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Kell DB. A protet-based, protonic charge transfer model of energy coupling in oxidative and photosynthetic phosphorylation. Adv Microb Physiol 2021; 78:1-177. [PMID: 34147184 DOI: 10.1016/bs.ampbs.2021.01.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Textbooks of biochemistry will explain that the otherwise endergonic reactions of ATP synthesis can be driven by the exergonic reactions of respiratory electron transport, and that these two half-reactions are catalyzed by protein complexes embedded in the same, closed membrane. These views are correct. The textbooks also state that, according to the chemiosmotic coupling hypothesis, a (or the) kinetically and thermodynamically competent intermediate linking the two half-reactions is the electrochemical difference of protons that is in equilibrium with that between the two bulk phases that the coupling membrane serves to separate. This gradient consists of a membrane potential term Δψ and a pH gradient term ΔpH, and is known colloquially as the protonmotive force or pmf. Artificial imposition of a pmf can drive phosphorylation, but only if the pmf exceeds some 150-170mV; to achieve in vivo rates the imposed pmf must reach 200mV. The key question then is 'does the pmf generated by electron transport exceed 200mV, or even 170mV?' The possibly surprising answer, from a great many kinds of experiment and sources of evidence, including direct measurements with microelectrodes, indicates it that it does not. Observable pH changes driven by electron transport are real, and they control various processes; however, compensating ion movements restrict the Δψ component to low values. A protet-based model, that I outline here, can account for all the necessary observations, including all of those inconsistent with chemiosmotic coupling, and provides for a variety of testable hypotheses by which it might be refined.
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Affiliation(s)
- Douglas B Kell
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative, Biology, University of Liverpool, Liverpool, United Kingdom; The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark.
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2
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Gerdes B, Rixen RM, Kramer K, Forbrig E, Hildebrandt P, Steinem C. Quantification of Hv1-induced proton translocation by a lipid-coupled Oregon Green 488-based assay. Anal Bioanal Chem 2018; 410:6497-6505. [PMID: 30027319 DOI: 10.1007/s00216-018-1248-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 06/22/2018] [Accepted: 07/05/2018] [Indexed: 10/28/2022]
Abstract
Passive proton translocation across membranes through proton channels is generally measured with assays that allow a qualitative detection of the H+-transfer. However, if a quantitative and time-resolved analysis is required, new methods have to be developed. Here, we report on the quantification of pH changes induced by the voltage-dependent proton channel Hv1 using the commercially available pH-sensitive fluorophore Oregon Green 488-DHPE (OG488-DHPE). We successfully expressed and isolated Hv1 from Escherichia coli and reconstituted the protein in large unilamellar vesicles. Reconstitution was verified by surface enhanced infrared absorption (SEIRA) spectroscopy and proton activity was measured by a standard 9-amino-6-chloro-2-methoxyacridine assay. The quantitative OG488-DHPE assay demonstrated that the proton translocation rate of reconstituted Hv1 is much smaller than those reported in cellular systems. The OG488-DHPE assay further enabled us to quantify the KD-value of the Hv1-inhibitor 2-guanidinobenzimidazole, which matches well with that found in cellular experiments. Our results clearly demonstrate the applicability of the developed in vitro assay to measure proton translocation in a quantitative fashion; the assay allows to screen for new inhibitors and to determine their characteristic parameters. Graphical abstract ᅟ.
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Affiliation(s)
- Benjamin Gerdes
- Institut für Organische und Biomolekulare Chemie, Universität Göttingen, Tammannstr. 2, 37077, Göttingen, Germany
| | - Rebecca M Rixen
- Institut für Organische und Biomolekulare Chemie, Universität Göttingen, Tammannstr. 2, 37077, Göttingen, Germany
| | - Kristina Kramer
- Institut für Organische und Biomolekulare Chemie, Universität Göttingen, Tammannstr. 2, 37077, Göttingen, Germany
| | - Enrico Forbrig
- Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 135, 10623, Berlin, Germany
| | - Peter Hildebrandt
- Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 135, 10623, Berlin, Germany
| | - Claudia Steinem
- Institut für Organische und Biomolekulare Chemie, Universität Göttingen, Tammannstr. 2, 37077, Göttingen, Germany. .,Max-Planck-Institut für Dynamik und Selbstorganisation, Am Fassberg 11, 37077, Göttingen, Germany.
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3
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Strand DD, Fisher N, Davis GA, Kramer DM. Redox regulation of the antimycin A sensitive pathway of cyclic electron flow around photosystem I in higher plant thylakoids. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:1-6. [DOI: 10.1016/j.bbabio.2015.07.012] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 07/27/2015] [Accepted: 07/29/2015] [Indexed: 10/23/2022]
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Chen Z, Gallie DR. Ethylene Regulates Energy-Dependent Non-Photochemical Quenching in Arabidopsis through Repression of the Xanthophyll Cycle. PLoS One 2015; 10:e0144209. [PMID: 26630486 PMCID: PMC4667945 DOI: 10.1371/journal.pone.0144209] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 11/13/2015] [Indexed: 11/20/2022] Open
Abstract
Energy-dependent (qE) non-photochemical quenching (NPQ) thermally dissipates excess absorbed light energy as a protective mechanism to prevent the over reduction of photosystem II and the generation of reactive oxygen species (ROS). The xanthophyll cycle, induced when the level of absorbed light energy exceeds the capacity of photochemistry, contributes to qE. In this work, we show that ethylene regulates the xanthophyll cycle in Arabidopsis. Analysis of eto1-1, exhibiting increased ethylene production, and ctr1-3, exhibiting constitutive ethylene response, revealed defects in NPQ resulting from impaired de-epoxidation of violaxanthin by violaxanthin de-epoxidase (VDE) encoded by NPQ1. Elevated ethylene signaling reduced the level of active VDE through decreased NPQ1 promoter activity and impaired VDE activation resulting from a lower transthylakoid membrane pH gradient. Increasing the concentration of CO2 partially corrected the ethylene-mediated defects in NPQ and photosynthesis, indicating that changes in ethylene signaling affect stromal CO2 solubility. Increasing VDE expression in eto1-1 and ctr1-3 restored light-activated de-epoxidation and qE, reduced superoxide production and reduced photoinhibition. Restoring VDE activity significantly reversed the small growth phenotype of eto1-1 and ctr1-3 without altering ethylene production or ethylene responses. Our results demonstrate that ethylene increases ROS production and photosensitivity in response to high light and the associated reduced plant stature is partially reversed by increasing VDE activity.
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Affiliation(s)
- Zhong Chen
- Department of Biochemistry, University of California, Riverside, California, United States of America
| | - Daniel R. Gallie
- Department of Biochemistry, University of California, Riverside, California, United States of America
- * E-mail:
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5
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Cid-Hernández M, Ramírez-Anguiano AC, Ortiz GG, Morales-Sánchez EW, González-Ortiz LJ, Velasco-Ramírez SF, Pacheco-Moisés FP. Mitochondrial ATPase activity and membrane fluidity changes in rat liver in response to intoxication with buckthorn (Karwinskia humboldtiana). Biol Res 2015; 48:17. [PMID: 25889629 PMCID: PMC4376499 DOI: 10.1186/s40659-015-0008-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 02/27/2015] [Indexed: 11/21/2022] Open
Abstract
Background Karwinskia humboldtiana (Kh) is a poisonous plant of the rhamnacea family. To elucidate some of the subcellular effects of Kh toxicity, membrane fluidity and ATPase activities as hydrolytic and as proton-pumping activity were assessed in rat liver submitochondrial particles. Rats were randomly assigned into control non-treated group and groups that received 1, 1.5 and 2 g/Kg body weight of dry powder of Kh fruit, respectively. Rats were euthanized at day 1 and 7 after treatment. Results Rats under Kh treatment at all dose levels tested, does not developed any neurologic symptoms. However, we detected alterations in membrane fluidity and ATPase activity. Lower dose of Kh on day 1 after treatment induced higher mitochondrial membrane fluidity than control group. This change was strongly correlated with increased ATPase activity and pH gradient driven by ATP hydrolysis. On the other hand, membrane fluidity was hardly affected on day 7 after treatment with Kh. Surprisingly, the pH gradient driven by ATPase activity was significantly higher than controls despite an diminution of the hydrolytic activity of ATPase. Conclusions The changes in ATPase activity and pH gradient driven by ATPase activity suggest an adaptive condition whereby the fluidity of the membrane is altered.
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Affiliation(s)
- Margarita Cid-Hernández
- Departamento de Química, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Blvd. Marcelino García Barragán 1421, 44430, Guadalajara, Jalisco, Mexico.
| | - Ana C Ramírez-Anguiano
- Departamento de Química, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Blvd. Marcelino García Barragán 1421, 44430, Guadalajara, Jalisco, Mexico.
| | - Genaro G Ortiz
- División de Neurociencias, Laboratorio de Desarrollo, Envejecimiento y Enfermedades Neurodegenerativas, Centro de Investigación Biomédica de Occidente (CIBO), Instituto Mexicano del Seguro Social (IMSS), Sierra Mojada 800, 44340, Guadalajara, Jalisco, Mexico.
| | - Eddic W Morales-Sánchez
- División de Neurociencias, Laboratorio de Desarrollo, Envejecimiento y Enfermedades Neurodegenerativas, Centro de Investigación Biomédica de Occidente (CIBO), Instituto Mexicano del Seguro Social (IMSS), Sierra Mojada 800, 44340, Guadalajara, Jalisco, Mexico.
| | - Luis J González-Ortiz
- Departamento de Química, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Blvd. Marcelino García Barragán 1421, 44430, Guadalajara, Jalisco, Mexico.
| | - Sandra F Velasco-Ramírez
- Departamento de Química, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Blvd. Marcelino García Barragán 1421, 44430, Guadalajara, Jalisco, Mexico.
| | - Fermín P Pacheco-Moisés
- Departamento de Química, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Blvd. Marcelino García Barragán 1421, 44430, Guadalajara, Jalisco, Mexico.
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Rodríguez-Enríquez S, Hernández-Esquivel L, Marín-Hernández A, Dong LF, Akporiaye ET, Neuzil J, Ralph SJ, Moreno-Sánchez R. Molecular mechanism for the selective impairment of cancer mitochondrial function by a mitochondrially targeted vitamin E analogue. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:1597-607. [PMID: 22627082 DOI: 10.1016/j.bbabio.2012.05.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 04/30/2012] [Accepted: 05/10/2012] [Indexed: 12/31/2022]
Abstract
The effects of α-tocopheryl succinate (α-TOS), α-tocopheryl acetyl ether (α-TEA) and triphenylphosphonium-tagged vitamin E succinate (mitochondrially targeted vitamin E succinate; MitoVES) on energy-related mitochondrial functions were determined in mitochondria isolated from AS-30D hepatoma and rat liver, bovine heart sub-mitochondrial particles (SMPs), and in rodent and human carcinoma cell lines and rat hepatocytes. In isolated mitochondria, MitoVES stimulated basal respiration and ATP hydrolysis, but inhibited net state 3 (ADP-stimulated) respiration and Ca(2+) uptake, by collapsing the membrane potential at low doses (1-10μM). Uncoupled mitochondrial respiration and basal respiration of SMPs were inhibited by the three drugs at concentrations at least one order of magnitude higher and with different efficacy: MitoVES>α-TEA>α-TOS. At high doses (>10μM), the respiratory complex II (CII) was the most sensitive MitoVES target. Acting as an uncoupler at low doses, this agent stimulated total O(2) uptake, collapsed ∆ψ(m), inhibited oxidative phosphorylation and induced ATP depletion in rodent and human cancer cells more potently than in normal rat hepatocytes. These findings revealed that in situ tumor mitochondria are preferred targets of the drug, indicating its clinical relevance.
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Pierson HE, Uhlemann EME, Dmitriev OY. Interaction with monomeric subunit c drives insertion of ATP synthase subunit a into the membrane and primes a-c complex formation. J Biol Chem 2011; 286:38583-38591. [PMID: 21900248 DOI: 10.1074/jbc.m111.294868] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Subunit a is the main part of the membrane stator of the ATP synthase molecular turbine. Subunit c is the building block of the membrane rotor. We have generated two molecular fusions of a and c subunits with different orientations of the helical hairpin of subunit c. The a/c fusion protein with correct orientation of transmembrane helices was inserted into the membrane, and co-incorporated into the F(0) complex of ATP synthase with wild type subunit c. The fused c subunit was incorporated into the c-ring tethering the ATP synthase rotor to the stator. The a/c fusion with incorrect orientation of the c-helices required wild type subunit c for insertion into the membrane. In this case, the fused c subunit remained on the periphery of the c-ring and did not interfere with rotor movement. Wild type subunit a inserted into the membrane equally well with wild type subunit c and c-ring assembly mutants that remained monomeric in the membrane. These results show that interaction with monomeric subunit c triggers insertion of subunit a into the membrane, and initiates formation of the a-c complex, the ion-translocating module of the ATP synthase. Correct assembly of the ATP synthase incorporating topologically correct fusion of subunits a and c validates using this model protein for high resolution structural studies of the ATP synthase proton channel.
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Affiliation(s)
- Hannah E Pierson
- Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
| | - Eva-Maria E Uhlemann
- Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
| | - Oleg Y Dmitriev
- Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada.
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8
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Novel mitochondrial alcohol metabolizing enzymes of Euglena gracilis. J Bioenerg Biomembr 2011; 43:519-30. [DOI: 10.1007/s10863-011-9373-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Accepted: 06/17/2011] [Indexed: 11/24/2022]
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9
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Wagner H, Gilbert M, Goss R, Wilhelm C. Light emission originating from photosystem II radical pair recombination is sensitive to zeaxanthin related non-photochemical quenching (NPQ). JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2006; 83:172-9. [PMID: 16488152 DOI: 10.1016/j.jphotobiol.2005.12.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2005] [Revised: 12/23/2005] [Accepted: 12/30/2005] [Indexed: 10/25/2022]
Abstract
We have used chlorophyll fluorescence, delayed luminescence and thermoluminescence measurements to study the influence of an artificial DeltapH in the presence or absence of zeaxanthin on photosystem II reactions. Energization of the pea thylakoid membranes induced non-photochemical fluorescence quenching and an increase in the overall luminescence emission of PSII during delayed luminescence and thermoluminescence measurements. This DeltapH-induced overall luminescence increase was caused by a strongly enhanced delayed luminescence in the seconds range before sample heating. In the subsequent thermoluminescence measurements the intensity of the B-band decreased after one and increased after two or more single turnover flashes. We propose that strong membrane energization shifted the redox potential of photosystem II radical pairs to more negative values causing the high delayed luminescence. The zeaxanthin-dependent non-photochemical fluorescence quenching component, however, did not alter thermoluminescence B-bands but decreased the delayed luminescence intensity by 30%. To our knowledge this is the first report that the radiative radical pair recombination, exhibited as delayed luminescence but not thermoluminescence emission, is sensitive to the antenna located zeaxanthin related non-photochemical fluorescence quenching. Our data can be interpreted within the frame of the exciton/radical pair equilibrium model that describes photosystem II as a shallow trap and incorporates the transfer of energy from the re-excitated reaction centre to the antenna of photosystem II.
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Affiliation(s)
- Heiko Wagner
- Universität Leipzig, Biologie I/Abteilung Pflanzenphysiologie, Johannisallee 23, 04103 Leipzig, Germany
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10
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Castelli MV, Lodeyro AF, Malheiros A, Zacchino SAS, Roveri OA. Inhibition of the mitochondrial ATP synthesis by polygodial, a naturally occurring dialdehyde unsaturated sesquiterpene. Biochem Pharmacol 2005; 70:82-9. [PMID: 15894293 DOI: 10.1016/j.bcp.2005.04.016] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2004] [Accepted: 04/11/2005] [Indexed: 10/25/2022]
Abstract
Polygodial is a naturally occurring sesquiterpene dialdehyde that exhibits several pharmacologically interesting activities. Among them, its antifungal properties have been more thoroughly studied. The mitochondrial ATPase has been suggested as one of the possible targets for polygodial action. However, its mechanism of action is not well defined yet. The effect of polygodial on the mitochondrial energy metabolism is described in this paper. Polygodial inhibited ATP synthesis coupled to succinate oxidation in beef-heart submitochondrial particles at concentrations (IC(50)=2.4+/-0.1 microM) which marginally affected electron transport and ATPase activity (IC(50)=97+/-4 microM). A transitory stimulation of the electron transport in intact rat liver mitochondria in state 4 was also obtained at low polygodial concentrations (EC(50)=20+/-4 microM). These results suggest that polygodial uncouples ATP synthesis from electron transport at low concentrations. Similar concentrations of polygodial partially abolished the ANS fluorescence enhancement (IC(50)=2.2+/-0.4 microM) induced by succinate oxidation in submitochondrial particles but did not collapse the DeltapH. We postulate that polygodial uncouples mitochondrial ATP synthesis by affecting the electrical properties of the membrane surface and consequently collapsing the membrane potential (Deltapsi) and/or the localized transmembrane pH difference (DeltapH(S)) without affecting the DeltapH between the two bulk aqueous phases (DeltapH(B)). The relevance of these findings for the understanding of the biochemical basis of the antifungal activity of polygodial and the evaluation of its potentiality as a therapeutic agent are discussed.
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Affiliation(s)
- María V Castelli
- Area Biofísica, Departamento de Química Biológica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, (S2002LRK) Rosario, Argentina
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11
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Pacheco-Moisés F, Minauro-Sanmiguel F, Bravo C, García JJ. Sulfite inhibits the F1F0-ATP synthase and activates the F1F0-ATPase of Paracoccus denitrificans. J Bioenerg Biomembr 2002; 34:269-78. [PMID: 12392190 DOI: 10.1023/a:1020252401675] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The F1F0 complex of Paracoccus denitrificans (PdF1F0) is the fastest ATP synthase but the slowest ATPase. Sulfite exerts maximal activation of the PdF1F0-ATPase (Pacheco-Moisés, F., García, J. J., Rodríguez-Zavala, J. S., and Moreno-Sánchez, R. (2000). Eur J. Biochem. 267, 993-1000) but its effect on the PdF1F0-ATP synthase activity remains unknown. Therefore, we studied the effect of sulfite on ATP synthesis and 32Pi <--> ATP exchange reactions of inside-out membrane vesicles of P. denitrificans. Sulfite inhibited both reactions under conditions of maximal delta pH and normal sensitivity to dicyclohexylcarbodiimide. Sulfite increased by 10- and 5-fold the K0.5 for Mg2+-ADP and Pi during ATP synthesis, respectively, and by 4-fold the IC50 of Mg2+-ADP for inhibition of the PdF1F0-ATPase activity. Thus, sulfite exerts opposite effects on the forward and reverse functioning of the PdF1F0 complex. These effects are not due to membrane or PdF1F0 uncoupling. Kinetic and structural modifications that could account for these results are discussed.
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Affiliation(s)
- Fermín Pacheco-Moisés
- Departamento de Bioquímica, Instituto Nacional de Cardiología, Ignacio Chavez, México, DF, México
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12
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Bizouarn T, Fjellström O, Axelsson M, Korneenko TV, Pestov NB, Ivanova MV, Egorov MV, Shakhparonov M, Rydström J. Interactions between the soluble domain I of nicotinamide nucleotide transhydrogenase from Rhodospirillum rubrum and transhydrogenase from Escherichia coli. Effects on catalytic and H+-pumping activities. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:3281-8. [PMID: 10824114 DOI: 10.1046/j.1432-1327.2000.01358.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Nicotinamide nucleotide transhydrogenase from Escherichia coli is composed of two subunits, the alpha and the beta subunits, each of which contains a hydrophilic domain, domain I and III, respectively, as well as several transmembrane helices, collectively denoted domain II. The interactions between domain I from Rhodospirillum rubrum (rrI) and the intact or the protease-treated enzyme from E. coli was investigated using the separately expressed and purified domain I from R. rubrum, and His-tagged intact and trypsin-treated E. coli transhydrogenase. Despite harsh treatments with, e.g. detergents and denaturing agents, the alpha and beta subunits remained tightly associated. A monoclonal antibody directed towards the alpha subunit was strongly inhibitory, an effect that was relieved by added rrI. In addition, rrI also reactivated the trypsin-digested E. coli enzyme in which domain I had been partly removed. This suggests that the hydrophilic domains I and III are not in permanent contact but are mobile during catalysis while being anchored to domain II. Replacement of domain I of intact, as well as trypsin-digested, E. coli transhydrogenase with rrI resulted in a markedly different pH dependence of the cyclic reduction of 3-acetyl-pyridine-NAD+ by NADH in the presence of NADP(H), suggesting that the protonation of one or more protonable groups in domain I is controlling this reaction. The reverse reaction and proton pumping showed a less pronounced change in pH dependence, demonstrating the regulatory role of domain II in these reactions.
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Affiliation(s)
- T Bizouarn
- Department of Biochemistry and Biophysics, Göteborg University, Sweden
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13
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Pacheco-Moisés F, García JJ, Rodríguez-Zavala JS, Moreno-Sánchez R. Sulfite and membrane energization induce two different active states of the Paracoccus denitrificans F0F1-ATPase. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:993-1000. [PMID: 10672007 DOI: 10.1046/j.1432-1327.2000.01088.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Activation of the latent ATPase activity of inside-out vesicles from plasma membranes of Paracoccus denitrificans was studied. Several factors were found to induce activation: heat, membrane energization by succinate oxidation, methanol, oxyanions (sulfite, phosphate, arsenate, bicarbonate) and limited proteolysis with trypsin. Among the oxyanions, sulfite induced the higher increase in ATPase activity. Sulfite functioned as a nonessential activator that slightly modified the affinity for ATP and increased notoriously the Vmax. There was a competitive effect between sulfite, bicarbonate and phosphate for ATPase activation; their similar chemical geometry suggests that these oxyanions have a common binding site on the enzyme. Dithiothreitol did not affect the ATPase activity. ATPase activation by sulfite was decreased by uncoupler, enhanced by trypsin and inhibited by ADP, oligomycin and venturicidin. In contrast, activation induced by succinate was less sensitive to ADP, oligomycin, venturicidin and trypsin. It is proposed that the active states induced by sulfite and succinate reflect two conformations of the enzyme, in which the inhibitory subunit epsilon is differently exposed to trypsin.
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Affiliation(s)
- F Pacheco-Moisés
- Departamento de Bioquímica, Instituto Nacional de Cardiología, México
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14
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Alvarez AH, Moreno-Sánchez R, Cervantes C. Chromate efflux by means of the ChrA chromate resistance protein from Pseudomonas aeruginosa. J Bacteriol 1999; 181:7398-400. [PMID: 10572148 PMCID: PMC103707 DOI: 10.1128/jb.181.23.7398-7400.1999] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Everted membrane vesicles of Pseudomonas aeruginosa PAO1 harboring plasmid pCRO616, expressing the ChrA chromate resistance protein, accumulated four times more (51)CrO(4)(2-) than vesicles from plasmidless cells, indicating that a chromate efflux system functions in the resistant strain. Chromate uptake showed saturation kinetics with an apparent K(m) of 0.12 mM chromate and a V(max) of 0. 5 nmol of chromate/min per mg of protein. Uptake of chromate by vesicles was dependent on NADH oxidation and was abolished by energy inhibitors and by the chromate analog sulfate. The mechanism of resistance to chromate determined by ChrA appears to be based on the active efflux of chromate driven by the membrane potential.
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Affiliation(s)
- A H Alvarez
- Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana, 58030 Morelia, Mich., D.F., México
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15
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Moreno-Sánchez R, Bravo C, Westerhoff HV. Determining and understanding the control of flux. An illustration in submitochondrial particles of how to validate schemes of metabolic control. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 264:427-33. [PMID: 10491087 DOI: 10.1046/j.1432-1327.1999.00621.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Two complementary methods were used to determine how the rate of respiration and that of ATP hydrolysis were controlled in rat liver submitochondrial particles. In the first, 'direct control analysis' method, respiration was titrated with malonate, antimycin or cyanide at 20, 30 and 37 degrees C, to determine the flux control exerted by succinate dehydrogenase, cytochrome bc1 complex and cytochrome c oxidase, respectively. Together, the three respiratory complexes only controlled the flux by about 50%, leaving the other 50% of flux control to the H+ leak. In the second, 'elasticity based' method, the elasticity coefficients of the respiratory chain or the H+-ATPase and the H+ leak towards the H+ gradient were determined. Then, the flux control coefficients were calculated using the connectivity and summation laws of metabolic control theory. The correspondence between the flux control coefficients determined in the two ways validated the two methods. This allowed us to use the second method to analyse what was the kinetic origin of the observed distribution of control. Control of ATP hydrolysis by the ATPase decreased with increasing ATPase activity; hence, the control exerted by the H+ leak increased with increasing ATPase activity, due to a diminishing elasticity towards the H+ gradient. Reverse electron transport was mainly controlled by the ATPase; the sum of flux control coefficients of succinate dehydrogenase, NADH-CoQ oxidoreductase, and H+-ATPase yielded a value greater than one, indicating that the H+ leak exerted a significant negative control on this pathway.
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Affiliation(s)
- R Moreno-Sánchez
- Instituto Nacional de Cariología, Departamento de Bioquímica, México
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Moreno-Sánchez R, Bravo C, Vásquez C, Ayala G, Silveira LH, Martínez-Lavín M. Inhibition and uncoupling of oxidative phosphorylation by nonsteroidal anti-inflammatory drugs: study in mitochondria, submitochondrial particles, cells, and whole heart. Biochem Pharmacol 1999; 57:743-52. [PMID: 10075080 DOI: 10.1016/s0006-2952(98)00330-x] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The effects of the anti-inflammatory drugs diclofenac, piroxicam, indomethacin, naproxen, nabumetone, nimesulide, and meloxicam on mitochondrial respiration, ATP synthesis, and membrane potential were determined. Except for nabumetone and naproxen, the other drugs stimulated basal and uncoupled respiration, inhibited ATP synthesis, and collapsed membrane potential in mitochondria incubated in the presence of either glutamate + malate or succinate. Plots of membrane potential versus ATP synthesis (or respiration) showed proportional variations in both parameters, induced by different concentrations of nimesulide, meloxicam, piroxicam, or indomethacin, but not by diclofenac. The activity of the adenine nucleotide translocase was blocked by diclofenac and nimesulide; diclofenac also slightly inhibited mitochondrial ATPase activity. Naproxen did not affect any of the mitochondrial parameters measured. Nabumetone inhibited respiration, ATP synthesis, and membrane potential in the presence of glutamate + malate, but not with succinate. NADH oxidation in submitochondrial particles also was inhibited by nabumetone. Nabumetone inhibited O2 uptake in intact cells and in whole heart, whereas the other five drugs stimulated respiration. These observations revealed that in situ mitochondria are an accessible target. Except for diclofenac, a negative inotropic effect on cardiac contractility was induced by the drugs. The data indicated that nimesulide, meloxicam, piroxicam, and indomethacin behaved as mitochondrial uncouplers, whereas nabumetone exerted a specific inhibition of site 1 of the respiratory chain. Diclofenac was an uncoupler too, but it also affected the adenine nucleotide translocase and the H+-ATPase.
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Affiliation(s)
- R Moreno-Sánchez
- Departamento de Bioquímica, Instituto Nacional de Cardiología, Mexico, DF, Mexico
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Peña A, Ramírez J, Rosas G, Calahorra M. Proton pumping and the internal pH of yeast cells, measured with pyranine introduced by electroporation. J Bacteriol 1995; 177:1017-22. [PMID: 7860582 PMCID: PMC176697 DOI: 10.1128/jb.177.4.1017-1022.1995] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The internal pH of yeast cells was determined by measuring the fluorescence changes of pyranine (8-hydroxy-1,3,6-pyrene-trisulfonic acid), which was introduced into the cells by electroporation. This may be a suitable procedure for the following reasons. (i) Only minor changes in the physiological status of the cells seemed to be produced. (ii) The dye did not seem to leak at a significant rate from the cells. (iii) Different incubation conditions produced large fluorescence changes in the dye, which in general agree with present knowledge of the proton movements of the yeast cell under different conditions. (iv) Pyranine introduced by electroporation seemed to be located in the cytoplasm and to avoid the vacuole, and therefore it probably measured actual cytoplasmic pH. (v) Correction factors to obtain a more precise estimation of the internal pH are not difficult to apply, and the procedure may be useful for other yeasts and microorganisms, as well as for the introduction of other substances into cells. Values for the cytoplasmic pHs of yeast cells that were higher than those reported previously were obtained, probably because this fluorescent indicator did not seem to penetrate into the cell vacuole.
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Affiliation(s)
- A Peña
- Departmento de Microbiología, Universidad Nacional Autónoma de México, D. F., México
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Peña A, Ramírez J, Rosas G, Calahorra M. Pyranine introduced by electroporation as an indicator of the internal pH of yeast. Folia Microbiol (Praha) 1994. [DOI: 10.1007/bf02814095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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