51
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Lee JJ, Park YS, Lee KJ. Hydrogen-deuterium exchange mass spectrometry for determining protein structural changes in drug discovery. Arch Pharm Res 2015; 38:1737-45. [PMID: 25743629 DOI: 10.1007/s12272-015-0584-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2015] [Accepted: 02/25/2015] [Indexed: 12/11/2022]
Abstract
Protein structures are dynamically changed in response to post-translational modifications, ligand or chemical binding, or protein-protein interactions. Understanding the structural changes that occur in proteins in response to potential candidate drugs is important for predicting the modes of action of drugs and their functions and regulations. Recent advances in hydrogen/deuterium exchange mass spectrometry (HDX-MS) have the potential to offer a tool for obtaining such understanding similarly to other biophysical techniques, such as X-ray crystallography and high resolution NMR. We present here, a review of basic concept and methodology of HDX-MS, how it is being applied for identifying the sites and structural changes in proteins following their interactions with other proteins and small molecules, and the potential of this tool to help in drug discovery.
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Affiliation(s)
- Jae-Jin Lee
- Graduate School of Pharmaceutical Sciences and College of Pharmacy, Ewha Womans University, Seoul, 120-750, Republic of Korea
| | - Yeon Seung Park
- Graduate School of Pharmaceutical Sciences and College of Pharmacy, Ewha Womans University, Seoul, 120-750, Republic of Korea
| | - Kong-Joo Lee
- Graduate School of Pharmaceutical Sciences and College of Pharmacy, Ewha Womans University, Seoul, 120-750, Republic of Korea.
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52
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Xu L, Pan Y. Coupled electro-mechanic-chemical dynamics model for F 1F 0-motor. RSC Adv 2015. [DOI: 10.1039/c5ra01226k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Considering the power system (respiratory chain) and the control system, a coupled electro-mechanic-chemical dynamics model for F1F0-motor was established.
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Affiliation(s)
- Lizhong Xu
- School of Mechanical Engineering
- Yanshan University
- Qinhuangdao 066004
- China
| | - Yue Pan
- School of Mechanical Engineering
- Yanshan University
- Qinhuangdao 066004
- China
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53
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Nakanishi-Matsui M, Sekiya M, Yano S, Futai M. Inhibition of F1-ATPase rotational catalysis by the carboxyl-terminal domain of the ϵ subunit. J Biol Chem 2014; 289:30822-30831. [PMID: 25228697 DOI: 10.1074/jbc.m114.578872] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Escherichia coli ATP synthase (F0F1) couples catalysis and proton transport through subunit rotation. The ϵ subunit, an endogenous inhibitor, lowers F1-ATPase activity by decreasing the rotation speed and extending the duration of the inhibited state (Sekiya, M., Hosokawa, H., Nakanishi-Matsui, M., Al-Shawi, M. K., Nakamoto, R. K., and Futai, M. (2010) Single molecule behavior of inhibited and active states of Escherichia coli ATP synthase F1 rotation. J. Biol. Chem. 285, 42058-42067). In this study, we constructed a series of ϵ subunits truncated successively from the carboxyl-terminal domain (helix 1/loop 2/helix 2) and examined their effects on rotational catalysis (ATPase activity, average rotation rate, and duration of inhibited state). As expected, the ϵ subunit lacking helix 2 caused about ½-fold reduced inhibition, and that without loop 2/helix 2 or helix 1/loop 2/helix 2 showed a further reduced effect. Substitution of ϵSer(108) in loop 2 and ϵTyr(114) in helix 2, which possibly interact with the β and γ subunits, respectively, decreased the inhibitory effect. These results suggest that the carboxyl-terminal domain of the ϵ subunit plays a pivotal role in the inhibition of F1 rotation through interaction with other subunits.
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Affiliation(s)
- Mayumi Nakanishi-Matsui
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Iwate Medical University, Nishitokuta 2-1-1, Yahaba, Iwate 028-3694, Japan.
| | - Mizuki Sekiya
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Iwate Medical University, Nishitokuta 2-1-1, Yahaba, Iwate 028-3694, Japan
| | - Shio Yano
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Iwate Medical University, Nishitokuta 2-1-1, Yahaba, Iwate 028-3694, Japan
| | - Masamitsu Futai
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Iwate Medical University, Nishitokuta 2-1-1, Yahaba, Iwate 028-3694, Japan
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54
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Zorov DB, Juhaszova M, Sollott SJ. Mitochondrial reactive oxygen species (ROS) and ROS-induced ROS release. Physiol Rev 2014; 94:909-50. [PMID: 24987008 DOI: 10.1152/physrev.00026.2013] [Citation(s) in RCA: 3187] [Impact Index Per Article: 318.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Byproducts of normal mitochondrial metabolism and homeostasis include the buildup of potentially damaging levels of reactive oxygen species (ROS), Ca(2+), etc., which must be normalized. Evidence suggests that brief mitochondrial permeability transition pore (mPTP) openings play an important physiological role maintaining healthy mitochondria homeostasis. Adaptive and maladaptive responses to redox stress may involve mitochondrial channels such as mPTP and inner membrane anion channel (IMAC). Their activation causes intra- and intermitochondrial redox-environment changes leading to ROS release. This regenerative cycle of mitochondrial ROS formation and release was named ROS-induced ROS release (RIRR). Brief, reversible mPTP opening-associated ROS release apparently constitutes an adaptive housekeeping function by the timely release from mitochondria of accumulated potentially toxic levels of ROS (and Ca(2+)). At higher ROS levels, longer mPTP openings may release a ROS burst leading to destruction of mitochondria, and if propagated from mitochondrion to mitochondrion, of the cell itself. The destructive function of RIRR may serve a physiological role by removal of unwanted cells or damaged mitochondria, or cause the pathological elimination of vital and essential mitochondria and cells. The adaptive release of sufficient ROS into the vicinity of mitochondria may also activate local pools of redox-sensitive enzymes involved in protective signaling pathways that limit ischemic damage to mitochondria and cells in that area. Maladaptive mPTP- or IMAC-related RIRR may also be playing a role in aging. Because the mechanism of mitochondrial RIRR highlights the central role of mitochondria-formed ROS, we discuss all of the known ROS-producing sites (shown in vitro) and their relevance to the mitochondrial ROS production in vivo.
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Affiliation(s)
- Dmitry B Zorov
- A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia; and Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Magdalena Juhaszova
- A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia; and Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Steven J Sollott
- A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia; and Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
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55
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Deckers M, Balleininger M, Vukotic M, Römpler K, Bareth B, Juris L, Dudek J. Aim24 stabilizes respiratory chain supercomplexes and is required for efficient respiration. FEBS Lett 2014; 588:2985-92. [PMID: 24928273 DOI: 10.1016/j.febslet.2014.06.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 05/24/2014] [Accepted: 06/02/2014] [Indexed: 10/25/2022]
Abstract
The mitochondrial respiratory chain is essential for the conversion of energy derived from the oxidation of metabolites into the membrane potential, which drives the synthesis of ATP. The electron transporting complexes bc1 complex and the cytochrome c oxidase assemble into large supercomplexes, allowing efficient energy transduction. Currently, we have only limited information about what determines the structure of the supercomplex. Here, we characterize Aim24 in baker's yeast as a protein, which is integrated in the mitochondrial inner membrane and is required for the structural integrity of the supercomplex. Deletion of AIM24 strongly affects activity of the respiratory chain and induces a growth defect on non-fermentable medium. Our data indicate that Aim24 has a function in stabilizing the respiratory chain supercomplexes.
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Affiliation(s)
- Markus Deckers
- Department of Cellular Biochemistry, University of Göttingen, D-37073 Göttingen, Germany
| | - Martina Balleininger
- Department of Cellular Biochemistry, University of Göttingen, D-37073 Göttingen, Germany
| | - Milena Vukotic
- Department of Cellular Biochemistry, University of Göttingen, D-37073 Göttingen, Germany
| | - Katharina Römpler
- Department of Cellular Biochemistry, University of Göttingen, D-37073 Göttingen, Germany
| | - Bettina Bareth
- Department of Cellular Biochemistry, University of Göttingen, D-37073 Göttingen, Germany
| | - Lisa Juris
- Department of Cellular Biochemistry, University of Göttingen, D-37073 Göttingen, Germany
| | - Jan Dudek
- Department of Cellular Biochemistry, University of Göttingen, D-37073 Göttingen, Germany.
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56
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Antoniel M, Giorgio V, Fogolari F, Glick GD, Bernardi P, Lippe G. The oligomycin-sensitivity conferring protein of mitochondrial ATP synthase: emerging new roles in mitochondrial pathophysiology. Int J Mol Sci 2014; 15:7513-36. [PMID: 24786291 PMCID: PMC4057687 DOI: 10.3390/ijms15057513] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2014] [Revised: 04/18/2014] [Accepted: 04/21/2014] [Indexed: 01/08/2023] Open
Abstract
The oligomycin-sensitivity conferring protein (OSCP) of the mitochondrial F(O)F1 ATP synthase has long been recognized to be essential for the coupling of proton transport to ATP synthesis. Located on top of the catalytic F1 sector, it makes stable contacts with both F1 and the peripheral stalk, ensuring the structural and functional coupling between F(O) and F1, which is disrupted by the antibiotic, oligomycin. Recent data have established that OSCP is the binding target of cyclophilin (CyP) D, a well-characterized inducer of the mitochondrial permeability transition pore (PTP), whose opening can precipitate cell death. CyPD binding affects ATP synthase activity, and most importantly, it decreases the threshold matrix Ca²⁺ required for PTP opening, in striking analogy with benzodiazepine 423, an apoptosis-inducing agent that also binds OSCP. These findings are consistent with the demonstration that dimers of ATP synthase generate Ca²⁺-dependent currents with features indistinguishable from those of the PTP and suggest that ATP synthase is directly involved in PTP formation, although the underlying mechanism remains to be established. In this scenario, OSCP appears to play a fundamental role, sensing the signal(s) that switches the enzyme of life in a channel able to precipitate cell death.
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Affiliation(s)
- Manuela Antoniel
- Department of Biomedical Sciences, University of Padova, via Ugo Bassi 58/B, 35121 Padua, Italy.
| | - Valentina Giorgio
- Department of Biomedical Sciences, University of Padova, via Ugo Bassi 58/B, 35121 Padua, Italy.
| | - Federico Fogolari
- Department of Biomedical Sciences, University of Udine, p.le Kolbe, 33100 Udine, Italy.
| | - Gary D Glick
- Department of Chemistry, Graduate Program in Immunology, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Paolo Bernardi
- Department of Biomedical Sciences, University of Padova, via Ugo Bassi 58/B, 35121 Padua, Italy.
| | - Giovanna Lippe
- Department of Food Science, University of Udine, via Sondrio 2/A, 33100 Udine, Italy.
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57
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Chaban Y, Boekema EJ, Dudkina NV. Structures of mitochondrial oxidative phosphorylation supercomplexes and mechanisms for their stabilisation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:418-26. [DOI: 10.1016/j.bbabio.2013.10.004] [Citation(s) in RCA: 200] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2013] [Revised: 10/01/2013] [Accepted: 10/15/2013] [Indexed: 01/13/2023]
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58
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Respiratory Chain Supercomplexes in Mitochondria. THE STRUCTURAL BASIS OF BIOLOGICAL ENERGY GENERATION 2014. [DOI: 10.1007/978-94-017-8742-0_12] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Kabala AM, Lasserre JP, Ackerman SH, di Rago JP, Kucharczyk R. Defining the impact on yeast ATP synthase of two pathogenic human mitochondrial DNA mutations, T9185C and T9191C. Biochimie 2013; 100:200-6. [PMID: 24316278 DOI: 10.1016/j.biochi.2013.11.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Accepted: 11/25/2013] [Indexed: 12/18/2022]
Abstract
Mutations in the human mitochondrial ATP6 gene encoding ATP synthase subunit a/6 (referred to as Atp6p in yeast) are at the base of neurodegenerative disorders like Neurogenic Ataxia and Retinitis Pigmentosa (NARP), Leigh syndrome (LS), Charcot-Marie-Tooth (CMT), and ataxia telangiectasia. In previous studies, using the yeast Saccharomyces cerevisiae as a model we were able to better define how several of these mutations impact the ATP synthase. Here we report the construction of yeast models of two other ATP6 pathogenic mutations, T9185C and T9191C. The first one was reported as conferring a mild, sometimes reversible, CMT clinical phenotype; the second one has been described in a patient presenting with severe LS. We found that an equivalent of the T9185C mutation partially impaired the functioning of yeast ATP synthase, with only a 30% deficit in mitochondrial ATP production. An equivalent of the mutation T9191C had much more severe effects, with a nearly complete block in yeast Atp6p assembly and an >95% drop in the rate of ATP synthesis. These findings provide a molecular basis for the relative severities of the diseases induced by T9185C and T9191C.
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Affiliation(s)
- Anna Magdalena Kabala
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland; Institut de Biochimie et Génétique Cellulaires, CNRS UMR5095, Université Bordeaux Segalen, 1 Rue Camille Saint-Saëns, Bordeaux 33077 cedex, France
| | - Jean-Paul Lasserre
- Institut de Biochimie et Génétique Cellulaires, CNRS UMR5095, Université Bordeaux Segalen, 1 Rue Camille Saint-Saëns, Bordeaux 33077 cedex, France
| | - Sharon H Ackerman
- Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Jean-Paul di Rago
- Institut de Biochimie et Génétique Cellulaires, CNRS UMR5095, Université Bordeaux Segalen, 1 Rue Camille Saint-Saëns, Bordeaux 33077 cedex, France
| | - Roza Kucharczyk
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland.
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60
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Nelson N. Evolution of photosystem I and the control of global enthalpy in an oxidizing world. PHOTOSYNTHESIS RESEARCH 2013; 116:145-151. [PMID: 23954951 DOI: 10.1007/s11120-013-9902-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2013] [Accepted: 07/26/2013] [Indexed: 05/28/2023]
Abstract
Life on earth is governed by light, chemical reactions, and the second law of thermodynamics, which defines the tendency for increasing entropy as an expression of disorder or randomness. Life is an expression of increasing order, and a constant influx of energy and loss of entropic wastes are required to maintain or increase order in living organisms. Most of the energy for life comes from sunlight and, thus, photosynthesis underlies the survival of all life forms. Oxygenic photosynthesis determines not only the global amount of enthalpy in living systems, but also the composition of the Earth's atmosphere and surface. Photosynthesis was established on the Earth more than 3.5 billion years ago. The primordial reaction center has been suggested to comprise a homodimeric unit resembling the core complex of the current reaction centers in Chlorobi, Heliobacteria, and Acidobacteria. Here, an evolutionary scenario based on the known structures of the current reaction centers is proposed.
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Affiliation(s)
- Nathan Nelson
- Department of Biochemistry and Molecular Biology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978, Tel Aviv, Israel,
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61
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Abstract
FO-ATP synthase (FO) is a rotary motor that converts potential energy from ions, usually protons, moving from high- to low-potential sides of a membrane into torque and rotary motion. Here we propose a mechanism whereby electric fields emanating from the proton entry and exit channels act on asymmetric charge distributions in the c-ring, due to protonated and deprotonated sites, and drive it to rotate. The model predicts a scaling between time-averaged torque and proton motive force, which can be hindered by mutations that adversely affect the channels. The torque created by the c-ring of FO drives the γ-subunit to rotate within the ATP-producing complex (F1) overcoming, with the aid of thermal fluctuations, an opposing torque that rises and falls with angular position. Using the analogy with thermal Brownian motion of a particle in a tilted washboard potential, we compute ATP production rates vs. proton motive force. The latter shows a minimum, needed to drive ATP production, which scales inversely with the number of proton binding sites on the c-ring.
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Abstract
Methanogenic archaea live at the thermodynamic limit of life and use sophisticated mechanisms for ATP synthesis and energy coupling. The group of methanogens without cytochromes use an Na(+) current across the membrane for ATP synthesis, whereas the cytochrome-containing methanogens have additional coupling sites that also translocate protons. The ATP synthase in this group is promiscuous and uses Na(+) and H(+) simultaneously.
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63
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Nakanishi-Matsui M, Sekiya M, Futai M. Rotating proton pumping ATPases: subunit/subunit interactions and thermodynamics. IUBMB Life 2013; 65:247-54. [PMID: 23441040 DOI: 10.1002/iub.1134] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 12/21/2012] [Indexed: 11/05/2022]
Abstract
In this article, we discuss single molecule observation of rotational catalysis by E. coli ATP synthase (F-ATPase) using small gold beads. Studies involving a low viscous drag probe showed the stochastic properties of the enzyme in alternating catalytically active and inhibited states. The importance of subunit interaction between the rotor and the stator, and thermodynamics of the catalysis are also discussed. "Single Molecule Enzymology" is a new trend for understanding enzyme mechanisms in biochemistry and physiology.
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Affiliation(s)
- Mayumi Nakanishi-Matsui
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Iwate Medical University, and Futai Special Laboratory, Yahaba, Iwate, Japan.
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64
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Sánchez-Aragó M, Formentini L, Cuezva JM. Mitochondria-mediated energy adaption in cancer: the H(+)-ATP synthase-geared switch of metabolism in human tumors. Antioxid Redox Signal 2013; 19:285-98. [PMID: 22901241 PMCID: PMC3691914 DOI: 10.1089/ars.2012.4883] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
SIGNIFICANCE Since the signing of the National Cancer Act in 1971, cancer still remains a major cause of death despite significant progresses made in understanding the biology and treatment of the disease. After many years of ostracism, the peculiar energy metabolism of tumors has been recognized as an additional phenotypic trait of the cancer cell. RECENT ADVANCES While the enhanced aerobic glycolysis of carcinomas has already been translated to bedside for precise tumor imaging and staging of cancer patients, accepting that an impaired bioenergetic function of mitochondria is pivotal to understand energy metabolism of tumors and in its progression is debated. However, mitochondrial bioenergetics and cell death are tightly connected. CRITICAL ISSUES Recent clinical findings indicate that H(+)-ATP synthase, a core component of mitochondrial oxidative phosphorylation, is repressed at both the protein and activity levels in human carcinomas. This review summarizes the relevance that mitochondrial function has to understand energy metabolism of tumors and explores the connection between the bioenergetic function of the organelle and the activity of mitochondria as tumor suppressors. FUTURE DIRECTIONS The reversible nature of energy metabolism in tumors highlights the relevance that the microenvironment has for tumor progression. Moreover, the stimulation of mitochondrial activity or the inhibition of glycolysis suppresses tumor growth. Future research should elucidate the mechanisms promoting the silencing of oxidative phosphorylation in carcinomas. The aim is the development of new therapeutic strategies tackling energy metabolism to eradicate tumors or at least, to maintain tumor dormancy and transform cancer into a chronic disease.
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Affiliation(s)
- María Sánchez-Aragó
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, Centro de Investigación Biomédica en Red de Enfermedades Raras, Centro de Investigación Hospital 12 de Octubre, Madrid, Spain
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65
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Fraser JM, Tulk SE, Jeans JA, Campbell DA, Bibby TS, Cockshutt AM. Photophysiological and photosynthetic complex changes during iron starvation in Synechocystis sp. PCC 6803 and Synechococcus elongatus PCC 7942. PLoS One 2013; 8:e59861. [PMID: 23527279 PMCID: PMC3602374 DOI: 10.1371/journal.pone.0059861] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 02/19/2013] [Indexed: 12/13/2022] Open
Abstract
Iron is an essential component in many protein complexes involved in photosynthesis, but environmental iron availability is often low as oxidized forms of iron are insoluble in water. To adjust to low environmental iron levels, cyanobacteria undergo numerous changes to balance their iron budget and mitigate the physiological effects of iron depletion. We investigated changes in key protein abundances and photophysiological parameters in the model cyanobacteria Synechococcus PCC 7942 and Synechocystis PCC 6803 over a 120 hour time course of iron deprivation. The iron stress induced protein (IsiA) accumulated to high levels within 48 h of the onset of iron deprivation, reaching a molar ratio of ∼42 IsiA : Photosystem I in Synechococcus PCC 7942 and ∼12 IsiA : Photosystem I in Synechocystis PCC 6803. Concomitantly the iron-rich complexes Cytochrome b6f and Photosystem I declined in abundance, leading to a decrease in the Photosystem I : Photosystem II ratio. Chlorophyll fluorescence analyses showed a drop in electron transport per Photosystem II in Synechococcus, but not in Synechocystis after iron depletion. We found no evidence that the accumulated IsiA contributes to light capture by Photosystem II complexes.
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Affiliation(s)
- Jared M Fraser
- Department of Chemistry & Biochemistry, Mount Allison University, Sackville, New Brunswick, Canada
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66
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Watanabe R, Noji H. Chemomechanical coupling mechanism of F(1)-ATPase: catalysis and torque generation. FEBS Lett 2013; 587:1030-5. [PMID: 23395605 DOI: 10.1016/j.febslet.2013.01.063] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 01/29/2013] [Accepted: 01/29/2013] [Indexed: 11/18/2022]
Abstract
F1-ATPase (F1), a rotary motor protein driven by ATP hydrolysis, is unique with respect to its high efficiency and reversibility in converting chemical energy into mechanical work. Single-molecule studies have improved our understanding about the energy-conversion mechanism of F1 and the chemomechanical-coupling scheme under ATP hydrolysis conditions. A novel single-molecule technique was recently established to estimate the free-energy change of F1 during catalysis at elementary-step resolution, advancing our understanding about the energy-conversion mechanism of ATP hydrolysis and synthesis. The energy conversion mechanism of F1 elucidated from single-molecule studies provides us with important insights into the operating principles underlying molecular motors.
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Affiliation(s)
- Rikiya Watanabe
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
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Stewart AG, Sobti M, Harvey RP, Stock D. Rotary ATPases: models, machine elements and technical specifications. BIOARCHITECTURE 2013; 3:2-12. [PMID: 23369889 PMCID: PMC3639240 DOI: 10.4161/bioa.23301] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Rotary ATPases are molecular rotary motors involved in biological energy conversion. They either synthesize or hydrolyze the universal biological energy carrier adenosine triphosphate. Recent work has elucidated the general architecture and subunit compositions of all three sub-types of rotary ATPases. Composite models of the intact F-, V- and A-type ATPases have been constructed by fitting high-resolution X-ray structures of individual subunits or sub-complexes into low-resolution electron densities of the intact enzymes derived from electron cryo-microscopy. Electron cryo-tomography has provided new insights into the supra-molecular arrangement of eukaryotic ATP synthases within mitochondria and mass-spectrometry has started to identify specifically bound lipids presumed to be essential for function. Taken together these molecular snapshots show that nano-scale rotary engines have much in common with basic design principles of man made machines from the function of individual “machine elements” to the requirement of the right “fuel” and “oil” for different types of motors.
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Affiliation(s)
- Alastair G Stewart
- The Victor Chang Cardiac Research Institute, Faculty of Medicine, The University of New South Wales, Sydney, NSW, Australia
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68
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Cumero S, Fogolari F, Domenis R, Zucchi R, Mavelli I, Contessi S. Mitochondrial F(0) F(1) -ATP synthase is a molecular target of 3-iodothyronamine, an endogenous metabolite of thyroid hormone. Br J Pharmacol 2012; 166:2331-47. [PMID: 22452346 DOI: 10.1111/j.1476-5381.2012.01958.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND AND PURPOSE 3-iodothyronamine (T1AM) is a metabolite of thyroid hormone acting as a signalling molecule via non-genomic effectors and can reach intracellular targets. Because of the importance of mitochondrial F(0) F(1) -ATP synthase as a drug target, here we evaluated interactions of T1AM with this enzyme. EXPERIMENTAL APPROACH Kinetic analyses were performed on F(0) F(1) -ATP synthase in sub-mitochondrial particles and soluble F(1) -ATPase. Activity assays and immunodetection of the inhibitor protein IF(1) were used and combined with molecular docking analyses. Effects of T1AM on H9c2 cardiomyocytes were measured by in situ respirometric analysis. KEY RESULTS T1AM was a non-competitive inhibitor of F(0) F(1) -ATP synthase whose binding was mutually exclusive with that of the inhibitors IF(1) and aurovertin B. Both kinetic and docking analyses were consistent with two different binding sites for T1AM. At low nanomolar concentrations, T1AM bound to a high-affinity region most likely located within the IF(1) binding site, causing IF(1) release. At higher concentrations, T1AM bound to a low affinity-region probably located within the aurovertin binding cavity and inhibited enzyme activity. Low nanomolar concentrations of T1AM increased ADP-stimulated mitochondrial respiration in cardiomyocytes, indicating activation of F(0) F(1) -ATP synthase consistent with displacement of endogenous IF(1,) , reinforcing the in vitro results. CONCLUSIONS AND IMPLICATIONS Effects of T1AM on F(0) F(1) -ATP synthase were twofold: IF(1) displacement and enzyme inhibition. By targeting F(0) F(1) -ATP synthase within mitochondria, T1AM might affect cell bioenergetics with a positive effect on mitochondrial energy production at low, endogenous, concentrations. T1AM putative binding locations overlapping with IF(1) and aurovertin binding sites are described.
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Affiliation(s)
- S Cumero
- Department of Medical and Biological Sciences, MATI Centre of Excellence, University of Udine, Udine, Italy
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Roles of AtpI and two YidC-type proteins from alkaliphilic Bacillus pseudofirmus OF4 in ATP synthase assembly and nonfermentative growth. J Bacteriol 2012; 195:220-30. [PMID: 23123906 DOI: 10.1128/jb.01493-12] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AtpI, a membrane protein encoded by many bacterial atp operons, is reported to be necessary for c-ring oligomer formation during assembly of some ATP synthase complexes. We investigated chaperone functions of AtpI and compared them to those of AtpZ, a protein encoded by a gene upstream of atpI that has a role in magnesium acquisition at near-neutral pH, and of SpoIIIJ and YqjG, two YidC/OxaI/Alb3 family proteins, in alkaliphilic Bacillus pseudofirmus OF4. A strain with a chromosomal deletion of atpI grew nonfermentatively, and its purified ATP synthase had a c-ring of normal size, indicating that AtpI is not absolutely required for ATP synthase function. However, deletion of atpI, but not atpZ, led to reduced stability of the ATP synthase rotor, reduced membrane association of the F(1) domain, reduced ATPase activity, and modestly reduced nonfermentative growth on malate at both pH 7.5 and 10.5. Both spoIIIJ and yqjG, but not atpI or atpZ, complemented a YidC-depleted Escherichia coli strain. Consistent with such overlapping functions, single deletions of spoIIIJ or yqjG in the alkaliphile did not affect membrane ATP synthase levels or activities, but functional specialization was indicated by YqjG and SpoIIIJ showing respectively greater roles in malate growth at pH 7.5 and 10.5. Expression of yqjG was elevated at pH 7.5 relative to that at pH 10.5 and in ΔspoIIIJ strains, but it was lower than constitutive spoIIIJ expression. Deletion of atpZ caused the largest increase among the mutants in magnesium concentrations needed for pH 7.5 growth. The basis for this phenotype is not yet resolved.
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Gol’dshtein BN, Aksirov AM, Zakrzhevskaya DT. Irregular activity oscillations of a rotary molecular motor: A simple kinetic model of F1-ATPase. Mol Biol 2012. [DOI: 10.1134/s0026893312040048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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71
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Vojtísková A, Jesina P, Kalous M, Kaplanová V, Houstek J, Tesarová M, Fornůsková D, Zeman J, Dubot A, Godinot C. Mitochondrial membrane potential and ATP production in primary disorders of ATP synthase. Toxicol Mech Methods 2012; 14:7-11. [PMID: 20021115 DOI: 10.1080/15376520490257347] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Studies of fibroblasts with primary defects in mitochondrial ATP synthase (ATPase) due to heteroplasmic mtDNA mutations in the ATP6 gene, affecting protonophoric function or synthesis of subunit a, show that at high mutation loads, mitochondrial membrane potential DeltaPsi(m) at state 4 is normal, but ADP-induced discharge of DeltaPsi(m) is impaired and ATP synthesis at state 3-ADP is decreased. Increased DeltaPsi(m) and low ATP synthesis is also found when the ATPase content is diminished by altered biogenesis of the enzyme complex. Irrespective of the different pathogenic mechanisms, elevated DeltaPsi(m) in primary ATPase disorders could increase mitochondrial production of reactive oxygen species and decrease energy provision.
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Affiliation(s)
- Alena Vojtísková
- Institute of Physiology and Centre for Integrated Genomics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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72
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Saroussi S, Schushan M, Ben-Tal N, Junge W, Nelson N. Structure and flexibility of the C-ring in the electromotor of rotary F(0)F(1)-ATPase of pea chloroplasts. PLoS One 2012; 7:e43045. [PMID: 23049735 PMCID: PMC3458034 DOI: 10.1371/journal.pone.0043045] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 07/16/2012] [Indexed: 01/19/2023] Open
Abstract
A ring of 8-15 identical c-subunits is essential for ion-translocation by the rotary electromotor of the ubiquitous F(O)F(1)-ATPase. Here we present the crystal structure at 3.4Å resolution of the c-ring from chloroplasts of a higher plant (Pisum sativum), determined using a native preparation. The crystal structure was found to resemble that of an (ancestral) cyanobacterium. Using elastic network modeling to investigate the ring's eigen-modes, we found five dominant modes of motion that fell into three classes. They revealed the following deformations of the ring: (I) ellipsoidal, (II) opposite twisting of the luminal circular surface of the ring against the stromal surface, and (III) kinking of the hairpin-shaped monomers in the middle, resulting in bending/stretching of the ring. Extension of the elastic network analysis to rings of different c(n)-symmetry revealed the same classes of dominant modes as in P. sativum (c(14)). We suggest the following functional roles for these classes: The first and third classes of modes affect the interaction of the c-ring with its counterparts in F(O), namely subunits a and bb'. These modes are likely to be involved in ion-translocation and torque generation. The second class of deformation, along with deformations of subunits γ and ε might serve to elastically buffer the torque transmission between F(O) and F(1).
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Affiliation(s)
- Shai Saroussi
- Department of Biochemistry and Molecular Biology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat Aviv, Israel
| | - Maya Schushan
- Department of Biochemistry and Molecular Biology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat Aviv, Israel
| | - Nir Ben-Tal
- Department of Biochemistry and Molecular Biology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat Aviv, Israel
| | - Wolfgang Junge
- Division of Biophysics, University of Osnabrück, Osnabrück, Germany
| | - Nathan Nelson
- Department of Biochemistry and Molecular Biology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat Aviv, Israel
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73
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Igamberdiev AU. Biomechanical and coherent phenomena in morphogenetic relaxation processes. Biosystems 2012; 109:336-45. [DOI: 10.1016/j.biosystems.2012.05.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Revised: 05/04/2012] [Accepted: 05/14/2012] [Indexed: 01/06/2023]
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74
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Bietenhader M, Martos A, Tetaud E, Aiyar RS, Sellem CH, Kucharczyk R, Clauder-Münster S, Giraud MF, Godard F, Salin B, Sagot I, Gagneur J, Déquard-Chablat M, Contamine V, Denmat SHL, Sainsard-Chanet A, Steinmetz LM, di Rago JP. Experimental relocation of the mitochondrial ATP9 gene to the nucleus reveals forces underlying mitochondrial genome evolution. PLoS Genet 2012; 8:e1002876. [PMID: 22916027 PMCID: PMC3420929 DOI: 10.1371/journal.pgen.1002876] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Accepted: 06/19/2012] [Indexed: 01/21/2023] Open
Abstract
Only a few genes remain in the mitochondrial genome retained by every eukaryotic organism that carry out essential functions and are implicated in severe diseases. Experimentally relocating these few genes to the nucleus therefore has both therapeutic and evolutionary implications. Numerous unproductive attempts have been made to do so, with a total of only 5 successes across all organisms. We have taken a novel approach to relocating mitochondrial genes that utilizes naturally nuclear versions from other organisms. We demonstrate this approach on subunit 9/c of ATP synthase, successfully relocating this gene for the first time in any organism by expressing the ATP9 genes from Podospora anserina in Saccharomyces cerevisiae. This study substantiates the role of protein structure in mitochondrial gene transfer: expression of chimeric constructs reveals that the P. anserina proteins can be correctly imported into mitochondria due to reduced hydrophobicity of the first transmembrane segment. Nuclear expression of ATP9, while permitting almost fully functional oxidative phosphorylation, perturbs many cellular properties, including cellular morphology, and activates the heat shock response. Altogether, our study establishes a novel strategy for allotopic expression of mitochondrial genes, demonstrates the complex adaptations required to relocate ATP9, and indicates a reason that this gene was only transferred to the nucleus during the evolution of multicellular organisms.
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Affiliation(s)
- Maïlis Bietenhader
- Université Bordeaux, IBGC, UMR5095 CNRS, Bordeaux, France
- CNRS, IBGC, UMR5095 CNRS, Bordeaux, France
| | - Alexandre Martos
- Université Bordeaux, IBGC, UMR5095 CNRS, Bordeaux, France
- CNRS, IBGC, UMR5095 CNRS, Bordeaux, France
| | - Emmanuel Tetaud
- Université Bordeaux, IBGC, UMR5095 CNRS, Bordeaux, France
- CNRS, IBGC, UMR5095 CNRS, Bordeaux, France
| | - Raeka S. Aiyar
- Genome Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Carole H. Sellem
- Université Paris-Sud, Centre de Génétique Moléculaire, UPR3404, CNRS, Gif-sur-Yvette, France
| | - Roza Kucharczyk
- Université Bordeaux, IBGC, UMR5095 CNRS, Bordeaux, France
- CNRS, IBGC, UMR5095 CNRS, Bordeaux, France
| | | | - Marie-France Giraud
- Université Bordeaux, IBGC, UMR5095 CNRS, Bordeaux, France
- CNRS, IBGC, UMR5095 CNRS, Bordeaux, France
| | - François Godard
- Université Bordeaux, IBGC, UMR5095 CNRS, Bordeaux, France
- CNRS, IBGC, UMR5095 CNRS, Bordeaux, France
| | - Bénédicte Salin
- Université Bordeaux, IBGC, UMR5095 CNRS, Bordeaux, France
- CNRS, IBGC, UMR5095 CNRS, Bordeaux, France
| | - Isabelle Sagot
- Université Bordeaux, IBGC, UMR5095 CNRS, Bordeaux, France
- CNRS, IBGC, UMR5095 CNRS, Bordeaux, France
| | - Julien Gagneur
- Genome Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Michelle Déquard-Chablat
- Université Paris-Sud, Institut de Génétique et Microbiologie, UMR 8621, Orsay, France
- CNRS, Orsay, France
| | - Véronique Contamine
- Université Paris-Sud, Institut de Génétique et Microbiologie, UMR 8621, Orsay, France
- CNRS, Orsay, France
| | - Sylvie Hermann-Le Denmat
- Université Paris-Sud, Institut de Génétique et Microbiologie, UMR 8621, Orsay, France
- CNRS, Orsay, France
- Ecole Normale Supérieure, Paris, France
| | - Annie Sainsard-Chanet
- Université Paris-Sud, Centre de Génétique Moléculaire, UPR3404, CNRS, Gif-sur-Yvette, France
| | - Lars M. Steinmetz
- Genome Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
- * E-mail: (J-PdR); (LMS)
| | - Jean-Paul di Rago
- Université Bordeaux, IBGC, UMR5095 CNRS, Bordeaux, France
- CNRS, IBGC, UMR5095 CNRS, Bordeaux, France
- * E-mail: (J-PdR); (LMS)
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75
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Covian R, Balaban RS. Cardiac mitochondrial matrix and respiratory complex protein phosphorylation. Am J Physiol Heart Circ Physiol 2012; 303:H940-66. [PMID: 22886415 DOI: 10.1152/ajpheart.00077.2012] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
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 (32)P 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 evaluation of this possibility will require the application of approaches developed for bacterial cell signaling to the mitochondria.
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Affiliation(s)
- Raul Covian
- Laboratory of Cardiac Energetics, National Heart Lung and Blood Institute, Bethesda, Maryland 20817, USA
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76
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Kellosalo J, Kajander T, Kogan K, Pokharel K, Goldman A. The structure and catalytic cycle of a sodium-pumping pyrophosphatase. Science 2012; 337:473-6. [PMID: 22837527 DOI: 10.1126/science.1222505] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Membrane-integral pyrophosphatases (M-PPases) are crucial for the survival of plants, bacteria, and protozoan parasites. They couple pyrophosphate hydrolysis or synthesis to Na(+) or H(+) pumping. The 2.6-angstrom structure of Thermotoga maritima M-PPase in the resting state reveals a previously unknown solution for ion pumping. The hydrolytic center, 20 angstroms above the membrane, is coupled to the gate formed by the conserved Asp(243), Glu(246), and Lys(707) by an unusual "coupling funnel" of six α helices. Comparison with our 4.0-angstrom resolution structure of the product complex suggests that helix 12 slides down upon substrate binding to open the gate by a simple binding-change mechanism. Below the gate, four helices form the exit channel. Superimposing helices 3 to 6, 9 to 12, and 13 to 16 suggests that M-PPases arose through gene triplication.
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Affiliation(s)
- Juho Kellosalo
- Structural Biology and Biophysics Program, Institute of Biotechnology, Post Office Box 65, University of Helsinki, FIN-00014, Finland
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77
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Sekiya M, Nakamoto RK, Nakanishi-Matsui M, Futai M. Binding of phytopolyphenol piceatannol disrupts β/γ subunit interactions and rate-limiting step of steady-state rotational catalysis in Escherichia coli F1-ATPase. J Biol Chem 2012; 287:22771-80. [PMID: 22582396 DOI: 10.1074/jbc.m112.374868] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In observations of single molecule behavior under V(max) conditions with minimal load, the F(1) sector of the ATP synthase (F-ATPase) rotates through continuous cycles of catalytic dwells (∼0.2 ms) and 120° rotation steps (∼0.6 ms). We previously established that the rate-limiting transition step occurs during the catalytic dwell at the initiation of the 120° rotation. Here, we use the phytopolyphenol, piceatannol, which binds to a pocket formed by contributions from α and β stator subunits and the carboxyl-terminal region of the rotor γ subunit. Piceatannol did not interfere with the movement through the 120° rotation step, but caused increased duration of the catalytic dwell. The duration time of the intrinsic inhibited state of F(1) also became significantly longer with piceatannol. All of the beads rotated at a lower rate in the presence of saturating piceatannol, indicating that the inhibitor stays bound throughout the rotational catalytic cycle. The Arrhenius plot of the temperature dependence of the reciprocal of the duration of the catalytic dwell (catalytic rate) indicated significantly increased activation energy of the rate-limiting step to trigger the 120° rotation. The activation energy was further increased by combination of piceatannol and substitution of γ subunit Met(23) with Lys, indicating that the inhibitor and the β/γ interface mutation affect the same transition step, even though they perturb physically separated rotor-stator interactions.
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Affiliation(s)
- Mizuki Sekiya
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, and Futai Special Laboratory, Iwate Medical University, Yahaba, Iwate 028-3694, Japan
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78
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Moldavski O, Levin-Kravets O, Ziv T, Adam Z, Prag G. The hetero-hexameric nature of a chloroplast AAA+ FtsH protease contributes to its thermodynamic stability. PLoS One 2012; 7:e36008. [PMID: 22558304 PMCID: PMC3339871 DOI: 10.1371/journal.pone.0036008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 03/29/2012] [Indexed: 12/27/2022] Open
Abstract
FtsH is an evolutionary conserved membrane-bound metalloprotease complex. While in most prokaryotes FtsH is encoded by a single gene, multiple FtsH genes are found in eukaryotes. Genetic and biochemical data suggest that the Arabidopsis chloroplast FtsH is a hetero-hexamer. This raises the question why photosynthetic organisms require a heteromeric complex, whereas in most bacteria a homomeric one is sufficient. To gain structural information of the possible complexes, the Arabidopsis FtsH2 (type B) and FtsH5 (type A) were modeled. An in silico study with mixed models of FtsH2/5 suggests that heteromeric hexamer structure with ratio of 4:2 is more likely to exists. Specifically, calculation of the buried surface area at the interfaces between neighboring subunits revealed that a hetero-complex should be thermodynamically more stable than a homo-hexamer, due to the presence of additional hydrophobic and hydrophilic interactions. To biochemically assess this model, we generated Arabidopsis transgenic plants, expressing epitope-tagged FtsH2 and immuno-purified the protein. Mass-spectrometry analysis showed that FtsH2 is associated with FtsH1, FtsH5 and FtsH8. Interestingly, we found that 'type B' subunits (FtsH2 and FtsH8) were 2-3 fold more abundant than 'type A' (FtsH1 and FtsH5). The biochemical data corroborate the in silico model and suggest that the thylakoid FtsH hexamer is composed of two 'type A' and four 'type B' subunits.
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Affiliation(s)
- Ofer Moldavski
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University of Jerusalem, Rehovot, Israel
| | - Olga Levin-Kravets
- Department of Biochemistry and Molecular Biology and the Institute for Structural Biology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Tamar Ziv
- Department of Biology, Smoler Proteomics Center, Technion, Haifa, Israel
| | - Zach Adam
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University of Jerusalem, Rehovot, Israel
| | - Gali Prag
- Department of Biochemistry and Molecular Biology and the Institute for Structural Biology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
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79
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Xu L, Liu F. The chemo-mechanical coupled model for F1F0-motor. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2012; 108:139-48. [DOI: 10.1016/j.pbiomolbio.2012.01.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Revised: 03/20/2011] [Accepted: 01/31/2012] [Indexed: 10/14/2022]
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80
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Rotational catalysis in proton pumping ATPases: from E. coli F-ATPase to mammalian V-ATPase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:1711-21. [PMID: 22459334 DOI: 10.1016/j.bbabio.2012.03.015] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2012] [Revised: 03/10/2012] [Accepted: 03/13/2012] [Indexed: 01/28/2023]
Abstract
We focus on the rotational catalysis of Escherichia coli F-ATPase (ATP synthase, F(O)F(1)). Using a probe with low viscous drag, we found stochastic fluctuation of the rotation rates, a flat energy pathway, and contribution of an inhibited state to the overall behavior of the enzyme. Mutational analyses revealed the importance of the interactions among β and γ subunits and the β subunit catalytic domain. We also discuss the V-ATPase, which has different physiological roles from the F-ATPase, but is structurally and mechanistically similar. We review the rotation, diversity of subunits, and the regulatory mechanism of reversible subunit dissociation/assembly of Saccharomyces cerevisiae and mammalian complexes. This article is part of a Special Issue entitled: 17th European Bioenergetics Conference (EBEC 2012).
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81
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Milgrom YM. Characteristics of protection by MgADP and MgATP of α3β3γ subcomplex of thermophilic Bacillus PS3 βY341W-mutant F1-ATPase from inhibition by 7-chloro-4-nitrobenz-2-oxa-1,3-diazole support a bi-site mechanism of catalysis. BIOCHEMISTRY (MOSCOW) 2012; 76:1253-61. [PMID: 22117552 DOI: 10.1134/s0006297911110071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
MgADP and MgATP binding to catalytic sites of βY341W-α(3)β(3)γ subcomplex of F(1)-ATPase from thermophilic Bacillus PS3 has been assessed using their effect on the enzyme inhibition by 7-chloro-4-nitrobenz-2-oxa-1,3-diazole (NBD-Cl). It was assumed that NBD-Cl can inhibit only when catalytic sites are empty, and inhibition is prevented if a catalytic site is occupied with a nucleotide. In the absence of an activator, MgADP and MgATP protect βY341W-α(3)β(3)γ subcomplex from inhibition by NBD-Cl by binding to two catalytic sites with an affinity of 37 µM and 12 mM, and 46 µM and 15 mM, respectively. In the presence of an activator lauryldimethylamine-N-oxide (LDAO), MgADP protects βY341W-α(3)β(3)γ subcomplex from inhibition by NBD-Cl by binding to a catalytic site with a K(d) of 12 mM. Nucleotide binding to a catalytic site with affinity in the millimolar range has not been previously revealed in the fluorescence quenching experiments with βY341W-α(3)β(3)γ subcomplex. In the presence of activators LDAO or selenite, MgATP protects βY341W-α(3)β(3)γ subcomplex from inhibition by NBD-Cl only partially, and the enzyme remains sensitive to inhibition by NBD-Cl even at MgATP concentrations that are saturating for ATPase activity. The results support a bi-site mechanism of catalysis by F(1)-ATPases.
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Affiliation(s)
- Y M Milgrom
- Department of Biochemistry and Molecular Biology, State University of New York, Upstate Medical University, Syracuse, New York 13210, USA.
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82
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Ma B, Qian D, Nan Q, Tan C, An L, Xiang Y. Arabidopsis vacuolar H+-ATPase (V-ATPase) B subunits are involved in actin cytoskeleton remodeling via binding to, bundling, and stabilizing F-actin. J Biol Chem 2012; 287:19008-17. [PMID: 22371505 DOI: 10.1074/jbc.m111.281873] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Vacuolar H(+)-ATPase (V-ATPase) is a membrane-bound multisubunit enzyme complex composed of at least 14 different subunits. The complex regulates the physiological processes of a cell by controlling the acidic environment, which is necessary for certain activities and the interaction with the actin cytoskeleton through its B and C subunits in both humans and yeast. Arabidopsis V-ATPase has three B subunits (AtVAB1, AtVAB2, and AtVAB3), which share 97.27% sequence identity and have two potential actin-binding sites, indicating that these AtVABs may have crucial functions in actin cytoskeleton remodeling and plant cell development. However, their biochemical functions are poorly understood. In this study, we demonstrated that AtVABs bind to and co-localize with F-actin, bundle F-actin to form higher order structures, and stabilize actin filaments in vitro. In addition, the AtVABs also show different degrees of activities in capping the barbed ends but no nucleating activities, and these activities were not regulated by calcium. The functional similarity and differences of the AtVABs implied that they may play cooperative and distinct roles in Arabidopsis cells.
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Affiliation(s)
- Binyun Ma
- School of life Sciences, Lanzhou University, Lanzhou 730070, China
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83
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Giraud MF, Paumard P, Sanchez C, Brèthes D, Velours J, Dautant A. Rotor architecture in the yeast and bovine F1-c-ring complexes of F-ATP synthase. J Struct Biol 2012; 177:490-7. [DOI: 10.1016/j.jsb.2011.10.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 10/07/2011] [Accepted: 10/27/2011] [Indexed: 11/16/2022]
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84
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Harsman A, Bartsch P, Hemmis B, Krüger V, Wagner R. Exploring protein import pores of cellular organelles at the single molecule level using the planar lipid bilayer technique. Eur J Cell Biol 2012; 90:721-30. [PMID: 21684628 DOI: 10.1016/j.ejcb.2011.04.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Proteins of living cells carry out their specialized functions within various subcellular membranes or aqueous spaces. Approximately half of all the proteins of a typical cell are transported into or across membranes. Targeting and transport to their correct subcellular destinations are essential steps in protein biosynthesis. In eukaryotic cells secretory proteins are transported into the endoplasmic reticulum before they are transported in vesicles to the plasma membrane. Virtually all proteins of the endosymbiotic organelles, chloroplasts and mitochondria, are synthesized on cytosolic ribosomes and posttranslationally imported. Genetic and biochemical techniques led to rather detailed knowledge on the subunit composition of the various protein transport complexes which carry out the membrane transport of the preproteins. Conclusive concepts on targeting and cytosolic transport of polypeptides emerged, while still few details on the molecular nature and mechanisms of the channel moieties of protein translocation complexes have been achieved. In this paper we will describe the history of how the individual subunits forming the channel pores of the chloroplast, mitochondrial and endoplasmic reticulum protein import machineries were identified and characterized by single channel electrophysiological techniques in planar bilayers. We will also highlight recent developments in the exploration of the molecular properties of protein translocating channels and the regulation of the diverse protein translocation systems using the planar bilayer technique.
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Affiliation(s)
- Anke Harsman
- University of Osnabrück, Faculty of Biology and Chemistry, Department of Biophysics, Barbarastr. 13, 49076 Osnabrück, Germany
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85
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Promiscuous archaeal ATP synthase concurrently coupled to Na+ and H+ translocation. Proc Natl Acad Sci U S A 2012; 109:947-52. [PMID: 22219361 DOI: 10.1073/pnas.1115796109] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
ATP synthases are the primary source of ATP in all living cells. To catalyze ATP synthesis, these membrane-associated complexes use a rotary mechanism powered by the transmembrane diffusion of ions down a concentration gradient. ATP synthases are assumed to be driven either by H(+) or Na(+), reflecting distinct structural motifs in their membrane domains, and distinct metabolisms of the host organisms. Here, we study the methanogenic archaeon Methanosarcina acetivorans using assays of ATP hydrolysis and ion transport in inverted membrane vesicles, and experimentally demonstrate that the rotary mechanism of its ATP synthase is coupled to the concurrent translocation of both H(+) and Na(+) across the membrane under physiological conditions. Using free-energy molecular simulations, we explain this unprecedented observation in terms of the ion selectivity of the binding sites in the membrane rotor, which appears to have been tuned via amino acid substitutions so that ATP synthesis in M. acetivorans can be driven by the H(+) and Na(+) gradients resulting from methanogenesis. We propose that this promiscuity is a molecular mechanism of adaptation to life at the thermodynamic limit.
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86
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Pan Y, Piyadasa H, O'Neil JD, Konermann L. Conformational dynamics of a membrane transport protein probed by H/D exchange and covalent labeling: the glycerol facilitator. J Mol Biol 2011; 416:400-13. [PMID: 22227391 DOI: 10.1016/j.jmb.2011.12.052] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Revised: 12/21/2011] [Accepted: 12/21/2011] [Indexed: 01/22/2023]
Abstract
Glycerol facilitator (GF) is a tetrameric membrane protein responsible for the selective permeation of glycerol and water. Each of the four GF subunits forms a transmembrane channel. Every subunit consists of six helices that completely span the lipid bilayer, as well as two half-helices (TM7 and TM3). X-ray crystallography has revealed that the selectivity of GF is due to its unique amphipathic channel interior. To explore the structural dynamics of GF, we employ hydrogen/deuterium exchange (HDX) and oxidative labeling with mass spectrometry (MS). HDX-MS reveals that transmembrane helices are generally more protected than extramembrane segments, consistent with data previously obtained for other membrane proteins. Interestingly, TM7 does not follow this trend. Instead, this half-helix undergoes rapid deuteration, indicative of a highly dynamic local structure. The oxidative labeling behavior of most GF residues is consistent with the static crystal structure. However, the side chains of C134 and M237 undergo labeling although they should be inaccessible according to the X-ray structure. In agreement with our HDX-MS data, this observation attests to the fact that TM7 is only marginally stable. We propose that the highly mobile nature of TM7 aids in the efficient diffusion of guest molecules through the channel ("molecular lubrication"). In the absence of such dynamics, host-guest molecular recognition would favor semipermanent binding of molecules inside the channel, thereby impeding transport. The current work highlights the complementary nature of HDX, covalent labeling, and X-ray crystallography for the characterization of membrane proteins.
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Affiliation(s)
- Yan Pan
- Department of Chemistry, The University of Western Ontario, London, ON, Canada N6A 5B7
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87
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Abstract
Integrins are integral membrane proteins that mediate cell-matrix and cell-cell adhesion. They are important for vascular development and hematopoiesis, immune and inflammatory responses, and hemostasis. Integrins are also signaling receptors that can transmit information bidirectionally across plasma membranes. Research in the past 2 decades has made progress in unraveling the mechanisms of integrin signaling and brings the field to the moment of attempting synthetic reconstruction of the signaling pathways in vitro. Reconstruction of biologic processes provides stringent tests of our understanding of the process, as evidenced by studies of other biologic machines, such as ATP synthase, lactose permease, and G-protein-coupled receptors. Here, we review recent progress in reconstructing integrin signaling and the insights that we have gained through these experiments.
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88
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Akella R, Min X, Wu Q, Gardner KH, Goldsmith EJ. The third conformation of p38α MAP kinase observed in phosphorylated p38α and in solution. Structure 2011; 18:1571-8. [PMID: 21134636 DOI: 10.1016/j.str.2010.09.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2010] [Revised: 09/01/2010] [Accepted: 09/22/2010] [Indexed: 01/22/2023]
Abstract
MAPKs engage substrates, MAP2Ks, and phosphatases via a docking groove in the C-terminal domain of the kinase. Prior crystallographic studies on the unphosphorylated MAPKs p38α and ERK2 defined the docking groove and revealed long-range conformational changes affecting the activation loop and active site of the kinase induced by peptide. Solution NMR data presented here for unphosphorylated p38α with a MEK3b-derived peptide (p38α/pepMEK3b) validate these findings. Crystallograhic data from doubly phosphorylated active p38α (p38α/T∗GY∗/pepMEK3b) reveal a structure similar to unphosphorylated p38α/MEK3b, and distinct from phosphorylated p38γ (p38γ/T∗GY∗) and ERK2 (ERK2/T∗EY∗). The structure supports the idea that MAP kinases adopt three distinct conformations: unphosphorylated, phosphorylated, and a docking peptide-induced form.
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Affiliation(s)
- Radha Akella
- Department of Biochemistry, The University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, TX 75390-8816, USA
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89
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Kutzner C, Czub J, Grubmüller H. Keep It Flexible: Driving Macromolecular Rotary Motions in Atomistic Simulations with GROMACS. J Chem Theory Comput 2011; 7:1381-1393. [PMID: 21566696 PMCID: PMC3091370 DOI: 10.1021/ct100666v] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Indexed: 11/28/2022]
Abstract
We describe a versatile method to enforce the rotation of subsets of atoms, e.g., a protein subunit, in molecular dynamics (MD) simulations. In particular, we introduce a "flexible axis" technique that allows realistic flexible adaptions of both the rotary subunit as well as the local rotation axis during the simulation. A variety of useful rotation potentials were implemented for the GROMACS 4.5 MD package. Application to the molecular motor F(1)-ATP synthase demonstrates the advantages of the flexible axis approach over the established fixed axis rotation technique.
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Affiliation(s)
- Carsten Kutzner
- Department of Theoretical and Computational Biophysics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
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90
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Godard F, Tetaud E, Duvezin-Caubet S, di Rago JP. A genetic screen targeted on the FO component of mitochondrial ATP synthase in Saccharomyces cerevisiae. J Biol Chem 2011; 286:18181-9. [PMID: 21454598 DOI: 10.1074/jbc.m110.214825] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In yeast, the two main F(O) proton-translocating subunits of the ATP synthase (subunits 6/a and 9/c) are encoded by mitochondrial DNA (mtDNA). Unfortunately, mutations that inactivate the F(O) typically result in loss of mtDNA under the form of ρ(-)/ρ(0) cells. Thus, we have designed a novel genetic strategy to circumvent this problem. It exploits previous findings that a null mutation in the nuclear ATP16 gene encoding ATP synthase subunit δ results in massive and lethal F(O)-mediated protons leaks across the inner mitochondrial membrane. Mutations that inactivate the F(O) can thus, in these conditions, be selected positively as cell viability rescuing events. A first set of seven mutants was analyzed and all showed, as expected, very severe F(O) deficiencies. Two mutants carried nuclear mutations in known genes (AEP1, AEP2) required for subunit c expression. The five other mutations were located in mtDNA. Of these, three affect synthesis or stability of subunit a transcripts and the two last consisted in a single amino acid replacement in subunit c. One of the subunit c mutations is particularly interesting. It consists in an alanine to valine change at position 60 of subunit c adjacent to the essential glutamate of subunit c (at position 59) that interacts with the essential arginine 186 of subunit a. The properties of this mutant suggest that the contact zone between subunit a and the ten subunits c-ring structure only involves critical transient interactions confined to the region where protons are exchanged between the subunit a and the c-ring.
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Affiliation(s)
- François Godard
- Institut de Biochimie et Génétique Cellulaires, UMR 5095 CNRS, Université Victor Segalen Bordeaux 2, 33077 Bordeaux, France
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91
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Rayalam S, Yang JY, Della-Fera MA, Baile CA. Novel molecular targets for prevention of obesity and osteoporosis. J Nutr Biochem 2011; 22:1099-104. [PMID: 21429725 DOI: 10.1016/j.jnutbio.2010.11.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Accepted: 11/23/2010] [Indexed: 10/18/2022]
Abstract
Evidence from both epidemiological studies and basic research suggests that obesity and osteoporosis are interrelated. Though there is an increase in the prevalence of these disorders, a limited number of treatments are available, one of the reasons being the complexity of the pathways involved and difficulty in identifying a single molecular target. Due to adverse effects of pharmaceuticals, intake of herbal drugs by patients without a physician's recommendation is increasing globally. Lack of success with targeted monotherapy has encouraged scientists to determine whether combinations of phytochemicals that interfere with numerous cell-signaling pathways can be a more effective approach to treat complex diseases. For example, evidence is emerging that specific combinations of phytochemicals are far more effective than single compounds in decreasing adipogenesis and promoting bone formation. Since multiple pathways are dysfunctional in obesity and osteoporosis, an ideal approach for preventing and treating these diseases may be to use a combination of phytochemicals to address several targets simultaneously.
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Affiliation(s)
- Srujana Rayalam
- Department of Animal and Dairy Science, University of Georgia, Athens, GA 30602, USA
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92
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Ma B, Xiang Y, An L. Structural bases of physiological functions and roles of the vacuolar H(+)-ATPase. Cell Signal 2011; 23:1244-56. [PMID: 21397012 DOI: 10.1016/j.cellsig.2011.03.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Accepted: 03/03/2011] [Indexed: 12/09/2022]
Abstract
Vacuolar-type H(+)-ATPases (V-ATPases) is a large multi-protein complex containing at least 14 different subunits, in which subunits A, B, C, D, E, F, G, and H compose the peripheral 500-kDa V(1) responsible for ATP hydrolysis, and subunits a, c, c', c″, and d assembly the 250-kDa membrane-integral V(0) harboring the rotary mechanism to transport protons across the membrane. The assembly of V-ATPases requires the presence of all V(1) and V(0) subunits, in which the V(1) must be completely assembled prior to association with the V(0), accordingly the V(0) failing to assemble cannot provide a membrane anchor for the V(1), thereby prohibiting membrane association of the V-ATPase subunits. The V-ATPase mediates acidification of intracellular compartments and regulates diverse critical physiological processes of cell for functions of its numerous functional subunits. The core catalytic mechanism of the V-ATPase is a rotational catalytic mechanism. The V-ATPase holoenzyme activity is regulated by the reversible assembly/disassembly of the V(1) and V(0), the targeting and recycling of V-ATPase-containing vesicles to and from the plasma membrane, the coupling ratio between ATP hydrolysis and proton pumping, ATP, Ca(2+), and its inhibitors and activators.
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Affiliation(s)
- Binyun Ma
- Key Laboratory of Arid and Grassland Agroecology of Ministry of Education, School of Life Sciences, Lanzhou University, 730000, Lanzhou, China
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93
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Effect of a mitochondria-targeted vitamin E derivative on mitochondrial alteration and systemic oxidative stress in mice. Br J Nutr 2011; 106:87-95. [PMID: 21324214 DOI: 10.1017/s0007114510005830] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The objective of the present study was to determine whether a mitochondria-targeted vitamin E derivative (MitoVit E) would affect certain mitochondrial parameters, as well as systemic oxidative stress. A total of sixty-four mice were fed a high-fat (HF) diet for 5 weeks. They were then switched to either a low-fat (LF) or a medium-fat (MF) diet, and administered orally with MitoVit E (40 mg MitoVit E/kg body weight) or drug vehicle (10 % (v/v) ethanol in 0·9 % (w/v) NaCl solution), every other day for 5 weeks. Mitochondrial ATP and H(2)O(2) production rates in both the liver and the gastrocnemius were not affected by MitoVit E administration in either LF or MF diet-fed mice. However, the number and average size of the subsarcolemmal mitochondria, but not the intermyofibrillar mitochondria, from the soleus muscle were significantly higher in the MF group receiving MitoVit E (MF-E) than in the MF group receiving vehicle only (MF-C). After the mice were switched from the HF diet to the four dietary treatments (LF-C, LF-E, MF-C and MF-E), the decrease in urinary isoprostane concentration was significantly greater in the LF-E group than in the other three groups during the whole study (weeks 6-10). In addition, MitoVit E significantly increased plasma superoxide dismutase (SOD) activity in the MF diet-fed group without affecting plasma glutathione peroxidase activity or H(2)O(2) levels. Overall, these data suggest that MitoVit E affects subsarcolemmal mitochondrial density and systemic oxidative stress parameters such as plasma SOD activity and urinary isoprostane concentration.
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94
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Alard JE, Hillion S, Guillevin L, Saraux A, Pers JO, Youinou P, Jamin C. Autoantibodies to endothelial cell surface ATP synthase, the endogenous receptor for hsp60, might play a pathogenic role in vasculatides. PLoS One 2011; 6:e14654. [PMID: 21326874 PMCID: PMC3034716 DOI: 10.1371/journal.pone.0014654] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Accepted: 01/13/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Heat shock protein (hsp) 60 that provides "danger signal" binds to the surface of resting endothelial cells (EC) but its receptor has not yet been characterized. In mitochondria, hsp60 specifically associates with adenosine triphosphate (ATP) synthase. We therefore examined the possible interaction between hsp60 and ATP synthase on EC surface. METHODOLOGY/PRINCIPAL FINDINGS Using Far Western blot approach, co-immunoprecipitation studies and surface plasmon resonance analyses, we demonstrated that hsp60 binds to the β-subunit of ATP synthase. As a cell surface-expressed molecule, ATP synthase is potentially targeted by anti-EC-antibodies (AECAs) found in the sera of patients suffering vasculitides. Based on enzyme-linked immunosorbent assay and Western blotting techniques with F1-ATP synthase as substrate, we established the presence of anti-ATP synthase antibodies at higher frequency in patients with primary vasculitides (group I) compared with secondary vasculitides (group II). Anti-ATP synthase reactivity from group I patients was restricted to the β-subunit of ATP synthase, whereas those from group II was directed to the α-, β- and γ-subunits. Cell surface ATP synthase regulates intracellular pH (pHi). In low extracellular pH medium, we detected abnormal decreased of EC pHi in the presence of anti-ATP synthase antibodies, irrespective of their fine reactivities. Interestingly, soluble hsp60 abrogated the anti-ATP synthase-induced pHi down-regulation. CONCLUSIONS/SIGNIFICANCE Our results indicate that ATP synthase is targeted by AECAs on the surface of EC that induce intracellular acidification. Such pathogenic effect in vasculitides can be modulated by hsp60 binding on ATP synthase which preserves ATP synthase activity.
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Affiliation(s)
- Jean-Eric Alard
- EA2216 “Immunology and Pathology” and IFR 148 ScInBioS, Université de Brest and Université Européenne de Bretagne, Brest, France
| | - Sophie Hillion
- EA2216 “Immunology and Pathology” and IFR 148 ScInBioS, Université de Brest and Université Européenne de Bretagne, Brest, France
| | - Loïc Guillevin
- Department of Internal Medicine, Hôpital Cochin, Paris, France
| | - Alain Saraux
- EA2216 “Immunology and Pathology” and IFR 148 ScInBioS, Université de Brest and Université Européenne de Bretagne, Brest, France
- Centre Hospitalier Universitaire, Brest, France
| | - Jacques-Olivier Pers
- EA2216 “Immunology and Pathology” and IFR 148 ScInBioS, Université de Brest and Université Européenne de Bretagne, Brest, France
- Centre Hospitalier Universitaire, Brest, France
| | - Pierre Youinou
- EA2216 “Immunology and Pathology” and IFR 148 ScInBioS, Université de Brest and Université Européenne de Bretagne, Brest, France
- Centre Hospitalier Universitaire, Brest, France
| | - Christophe Jamin
- EA2216 “Immunology and Pathology” and IFR 148 ScInBioS, Université de Brest and Université Européenne de Bretagne, Brest, France
- Centre Hospitalier Universitaire, Brest, France
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95
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Modular assembly of yeast mitochondrial ATP synthase. EMBO J 2011; 30:920-30. [PMID: 21266956 DOI: 10.1038/emboj.2010.364] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Accepted: 12/16/2010] [Indexed: 11/08/2022] Open
Abstract
The mitochondrial ATP synthase (F(1)-F(0) complex) of Saccharomces cerevisiae is a composite of different structural and functional units that jointly couple ATP synthesis and hydrolysis to proton transfer across the inner membrane. In organello, pulse labelling and pulse-chase experiments have enabled us to track the mitochondrially encoded Atp6p, Atp8p and Atp9p subunits of F(0) and to identify different assembly intermediates into which they are assimilated. Surprisingly, these core subunits of F(0) segregated into two different assembly intermediates one of which is composed of Atp6p, Atp8p, at least two stator subunits, and the Atp10p chaperone while the second consists of the F(1) ATPase and Atp9p ring. These studies show that assembly of the ATP synthase is not a single linear process, as previously thought, but rather involves two separate but coordinately regulated pathways that converge at the end stage.
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96
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On the relation between the Kautsky effect (chlorophyll a fluorescence induction) and Photosystem II: basics and applications of the OJIP fluorescence transient. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2011; 104:236-57. [PMID: 21295993 DOI: 10.1016/j.jphotobiol.2010.12.010] [Citation(s) in RCA: 482] [Impact Index Per Article: 37.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Revised: 12/20/2010] [Accepted: 12/22/2010] [Indexed: 11/23/2022]
Abstract
Chlorophyll a fluorescence is a highly sensitive, non-destructive, and reliable tool for measuring, rather quickly, photosynthetic efficiency, particularly of Photosystem II (PSII), the water-plastoquinone oxidoreductase. We briefly review here the connection between the fast (up to 2 s) chlorophyll fluorescence rise and PSII, as well as the empirical use of the fluorescence rise kinetics in understanding photosynthetic reactions, particularly of PSII. When dark-adapted photosynthetic samples are exposed to light, a fluorescence induction is observed, known as the Kautsky effect, after Hans Kautsky, the discoverer of the phenomenon showing the existence of variable fluorescence. The chlorophyll fluorescence intensity rises from a minimum level (the O level), in less than 1 s, to a maximum level (the P-level) via two intermediate steps labeled J and I. This is followed by a decline to a lower semi-steady state level, the S level, which is reached in about one minute. We provide here an educational review on how this phenomenon has been exploited through analysis of the fast OJIP fluorescence transient, by discussing basic assumptions, derivation of equations, as well as application to PSII-related questions.
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97
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Kramer DM, Evans JR. The importance of energy balance in improving photosynthetic productivity. PLANT PHYSIOLOGY 2011; 155:70-8. [PMID: 21078862 PMCID: PMC3075755 DOI: 10.1104/pp.110.166652] [Citation(s) in RCA: 319] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Accepted: 11/10/2010] [Indexed: 05/18/2023]
Affiliation(s)
- David M Kramer
- Biochemistry and Molecular Biology and Department of Energy, Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824, USA.
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98
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Vantourout P, Radojkovic C, Lichtenstein L, Pons V, Champagne E, Martinez LO. Ecto-F 1-ATPase: A moonlighting protein complex and an unexpected apoA-I receptor. World J Gastroenterol 2010; 16:5925-35. [PMID: 21157968 PMCID: PMC3007107 DOI: 10.3748/wjg.v16.i47.5925] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Mitochondrial ATP synthase has been recently detected at the surface of different cell types, where it is a high affinity receptor for apoA-I, the major protein component in high density lipoproteins (HDL). Cell surface ATP synthase (namely ecto-F1-ATPase) expression is related to different biological effects, such as regulation of HDL uptake by hepatocytes, endothelial cell proliferation or antitumor activity of Vγ9/Vδ2 T lymphocytes. This paper reviews the recently discovered functions and regulations of ecto-F1-ATPase. Particularly, the role of the F1-ATPase pathway(s) in HDL-cholesterol uptake and apoA-I-mediated endothelial protection suggests its potential importance in reverse cholesterol transport and its regulation might represent a potential therapeutic target for HDL-related therapy for cardiovascular diseases. Therefore, it is timely for us to better understand how this ecto-enzyme and downstream pathways are regulated and to develop pharmacologic interventions.
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99
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Abstract
Proton circuits across the inner mitochondrial membrane link the primary energy generators, namely the complexes of the electron transport chain, to multiple energy utilizing processes, including the ATP synthase, inherent proton leak pathways, metabolite transport and linked circuits of sodium and calcium. These mitochondrial circuits can be monitored in both isolated preparations and intact cells and, for the primary proton circuit techniques, exist to follow both the proton current and proton electrochemical potential components of the circuit in parallel experiments, providing a quantitative means of assessing mitochondrial function and, equally importantly, dysfunction.
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100
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Sekiya M, Hosokawa H, Nakanishi-Matsui M, Al-Shawi MK, Nakamoto RK, Futai M. Single molecule behavior of inhibited and active states of Escherichia coli ATP synthase F1 rotation. J Biol Chem 2010; 285:42058-67. [PMID: 20974856 DOI: 10.1074/jbc.m110.176701] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
ATP hydrolysis-dependent rotation of the F(1) sector of the ATP synthase is a successive cycle of catalytic dwells (∼0.2 ms at 24 °C) and 120° rotation steps (∼0.6 ms) when observed under V(max) conditions using a low viscous drag 60-nm bead attached to the γ subunit (Sekiya, M., Nakamoto, R. K., Al-Shawi, M. K., Nakanishi-Matsui, M., and Futai, M. (2009) J. Biol. Chem. 284, 22401-22410). During the normal course of observation, the γ subunit pauses in a stochastic manner to a catalytically inhibited state that averages ∼1 s in duration. The rotation behavior with adenosine 5'-O-(3-thiotriphosphate) as the substrate or at a low ATP concentration (4 μM) indicates that the rotation is inhibited at the catalytic dwell when the bound ATP undergoes reversible hydrolysis/synthesis. The temperature dependence of rotation shows that F(1) requires ∼2-fold higher activation energy for the transition from the active to the inhibited state compared with that for normal steady-state rotation during the active state. Addition of superstoichiometric ε subunit, the inhibitor of F(1)-ATPase, decreases the rotation rate and at the same time increases the duration time of the inhibited state. Arrhenius analysis shows that the ε subunit has little effect on the transition between active and inhibited states. Rather, the ε subunit confers lower activation energy of steady-state rotation. These results suggest that the ε subunit plays a role in guiding the enzyme through the proper and efficient catalytic and transport rotational pathway but does not influence the transition to the inhibited state.
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Affiliation(s)
- Mizuki Sekiya
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, and Futai Special Laboratory, Iwate Medical University, Yahaba, Iwate 028-3694, Japan
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