DOCSLIB.ORG

ATP Synthase • Boyer’S Conformational Model • Racker’S Experiment • Jagendorf’S Experiment • Role of Uncouplers

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
ATP Synthase • Boyer’S Conformational Model • Racker’S Experiment • Jagendorf’S Experiment • Role of Uncouplers ATP Synthesis Dr. Roshni Rajamohan Department of Botany Deshbandhu College Dr. Roshni Rajamohan ATP Synthesis • Mechanism of ATP Synthesis • Substrate level phosphorylation • Chemiosmotic mechanism (oxidative and photophosphorylation) • ATP Synthase • Boyer’s conformational model • Racker’s experiment • Jagendorf’s experiment • Role of uncouplers Dr. Roshni Rajamohan Mechanism of ATP Synthesis 1. Oxidative phosphorylation-It is the chemiosmotic synthesis of ATP associated with the transfer of electrons through the electron transport chain (from NADH / FADH 2 to O 2 by a series of electron carriers) and the accompanying consumption of oxygen. ATP is formed as a result of the transfer of electrons This process, which takes place in mitochondria, is the major source of ATP in aerobic organisms. 2. Photophosphorylation- The light-dependent chemiosmotic synthesis of ATPin the chloroplast in the presence of light. ATP is formed as a result of the transfer of electrons which takes place in chloroplast, is the major source of ATP in photosynthetic organisms 3. Substrate level phosphorylation-ATP synthesis by the transfer from a high-energy compound (phosphate group) ADP, without involvement of any electron transport is called substrate-level phosphorylation. Dr. Roshni Rajamohan Photophosphorylation Light-dependent ATPsynthesis- coupled reaction • This process was discovered by Daniel Arnon and co-workers in 1950s • Electron flow without accompanying phosphorylation is said to be uncoupled. • Photophosphorylation works via the chemiosmotic mechanism, first proposed in the 1960s by Peter Mitchell. • The total energy available for ATP synthesis, called the proton motive force (∆p), is the sum of a proton chemical potential and a transmembrane electric potential, ∆p = ∆E − 59(pΗi − pΗο) • A transmembrane pH difference of 1 pH unit is equivalent to a membrane potential of 59 mV. Dr. Roshni Rajamohan Substrate-level phosphorylation • ATP synthesis by the transfer from a high-energy compound (phosphate group) ADP, without involvement of any electron transport is called substrate-level phosphorylation. • In simple terms, it is the production of ATP by the transfer of a phosphoryl group from the substrate of a reaction to ADP. • Substrate-level phosphorylation differs from the other two ways of ATP synthesis i.e., oxidative-phosphorylation and photo- phosphorylation, in that the ATP synthesis is not coupled to any electron transport. • Oxidative-phosphorylation and photo-phosphorylation involves ATP synthesis coupled with electron transport. Dr. Roshni Rajamohan 2 Steps in Glycolysis where substrate level phosphorylation occurs Dr. Roshni Rajamohan • In the first reaction, energy is harvested in the form of ATP. The enzyme phosphoglycerate kinase catalyzes the transfer of the phosphoryl group of 1,3-bisphosphoglycerate to ADP. This is the first substrate-level phosphorylation of glycolysis, and it produces ATP and 3-phosphoglycerate. It is a coupled reaction in which the high energy bond is hydrolyzed and the energy released is used to drive the synthesis of ATP. • The final substrate-level phosphorylation in the pathway is catalyzed by pyruvate kinase where Phosphoenolpyruvate is coverted to Pyruvate. Phosphoenolpyruvate serves as a donor of the phosphoryl group that is transferred to ADP to produce ATP. This is another coupled reaction in which hydrolysis of the phosphoester bond in phosphoenolpyruvate provides energy for the formation of the phospho-anhydride bond of ATP. Dr. Roshni Rajamohan ATP synthase • The ATP is synthesized by a large (400 kDa) enzyme complex known by several names: ATP synthase, ATP ase (afterthe reverse reaction of ATP hydrolysis), and CFo–C1 (Boyer,1997). • This enzyme consists of two parts: a hydrophobic membrane-bound portion called CFo and a portion that sticks out into the stroma called CF1. • CF1 is the portion of the complex that synthesizes ATP. CF1 is made up of several peptides, including three copies of each of the αand βpeptides arranged alternately much like the sections of an orange. Whereas the catalytic sites are located largely on the βpolypeptide, many of the other peptides are thought to have primarily regulatory functions. • CFo appears to form a channel across the membrane through which protons can pass. • The molecular structure of the mitochondrial ATP synthase has been determined by X-ray crystallography (Stock et al. 1999). Although there are significant differences between the chloroplast and mitochondrial enzymes, they have the same overall architecture and probably nearly identical catalytic sites. In fact, there are remarkable similarities in the way electron flow is coupled to proton translocation in chloroplasts, mitochondria, and purple bacteria . • Another remarkable aspect of the mechanism of the ATP synthase is that the internal stalk and probably much of the CFo portion of the enzyme rotate during catalysis (Yasuda et al. 2001). The enzyme is actually a tiny molecular motor.Dr. Roshni Rajamohan Structure of ATP synthase Dr. Roshni Rajamohan ATP synthase- A tiny molecular motor ATPase or CFo–CF1 • CF1 is the portion of the complex that synthesizes ATP. • CFo appears to form a channel across the membrane through which protons can pass. • It is a large multi-subunit complex, CF1, attached on the stromal side of the membrane to an integral membrane portion, known as CFo. • CF1 consists of five different polypeptides, with a stoichiometry of α3, β3, γ, δ, ε. Cfo contains probably four different polypeptides, with a stoichiometry of a, b, b′, c12. Dr. Roshni Rajamohan • Model of the FoF1-ATPase, showing the attachment of the catalytic complex to the membrane via the β subunit and the δ subunit. • When the reaction runs in reverse (ATP synthesis), protons diffuse through the Fo complex down their electrochemical gradient. The movement of protons through the channel drives the rotation of the entire Fo complex within the membrane. • The γ subunit, which is attached to the Fo complex, then turns within the catalytic complex, causing the conformational changes that are required for ATP synthesis. • It is assumed that the catalytic complex itself does not rotate, but is anchored to the membrane. The δ subunit is located on the outside of the β subunit and serves as the site of attachment of the β subunit, which anchors the catalytic complex to the membrane and prevents it from spinning. • In mechanical terms, the F1 complex and its membrane anchor act as a stationary housing, or “stator,” while γ subunit (and possibly the Fo complex) serves as the “rotor.” (From Junge et al. 1997.) Dr. Roshni Rajamohan Uncouplers / Protonophores • Uncouplers are amphiphilic compounds(which are soluble both in water and lipids). They are agents with conjugated double bonds which allow them to diffuse across the membrane in both the protonated form and the unprotonated form, and thus dissipate the electrochemical proton gradient. • Uncouplers which transfer protons across the membrane are known as protonophores. • They disrupts phosphorylation by dissociating the reactions of ATP synthesis from the electron transport chain. They directly bypasses the ATP synthase by allowing passive proton influx, without affecting electron flow, but ATP synthesis does not occur. • The result is that the cell or mitochondrion expends energy to generate a proton motive force, but the proton motive force is dissipated before the ATP synthase can recapture this energy and use it to make ATP. • Uncouplers increases the proton permeability of the inner mitochondrial membrane and dissipates the proton gradient. Uncouplers are capable of transporting protons through mitochondrial and chloroplast membranes. • Both mammalian and plant mitochondria contain uncoupling protein (UCP). This protein facilitates the movement of protons across the inner membrane and therefore partially uncouples electron transport and decreases the ATP yield of respiration. Electron flow without accompanying phosphorylation is said to be uncoupled. • Uncoupling proteins (UCPs) occur in the inner mitochondrial membrane and dissipate the proton gradient across this membrane that is normally usedDr. Roshnifor ATP Rajamohan synthesis. Role of uncoupling agents • Addition of uncouplers results in continuation of electron transport and proton pumping, without generation of any proton gradient. ATP synthesis does not occur without affecting uptake of oxygen. In the absence of proton gradient, however, protons are transported in reverse direction through ATP synthase at the expense of ATP. Protonated DNP (a weak acid) diffuses from high proton concentration side of the membrane to low proton concentration side where it gets dissociated to generate protons resulting in dissipation of proton gradient. Membrane is permeable to both protonated and anionic forms of these. • E.g. FCCP (trifluoromethoxy carbonyl cyanide phenylhydrazone), a very efficient mitochondrial uncoupler. Other exampes of uncouplers- Carbonyl cyanide phenylhydrazone (CCP) 2,4-dinitrophenol (DNP), Carbonyl cyanide m-chlorophenyl hydrazine (CCCP) Dr. Roshni Rajamohan The mechanism of action of uncouplers (A) The protonation / deprotonation of FCCP which is a weak acid. (B) In the presence of an electrochemical proton gradient across the membrane, FCCP will become protonated and thus pick up a proton on the positive side of the membrane, move across the membrane in the neutral form, and lose the proton on the negative side. This is driven by the electrochemical proton gradient. In the negative
Load more

Recommended publications
  • Uncoupling Proteins: Functional Characteristics and Role in the Pathogenesis of Obesity and Type II Diabetes
    Diabetologia 2001) 44: 946±965 Ó Springer-Verlag 2001 Uncoupling proteins: functional characteristics and role in the pathogenesis of obesity and Type II diabetes L. T.Dalgaard, O.Pedersen Steno Diabetes Center, Gentofte, Denmark Abstract obesity. The three uncoupling protein homologue genes UCP1, UCP2, and UCP3 have been investigat- Uncoupling proteins are mitochondrial carrier pro- ed for polymorphisms and mutations and their impact teins which are able to dissipate the proton gradient on Type II diabetes mellitus, obesity, and body weight of the inner mitochondrial membrane. This uncou- gain or BMI. The main conclusion is that variation in pling process reduces the amount of ATP generated the UCP1, UCP2 or UCP3 genes is not associated through an oxidation of fuels. The hypothesis that un- with major alterations of body weight gain. The con- coupling proteins UCPs) are candidate genes for hu- tribution of UCP genes towards polygenic obesity man obesity or Type II non-insulin-dependent) dia- and Type II diabetes is evaluated and discussed. [Dia- betes mellitus is based on the finding that a chemical betologia 2001) 44: 946±965] uncoupling of the mitochondrial membrane reduces body adiposity, and that lower metabolic rates predict Keywords Uncoupling proteins, Type II diabetes weight gain. It is straightforward to hypothesize that mellitus, obesity, genetics, body weight regulation, common polymorphisms of UCP1, UCP2 and UCP3 energy expenditure, metabolic rate, brown adipose genes lower metabolic rate by a more efficient energy tissue, white adipose tissue, reactive oxygen species, coupling in the mitochondria. Furthermore, geneti- polymorphism, mutation, transgenics, gene knock- cally engineered mice over expressing different UCP out.
    [Show full text]
  • Effects of 2,4-Dinitrophenol and Other Metabolic Inhibitors on The
    (CANCER RESEARCH 40, 3669-3673. October 1980] 0008-5472/80-0040-OOOOS02.00 Effects of 2,4-Dinitrophenol and Other Metabolic Inhibitors on the Bidirectional Carrier Fluxes, Net Transport, and Intracellular Binding of Methotrexate in Ehrlich Ascites Tumor Cells1 David W. Fry, J. Courtland White, and I. David Goldman2 Department ol Medicine, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia 23298 ABSTRACT edly influenced by (a) the concentration of the inhibitor, (b) whether measurements are taken during influx, net transport, 2,4-Dinitrophenol (DNP), an uncoupler of oxidative phos- or the steady state, (c) whether total intracellular or freely phorylation, has been frequently used to evaluate the effects exchangeable MTX is determined, and (d) whether or not of energy depletion on methotrexate (MTX) transport. The glucose or other energy-producing substrates are present. results from these studies, however, have shown a multiplicity of effects that suggest a more complicated interaction with the MTX transport system than adenosine 5'-triphosphate deple INTRODUCTION tion alone. Accordingly, studies were undertaken to compare Membrane transport of MTX3 is a complex process. While the effects of DNP with a variety of other metabolic inhibitors this system conforms in many respects to other carrier-me on influx, efflux, net uptake, and intracellular binding of MTX in diated processes with the demonstration of temperature and Ehrlich ascites tumor cells. Low concentrations of DNP (0.1 sulfhydryl dependence (10), heteroexchange diffusion (9, 25), mw) inhibited efflux and increased the intracellular steady-state and inhibition by structural analogs (8, 10), some properties of concentration of MTX, both of which were totally reversed by the transport system are poorly understood.
    [Show full text]
  • Metabolic Plasticity Is an Essential Requirement of Acquired Tyrosine Kinase Inhibitor Resistance in Chronic Myeloid Leukemia
    cancers Article Metabolic Plasticity Is an Essential Requirement of Acquired Tyrosine Kinase Inhibitor Resistance in Chronic Myeloid Leukemia Miriam G. Contreras Mostazo 1,2,3, Nina Kurrle 3,4,5, Marta Casado 6,7 , Dominik Fuhrmann 8, Islam Alshamleh 4,9, Björn Häupl 3,4,5, Paloma Martín-Sanz 7,10, Bernhard Brüne 5,8,11 , 3,4,5 4,9 3,4,5, 1,2,7,12, , Hubert Serve , Harald Schwalbe , Frank Schnütgen y , Silvia Marin * y 1,2,7,12, , and Marta Cascante * y 1 Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, Universitat de Barcelona, 08028 Barcelona, Spain; [email protected] 2 Institute of Biomedicine of University of Barcelona, 08028 Barcelona, Spain 3 Department of Medicine, Hematology/Oncology, University Hospital Frankfurt, Goethe-University, 60590 Frankfurt am Main, Germany; [email protected] (N.K.); [email protected] (B.H.); [email protected] (H.S.); [email protected] (F.S.) 4 German Cancer Consortium (DKTK), Partner Site Frankfurt/Mainz, and German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany; [email protected] (I.A.); [email protected] (H.S.) 5 Frankfurt Cancer Institute (FCI), Goethe University, 60590 Frankfurt am Main, Germany; [email protected] 6 Biomedicine Institute of Valencia, IBV-CSIC, 46010 Valencia, Spain; [email protected] 7 CIBER of Hepatic and Digestive Diseases (CIBEREHD), Institute of Health Carlos III (ISCIII), 28029 Madrid, Spain; [email protected] 8 Institute of Biochemistry I, Faculty of
    [Show full text]
  • Molecular Biology of the Cell 6Th Edition
    753 CHAPTER Energy Conversion: Mitochondria and Chloroplasts 14 To maintain their high degree of organization in a universe that is constantly drift- IN THIS CHAPTER ing toward chaos, cells have a constant need for a plentiful supply of ATP, as we have explained in Chapter 2. In eukaryotic cells, most of the ATP that powers life THE MITOCHONDRION processes is produced by specialized, membrane-enclosed, energy-converting organelles. Tese are of two types. Mitochondria, which occur in virtually all cells THE PROTON PUMPS OF THE of animals, plants, and fungi, burn food molecules to produce ATP by oxidative ELECTRON-TRANSPORT CHAIN phosphorylation. Chloroplasts, which occur only in plants and green algae, har- ness solar energy to produce ATP by photosynthesis. In electron micrographs, the ATP PRODUCTION IN most striking features of both mitochondria and chloroplasts are their extensive MITOCHONDRIA internal membrane systems. Tese internal membranes contain sets of mem- brane protein complexes that work together to produce most of the cell’s ATP. In CHLOROPLASTS AND bacteria, simpler versions of essentially the same protein complexes produce ATP, PHOTOSYNTHESIS but they are located in the cell’s plasma membrane (Figure 14–1). Comparisons of DNA sequences indicate that the energy-converting organ- THE GENETIC SYSTEMS elles in present-day eukaryotes originated from prokaryotic cells that were endo- OF MITOCHONDRIA AND cytosed during the evolution of eukaryotes (discussed in Chapter 1). This explains CHLOROPLASTS why mitochondria and chloroplasts contain their own DNA, which still encodes a subset of their proteins. Over time, these organelles have lost most of their own genomes and become heavily dependent on proteins that are encoded by genes in the nucleus, synthesized in the cytosol, and then imported into the organelle.
    [Show full text]
  • Lecture 37 & 38: Electron Transport Chain and Oxidative Phosphorylation
    CHM333 LECTURES 37 & 38: 4/27 – 29/13 SPRING 2013 Professor Christine Hrycyna Electron Transport and Oxidative Phosphorylation • Final stages of aerobic Mitochondrial Electron Transport oxidation of biomolecules in • How did we get here? eukaryotes occur in the mitochondrion • Summary of glycolysis glucose + 2 NAD+ + 2P + 2ADP 2 pyruvate + 2ATP + 2NADH + 2H+ • Reduced coenzymes NADH i → and FADH2 from: • Summary of the citric acid cycle (including pyruvate dehydrogenase) pyruvate + 4 NAD+ + FAD + GDP + 2 H 0 3 CO + 4NADH + 4H+ + P + GTP + FADH (1) Aerobic oxidation of 2 → 2 i 2 pyruvate by the citric acid cycle (2) Oxidation of fatty acids and amino acids Electron Transport Chain is the process by which NADH and FADH2 are oxidized and a proton gradient is formed. Electron Transport and Oxidative Phosphorylation Oxidative phosphorylation is the process of making ATP by using the proton gradient generated by the ETC. Respiration by mitochondria • Oxidation of substrates is coupled to the phosphorylation of ADP • Respiration (consumption of oxygen) proceeds only when ADP is present • The amount of O2 consumed depends upon the amount of ADP added Location of mitochondrial complexes • Inner mitochondrial membrane: a. Electron transport chain: oxidizes reduced coenzymes b. ATP synthase: machinery to synthesize ATP 280 CHM333 LECTURES 37 & 38: 4/27 – 29/13 SPRING 2013 Professor Christine Hrycyna Electron transport and oxidative phosphorylation capture the energy in the redox potential of NADH and FADH2 – 2 separate processes that are COUPLED to result in ATP production Extensive folding of IMM provides a large surface area on the matrix side to form lots of assemblies of proteins to maximize ATP production (1) Respiratory electron-transport chain (ETC) Series of enzyme complexes embedded in the inner mitochondrial membrane, which oxidize NADH and FADH2.
    [Show full text]
  • Why Cancer Cells Have a More Hyperpolarised Mitochondrial Membrane Potential and Emergent Prospects for Therapy
    bioRxiv preprint doi: https://doi.org/10.1101/025197; this version posted August 21, 2015. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. Why cancer cells have a more hyperpolarised mitochondrial membrane potential and emergent prospects for therapy Michael D. Forrest Ph.D. Department of Computer Science, University of Warwick, Coventry, UK E-Mail: [email protected] ABSTRACT Cancer cells have a more hyperpolarised mitochondrial membrane potential (ΨIM) than normal cells. ΨIM = ~-220 mV in cancer cells as compared to ~-140 mV in normal cells. Until now it has not been known why. This paper explains this disparity, in a mathematical framework, and identifies molecular targets and operations unique to cancer cells. These are thence prospective cancer drug targets. BMS-199264 is proposed as an anti-cancer drug. It inhibits the reverse, proton-pumping mode of ATP synthase, which this paper identifies as crucial to cancer cells but not to healthy, normal adult cells. In the cancer cell model, the adenine nucleotide exchanger (ANT) is inversely orientated in the mitochondrial inner membrane as compared to normal cells. This predicts it to have a different drug interaction profile, which can be leveraged for cancer therapy. Uncouplers, which dissipate the proton motive force, are proposed as anti-cancer medicines e.g. 2,4-dinitrophenol. ARTICLE During aerobic respiration, the movement of electrons along the respiratory chain pumps protons across the inner mitochondrial membrane to build a proton motive force (pmf) [1-3]. The pmf is electrochemical, consisting of a hyperpolarised transmembrane voltage (ΨIM, negative inside) and a proton concentration gradient (δpH, alkali inside).
    [Show full text]
  • Respirometric Screening and Characterization of Mitochondrial Toxicities Induced by Toxcast Chemicals
    Respirometric Screening and Characterization of Mitochondrial Toxicities Induced by ToxCast Chemicals Steven O. Simmons The views expressed in this presentation are those of the author[s] and do not necessarily reflect the views or policies of the U.S. Environmental Protection Agency. Office of Research and Development National Center for Computational Toxicology September 3, 2018 Mitochondria as Targets of Toxicity • Mitochondria are critical in eukaryotic cells because they generate >90% of the cellular supply of ATP • Also key to regulating cell cycle/growth, differentiation and apoptosis • Many chemicals are known to impair mitochondrial function through various mechanisms: • Electron transport chain (ETC; Complexes I-IV) inhibition • Uncoupling and Ionophores • Phosphorylation (Complex V) inhibition • Transport inhibition (ATP) • Kreb cycle inhibitors • Disease states associated with genetic mitochondrial disorders provide insights about possible adverse outcomes • In many of these cases, mitochondria have normal morphology- the impact is functional, not structural • Current ToxCast/Tox21 high-throughput test methods typically use immortalized/tumor cells (Warburg Effect) cultured in high-glucose medium (Crabtree Effect), and thus are impervious to mitochondrial insult • ToxCast/Tox21 mitochondrial assays have focused on two endpoints: mitochondrial mass (swelling) and mitochondrial membrane potential (MMP) • These assay use dye probes to measure structural mitochondrial defects due primarily to membrane changes and are not sensitive
    [Show full text]
  • A New Amine As an Uncoupler of Chloroplast Electron Transport
    A New Amine as an Uncoupler of Chloroplast Electron Transport Jonathan Leeds, Lynne Bemis, Rita Barr and Frederick L. Crane Department of Biological Sciences Purdue University West Lafayette, Indiana 47907 Abbreviations used: DAD-diaminodurene; DBMIB-2,5,8-dibromo-3-methyl-6- isopropyl-p-benzoquinone; DCMU-dichlorophenyl-dimethylurea; DMBQ-2, 5-dimethylbenzoquinone; DNP-INT -2, 4-dinitrophenylether of iodonitrothymol; FCCP- carbonylcyanide-p-trifluoromethoxyphenylhydrazone; MV-methylviologen; TMPD-N-tetramethyl-p-phenylenediamine. Introduction In isolated chloroplasts electron transport is coupled to photophosphorylation (1,2). To study electron transport rates in Photosystem I and II, certain chloroplast reactions require an uncoupler to be present. The common uncouplers used for this purpose are FCCP, ammonia and such ionophores as gramicidin (2). In this study we describe a new amine-type uncoupler, N-[bis-(3,5-trifluoromethyl)- phenyl]-2,4-dinitro(3-trifluromethyl)-benzamine (DPA, Figure 1), which appears to work w 3 ' 3 Figure 1. The Chemical Composition of the Uncoupler, DPA. best at coupling site 1, located between the two photosystems in the chloroplast elec- ~ 7 tron transport chain. We show that low concentrations (1 x 10 ) are required to stimulate electron transport 60% or to inhibit the proton gradients associated with photophosphorylation. Materials and Methods Spinach or lettuce chloroplasts were prepared from commercially available sources by methods previously reported (3). Briefly, about 20g of leaves were ground in a Waring blender in 100 ml sucrose-NaCl (0.4 M sucrose, 0.05 M NaCl) with 6 on-and- off bursts of energy. The resulting green suspension was filtered through 10 layers of cheesecloth and a single layer of Miracloth into 2 50-ml centrifuge tubes.
    [Show full text]
  • Burn After Feeding. an Old Uncoupler of Oxidative Phosphorylation Is Redesigned for the Treatment of Nonalcoholic Fatty Liver Disease
    Burn after feeding. An old uncoupler of oxidative phosphorylation is redesigned for the treatment of nonalcoholic fatty liver disease. Bernard Fromenty To cite this version: Bernard Fromenty. Burn after feeding. An old uncoupler of oxidative phosphorylation is redesigned for the treatment of nonalcoholic fatty liver disease.. Clinics and Research in Hepatology and Gas- troenterology, Elsevier, 2014, 38 (5), pp.545-549. 10.1016/j.clinre.2014.04.013. hal-01068679 HAL Id: hal-01068679 https://hal-univ-rennes1.archives-ouvertes.fr/hal-01068679 Submitted on 26 Sep 2014 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. COMMENTARY Burn after feeding. An old uncoupler of oxidative phosphorylation is redesigned for the treatment of nonalcoholic fatty liver disease. B. Fromenty INSERM, U991, Université de Rennes 1, 35000 Rennes, France, E-mail address: [email protected] Key words: Oxidative phosphorylation Mitochondria Uncoupling Dinitrophenol Fatty liver Steatosis Triacylglycerol Abbreviations: BAT, brown adipose tissue; CYP, cytochrome P450; DAG, diacylglycerol; DNP, 2,4-dinitrophenol; FAO, fatty acid oxidation; DNPME, 2,4-dinitrophenol-methyl ether; NAFLD, nonalcoholic fatty liver disease; OXPHOS, oxidative phosphorylation; PKCprotein kinase C-;ROS, reactive oxygen species;TAG, triacylglycerol; T2D, type 2 diabetes; UCP1, uncoupling protein-1; WAT, white adipose tissue 1 Summary Uncoupling of oxidative phosphorylation (OXPHOS) in brown adipose tissue can be used by hibernating animals to produce heat at the expense of their fat mass.
    [Show full text]
  • Mitochondrial Dysfunction in Skeletal Muscle Promotes Metabolic Shift
    1 Targeted mitochondrial uncoupling beyond UCP1 – the fine line between death 2 and metabolic health 3 Mario Ost1,*, Susanne Keipert2, and Susanne Klaus1 4 1Research Group Physiology of Energy Metabolism, German Institute of Human Nutrition, 5 Potsdam-Rehbruecke, 14558, Germany 6 2Helmholtz Diabetes Center, Helmholtz Zentrum München, Neuherberg, 85764, Germany 7 *Corresponding author: 8 Mario Ost 9 Research Group Physiology of Energy Metabolism 10 German Institute of Human Nutrition Potsdam-Rehbrücke 11 Nuthetal, 14558 (Germany) 12 Phone: (0049) 33200 88-2430 13 Email: [email protected] 14 Highlights: 15 Ectopic mitochondrial uncoupling increases substrate oxidation in target tissues. 16 Novel chemical uncouplers tackle obesity, diabetes and fatty liver disease. 17 Targeted UCP1 overexpression ameliorates obesity, hypertriglyceridemia and insulin resistance. 18 Muscle-targeted UCP1 overexpression promotes adaptive metabolic remodeling, endocrine 19 crosstalk and survival. 1 20 Graphical abstract 21 2 22 ABSTRACT 23 In the early 1930s, the chemical uncoupling agent 2,4-dinitrophenol (DNP) was promoted for the 24 very first time as a powerful and effective weight loss pill but quickly withdrawn from the market 25 due to its lack of tissue-selectivity with resulting dangerous side effects, including hyperthermia and 26 death. Today, novel mitochondria- or tissue-targeted chemical uncouplers with higher safety and 27 therapeutic values are under investigation in order to tackle obesity, diabetes and fatty liver disease. 28 Moreover, in the past 20 years, transgenic mouse models were generated to understand the 29 molecular and metabolic consequences of targeted uncoupling, expressing functional uncoupling 30 protein 1 (UCP1) ectopically in white adipose tissue or skeletal muscle.
    [Show full text]
  • Antiinfectives Targeting Enzymes and the Proton Motive Force
    Antiinfectives targeting enzymes and the proton PNAS PLUS motive force Xinxin Fenga, Wei Zhua, Lici A. Schurig-Bricciob, Steffen Lindertc, Carolyn Shoend, Reese Hitchingse, Jikun Lia, Yang Wanga, Noman Baiga, Tianhui Zhoua, Boo Kyung Kima, Dean C. Cricke, Michael Cynamond, J. Andrew McCammonf,g,h,1, Robert B. Gennisa,b,i, and Eric Oldfielda,i,1 aDepartment of Chemistry, University of Illinois, Urbana, IL 61801; bDepartment of Biochemistry, University of Illinois, Urbana, IL 61801; cDepartment of Chemistry and Biochemistry, Ohio State University, Columbus, OH 43210; dCentral New York Research Corporation, Veterans Affairs Medical Center, Syracuse, NY 13210; eDepartment of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO 80523; fDepartment of Pharmacology and Department of Chemistry & Biochemistry, University of California San Diego, La Jolla, CA 92093; gHoward Hughes Medical Institute, University of California San Diego, La Jolla, CA 92093; hNational Biomedical Computation Resource, University of California San Diego, La Jolla, CA 92093; and iCenter for Biophysics and Computational Biology, University of Illinois at Urbana–Champaign, Urbana, IL 61801 Contributed by J. Andrew McCammon, November 6, 2015 (sent for review September 9, 2015; reviewed by Hiroshi Nikaido and David G. Russell) There is a growing need for new antibiotics. Compounds that target ethanolamine (3) was more potent than was SQ109 (2)against the proton motive force (PMF), uncouplers, represent one possible M. tuberculosis H37Rv [0.063 vs. 0.25 μg/mL minimal inhibitory class of compounds that might be developed because they are concentration (MIC)], and that at least one protonatable nitrogen in already used to treat parasitic infections, and there is interest in the linker was essential for activity.
    [Show full text]
  • Slipping Pumps Or Proton Leaks in Oxidative Phosphorylation
    CORE Metadata, citation and similar papers at core.ac.uk Provided by Elsevier - Publisher Connector Volume 277, number 1,2, 131-133 FEBS 09252 December 1990 Slipping pumps or proton leaks in oxidative phosphorylation The local anesthetic bupivacaine causes slip in cytochrome c oxidase of mitochondria Karel van Dam13, Yasuo Shinoharal, Akira Unamil, Kenji Yoshidal and Hiroshi Teradal 1Faculty of Pharmaceutical Sciences, University of Tokushima, Shomachi-I, Tokushima 770, Japan and =E.C. Slater Institute for Biochemical Research, University of Amsterdam, Plantage Muidergracht 12,1018 TV Amsterdam, The Netherlanris Received 29 October 1990 Evidence is presented to show that the local anesthetic bupivacaine causes slip in the mitochondrial proton pump cytochrome c oxidase. Oxidative phosphorylation; Uncoupling; Mitochondria; Local anesthetic; Proton pump 1. INTRODUCTION were always present in the mitochondrial suspension. The reduction of 02 by cytochrome c oxidase upon addition of 1.33 mM ferro- Recently, we found that the local anesthetic bupiva- cyanide was monitored polarographically at 25°C as described previously [9]. The concentration of mitochondria was 5 mg pro- Caine inhibits ATP synthesis by uncoupling of oxidative tein/ml. Bupivacaine was a generous gift from Fujisawa Phar- phosphorylation in mitochondria, but without increase maceutical Industry Co, Osaka, Japan. In the experiments of Fig. 2 in the proton permeability of the mitochondrial mem- valinomycin at 0.53 rg/mg mitochondrial protein was present in the brane [ 11, in contrast to the classical chemiosmotic con- incubation medium. The movement of protons was monitored with a glass electrode connected with a pH meter, Horiba F-7. The extent of cept [2].
    [Show full text]