Mikhail; Gillespie, Mark N; Downey, James M; Cohen, Michael V

    2015-03-01

    Recent reports indicate that elevating DNA glycosylase/AP lyase repair enzyme activity offers marked cytoprotection in cultured cells and a variety of injury models. In this study, we measured the effect of EndoIII, a fusion protein construct that traffics Endonuclease III, a DNA glycosylase/AP lyase, to the mitochondria, on infarct size in a rat model of myocardial ischemia/reperfusion. Open-chest, anesthetized rats were subjected to 30 min of occlusion of a coronary artery followed by 2 h of reperfusion. An intravenous bolus of EndoIII, 8 mg/kg, just prior to reperfusion reduced infarct size from 43.8 ± 1.4% of the risk zone in control animals to 24.0 ± 1.3% with no detectable hemodynamic effect. Neither EndoIII's vehicle nor an enzymatically inactive EndoIII mutant (K120Q) offered any protection. The magnitude of EndoIII's protection was comparable to that seen with the platelet aggregation inhibitor cangrelor (25.0 ± 1.8% infarction of risk zone). Because loading with a P2Y12 receptor blocker to inhibit platelets is currently the standard of care for treatment of acute myocardial infarction, we tested whether EndoIII could further reduce infarct size in rats treated with a maximally protective dose of cangrelor. The combination reduced infarct size to 15.1 ± 0.9% which was significantly smaller than that seen with either cangrelor or EndoIII alone. Protection from cangrelor but not EndoIII was abrogated by pharmacologic blockade of phosphatidylinositol-3 kinase or adenosine receptors indicating differing cellular mechanisms. We hypothesized that EndoIII protected the heart from spreading necrosis by preventing the release of proinflammatory fragments of mitochondrial DNA (mtDNA) into the heart tissue. In support of this hypothesis, an intravenous bolus at reperfusion of deoxyribonuclease I (DNase I) which should degrade any DNA fragments escaping into the extracellular space was as protective as EndoIII. Furthermore, the combination of EndoIII and DNase I

  2. Investigation of Dipodal oxy-Schiff base and its salen and salophen Fe(III)/Cr(III)/Mn(III) Schiff bases (N2O2) caped complexes and their magnetic and thermal behaviors

    NASA Astrophysics Data System (ADS)

    Çelikbilek, Şeyma; Koç, Ziya Erdem

    2014-05-01

    Six new dinuclear Fe(III)/Cr(III)/Mn(III) complexes have been involved tetradentate (N2O2) Schiff bases (salenH2) and (salophenH2) with 2,4-bis(4-hydroxyphenylimino-4‧-formylphenoxy)-6-methoxy-1,3,5-triazine have been synthesized. The complexes were characterized as high-spin (S = 5/2) distorted trigonal bipyramidal salen/salophenFe(III) bridged, distorted trigonal bipyramidal (S = 3/2) salen/salophenCr(III) and high-spin distorted trigonal bipyramidal (S = 2) salen/salophenMn(III) by OH- groups. The structures of ligand and complexes were identified by using elemental analysis, thermal analysis, magnetic susceptibility, LC-MS, ICP-AES, 1H NMR and FT-IR spectral data.

  3. Substrate complexes of human dipeptidyl peptidase III reveal the mechanism of enzyme inhibition

    PubMed Central

    Kumar, Prashant; Reithofer, Viktoria; Reisinger, Manuel; Wallner, Silvia; Pavkov-Keller, Tea; Macheroux, Peter; Gruber, Karl

    2016-01-01

    Human dipeptidyl-peptidase III (hDPP III) is a zinc-dependent hydrolase cleaving dipeptides off the N-termini of various bioactive peptides. Thus, the enzyme is likely involved in a number of physiological processes such as nociception and is also implicated in several forms of cancer. We present high-resolution crystal structures of hDPP III in complex with opioid peptides (Met-and Leu-enkephalin, endomorphin-2) as well as with angiotensin-II and the peptide inhibitor IVYPW. These structures confirm the previously reported large conformational change of the enzyme upon ligand binding and show that the structure of the closed conformation is independent of the nature of the bound peptide. The overall peptide-binding mode is also conserved ensuring the correct positioning of the scissile peptide bond with respect to the catalytic zinc ion. The structure of the angiotensin-II complex shows, how longer peptides are accommodated in the binding cleft of hDPP III. Differences in the binding modes allow a distinction between real substrates and inhibitory peptides or “slow” substrates. The latter displace a zinc bound water molecule necessitating the energetically much less favoured anhydride mechanism as opposed to the favoured promoted-water mechanism. The structural data also form the necessary framework for the design of specific hDPP III inhibitors. PMID:27025154

  4. Spectrophotometric determination of trace amounts of iron(III) with norfloxacin as complexing reagent.

    PubMed

    Issopoulos, P B

    1989-05-01

    The complexation of iron(III) with norfloxacin in acidic solution at 25 degrees C, at an ionic strength of about 0.3 M and a pH of 3.0 has been studied. The water-soluble complex formed, which exhibits an absorption maximum at 377 nm, was used for the spectrophotometric determination of trace amounts of iron(III). The molar absorptivity was 9.05 x 10(3) I mol-1 cm-1 and the Sandell sensitivity 6.2 ng cm-2 of iron(III) per 0.001 A. The formation constant (Kf) was determined spectrophotometrically and was found to be 4.0 x 10(8) at 25 degrees C. The calibration graph was rectilinear over the range 0.25-12.0 p.p.m. of iron(III) and the regression line equation was A = 0.163c - 0.00042 with a correlation coefficient of 0.9998 (n = 9). Common cations, except cerium (IV), did not interfere with the determination. The results obtained for the determination of iron(III) using the described procedure and the thiocyanate method were compared statistically by means of the Student t-test and no significant difference was found. PMID:2757232

  5. Heterometallic trinuclear {CoLn(III)} (Ln = Gd, Tb, Ho and Er) complexes in a bent geometry. Field-induced single-ion magnetic behavior of the Er(III) and Tb(III) analogues.

    PubMed

    Goura, Joydeb; Brambleby, Jamie; Topping, Craig V; Goddard, Paul A; Suriya Narayanan, Ramakirushnan; Bar, Arun Kumar; Chandrasekhar, Vadapalli

    2016-05-31

    Through the use of a multi-site compartmental ligand, 2-methoxy-6-[{2-(2-hydroxyethylamino)ethylimino}methyl]phenol (LH3), the family of heterometallic, trinuclear complexes of the formula [CoLn(L)2(μ-O2CCH3)2(H2O)3]·NO3·xMeOH·yH2O has been expanded beyond Ln = Dy(III) to include Gd(III) (), Tb(III) (), Ho(III) () and Er(III) () for , and (x = 1; y = 1) and for (x = 0; y = 2). The metallic core of these complexes consists of a (Co(III)-Ln(III)-Co(III)) motif bridged in a bent geometry resulting in six-coordinated distorted Co(III) octahedra and nine-coordinated Ln(III) monocapped square-antiprisms. The magnetic characterization of these compounds reveals the erbium and terbium analogues to display a field induced single-ion magnetic behavior similar to the dysprosium analogue but at lower temperatures. The energy barrier for the reversal of the magnetization of the CoTb(III) analogue is Ueff ≥ 15.6(4) K, while for the CoEr(III) analogue Ueff ≥ 9.9(8) K. The magnetic properties are discussed in terms of distortions of the 4f electron cloud. PMID:27180723

  6. Thermodynamic Features of the Complexation of Neodymium(III) and Americium(III) by Lactate in Trifluoromethanesulfonate Media.

    SciTech Connect

    Peter R. Zalupski; Leigh R. Martin; Kenneth L. Nash

    2010-10-01

    The protonation of lactate has been studied in a variety of electrolyte solutions using microcalorimetry to reveal a distinct medium influence imposed on the thermochemistry of the investigated equilibrium. The thermochemistry of lactate protonation, when studied directly in 1.0 M sodium lactate, agreed well with the studies performed in trifluoromethanesulfonate (triflate). This thermodynamic agreement suggests that the physical chemistry of lactate in the solutions applicable to the TALSPEAK process – a solvent extraction method for separating trivalent actinides from trivalent lanthanides within the scope of used nuclear fuel processing efforts – may be simulated in triflate solutions. Potentiometry, spectrophotometry and microcalorimetry have been subsequently used to study the thermodynamic features of neodymium and americium complexation by lactate using triflate as a strong background electrolyte. Three successive mononuclear lactate complexes were identified for Nd(III) and Am(III). The stability constants for neodymium, log ß1 = 2.60 ± 0.01, log ß2 = 4.66 ± 0.02 and log ß3 = 5.6 ± 0.1, and for americium, log ß1 = 2.60 ± 0.06, log ß2 = 4.7 ± 0.1 and log ß3 = 6.2 ± 0.2, were found to closely agree with the thermodynamic studies reported in sodium perchlorate solutions. Consequently, the thermodynamic medium effect, imposed on the TALSPEAK-related solution equilibria by the presence of strong background electrolytes such as NaClO4 and NaNO3, do not significantly impact the speciation in solution.

  7. Mitochondrial Diseases

    PubMed Central

    Lee, Young-Mock

    2012-01-01

    Mitochondria contain the respiratory chain enzyme complexes that carry out oxidative phosphorylation and produce the main part of cellular energy in the form of ATP. Although several proteins related with signalling, assembling, transporting, and enzymatic function can be impaired in mitochondrial diseases, most frequently the activity of the respiratory chain protein complexes is primarily or secondarily affected, leading to impaired oxygen utilization and reduced energy production. Mitochondrial diseases usually show a chronic, slowly progressive course and present with multiorgan involvement with varying onset between birth and late adulthood. Neuromuscular system is frequently affected in mitochondrial diseases. Although there is actually no specific therapy and cure for mitochondrial diseases, the understanding of the pathophysiology may further facilitate the diagnostic approach and open perspectives to future in mitochondrial diseases. PMID:24649452

  8. The tumor proteasome as a novel target for gold(III) complexes: implications for breast cancer therapy

    PubMed Central

    Milacic, Vesna; Dou, Q. Ping

    2009-01-01

    Although cisplatin plays a vital role in the treatment of several types of human cancer, its wide use is limited by the development of drug resistance and associated toxic side effects. Gold and gold complexes have been used to treat a wide range of ailments for many centuries. In recent years, the use of gold(III) complexes as an alternative to cisplatin treatment was proposed due to the similarities of gold and platinum. Gold(III) is isoelectronic with platinum(II) and gold(III) complexes have the same square-planar geometries as platinum(II) complexes, such as cisplatin. Although it was originally thought that gold(III) complexes might have the same molecular target as cisplatin, several lines of data indicated that proteins, rather than DNA, are targeted by gold complexes. We have recently evaluated cytotoxic and anti-cancer effects of several gold(III) dithiocarbamates against human breast cancer cells in vitro and in vivo. We have identified the tumor proteasome as an important target for gold(III) complexes and have shown that proteasome inhibition by gold(III) complexes is associated with apoptosis induction in breast cancer cells in vitro and in vivo. Furthermore, treatment of human breast tumor-bearing nude mice with a gold(III) dithiocarbamate complex was associated with tumor growth inhibition, supporting the significance of its potential development for breast cancer treatment. PMID:20047011

  9. Synthesis, spectroscopic, thermal and anticancer studies of metal-antibiotic chelations: Ca(II), Fe(III), Pd(II) and Au(III) chloramphenicol complexes

    NASA Astrophysics Data System (ADS)

    Al-Khodir, Fatima A. I.; Refat, Moamen S.

    2016-09-01

    Four Ca(II), Fe(III), Pd(II) and Au(III) complexes of chloramphenicol drug have been synthesized and well characterized using elemental analyses, (infrared, electronic, and 1H-NMR) spectra, magnetic susceptibility measurement, and thermal analyses. Infrared spectral data show that the chloramphenicol drug coordinated to Ca(II), Pd(II) and Au(III) metal ions through two hydroxyl groups with 1:1 or 1:2 M ratios, but Fe(III) ions chelated towards chloramphenicol drug via the oxygen and nitrogen atoms of amide group with 1:2 ratio based on presence of keto↔enol form. The X-ray powder diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM) techniques were used to identify the nano-size particles of both iron(III) and gold(III) chloramphenicol complexes. The antimicrobial assessments of the chloramphenicol complexes were scanned and collected the results against of some kind of bacteria and fungi. The cytotoxic activity of the gold(III) complex was tested against the human colon carcinoma (HCT-116) and human hepatocellular carcinoma (HepG-2) tumor cell lines.

  10. Mitochondrial Myopathies

    MedlinePlus

    ... line and are therefore called the electron transport chain, and complex V actually churns out ATP, so ... coQ10 , is a component of the electron transport chain, which uses oxygen to manufacture ATP. Some mitochondrial ...

  11. Anion Effects on Lanthanide(III) Tetrazole-1-acetate Dinuclear Complexes Showing Slow Magnetic Relaxation and Photofluorescent Emission.

    PubMed

    Lu, Ying-Bing; Jiang, Xiao-Ming; Zhu, Shui-Dong; Du, Zi-Yi; Liu, Cai-Ming; Xie, Yong-Rong; Liu, Liang-Xian

    2016-04-18

    Three types of lanthanide complexes based on the tetrazole-1-acetic acid ligand and the 2,2'-bipyridine coligand were prepared and characterized by single-crystal X-ray diffraction, IR spectroscopy, and elemental analyses; the formulas of these complexes are [Ln2(1-tza)4(NO3)2(2,2'-bipy)2] (Ln = Sm (1), Eu (2), Gd (3), Tb (4), Dy (5)), [Dy2(1-tza)4Cl2(2,2'-bipy)2] (6), and [Yb2(1-tza)4(NO3)2(2,2'-bipy)2] (7) (1-tza = tetrazole-1-acetate and 2,2'-bipy = 2,2'-bipyridine). They are dinuclear complexes possessing similar structures but different lanthanide(III) ion coordination geometries because of the distinction of peripheral anions (such as NO3(-) and Cl(-)) and the effect of lanthanide contraction. The variable-temperature magnetic susceptibilities of 1-6 were measured. Both Dy(III) complexes (5 and 6) display field-induced single-molecule magnet behaviors. Ab initio calculations revealed that the Dy(III) complex 6 possesses a more anisotropic Dy(III) ion in comparison to that in 5. The room-temperature photoluminescence spectra of Sm(III) (1), Eu(III) (2), Tb(III) (4), and Dy(III) (5 and 6) complexes exhibit strong characteristic emissions in the visible region, whereas the Yb(III) (7) complex shows near-infrared (NIR) luminescence. PMID:27023680

  12. Synthesis, characterization, hydrolase and catecholase activity of a dinuclear iron(III) complex: Catalytic promiscuity.

    PubMed

    Camargo, Tiago P; Maia, Fernanda F; Chaves, Cláudia; de Souza, Bernardo; Bortoluzzi, Adailton J; Castilho, Nathalia; Bortolotto, Tiago; Terenzi, Hernán; Castellano, Eduardo E; Haase, Wolfgang; Tomkowicz, Zbigniew; Peralta, Rosely A; Neves, Ademir

    2015-05-01

    Herein, we report the synthesis and characterization of the new di-iron(III) complex [(bbpmp)(H2O)(Cl)Fe(III)(μ-Ophenoxo)Fe(III)(H2O)Cl)]Cl (1), with the symmetrical ligand 2,6-bis{[(2-hydroxybenzyl)(pyridin-2-yl)methylamino]methyl}-4-methylphenol (H3bbpmp). Complexes 2 with the unsymmetrical ligand H2bpbpmp - {2-[[(2-hydroxybenzyl)(2-pyridylmethyl)]aminomethyl]-6-bis(pyridylmethyl) aminomethyl}-4-methylphenol and 3 with the ligand L(1)=4,11-dimethyl-1,8-bis{2-[N-(di-2-pyridylmethyl)amino]ethyl}cyclam were included for comparison purposes. Complex 1 was characterized through elemental analysis, X-ray crystallography, magnetochemistry, electronic spectroscopy, electrochemistry, mass spectrometry and potentiometric titration. The magnetic data show a very weak antiferromagnetic coupling between the two iron centers of the dinuclear complex 1 (J=-0.29cm(-1)). Due to the presence of labile coordination sites in both iron centers the hydrolysis of both the diester model substrate 2,4-BDNPP and DNA was studied in detail. Complex 1 was also able to catalyze the oxidation of the substrate 3,5-di-tert-butylcatechol (3,5-DTBC) to give the corresponding quinone, and thus it can be considered as a catalytically promiscuous system. PMID:25792035

  13. Complex formation of Am(III) and Am(IV) with phosphate ions in acetonitrile solutions

    SciTech Connect

    Perevalov, S.A.; Lebedev, I.A.; Myasoedov, B.F.

    1988-05-01

    The first dissociation constant of H/sub 3/PO/sub 4/ in acetonitrile solution (K/sub 1//sup 0/ = 1.75/centered dot/10/sup /minus/13/) and the constant of formation of H(H/sub 2/PO/sub 4/)/sub 2//sup /minus// dimers (K/sub d//sup 0/ = 8/centered dot/10/sup 2/) were determined by the method of pH-potentiometry. The complex formation of Am(III) in acetonitrile solutions containing 0.05-2.0 M H/sub 3/PO/sub 4/ was investigated by a spectrophotometric method; the stability constants of the complexes AmH/sub 2/PO/sub 4//sup 2+/ (/beta//sub 1//sup III/ = 1.0/centered dot/10/sup 12/) and Am(H/sub 2/PO/sub 4/)/sub 2//sup +/ (/beta//sub 2//sup III/ = 4.3/centered dot/10/sup 24/) were determined. The formal potentials of the couple Am/sup (IV)//Am/sup (III)/ in 0.3-1.9 M solutions of H/sub 3/PO/sub 4/ in acetonitrile were measured, and the stability constant of the phosphate complex of tetravalent americium Am(H/sub 2/PO/sub 4/)/sub 3//sup +/ (/beta//sub 3//sup IV/ = 2.5/centered dot/10/sup 46/) was calculated according to the value of the shift of the potential relative to the standard.

  14. Synthesis of Cr(III)-Morin Complex: Characterization and Antioxidant Study

    PubMed Central

    Panhwar, Qadeer K.; Memon, Shahabuddin

    2014-01-01

    The complex formation between Cr(III) and morin was carried out in methanol and confirmed by analytical characterization using UV-Vis, IR, 1H NMR, and TG-DTA. UV-Vis shows significant bathochromic shift in benzoyl upon coordination as well as IR well illustrates the peak shift of C=O group and formation of a O–Cr(III) bond. Likewise, 1H NMR studies clarify that Cr(III) metal ion replaces the 5OH proton hence; 5-hydroxy-4-keto site is employed by morin in chelation to form six-membered stable ring system out of three available chelating sites. In addition, TG-DTA denotes the presence of coordinated and crystalline water molecules. The melting point of the complex was found to be 389°C by DSC. In addition, Cr(III)-morin complex was found to be a more potent antioxidant than morin as evaluated by DPPH• and FRAP methods. PMID:24688439

  15. Promising anticancer mono- and dinuclear ruthenium(III) dithiocarbamato complexes: systematic solution studies.

    PubMed

    Nagy, Eszter Márta; Nardon, Chiara; Giovagnini, Lorena; Marchiò, Luciano; Trevisan, Andrea; Fregona, Dolores

    2011-11-28

    During the last decade, our research group has prepared a number of metal dithiocarbamato derivatives of Pt, Pd and Au that were expected to resemble the main features of cisplatin together with higher activity, improved selectivity and bioavailability, and lower side-effects. Furthermore, we have already published the synthesis, characterization and in vitro cytotoxicity studies of novel ruthenium(III) dithiocarbamato complexes such as [RuL(3)] monomers (11) and α-[Ru(2)L(5)]Cl dimers (12) with five different dithiocarbamate ligands. As both the monomer and the dinuclear complexes have shown significant antitumor activity in different human tumor cell lines, we decided to widen the characterization studies and to analyse thoroughly their behavior in physiological-like medium by UV-visible and CD spectroscopy. In the present paper we report on the crystal structure of [Ru(DMDT)(3)], [Ru(PDT)(3)] and [Ru(ESDT)(3)] complexes and we determine the spin state of the paramagnetic Ru(III) by means of Evans' method. Then, we discuss in detail the UV-visible spectral data of the complexes in different medium. All the studied complexes are stable in dimethyl sulfoxide, and show low solubility in phosphate buffered saline solution, particularly the monomer species, even at low concentration, while increased solubility for both types of complexes have been found in the presence of bovine serum albumin (BSA). Moreover, no changes on the coordination sphere of the metal, as well as no direct interaction between the BSA protein and the complex have been identified by UV-visible spectroscopy. However, some conformational changes on the BSA structure, induced by the ruthenium(III) complexes have been confirmed by CD spectroscopy, indicating a probable secondary electrostatic interaction between the metal complex and the peptide. In addition, no significant interaction has been demonstrated with the components of Dulbecco's Modified Eagle's Medium, used for the in vitro assays

  16. Microwave-Assisted Synthesis of Heteroleptic Ir(III)(+) Polypyridyl Complexes.

    PubMed

    Monos, Timothy M; Sun, Alexandra C; McAtee, Rory C; Devery, James J; Stephenson, Corey R J

    2016-08-19

    We report a rapid, one-pot, operationally simple, and scalable preparation of valuable cationic heteroleptic iridium(III) polypyridyl photosensitizers. This method takes advantage of two consecutive microwave irradiation steps in the same reactor vial, avoiding the need for additional reaction purifications. A number of known heteroleptic iridium(III) complexes are prepared in up to 96% yield. Notably, this method is demonstrated to provide the synthetically versatile photosensitizer [Ir(ppy)2(dtbbpy)]PF6 in >1 g quantities in less than 5 h of bench time. We envision this method will help accelerate future developments in visible-light-dependent chemistry. PMID:27301646

  17. Targeting and assembly of rat mitochondrial translocase of outer membrane 22 (TOM22) into the TOM complex.

    PubMed

    Nakamura, Yasuhiko; Suzuki, Hiroyuki; Sakaguchi, Masao; Mihara, Katsuyoshi

    2004-05-14

    Tom22 is a preprotein receptor and organizer of the mitochondrial outer membrane translocase complex (TOM complex). Rat Tom22 (rTOM22) is a 142-residue protein, embedded in the outer membrane through the internal transmembrane domain (TMD) with 82 N-terminal residues in the cytosol and 41 C-terminal residues in the intermembrane space. We analyzed the signals that target rTOM22 to the mitochondrial outer membrane and assembly into the TOM complex in cultured mammalian cells. Deletions or mutations were systematically introduced into the molecule, and the intracellular localization of the mutant constructs in HeLa cells was examined by confocal microscopy and cell fractionation. Their assembly into the TOM complex was also examined using blue native gel electrophoresis. These experiments revealed three separate structural elements: a cytoplasmic 10-residue segment with an acidic alpha-helical structure located 30 residues upstream of the TMD (the import sequence), TMD with an appropriate hydrophobicity, and a 20-residue C-terminal segment located 22 residues downstream of the TMD (C-tail signal). The import sequence and TMD were both essential for targeting and integration into the TOM complex, whereas the C-tail signal affected the import efficiency. The import sequence combined with foreign TMD functioned as a mitochondrial targeting and anchor signal but failed to integrate the construct into the TOM complex. Thus, the mitochondrial-targeting and TOM integration signal could be discriminated. A yeast two-hybrid assay revealed that the import sequence interacted with two intramolecular elements, the TMD and C-tail signal, and that it also interacted with the import receptor Tom20. PMID:14985332

  18. Mitochondrial Complex 1 Activity Measured by Spectrophotometry Is Reduced across All Brain Regions in Ageing and More Specifically in Neurodegeneration

    PubMed Central

    Chakrabarti, Lisa

    2016-01-01

    Mitochondrial function, in particular complex 1 of the electron transport chain (ETC), has been shown to decrease during normal ageing and in neurodegenerative disease. However, there is some debate concerning which area of the brain has the greatest complex 1 activity. It is important to identify the pattern of activity in order to be able to gauge the effect of age or disease related changes. We determined complex 1 activity spectrophotometrically in the cortex, brainstem and cerebellum of middle aged mice (70–71 weeks), a cerebellar ataxic neurodegeneration model (pcd5J) and young wild type controls. We share our updated protocol on the measurements of complex1 activity and find that mitochondrial fractions isolated from frozen tissues can be measured for robust activity. We show that complex 1 activity is clearly highest in the cortex when compared with brainstem and cerebellum (p<0.003). Cerebellum and brainstem mitochondria exhibit similar levels of complex 1 activity in wild type brains. In the aged brain we see similar levels of complex 1 activity in all three-brain regions. The specific activity of complex 1 measured in the aged cortex is significantly decreased when compared with controls (p<0.0001). Both the cerebellum and brainstem mitochondria also show significantly reduced activity with ageing (p<0.05). The mouse model of ataxia predictably has a lower complex 1 activity in the cerebellum, and although reductions are measured in the cortex and brain stem, the remaining activity is higher than in the aged brains. We present clear evidence that complex 1 activity decreases across the brain with age and much more specifically in the cerebellum of the pcd5j mouse. Mitochondrial impairment can be a region specific phenomenon in disease, but in ageing appears to affect the entire brain, abolishing the pattern of higher activity in cortical regions. PMID:27333203

  19. Complexation of Lactate with Nd(III) and Eu(III) at Variable Temperatures: Studies by Potentiometry, Microcalorimetry, Optical Absorption and Luminescence Spectroscopy

    SciTech Connect

    Tian, Guoxin; Martin, Leigh R.; Rao, Linfeng

    2010-10-01

    Complexation of neodymium(III) and europium(III) with lactate was studied at variable temperatures by potentiometry, absorption spectrophotometry, luminescence spectroscopy and microcalorimetry. Stability constants of three successive lactate complexes (ML{sup 2+}, ML{sup 2+} and ML{sub 3}(aq), where M stands for Nd and Eu, and L stands for lactate) at 10, 25, 40, 55 and 70 C were determined. The enthalpies of complexation at 25 C were determined by microcalorimetry. Thermodynamic data show that the complexation of trivalent lanthanides (Nd{sup 3+} and Eu{sup 3+}) with lactate is exothermic, and the complexation becomes weaker at higher temperatures. Results from optical absorption and luminescence spectroscopy suggest that the complexes are inner-sphere chelate complexes in which the protonated {alpha}-hydroxyl group of lactate participates in the complexation.

  20. Damage to mitochondrial complex I during cardiac ischemia reperfusion injury is reduced indirectly by anti-anginal drug ranolazine

    PubMed Central

    Gadicherla, Ashish K.; Stowe, David F.; Antholine, William E.; Yang, Meiying; Camara, Amadou K.S.

    2011-01-01

    Ranolazine (Ran), an anti-anginal drug, is a late Na+ channel current blocker that is also believed to attenuate fatty acid oxidation and mitochondrial respiratory complex I activity, especially during ischemia. In this study, we investigated if Ran's protective effect against cardiac ischemia/reperfusion (IR) injury is mediated at the mitochondrial level and specifically if respiratory complex I (NADH oxidoreductase) function is protected. We treated isolated and perfused guinea pig hearts with Ran just before 30 min ischemia and then isolated cardiac mitochondria at the end of 30 min ischemia and/or 30 min ischemia followed by 10 min reperfusion. We utilized spectrophotometric and histochemical techniques to assay complex I activity, western blot analysis for complex I subunit NDUFA9, electron paramagnetic resonance for activity of complex I Fe-S clusters, ELISA for determination of protein acetylation, native gel histochemical staining for respiratory supercomplex assemblies, and high pressure liquid chromatography for cardiolipin integrity; cardiac function was measured during IR. Ran treated hearts showed higher complex I activity and greater detectable complex I protein levels compared to untreated IR hearts. Ran treatment also led to more normalized electron transfer via Fe-S centers, supercomplex assembly and cardiolipin integrity. These improvements in complex I structure and function with Ran were associated with improved cardiac function after IR. However, these protective effects of Ran are not mediated by a direct action on mitochondria, but rather indirectly via cytosolic mechanisms that lead to less oxidation and better structural integrity of complex I. PMID:22178605

  1. Age-Dependent Decrease of Mitochondrial Complex II Activity in Human Skin Fibroblasts.

    PubMed

    Bowman, Amy; Birch-Machin, Mark A

    2016-05-01

    The mitochondrial theory of aging remains one of the most widely accepted aging theories and implicates mitochondrial electron transport chain dysfunction with subsequent increasing free radical generation. Recently, complex II of the electron transport chain appears to be more important than previously thought in this process, suggested predominantly by nonhuman studies. We investigated the relationship between complex II and aging using human skin as a model tissue. The rate of complex II activity per unit of mitochondria was determined in fibroblasts and keratinocytes cultured from skin covering a wide age range. Complex II activity significantly decreased with age in fibroblasts (P = 0.015) but not in keratinocytes. This was associated with a significant decline in transcript expression (P = 0.008 and P = 0.001) and protein levels (P = 0.0006 and P = 0.005) of the succinate dehydrogenase complex subunit A and subunit B catalytic subunits of complex II, respectively. In addition, there was a significant decrease in complex II activity with age (P = 0.029) that was specific to senescent skin cells. There was no decrease in complex IV activity with increasing age, suggesting possible locality to complex II. PMID:26829036

  2. Effect of monovalent cations on the kinetics of hypoxic conformational change of mitochondrial complex I

    PubMed Central

    Stepanova, Anna; Valls, Alba; Galkin, Alexander

    2015-01-01

    Mitochondrial complex I is a large, membrane-bound enzyme central to energy metabolism, and its dysfunction is implicated in cardiovascular and neurodegenerative diseases. An interesting feature of mammalian complex I is the so-called A/D transition, when the idle enzyme spontaneously converts from the active (A) to the de-active, dormant (D) form. The A/D transition plays an important role in tissue response to ischemia and rate of the conversion can be a crucial factor determining outcome of ischemia/reperfusion. Here, we describe the effects of alkali cations on the rate of the D-to-A transition to define whether A/D conversion may be regulated by sodium. At neutral pH (7–7.5) sodium resulted in a clear increase of rates of activation (D-to-A conversion) while other cations had minor effects. The stimulating effect of sodium in this pH range was not caused by an increase in ionic strength. EIPA, an inhibitor of Na+/H+ antiporters, decreased the rate of D-to-A conversion and sodium partially eliminated this effect of EIPA. At higher pH (> 8.0), acceleration of the D-to-A conversion by sodium was abolished, and all tested cations decreased the rate of activation, probably due to the effect of ionic strength. The implications of this finding for the mechanism of complex I energy transduction and possible physiological importance of sodium stimulation of the D-to-A conversion at pathophysiological conditions in vivo are discussed. PMID:26009015

  3. Novel reduction of Cr(VI) from wastewater using a naturally derived microcapsule loaded with rutin-Cr(III) complex.

    PubMed

    Qi, Yun; Jiang, Meng; Cui, Yuan-Lu; Zhao, Lin; Liu, Shejiang

    2015-03-21

    The harmfulness of carcinogenic hexavalent chromium (Cr(VI)) is dramatically decreased when Cr(VI) is reduced to trivalent chromium (Cr(III)). Rutin, a natural flavonoid, exhibits excellent antioxidant activity by coordinating metal ions. In this study, a complex containing rutin and Cr(III) (rutin-Cr(III)) was synthesized and characterized. The rutin-Cr(III) complex was much easier to reduce than rutin. The reduction of the rutin-Cr(III) complex was highly pH-dependent, with 90% of the Cr(VI) being reduced to Cr(III) in 2h under optimal conditions. A biodegradable, sustained-release system encapsulating the rutin-Cr(III) complex in a alginate-chitosan microcapsule (rutin-Cr(III) ACMS) was also evaluated, and the reduction of Cr(VI) was assessed. This study also demonstrated that low-pH solutions increased the reduction rate of Cr(VI). The environmentally friendly microcapsules can reduce Cr(VI) for prolonged periods of time and can easily biodegrade after releasing the rutin-Cr(III) complex. Given the excellent performance of rutin-Cr(III) ACMS, the microcapsule system represents an effective system for the remediation of Cr(VI) pollution. PMID:25528232

  4. Antitumor properties of five-coordinate gold(III) complexes bearing substituted polypyridyl ligands.

    PubMed

    Sanghvi, Chinar D; Olsen, Pauline M; Elix, Catherine; Peng, Shifang Bruce; Wang, Dongsheng; Chen, Zhuo Georgia; Shin, Dong M; Hardcastle, Kenneth I; MacBeth, Cora E; Eichler, Jack F

    2013-11-01

    In an on-going effort to discover metallotherapeutic alternatives to the chemotherapy drug cisplatin, neutral distorted square pyramidal gold(III) coordination complexes possessing 2,9-disubstituted-1,10-phenanthroline ligands {[((R)phen)AuCl3]; R = n-butyl, sec-butyl} have been previously synthesized and characterized. A structurally analogous gold(III) complex bearing a 6,6'-di-methylbipyridine ligand ([((methyl)bipy)AuCl3]) has been synthesized and fully characterized to probe the effect of differing aromatic character of the ligand on solution stability and tumor cell cytotoxicity. The two compounds [((sec-butyl)phen)AuCl3] and [((methyl)bipy)AuCl3]) were subsequently assessed for their stability against the biological reductant glutathione, and it was found that the [((sec-butyl)phen)AuCl3] complex exhibits slightly enhanced stability compared to the [((methyl)bipy)AuCl3] complex and significantly higher stability than previously reported square planar gold(III) complex ions. Furthermore, these complexes were tested for cytotoxic effects against existing lung and head and neck cancer cell lines in vitro. The [((sec-butyl)phen)AuCl3] complex was found to be more cytotoxic than cisplatin against five different tumor cell lines, whereas [((methyl)bipy)AuCl3] had more limited in vitro antitumor activity. Given that [((sec-butyl)phen)AuCl3] had significantly higher antitumor activity, it was tested against an in vivo tumor model. It was found that this complex did not significantly reduce the growth of xenograft tumors in mice and initial model binding studies with bovine serum albumin indicate that interactions with serum albumin proteins may be the cause for the limited in vivo activity of this potential metallotherapeutic. PMID:23948576

  5. Synthesis, structural characterization and photoluminescence properties of a novel La(III) complex

    NASA Astrophysics Data System (ADS)

    Köse, Muhammet; Ceyhan, Gökhan; Atcı, Emine; McKee, Vickie; Tümer, Mehmet

    2015-05-01

    In this study, a novel La(III) complex [La(H2L)2(NO3)3(MeOH)] of a Schiff base ligand was synthesized and characterized by spectroscopic and analytical methods. Single crystals of the complex suitable for X-ray diffraction study were obtained by slow diffusion of diethyl ether into a MeOH solution of the complex which was found to crystallise as [La(H2L)2(NO3)3(MeOH)]ṡ2MeOHṡH2O. The structure was solved in monoclinic crystal system, P21/n space group with unit cell parameters a = 10.5641(11), b = 12.6661(16), c = 16.0022(17) Å, α = 67.364(2), β = 83.794(2)°, γ = 70.541(2)°, V = 1862.9(4) Å3 and Z = 2 with R final value of 0.526. In the complex, the La(III) ion is ten-coordinated by O atoms, five of which come from three nitrate ions, four from the two Schiff base ligands and one from MeOH oxygen atom. The Schiff base ligands in the structure are in a zwitter ion form with the phenolic H transferred to the imine N atom. Thermal properties of the La(III) complex were examined by thermogravimetric analysis and the complex was found to be thermally stable up to 310 °C. The Schiff base ligand and its La(II) complex were screened for their in vitro antimicrobial activity against Bacillus megaterium, Staphylococcus aureus, Bacillus subtilis, Micrococcus luteus (Gram positive bacteria), Klebsiella pneumonia, Escherichia coli, Enterobacter aerogenes, Pseudomonas aeruginosa (Gram negative bacteria), Candida albicans,Yarrowia lipolytica (fungus) and Saccharomyces cerevisiae (yeast). The complex shows more antimicrobial activity than the free ligand.

  6. Mitochondrially targeted Endonuclease III has a powerful anti-infarct effect in an in vivo rat model of myocardial ischemia/reperfusion

    PubMed Central

    Yang, Xi-Ming; Cui, Lin; White, James; Kuck, Jamie; Ruchko, Mykhaylo V.; Wilson, Glenn L.; Alexeyev, Mikhail; Gillespie, Mark N.; Downey, James M.

    2016-01-01

    Recent reports indicate that elevating DNA glycosylase/AP lyase repair enzyme activity offers marked cytoprotection in cultured cells and a variety of injury models. In this study, we measured the effect of EndoIII, a fusion protein construct that traffics Endonuclease III, a DNA glycosylase/AP lyase, to the mitochondria, on infarct size in a rat model of myocardial ischemia/reperfusion. Open-chest, anesthetized rats were subjected to 30 min of occlusion of a coronary artery followed by 2 h of reperfusion. An intravenous bolus of EndoIII, 8 mg/kg, just prior to reperfusion reduced infarct size from 43.8 ± 1.4 % of the risk zone in control animals to 24.0 ± 1.3 % with no detectable hemodynamic effect. Neither EndoIII’s vehicle nor an enzymatically inactive EndoIII mutant (K120Q) offered any protection. The magnitude of EndoIII’s protection was comparable to that seen with the platelet aggregation inhibitor cangrelor (25.0 ± 1.8 % infarction of risk zone). Because loading with a P2Y12 receptor blocker to inhibit platelets is currently the standard of care for treatment of acute myocardial infarction, we tested whether EndoIII could further reduce infarct size in rats treated with a maximally protective dose of cangrelor. The combination reduced infarct size to 15.1 ± 0.9 % which was significantly smaller than that seen with either cangrelor or EndoIII alone. Protection from cangrelor but not EndoIII was abrogated by pharmacologic blockade of phosphatidylinositol-3 kinase or adenosine receptors indicating differing cellular mechanisms. We hypothesized that EndoIII protected the heart from spreading necrosis by preventing the release of proinflammatory fragments of mitochondrial DNA (mtDNA) into the heart tissue. In support of this hypothesis, an intravenous bolus at reperfusion of deoxyribonuclease I (DNase I) which should degrade any DNA fragments escaping into the extracellular space was as protective as EndoIII. Furthermore, the combination of EndoIII and

  7. Modulation of Mitochondrial Complex I Activity Averts Cognitive Decline in Multiple Animal Models of Familial Alzheimer's Disease

    PubMed Central

    Zhang, Liang; Zhang, Song; Maezawa, Izumi; Trushin, Sergey; Minhas, Paras; Pinto, Matthew; Jin, Lee-Way; Prasain, Keshar; Nguyen, Thi D.T.; Yamazaki, Yu; Kanekiyo, Takahisa; Bu, Guojun; Gateno, Benjamin; Chang, Kyeong-Ok; Nath, Karl A.; Nemutlu, Emirhan; Dzeja, Petras; Pang, Yuan-Ping; Hua, Duy H.; Trushina, Eugenia

    2015-01-01

    Development of therapeutic strategies to prevent Alzheimer's disease (AD) is of great importance. We show that mild inhibition of mitochondrial complex I with small molecule CP2 reduces levels of amyloid beta and phospho-Tau and averts cognitive decline in three animal models of familial AD. Low-mass molecular dynamics simulations and biochemical studies confirmed that CP2 competes with flavin mononucleotide for binding to the redox center of complex I leading to elevated AMP/ATP ratio and activation of AMP-activated protein kinase in neurons and mouse brain without inducing oxidative damage or inflammation. Furthermore, modulation of complex I activity augmented mitochondrial bioenergetics increasing coupling efficiency of respiratory chain and neuronal resistance to stress. Concomitant reduction of glycogen synthase kinase 3β activity and restoration of axonal trafficking resulted in elevated levels of neurotrophic factors and synaptic proteins in adult AD mice. Our results suggest that metabolic reprogramming induced by modulation of mitochondrial complex I activity represents promising therapeutic strategy for AD. PMID:26086035

  8. Mononuclear Ru(III) Schiff base complexes: Synthesis, spectral, redox, catalytic and biological activity studies

    NASA Astrophysics Data System (ADS)

    Priya, N. Padma; Arunachalam, S.; Manimaran, A.; Muthupriya, D.; Jayabalakrishnan, C.

    2009-04-01

    An octahedral ruthenium(III) Schiff base complexes of the type [RuX(EPh 3)(L)] (where, X = Cl/Br; E = As/P; L = dianion of the Schiff bases derived from acetoacetanilide with o-phenylenediamine and salicylaldehyde/ o-hydroxyacetophenone/ o-vanillin/2-hydroxy-1-naphthaldehyde) have been synthesized from the reactions of equimolar reactions of [RuX 3(EPh 3) 3] and Schiff bases in benzene. The new Ru(III) Schiff base complexes have been characterized by elemental analyses, FT-IR, electronic, 1H NMR and 13C NMR spectra, EPR spectral studies, powder X-ray diffraction (XRD) and electrochemical studies. The new complexes were found to be effective catalysts for aryl-aryl coupling and the oxidation of alcohols into their corresponding carbonyl compounds, respectively, using molecular oxygen atmosphere at ambient temperature. Further, the new Ru(III) Schiff base complexes were screened for their antibacterial activity against Pseudomonas aeruginosa, Vibrio cholera, Salomonella typhi and Staphylococcus aureaus.

  9. Aerobic Oxidation of an Osmium(III) N-Hydroxyguanidine Complex To Give Nitric Oxide.

    PubMed

    Xiang, Jing; Wang, Qian; Yiu, Shek-Man; Man, Wai-Lun; Kwong, Hoi-Ki; Lau, Tai-Chu

    2016-05-16

    The aerobic oxidation of the N-hydroxyguanidinum moiety of N-hydroxyarginine to NO is a key step in the biosynthesis of NO by the enzyme nitric oxide synthase (NOS). So far, there is no chemical system that can efficiently carry out similar aerobic oxidation to give NO. We report here the synthesis and X-ray crystal structure of an osmium(III) N-hydroxyguanidine complex, mer-[Os(III){NH═C(NH2)(NHOH)}(L)(CN)3](-) (OsGOH, HL = 2-(2-hydroxyphenyl)benzoxazole), which to the best of our knowledge is the first example of a transition metal N-hydroxyguanidine complex. More significantly, this complex readily undergoes aerobic oxidation at