1
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Moore V, Vermaas W. Functional consequences of modification of the photosystem I/photosystem II ratio in the cyanobacterium Synechocystis sp. PCC 6803. J Bacteriol 2024; 206:e0045423. [PMID: 38695523 PMCID: PMC11112997 DOI: 10.1128/jb.00454-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Accepted: 03/16/2024] [Indexed: 05/24/2024] Open
Abstract
The stoichiometry of photosystem II (PSII) and photosystem I (PSI) varies between photoautotrophic organisms. The cyanobacterium Synechocystis sp. PCC 6803 maintains two- to fivefold more PSI than PSII reaction center complexes, and we sought to modify this stoichiometry by changing the promoter region of the psaAB operon. We thus generated mutants with varied psaAB expression, ranging from ~3% to almost 200% of the wild-type transcript level, but all showing a reduction in PSI levels, relative to wild type, suggesting a role of the psaAB promoter region in translational regulation. Mutants with 25%-70% of wild-type PSI levels were photoautotrophic, with whole-chain oxygen evolution rates on a per-cell basis comparable to that of wild type. In contrast, mutant strains with <10% of the wild-type level of PSI were obligate photoheterotrophs. Variable fluorescence yields of all mutants were much higher than those of wild type, indicating that the PSI content is localized differently than in wild type, with less transfer of PSII-absorbed energy to PSI. Strains with less PSI saturate at a higher light intensity, enhancing productivity at higher light intensities. This is similar to what is found in mutants with reduced antennae. With 3-(3,4-dichlorophenyl)-1,1-dimethylurea present, P700+ re-reduction kinetics in the mutants were slower than in wild type, consistent with the notion that there is less cyclic electron transport if less PSI is present. Overall, strains with a reduction in PSI content displayed surprisingly vigorous growth and linear electron transport. IMPORTANCE Consequences of reduction in photosystem I content were investigated in the cyanobacterium Synechocystis sp. PCC 6803 where photosystem I far exceeds the number of photosystem II complexes. Strains with less photosystem I displayed less cyclic electron transport, grew more slowly at lower light intensity and needed more light for saturation but were surprisingly normal in their whole-chain electron transport rates, implying that a significant fraction of photosystem I is dispensable for linear electron transport in cyanobacteria. These strains with reduced photosystem I levels may have biotechnological relevance as they grow well at higher light intensities.
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Affiliation(s)
- Vicki Moore
- School of Life Sciences and Center for Bioenergy and Photosynthesis, Arizona State University, Tempe, Arizona, USA
| | - Wim Vermaas
- School of Life Sciences and Center for Bioenergy and Photosynthesis, Arizona State University, Tempe, Arizona, USA
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2
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Turina P. Modulation of the H+/ATP coupling ratio by ADP and ATP as a possible regulatory feature in the F-type ATP synthases. Front Mol Biosci 2022; 9:1023031. [PMID: 36275634 PMCID: PMC9583940 DOI: 10.3389/fmolb.2022.1023031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 09/12/2022] [Indexed: 11/13/2022] Open
Abstract
F-type ATP synthases are transmembrane enzymes, which play a central role in the metabolism of all aerobic and photosynthetic cells and organisms, being the major source of their ATP synthesis. Catalysis occurs via a rotary mechanism, in which the free energy of a transmembrane electrochemical ion gradient is converted into the free energy of ATP phosphorylation from ADP and Pi, and vice versa. An ADP, tightly bound to one of the three catalytic sites on the stator head, is associated with catalysis inhibition, which is relieved by the transmembrane proton gradient and by ATP. By preventing wasteful ATP hydrolysis in times of low osmotic energy and low ATP/ADP ratio, such inhibition constitutes a classical regulatory feedback effect, likely to be an integral component of in vivo regulation. The present miniview focuses on an additional putative regulatory phenomenon, which has drawn so far little attention, consisting in a substrate-induced tuning of the H+/ATP coupling ratio during catalysis, which might represent an additional key to energy homeostasis in the cell. Experimental pieces of evidence in support of such a phenomenon are reviewed.
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3
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Li JL, Lin TY, Chen PL, Guo TN, Huang SY, Chen CH, Lin CH, Chan CC. Mitochondrial Function and Parkinson's Disease: From the Perspective of the Electron Transport Chain. Front Mol Neurosci 2021; 14:797833. [PMID: 34955747 PMCID: PMC8695848 DOI: 10.3389/fnmol.2021.797833] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 11/18/2021] [Indexed: 12/21/2022] Open
Abstract
Parkinson’s disease (PD) is known as a mitochondrial disease. Some even regarded it specifically as a disorder of the complex I of the electron transport chain (ETC). The ETC is fundamental for mitochondrial energy production which is essential for neuronal health. In the past two decades, more than 20 PD-associated genes have been identified. Some are directly involved in mitochondrial functions, such as PRKN, PINK1, and DJ-1. While other PD-associate genes, such as LRRK2, SNCA, and GBA1, regulate lysosomal functions, lipid metabolism, or protein aggregation, some have been shown to indirectly affect the electron transport chain. The recent identification of CHCHD2 and UQCRC1 that are critical for functions of complex IV and complex III, respectively, provide direct evidence that PD is more than just a complex I disorder. Like UQCRC1 in preventing cytochrome c from release, functions of ETC proteins beyond oxidative phosphorylation might also contribute to the pathogenesis of PD.
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Affiliation(s)
- Jeng-Lin Li
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan.,Division of Neurology, Department of Internal Medicine, Lo-Hsu Medical Foundation, Lotung Poh-Ai Hospital, Yilan County, Taiwan
| | - Tai-Yi Lin
- College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Po-Lin Chen
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Miaoli County, Taiwan
| | - Ting-Ni Guo
- Graduate Institute of Physiology, National Taiwan University, Taipei, Taiwan
| | - Shu-Yi Huang
- Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan
| | - Chun-Hong Chen
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Miaoli County, Taiwan
| | - Chin-Hsien Lin
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan.,Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan
| | - Chih-Chiang Chan
- Graduate Institute of Physiology, National Taiwan University, Taipei, Taiwan
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4
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Bai Y, Li X, Zhang D, Hou C, Zheng X, Chen L, Ren C. Effects of different ATP contents on phosphorylation level of glycogen phosphorylase and its activity in lamb during incubation at 4 ℃
in vitro. Int J Food Sci Technol 2020. [DOI: 10.1111/ijfs.14565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Yuqiang Bai
- Key Laboratory of Agro‐Products Processing Ministry of Agriculture and Rural Affairs Institute of Food Science and Technology Chinese Academy of Agricultural Sciences Beijing 100193 China
| | - Xin Li
- Key Laboratory of Agro‐Products Processing Ministry of Agriculture and Rural Affairs Institute of Food Science and Technology Chinese Academy of Agricultural Sciences Beijing 100193 China
| | - Dequan Zhang
- Key Laboratory of Agro‐Products Processing Ministry of Agriculture and Rural Affairs Institute of Food Science and Technology Chinese Academy of Agricultural Sciences Beijing 100193 China
| | - Chengli Hou
- Key Laboratory of Agro‐Products Processing Ministry of Agriculture and Rural Affairs Institute of Food Science and Technology Chinese Academy of Agricultural Sciences Beijing 100193 China
| | - Xiaochun Zheng
- Key Laboratory of Agro‐Products Processing Ministry of Agriculture and Rural Affairs Institute of Food Science and Technology Chinese Academy of Agricultural Sciences Beijing 100193 China
| | - Li Chen
- Key Laboratory of Agro‐Products Processing Ministry of Agriculture and Rural Affairs Institute of Food Science and Technology Chinese Academy of Agricultural Sciences Beijing 100193 China
| | - Chi Ren
- Key Laboratory of Agro‐Products Processing Ministry of Agriculture and Rural Affairs Institute of Food Science and Technology Chinese Academy of Agricultural Sciences Beijing 100193 China
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5
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Lambrecht N, Katsev S, Wittkop C, Hall SJ, Sheik CS, Picard A, Fakhraee M, Swanner ED. Biogeochemical and physical controls on methane fluxes from two ferruginous meromictic lakes. GEOBIOLOGY 2020; 18:54-69. [PMID: 31592570 DOI: 10.1111/gbi.12365] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 08/20/2019] [Accepted: 08/31/2019] [Indexed: 05/28/2023]
Abstract
Meromictic lakes with anoxic bottom waters often have active methane cycles whereby methane is generally produced biogenically under anoxic conditions and oxidized in oxic surface waters prior to reaching the atmosphere. Lakes that contain dissolved ferrous iron in their deep waters (i.e., ferruginous) are rare, but valuable, as geochemical analogues of the conditions that dominated the Earth's oceans during the Precambrian when interactions between the iron and methane cycles could have shaped the greenhouse regulation of the planet's climate. Here, we explored controls on the methane fluxes from Brownie Lake and Canyon Lake, two ferruginous meromictic lakes that contain similar concentrations (max. >1 mM) of dissolved methane in their bottom waters. The order Methanobacteriales was the dominant methanogen detected in both lakes. At Brownie Lake, methanogen abundance, an increase in methane concentration with respect to depths closer to the sediment, and isotopic data suggest methanogenesis is an active process in the anoxic water column. At Canyon Lake, methanogenesis occurred primarily in the sediment. The most abundant aerobic methane-oxidizing bacteria present in both water columns were associated with the Gammaproteobacteria, with little evidence of anaerobic methane oxidizing organisms being present or active. Direct measurements at the surface revealed a methane flux from Brownie Lake that was two orders of magnitude greater than the flux from Canyon Lake. Comparison of measured versus calculated turbulent diffusive fluxes indicates that most of the methane flux at Brownie Lake was non-diffusive. Although the turbulent diffusive methane flux at Canyon Lake was attenuated by methane oxidizing bacteria, dissolved methane was detected in the epilimnion, suggestive of lateral transport of methane from littoral sediments. These results highlight the importance of direct measurements in estimating the total methane flux from water columns, and that non-diffusive transport of methane may be important to consider from other ferruginous systems.
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Affiliation(s)
- Nicholas Lambrecht
- Department of Geological and Atmospheric Sciences, Iowa State University, Ames, IA, USA
| | - Sergei Katsev
- Department of Physics, University of Minnesota Duluth, Duluth, MN, USA
- Large Lakes Observatory, University of Minnesota Duluth, Duluth, MN, USA
| | - Chad Wittkop
- Department of Chemistry and Geology, Minnesota State University, Mankato, MN, USA
| | - Steven J Hall
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, USA
| | - Cody S Sheik
- Large Lakes Observatory, University of Minnesota Duluth, Duluth, MN, USA
- Department of Biology, University of Minnesota Duluth, Duluth, MN, USA
| | - Aude Picard
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, USA
| | - Mojtaba Fakhraee
- Large Lakes Observatory, University of Minnesota Duluth, Duluth, MN, USA
| | - Elizabeth D Swanner
- Department of Geological and Atmospheric Sciences, Iowa State University, Ames, IA, USA
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6
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Qiao J, Chen C, Shangguan D, Mu X, Wang S, Jiang L, Qi L. Simultaneous Monitoring of Mitochondrial Temperature and ATP Fluctuation Using Fluorescent Probes in Living Cells. Anal Chem 2018; 90:12553-12558. [PMID: 30295464 DOI: 10.1021/acs.analchem.8b02496] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Real-time monitoring of the distribution of energy released during oxidative phosphorylation (OXPHOS) in living cells would advance the understanding of metabolic pathways and cell biology. However, the relationship between intracellular temperature and ATP fluctuation during the OXPHOS process is rarely studied due to the limitation of the sensing approach. Novel fluorescent polymer probes were developed for accurate simultaneous measurements of intracellular temperature and ATP. Utilizing the fluorescence imaging techniques, it was demonstrated for the first time that the temperature in mitochondria increased 2.4 °C and the ATP fluctuation level simultaneously decreased 75% within 2 min during the OXPHOS process. Moreover, the resultant fluorescent polymer probes had good performance and properties for mitochondrial targeting, providing an effective way for investigating mechanisms by which energy is released during the OXPHOS process.
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Affiliation(s)
- Juan Qiao
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems , Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190 , P.R. China.,School of Chemical Sciences , University of Chinese Academy of Sciences , Beijing 100049 , P.R. China
| | - Chuanfang Chen
- Beijing Key Laboratory of Bioelectromagnetism , Institute of Electrical Engineering, Chinese Academy of Sciences , Beijing 100190 , P.R. China
| | - Dihua Shangguan
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems , Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190 , P.R. China.,School of Chemical Sciences , University of Chinese Academy of Sciences , Beijing 100049 , P.R. China
| | - Xiaoyu Mu
- College of Polymer Science & Engineering , Sichuan University , Sichuan 610065 , P.R. China
| | - Shutao Wang
- CAS Key Laboratory of Bio-inspired Materials and Interfacial Science , Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing 100190 , P.R. China.,School of Chemical Sciences , University of Chinese Academy of Sciences , Beijing 100049 , P.R. China
| | - Lei Jiang
- CAS Key Laboratory of Bio-inspired Materials and Interfacial Science , Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing 100190 , P.R. China.,School of Chemical Sciences , University of Chinese Academy of Sciences , Beijing 100049 , P.R. China
| | - Li Qi
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems , Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190 , P.R. China.,School of Chemical Sciences , University of Chinese Academy of Sciences , Beijing 100049 , P.R. China
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7
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pH determines the energetic efficiency of the cyanobacterial CO2 concentrating mechanism. Proc Natl Acad Sci U S A 2016; 113:E5354-62. [PMID: 27551079 DOI: 10.1073/pnas.1525145113] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Many carbon-fixing bacteria rely on a CO2 concentrating mechanism (CCM) to elevate the CO2 concentration around the carboxylating enzyme ribulose bisphosphate carboxylase/oxygenase (RuBisCO). The CCM is postulated to simultaneously enhance the rate of carboxylation and minimize oxygenation, a competitive reaction with O2 also catalyzed by RuBisCO. To achieve this effect, the CCM combines two features: active transport of inorganic carbon into the cell and colocalization of carbonic anhydrase and RuBisCO inside proteinaceous microcompartments called carboxysomes. Understanding the significance of the various CCM components requires reconciling biochemical intuition with a quantitative description of the system. To this end, we have developed a mathematical model of the CCM to analyze its energetic costs and the inherent intertwining of physiology and pH. We find that intracellular pH greatly affects the cost of inorganic carbon accumulation. At low pH the inorganic carbon pool contains more of the highly cell-permeable H2CO3, necessitating a substantial expenditure of energy on transport to maintain internal inorganic carbon levels. An intracellular pH ≈8 reduces leakage, making the CCM significantly more energetically efficient. This pH prediction coincides well with our measurement of intracellular pH in a model cyanobacterium. We also demonstrate that CO2 retention in the carboxysome is necessary, whereas selective uptake of HCO3 (-) into the carboxysome would not appreciably enhance energetic efficiency. Altogether, integration of pH produces a model that is quantitatively consistent with cyanobacterial physiology, emphasizing that pH cannot be neglected when describing biological systems interacting with inorganic carbon pools.
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8
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Turina P, Petersen J, Gräber P. Thermodynamics of proton transport coupled ATP synthesis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:653-64. [PMID: 26940516 DOI: 10.1016/j.bbabio.2016.02.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 01/16/2016] [Accepted: 02/28/2016] [Indexed: 10/22/2022]
Abstract
The thermodynamic H(+)/ATP ratio of the H(+)-ATP synthase from chloroplasts was measured in proteoliposomes after energization of the membrane by an acid base transition (Turina et al. 2003 [13], 418-422). The method is discussed, and all published data obtained with this system are combined and analyzed as a single dataset. This meta-analysis led to the following results. 1) At equilibrium, the transmembrane ΔpH is energetically equivalent to the transmembrane electric potential difference. 2) The standard free energy for ATP synthesis (reference reaction) is ΔG°(ref)=33.8±1.3kJ/mol. 3) The thermodynamic H(+)/ATP ratio, as obtained from the shift of the ATP synthesis equilibrium induced by changing the transmembrane ΔpH (varying either pH(in) or pH(out)) is 4.0±0.1. The structural H(+)/ATP ratio, calculated from the ratio of proton binding sites on the c-subunit-ring in F(0) to the catalytic nucleotide binding sites on the β-subunits in F(1), is c/β=14/3=4.7. We infer that the energy of 0.7 protons per ATP that flow through the enzyme, but do not contribute to shifting the ATP/(ADP·Pi) ratio, is used for additional processes within the enzyme, such as activation, and/or energy dissipation, due e.g. to internal uncoupling. The ratio between the thermodynamic and the structural H(+)/ATP values is 0.85, and we conclude that this value represents the efficiency of the chemiosmotic energy conversion within the chloroplast H(+)-ATP synthase.
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Affiliation(s)
- Paola Turina
- Department of Biology, BiGeA, University of Bologna, Via Irnerio 42, I-40126 Bologna, Italy
| | - Jan Petersen
- Biomedicine Discovery Institute, Monash University, 1 Wellington Rd., Clayton, Vic 3800, Australia
| | - Peter Gräber
- Institut für Physikalische Chemie, University of Freiburg, Albertstr, 23a, D-79104 Freiburg, Germany.
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9
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Photosynthetic, respiratory and extracellular electron transport pathways in cyanobacteria. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1857:247-55. [PMID: 26498190 DOI: 10.1016/j.bbabio.2015.10.007] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Revised: 10/09/2015] [Accepted: 10/14/2015] [Indexed: 01/05/2023]
Abstract
Cyanobacteria have evolved elaborate electron transport pathways to carry out photosynthesis and respiration, and to dissipate excess energy in order to limit cellular damage. Our understanding of the complexity of these systems and their role in allowing cyanobacteria to cope with varying environmental conditions is rapidly improving, but many questions remain. We summarize current knowledge of cyanobacterial electron transport pathways, including the possible roles of alternative pathways in photoprotection. We describe extracellular electron transport, which is as yet poorly understood. Biological photovoltaic devices, which measure electron output from cells, and which have been proposed as possible means of renewable energy generation, may be valuable tools in understanding cyanobacterial electron transfer pathways, and enhanced understanding of electron transfer may allow improvements in the efficiency of power output. This article is part of a Special Issue entitled Organization and dynamics of bioenergetic systems in bacteria, edited by Conrad Mullineaux.
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10
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Subramanian S, Barry AN, Pieris S, Sayre RT. Comparative energetics and kinetics of autotrophic lipid and starch metabolism in chlorophytic microalgae: implications for biomass and biofuel production. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:150. [PMID: 24139286 PMCID: PMC4015678 DOI: 10.1186/1754-6834-6-150] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 09/12/2013] [Indexed: 05/03/2023]
Abstract
Due to the growing need to provide alternatives to fossil fuels as efficiently, economically, and sustainably as possible there has been growing interest in improved biofuel production systems. Biofuels produced from microalgae are a particularly attractive option since microalgae have production potentials that exceed the best terrestrial crops by 2 to 10-fold. In addition, autotrophically grown microalgae can capture CO2 from point sources reducing direct atmospheric greenhouse gas emissions. The enhanced biomass production potential of algae is attributed in part to the fact that every cell is photosynthetic. Regardless, overall biological energy capture, conversion, and storage in microalgae are inefficient with less than 8% conversion of solar into chemical energy achieved. In this review, we examine the thermodynamic and kinetic constraints associated with the autotrophic conversion of inorganic carbon into storage carbohydrate and oil, the dominant energy storage products in Chlorophytic microalgae. We discuss how thermodynamic restrictions including the loss of fixed carbon during acetyl CoA synthesis reduce the efficiency of carbon accumulation in lipids. In addition, kinetic limitations, such as the coupling of proton to electron transfer during plastoquinone reduction and oxidation and the slow rates of CO2 fixation by Rubisco reduce photosynthetic efficiency. In some cases, these kinetic limitations have been overcome by massive increases in the numbers of effective catalytic sites, e.g. the high Rubisco levels (mM) in chloroplasts. But in other cases, including the slow rate of plastoquinol oxidation, there has been no compensatory increase in the abundance of catalytically limiting protein complexes. Significantly, we show that the energetic requirements for producing oil and starch relative to the recoverable energy stored in these molecules are very similar on a per carbon basis. Presently, the overall rates of starch and lipid synthesis in microalgae are very poorly characterized. Increased understanding of the kinetic constraints of lipid and starch synthesis, accumulation and turnover would facilitate the design of improved biomass production systems.
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Affiliation(s)
| | - Amanda N Barry
- Bioscience Division, Los Alamos National Lab, M888, Los Alamos, NM 87545, USA
| | - Shayani Pieris
- Natural Sciences Division, Missouri Baptist University, One College Park Drive, St. Louis, MO 63141, USA
| | - Richard T Sayre
- New Mexico Consortium, 100 Entrada Rd., Los Alamos, NM 87544, USA
- Bioscience Division, Los Alamos National Lab, M888, Los Alamos, NM 87545, USA
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11
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Solar-Powered Production of Biofuels and Other Petroleum Substitutes by Cyanobacteria: Stoichiometries of Reducing Equivalents and Chemical Energy, and Energy Conversion Efficiency. ACTA ACUST UNITED AC 2013. [DOI: 10.1007/978-3-642-32034-7_74] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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12
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Ferencz C, Petrovszki P, Kóta Z, Fodor-Ayaydin E, Haracska L, Bóta A, Varga Z, Dér A, Marsh D, Páli T. Estimating the rotation rate in the vacuolar proton-ATPase in native yeast vacuolar membranes. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2012; 42:147-58. [PMID: 23160754 DOI: 10.1007/s00249-012-0871-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Revised: 10/10/2012] [Accepted: 10/25/2012] [Indexed: 11/25/2022]
Abstract
The rate of rotation of the rotor in the yeast vacuolar proton-ATPase (V-ATPase), relative to the stator or steady parts of the enzyme, is estimated in native vacuolar membrane vesicles from Saccharomyces cerevisiae under standardised conditions. Membrane vesicles are formed spontaneously after exposing purified yeast vacuoles to osmotic shock. The fraction of total ATPase activity originating from the V-ATPase is determined by using the potent and specific inhibitor of the enzyme, concanamycin A. Inorganic phosphate liberated from ATP in the vacuolar membrane vesicle system, during ten min of ATPase activity at 20 °C, is assayed spectrophotometrically for different concanamycin A concentrations. A fit of the quadratic binding equation, assuming a single concanamycin A binding site on a monomeric V-ATPase (our data are incompatible with models assuming multiple binding sites), to the inhibitor titration curve determines the concentration of the enzyme. Combining this with the known ATP/rotation stoichiometry of the V-ATPase and the assayed concentration of inorganic phosphate liberated by the V-ATPase, leads to an average rate of ~10 Hz for full 360° rotation (and a range of 6-32 Hz, considering the ± standard deviation of the enzyme concentration), which, from the time-dependence of the activity, extrapolates to ~14 Hz (8-48 Hz) at the beginning of the reaction. These are lower-limit estimates. To our knowledge, this is the first report of the rotation rate in a V-ATPase that is not subjected to genetic or chemical modification and is not fixed to a solid support; instead it is functioning in its native membrane environment.
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Affiliation(s)
- Csilla Ferencz
- Institute of Biophysics, Biological Research Centre, Temesvári krt. 62, 6726, Szeged, Hungary
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13
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Tikhonov AN. Energetic and regulatory role of proton potential in chloroplasts. BIOCHEMISTRY (MOSCOW) 2012; 77:956-74. [DOI: 10.1134/s0006297912090027] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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14
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Comparison of the H+/ATP ratios of the H+-ATP synthases from yeast and from chloroplast. Proc Natl Acad Sci U S A 2012; 109:11150-5. [PMID: 22733773 DOI: 10.1073/pnas.1202799109] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
F(0)F(1)-ATP synthases use the free energy derived from a transmembrane proton transport to synthesize ATP from ADP and inorganic phosphate. The number of protons translocated per ATP (H(+)/ATP ratio) is an important parameter for the mechanism of the enzyme and for energy transduction in cells. Current models of rotational catalysis predict that the H(+)/ATP ratio is identical to the stoichiometric ratio of c-subunits to β-subunits. We measured in parallel the H(+)/ATP ratios at equilibrium of purified F(0)F(1)s from yeast mitochondria (c/β = 3.3) and from spinach chloroplasts (c/β = 4.7). The isolated enzymes were reconstituted into liposomes and, after energization of the proteoliposomes with acid-base transitions, the initial rates of ATP synthesis and hydrolysis were measured as a function of ΔpH. The equilibrium ΔpH was obtained by interpolation, and from its dependency on the stoichiometric ratio, [ATP]/([ADP]·[P(i)]), finally the thermodynamic H(+)/ATP ratios were obtained: 2.9 ± 0.2 for the mitochondrial enzyme and 3.9 ± 0.3 for the chloroplast enzyme. The data show that the thermodynamic H(+)/ATP ratio depends on the stoichiometry of the c-subunit, although it is not identical to the c/β ratio.
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15
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Agarwal B. A role for anions in ATP synthesis and its molecular mechanistic interpretation. J Bioenerg Biomembr 2011; 43:299-310. [PMID: 21647635 DOI: 10.1007/s10863-011-9358-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Accepted: 04/28/2011] [Indexed: 01/26/2023]
Abstract
ATP, the 'universal biological energy currency', is synthesized by utilizing energy either from oxidation of fuels or from light, via the process of oxidative and photo-phosphorylation respectively. The process is mediated by the enzyme F(1)F(0)-ATP synthase, using the free energy of ion gradients in the final energy catalyzing step, i.e., the synthesis of ATP from ADP and inorganic phosphate (P(i)). The details of the molecular mechanism of ATP synthesis are among the most important fundamental issues in biology and hence need to be properly understood. In this work, a role for anions in making ATP has been found. New experimental data has been reported on the inhibition of ATP synthesis at nanomolar concentrations by the potent, specific anion channel blockers 4,4'-diisothiocyanostilbene-2, 2'-disulphonic acid (DIDS) and tributyltin chloride (TBTCl). Based on these inhibition studies, attention has been drawn to anion translocation (in addition to proton translocation) as a requirement for ATP synthesis. The type of inhibition has been quantified and an overall kinetic scheme for mixed inhibition that explains the data has been evolved. The experimental data and the type of inhibition found have been interpreted in the light of the torsional mechanism of energy transduction and ATP synthesis (Nath J Bioenerg Biomembr 42:293-300, 2010a; J Bioenerg Biomembr 42:301-309, 2010b). This detailed and unified mechanism resolves long-standing problems and inconsistencies in the first theories (Slater Nature 172:975-978, 1953; Williams J Theor Biol 1:1-17, 1961; Mitchell Nature 191:144-148, 1961; Mitchell Biol Rev 41:445-502, 1966), makes several novel predictions that are experimentally verifiable (Nath Biophys J 90:8-21, 2006a; Process Biochem 41:2218-2235, 2006b), and provides us with a new and fruitful paradigm in bioenergetics. The interpretation presented here provides intelligent answers to the unexplained existing results in the literature. It is shown that mechanistic interpretation of the experimental data requires substantial addition to available conceptual foundations such that present concepts, theories, and mechanisms must be revised.
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Affiliation(s)
- Bhawana Agarwal
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi, 110 016, India.
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Amthor JS. From sunlight to phytomass: on the potential efficiency of converting solar radiation to phyto-energy. THE NEW PHYTOLOGIST 2010; 188:939-59. [PMID: 20977480 DOI: 10.1111/j.1469-8137.2010.03505.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The relationship between solar radiation capture and potential plant growth is of theoretical and practical importance. The key processes constraining the transduction of solar radiation into phyto-energy (i.e. free energy in phytomass) were reviewed to estimate potential solar-energy-use efficiency. Specifically, the out-put:input stoichiometries of photosynthesis and photorespiration in C(3) and C(4) systems, mobilization and translocation of photosynthate, and biosynthesis of major plant biochemical constituents were evaluated. The maintenance requirement, an area of important uncertainty, was also considered. For a hypothetical C(3) grain crop with a full canopy at 30°C and 350 ppm atmospheric [CO(2) ], theoretically potential efficiencies (based on extant plant metabolic reactions and pathways) were estimated at c. 0.041 J J(-1) incident total solar radiation, and c. 0.092 J J(-1) absorbed photosynthetically active radiation (PAR). At 20°C, the calculated potential efficiencies increased to 0.053 and 0.118 J J(-1) (incident total radiation and absorbed PAR, respectively). Estimates for a hypothetical C(4) cereal were c. 0.051 and c. 0.114 J J(-1), respectively. These values, which cannot be considered as precise, are less than some previous estimates, and the reasons for the differences are considered. Field-based data indicate that exceptional crops may attain a significant fraction of potential efficiency.
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Affiliation(s)
- Jeffrey S Amthor
- Faculty of Agriculture, Food and Natural Resources (C81), University of Sydney, NSW 2006, Australia.
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18
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Häsle KM, Fritsch O, Groth G, Junge W. ATP synthase: Driven and activated by protonmotive force. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/bbpc.19961001217] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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19
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Junge W, Sabber D, Engelbrecht S. ATP-synthesis. Rotatory catalysis by F-ATPase: Real-time recording of intersubunit rotation. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/bbpc.19961001215] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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20
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Saita EI, Iino R, Suzuki T, Feniouk BA, Kinosita K, Yoshida M. Activation and stiffness of the inhibited states of F1-ATPase probed by single-molecule manipulation. J Biol Chem 2010; 285:11411-7. [PMID: 20154086 DOI: 10.1074/jbc.m109.099143] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
F(1)-ATPase (F(1)), a soluble portion of F(o)F(1)-ATP synthase (F(o)F(1)), is an ATP-driven motor in which gammaepsilon subunits rotate in the alpha(3)beta(3) cylinder. Activity of F(1) and F(o)F(1) from Bacillus PS3 is attenuated by the epsilon subunit in an inhibitory extended form. In this study we observed ATP-dependent transition of epsilon in single F(1) molecules from extended form to hairpin form by fluorescence resonance energy transfer. The results justify the previous bulk experiments and ensure that fraction of F(1) with hairpin epsilon directly determines the fraction of active F(1) at any ATP concentration. Next, mechanical activation and stiffness of epsilon-inhibited F(1) were examined by the forced rotation of magnetic beads attached to gamma. Compared with ADP inhibition, which is another manner of inhibition, rotation by a larger angle was required for the activation from epsilon inhibition when the beads were forced to rotate to ATP hydrolysis direction, and more torque was required to reach the same rotation angle when beads were forced to rotate to ATP synthesis direction. The results imply that if F(o)F(1) is resting in the epsilon-inhibited state, F(o) motor must transmit to gamma a torque larger than expected from thermodynamic equilibrium to initiate ATP synthesis.
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Affiliation(s)
- Ei-ichiro Saita
- ICORP ATP Synthesis Regulation Project, Japan Science and Technology Corporation, Aomi 2-3-6, Tokyo 135-0064, Japan
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21
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Complete ion-coordination structure in the rotor ring of Na+-dependent F-ATP synthases. J Mol Biol 2009; 391:498-507. [PMID: 19500592 DOI: 10.1016/j.jmb.2009.05.082] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Revised: 05/28/2009] [Accepted: 05/29/2009] [Indexed: 11/23/2022]
Abstract
The membrane-embedded rotors of Na(+)-dependent F-ATP synthases comprise 11 c-subunits that form a ring, with 11 Na(+) binding sites in between adjacent subunits. Following an updated crystallographic analysis of the c-ring from Ilyobacter tartaricus, we report the complete ion-coordination structure of the Na(+) sites. In addition to the four residues previously identified, there exists a fifth ligand, namely, a buried structural water molecule. This water is itself coordinated by Thr67, which, sequence analysis reveals, is the only residue involved in binding that distinguishes Na(+) synthases from H(+)-ATP synthases known to date. Molecular dynamics simulations and free-energy calculations of the c-ring in a lipid membrane lend clear support to the notion that this fifth ligand is a water molecule, and illustrate its influence on the selectivity of the binding sites. Given the evolutionary ascendancy of sodium over proton bioenergetics, this structure uncovers an ancient strategy for selective ion coupling in ATP synthases.
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22
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Tomashek JJ, Brusilow WS. Stoichiometry of energy coupling by proton-translocating ATPases: a history of variability. J Bioenerg Biomembr 2009; 32:493-500. [PMID: 15254384 DOI: 10.1023/a:1005617024904] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
One of the central energy-coupling reactions in living systems is the intraconversion of ATP with a transmembrane proton gradient, carried out by proton-translocating F- and V-type ATPases/synthases. These reversible enzymes can hydrolyze ATP and pump protons, or can use the energy of a transmembrane proton gradient to synthesize ATP from ADP and inorganic phosphate. The stoichiometry of these processes (H(+)/ATP, or coupling ratio) has been studied in many systems for many years, with no universally agreed upon solution. Recent discoveries concerning the structure of the ATPases, their assembly and the stoichiometry of their numerous subunits, particularly the proton-carrying proteolipid (subunit c) of the F(O) and V(0) sectors, have shed new light on this question and raise the possibility of variable coupling ratios modulated by variable proteolipid stoichiometries.
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Affiliation(s)
- J J Tomashek
- Wayne State University School of Medicine, Department of Biochemistry and Molecular Biology, Detroit, Michigan 48201, USA
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Proton Translocation and ATP Synthesis by the FoF1-ATPase of Purple Bacteria. THE PURPLE PHOTOTROPHIC BACTERIA 2009. [DOI: 10.1007/978-1-4020-8815-5_24] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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24
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Caldwell SL, Laidler JR, Brewer EA, Eberly JO, Sandborgh SC, Colwell FS. Anaerobic oxidation of methane: mechanisms, bioenergetics, and the ecology of associated microorganisms. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2008; 42:6791-6799. [PMID: 18853791 DOI: 10.1021/es800120b] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Microbially mediated anaerobic oxidation of methane (AOM) moderates the input of methane, an important greenhouse gas, to the atmosphere by consuming methane produced in various marine, terrestrial, and subsurface environments. AOM coupled to sulfate reduction has been most extensively studied because of the abundance of sulfate in marine systems, but electron acceptors otherthan sulfate are more energetically favorable. Phylogenetic trees based on 16S rRNA gene clone libraries derived from microbial communities where AOM occurs show evidence of diverse, methanotrophic archaea (ANME) closely associated with sulfate-reducing bacteria, but these organisms have not yet been isolated as pure cultures. Several biochemical pathways for AOM have been proposed, including reverse methanogenesis, acetogenesis, and methylogenesis, and both culture-dependent and independent techniques have provided some clues to howthese communities function. Still, questions remain regarding the diversity, physiology, and metabolic restrictions of AOM-related organisms.
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Affiliation(s)
- Sara L Caldwell
- Department of Biology, Portland State University, Portland, Oregon 97201, USA
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25
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Buettner FFR, Bendallah IM, Bosse JT, Dreckmann K, Nash JHE, Langford PR, Gerlach GF. Analysis of the Actinobacillus pleuropneumoniae ArcA regulon identifies fumarate reductase as a determinant of virulence. Infect Immun 2008; 76:2284-95. [PMID: 18378638 PMCID: PMC2423083 DOI: 10.1128/iai.01540-07] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2007] [Revised: 01/10/2008] [Accepted: 03/23/2008] [Indexed: 11/20/2022] Open
Abstract
The ability of the bacterial pathogen Actinobacillus pleuropneumoniae to grow anaerobically allows the bacterium to persist in the lung. The ArcAB two-component system is crucial for metabolic adaptation in response to anaerobic conditions, and we recently showed that an A. pleuropneumoniae arcA mutant had reduced virulence compared to the wild type (F. F. Buettner, A. Maas, and G.-F. Gerlach, Vet. Microbiol. 127:106-115, 2008). In order to understand the attenuated phenotype, we investigated the ArcA regulon of A. pleuropneumoniae by using a combination of transcriptome (microarray) and proteome (two-dimensional difference gel electrophoresis and subsequent mass spectrometry) analyses. We show that ArcA negatively regulates the expression of many genes, including those encoding enzymes which consume intermediates during fumarate synthesis. Simultaneously, the expression of glycerol-3-phosphate dehydrogenase, a component of the respiratory chain serving as a direct reduction equivalent for fumarate reductase, was upregulated. This result, together with the in silico analysis finding that A. pleuropneumoniae has no oxidative branch of the citric acid cycle, led to the hypothesis that fumarate reductase might be crucial for virulence by providing (i) energy via fumarate respiration and (ii) succinate and other essential metabolic intermediates via the reductive branch of the citric acid cycle. To test this hypothesis, an isogenic A. pleuropneumoniae fumarate reductase deletion mutant was constructed and studied by using a pig aerosol infection model. The mutant was shown to be significantly attenuated, thereby strongly supporting a crucial role for fumarate reductase in the pathogenesis of A. pleuropneumoniae infection.
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Affiliation(s)
- Falk F R Buettner
- Department of Infectious Diseases, Institute for Microbiology, University of Veterinary Medicine Hannover, Hannover, Germany
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26
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The thermodynamic H+/ATP ratios of the H+-ATPsynthases from chloroplasts and Escherichia coli. Proc Natl Acad Sci U S A 2008; 105:3745-50. [PMID: 18316723 DOI: 10.1073/pnas.0708356105] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The H(+)/ATP ratio is an important parameter for the energy balance of all cells and for the coupling mechanism between proton transport and ATP synthesis. A straightforward interpretation of rotational catalysis predicts that the H(+)/ATP coincides with the ratio of the c-subunits to beta-subunits, implying that, for the chloroplast and Escherichia coli ATPsynthases, numbers of 4.7 and 3.3 are expected. Here, the energetics described by the chemiosmotic theory was used to determine the H(+)/ATP ratio for the two enzymes. The isolated complexes were reconstituted into liposomes, and parallel measurements were performed under identical conditions. The internal phase of the liposomes was equilibrated with the acidic medium during reconstitution, allowing to measure the internal pH with a glass electrode. An acid-base transition was carried out and the initial rates of ATP synthesis or ATP hydrolysis were measured with luciferin/luciferase as a function of DeltapH at constant Q = [ATP]/([ADP][P(i)]). From the shift of the equilibrium DeltapH as a function of Q the standard Gibbs free energy for phosphorylation, DeltaG(p)(0)'; and the H(+)/ATP ratio were determined. It resulted DeltaG(p)(0)' = 38 +/- 3 kJ.mol(-1) and H(+)/ATP = 4.0 +/- 0.2 for the chloroplast and H(+)/ATP = 4.0 +/- 0.3 for the E. coli enzyme, indicating that the thermodynamic H(+)/ATP ratio is the same for both enzymes and that it is different from the subunit stoichiometric ratio.
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27
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Tikhonov AN, Agafonov RV, Grigor'ev IA, Kirilyuk IA, Ptushenko VV, Trubitsin BV. Spin-probes designed for measuring the intrathylakoid pH in chloroplasts. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:285-94. [PMID: 18226594 DOI: 10.1016/j.bbabio.2007.12.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Revised: 12/11/2007] [Accepted: 12/26/2007] [Indexed: 10/22/2022]
Abstract
Nitroxide radicals are widely used as molecular probes in different fields of chemistry and biology. In this work, we describe pH-sensitive imidazoline- and imidazolidine-based nitroxides with pK values in the range 4.7-7.6 (2,2,3,4,5,5-hexamethylperhydroimidazol-1-oxyl, 4-amino-2,2,5,5-tetramethyl-2,5-dihydro-1H-imidazol-1-oxyl, 4-dimethylamino-2,2-diethyl-5,5-dimethyl-2,5-dihydro-1H-imidazol-1-oxyl, and 2,2-diethyl-5,5-dimethyl-4-pyrrolidyline-1-yl-2,5-dihydro-1H-imidazol-1-oxyl), which allow the pH-monitoring inside chloroplasts. We have demonstrated that EPR spectra of these spin-probes localized in the thylakoid lumen markedly change with the light-induced acidification of the thylakoid lumen in chloroplasts. Comparing EPR spectrum parameters of intrathylakoid spin-probes with relevant calibrating curves, we could estimate steady-state values of lumen pHin established during illumination of chloroplasts with continuous light. For isolated bean (Vicia faba) chloroplasts suspended in a medium with pHout=7.8, we found that pHin approximately 5.4-5.7 in the state of photosynthetic control, and pHin approximately 5.7-6.0 under photophosphorylation conditions. Thus, ATP synthesis occurs at a moderate acidification of the thylakoid lumen, corresponding to transthylakoid pH difference DeltapH approximately 1.8-2.1. These values of DeltapH are consistent with a point of view that under steady-state conditions the proton gradient DeltapH is the main contributor to the proton motive force driving the operation of ATP synthesis, provided that stoichiometric ratio H+/ATP is n> or =4-4.7.
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Affiliation(s)
- Alexander N Tikhonov
- Department of Biophysics, Faculty of Physics, M.V. Lomonosov Moscow State University, Moscow, 119992, Russia.
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Hattori S. Syntrophic Acetate-Oxidizing Microbes in Methanogenic Environments. Microbes Environ 2008; 23:118-27. [DOI: 10.1264/jsme2.23.118] [Citation(s) in RCA: 326] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Satoshi Hattori
- Department of Bioresource Engineering, Faculty of Agriculture, Yamagata University
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Dodecamer rotor ring defines H+/ATP ratio for ATP synthesis of prokaryotic V-ATPase from Thermus thermophilus. Proc Natl Acad Sci U S A 2007; 104:20256-61. [PMID: 18077374 DOI: 10.1073/pnas.0706914105] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
ATP synthesis by V-ATPase from the thermophilic bacterium Thermus thermophilus driven by the acid-base transition was investigated. The rate of ATP synthesis increased in parallel with the increase in proton motive force (PMF) >110 mV, which is composed of a difference in proton concentration (DeltapH) and the electrical potential differences (DeltaPsi) across membranes. The optimum rate of synthesis reached 85 s(-1), and the H(+)/ATP ratio of 4.0 +/- 0.1 was obtained. ATP was synthesized at a considerable rate solely by DeltapH, indicating DeltaPsi was not absolutely required for synthesis. Consistent with the H(+)/ATP ratio, cryoelectron micrograph images of 2D crystals of the membrane-bound rotor ring of the V-ATPase at 7.0-A resolution showed the presence of 12 V(o)-c subunits, each composed of two transmembrane helices. These results indicate that symmetry mismatch between the rotor and catalytic domains is not obligatory for rotary ATPases/synthases.
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30
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Gubellini F, Francia F, Turina P, Lévy D, Venturoli G, Melandri BA. Heterogeneity of photosynthetic membranes from Rhodobacter capsulatus: size dispersion and ATP synthase distribution. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2007; 1767:1340-52. [PMID: 17961501 DOI: 10.1016/j.bbabio.2007.08.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2007] [Revised: 08/26/2007] [Accepted: 08/29/2007] [Indexed: 10/22/2022]
Abstract
The density distribution of photosynthetic membrane vesicles (chromatophores) from Rhodobacter capsulatus has been studied by isopicnic centrifugation. The average vesicle diameters, examined by electron microscopy, varied between 61 and 72 nm in different density fractions (70 nm in unfractionated chromatophores). The ATP synthase catalytic activities showed maxima displaced toward the higher density fractions relative to bacteriochlorophyll, resulting in higher specific activities in those fractions (about threefold). The amount of ATP synthase, measured by quantitative Western blotting, paralleled the catalytic activities. The average number of ATP synthases per chromatophore, evaluated on the basis of the Western blotting data and of vesicle density analysis, ranged between 8 and 13 (10 in unfractionated chromatophores). Poisson distribution analysis indicated that the probability of chromatophores devoid of ATP synthase was negligible. The effects of ATP synthase inhibition by efrapeptin on the time course of the transmembrane electric potential (evaluated as carotenoid electrochromic response) and on ATP synthesis were studied comparatively. The ATP produced after a flash and the total charge associated with the proton flow coupled to ATP synthesis were more resistant to efrapeptin than the initial value of the phosphorylating currents, indicating that several ATP synthases are fed by protons from the same vesicle.
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Affiliation(s)
- Francesca Gubellini
- Department of Biology, University of Bologna, Laboratory of Biochemistry and Biophysics, Via Irnerio, 42 I-40126, Bologna, Italy
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Pogoryelov D, Reichen C, Klyszejko AL, Brunisholz R, Muller DJ, Dimroth P, Meier T. The oligomeric state of c rings from cyanobacterial F-ATP synthases varies from 13 to 15. J Bacteriol 2007; 189:5895-902. [PMID: 17545285 PMCID: PMC1952053 DOI: 10.1128/jb.00581-07] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We isolated the c rings of F-ATP synthases from eight cyanobacterial strains belonging to four different taxonomic classes (Chroococcales, Nostocales, Oscillatoriales, and Gloeobacteria). These c rings showed different mobilities on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), probably reflecting their molecular masses. This supposition was validated with the previously characterized c(11), c(14), and c(15) rings, which migrated on SDS-PAGE in proportion to their molecular masses. Hence, the masses of the cyanobacterial c rings can conveniently be deduced from their electrophoretic mobilities and, together with the masses of the c monomers, allow the calculation of the c ring stoichiometries. The method is a simple and fast way to determine stoichiometries of SDS-stable c rings and hence a convenient means to unambiguously determine the ion-to-ATP ratio, a parameter reflecting the bioenergetic efficacy of F-ATP synthases. AFM imaging was used to prove the accuracy of the method and confirmed that the c ring of Synechococcus elongatus SAG 89.79 is a tridecameric oligomer. Despite the high conservation of the c-subunit sequences from cyanobacterial strains from various environmental groups, the stoichiometries of their c rings varied between c(13) and c(15). This systematic study of the c-ring stoichiometries suggests that variability of c-ring sizes might represent an adaptation of the individual cyanobacterial species to their particular environmental and physiological conditions. Furthermore, the two new examples of c(15) rings underline once more that an F(1)/F(o) symmetry mismatch is not an obligatory feature of all F-ATP synthases.
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Affiliation(s)
- Denys Pogoryelov
- Max-Planck-Institute of Biophysics, Max-von-Laue-Strasse 3, 60438 Frankfurt am Main, Germany
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Adams CJ, Redmond MC, Valentine DL. Pure-culture growth of fermentative bacteria, facilitated by H2 removal: bioenergetics and H2 production. Appl Environ Microbiol 2006; 72:1079-85. [PMID: 16461652 PMCID: PMC1392933 DOI: 10.1128/aem.72.2.1079-1085.2006] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We used an H2-purging culture vessel to replace an H2-consuming syntrophic partner, allowing the growth of pure cultures of Syntrophothermus lipocalidus on butyrate and Aminobacterium colombiense on alanine. By decoupling the syntrophic association, it was possible to manipulate and monitor the single organism's growth environment and determine the change in Gibbs free energy yield (DeltaG) in response to changes in the concentrations of reactants and products, the purging rate, and the temperature. In each of these situations, H2 production changed such that DeltaG remained nearly constant for each organism (-11.1 +/- 1.4 kJ mol butyrate(-1) for S. lipocalidus and -58.2 +/- 1.0 kJ mol alanine(-1) for A. colombiense). The cellular maintenance energy, determined from the DeltaG value and the hydrogen production rate at the point where the cell number was constant, was 4.6 x 10(-13) kJ cell(-1) day(-1) for S. lipocalidus at 55 degrees C and 6.2 x 10(-13) kJ cell(-1) day(-1) for A. colombiense at 37 degrees C. S. lipocalidus, in particular, seems adapted to thrive under conditions of low energy availability.
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Affiliation(s)
- Cameron J Adams
- Marine Biology Research Division, Scripps Institution of Oceanography, and Department of Chemistry and Biochemistry, University of California, San Diego, USA
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Meyer Zu Tittingdorf JMW, Rexroth S, Schäfer E, Schlichting R, Giersch C, Dencher NA, Seelert H. The stoichiometry of the chloroplast ATP synthase oligomer III in Chlamydomonas reinhardtii is not affected by the metabolic state. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2004; 1659:92-9. [PMID: 15511531 DOI: 10.1016/j.bbabio.2004.08.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2004] [Revised: 08/13/2004] [Accepted: 08/18/2004] [Indexed: 10/26/2022]
Abstract
The chloroplast H(+)-ATP synthase is a key component for the energy supply of higher plants and green algae. An oligomer of identical protein subunits III is responsible for the conversion of an electrochemical proton gradient into rotational motion. It is highly controversial if the oligomer III stoichiometry is affected by the metabolic state of any organism. Here, the intact oligomer III of the ATP synthase from Chlamydomonas reinhardtii has been isolated for the first time. Due to the importance of the subunit III stoichiometry for energy conversion, a gradient gel system was established to distinguish oligomers with different stoichiometries. With this methodology, a possible alterability of the stoichiometry in respect to the metabolic state of the cells was examined. Several growth parameters, i.e., light intensity, pH value, carbon source, and CO(2) concentration, were varied to determine their effects on the stoichiometry. Contrary to previous suggestions for E. coli, the oligomer III of the chloroplast H(+)-ATP synthase always consists of a constant number of monomers over a wide range of metabolic states. Furthermore, mass spectrometry indicates that subunit III from C. reinhardtii is not modified posttranslationally. Data suggest a subunit III stoichiometry of the algae ATP synthase divergent from higher plants.
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Affiliation(s)
- Jürgen M W Meyer Zu Tittingdorf
- Department of Chemistry, Physical Biochemistry, Darmstadt University of Technology, Petersenstrasse 22, D-64287 Darmstadt, Germany
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Feniouk BA, Kozlova MA, Knorre DA, Cherepanov DA, Mulkidjanian AY, Junge W. The proton-driven rotor of ATP synthase: ohmic conductance (10 fS), and absence of voltage gating. Biophys J 2004; 86:4094-109. [PMID: 15189903 PMCID: PMC1304308 DOI: 10.1529/biophysj.103.036962] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2003] [Accepted: 02/11/2004] [Indexed: 11/18/2022] Open
Abstract
The membrane portion of F(0)F(1)-ATP synthase, F(0), translocates protons by a rotary mechanism. Proton conduction by F(0) was studied in chromatophores of the photosynthetic bacterium Rhodobacter capsulatus. The discharge of a light-induced voltage jump was monitored by electrochromic absorption transients to yield the unitary conductance of F(0). The current-voltage relationship of F(0) was linear from 7 to 70 mV. The current was extremely proton-specific (>10(7)) and varied only slightly ( approximately threefold) from pH 6 to 10. The maximum conductance was approximately 10 fS at pH 8, equivalent to 6240 H(+) s(-1) at 100-mV driving force, which is an order-of-magnitude greater than of coupled F(0)F(1). There was no voltage-gating of F(0) even at low voltage, and proton translocation could be driven by deltapH alone, without voltage. The reported voltage gating in F(0)F(1) is thus attributable to the interaction of F(0) with F(1) but not to F(0) proper. We simulated proton conduction by a minimal rotary model including the rotating c-ring and two relay groups mediating proton exchange between the ring and the respective membrane surface. The data fit attributed pK values of approximately 6 and approximately 10 to these relays, and placed them close to the membrane/electrolyte interface.
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Affiliation(s)
- Boris A Feniouk
- Division of Biophysics, Faculty of Biology/Chemistry, University of Osnabruck, Osnabruck, Germany
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de Bok FAM, Plugge CM, Stams AJM. Interspecies electron transfer in methanogenic propionate degrading consortia. WATER RESEARCH 2004; 38:1368-75. [PMID: 15016514 DOI: 10.1016/j.watres.2003.11.028] [Citation(s) in RCA: 145] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 11/21/2003] [Indexed: 05/11/2023]
Abstract
Propionate is a key intermediate in the conversion of complex organic matter under methanogenic conditions. Oxidation of this compound requires obligate syntrophic consortia of acetogenic proton- and bicarbonate reducing bacteria and methanogenic archaea. Although H(2) acts as an electron-carrier in these consortia, evidence accumulates that formate plays an even more important role. To make energy yield from propionate oxidation energetically feasible for the bacteria and archaea involved, the concentrations of H(2) and formate have to be extremely low. On the other hand, the diffusion distance of these carriers has to be small to allow high propionate conversion rates. Accordingly, the high conversion rates observed in methanogenic bioreactors are due to the fact that the propionate-oxidizing bacteria and their methanogenic partners form micro-colonies within the densely packed granules.
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Affiliation(s)
- F A M de Bok
- Laboratory of Microbiology, Wageningen University, Hesselink van Suchtelenweg 4, Wageningen 6703 CT, The Netherlands.
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36
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Cherepanov DA, Feniouk BA, Junge W, Mulkidjanian AY. Low dielectric permittivity of water at the membrane interface: effect on the energy coupling mechanism in biological membranes. Biophys J 2003; 85:1307-16. [PMID: 12885673 PMCID: PMC1303247 DOI: 10.1016/s0006-3495(03)74565-2] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Protonmotive force (the transmembrane difference in electrochemical potential of protons, ) drives ATP synthesis in bacteria, mitochondria, and chloroplasts. It has remained unsettled whether the entropic (chemical) component of relates to the difference in the proton activity between two bulk water phases (deltapH(B)) or between two membrane surfaces (deltapH(S)). To scrutinize whether deltapH(S) can deviate from deltapH(B), we modeled the behavior of protons at the membrane/water interface. We made use of the surprisingly low dielectric permittivity of interfacial water as determined by O. Teschke, G. Ceotto, and E. F. de Souza (O. Teschke, G. Ceotto, and E. F. de Sousa, 2001, PHYS: Rev. E. 64:011605). Electrostatic calculations revealed a potential barrier in the water phase some 0.5-1 nm away from the membrane surface. The barrier was higher for monovalent anions moving toward the surface (0.2-0.3 eV) than for monovalent cations (0.1-0.15 eV). By solving the Smoluchowski equation for protons spreading away from proton "pumps" at the surface, we found that the barrier could cause an elevation of the proton concentration at the interface. Taking typical values for the density of proton pumps and for their turnover rate, we calculated that a potential barrier of 0.12 eV yielded a steady-state pH(S) of approximately 6.0; the value of pH(S) was independent of pH in the bulk water phase under neutral and alkaline conditions. These results provide a rationale to solve the long-lasting problem of the seemingly insufficient protonmotive force in mesophilic and alkaliphilic bacteria.
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Affiliation(s)
- Dmitry A Cherepanov
- Division of Biophysics, Faculty of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
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37
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Murata T, Arechaga I, Fearnley IM, Kakinuma Y, Yamato I, Walker JE. The membrane domain of the Na+-motive V-ATPase from Enterococcus hirae contains a heptameric rotor. J Biol Chem 2003; 278:21162-7. [PMID: 12651848 DOI: 10.1074/jbc.m301620200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
In F-ATPases, ATP hydrolysis is coupled to translocation of ions through membranes by rotation of a ring of c subunits in the membrane. The ring is attached to a central shaft that penetrates the catalytic domain, which has pseudo-3-fold symmetry. The ion translocation pathway lies between the external circumference of the ring and another hydrophobic protein. The H+ or Na+:ATP ratio depends upon the number of ring protomers, each of which has an essential carboxylate involved directly in ion translocation. This number and the ratio differ according to the source, and 10, 11, and 14 protomers have been found in various enzymes, with corresponding calculated H+ or Na+:ATP ratios of 3.3, 3.7, and 4.7. V-ATPases are related in structure and function to F-ATPases. Oligomers of subunit K from the Na+-motive V-ATPase of Enterococcus hirae also form membrane rings but, as reported here, with 7-fold symmetry. Each protomer has one essential carboxylate. Thus, hydrolysis of one ATP provides energy to extrude 2.3 sodium ions. Symmetry mismatch between the catalytic and membrane domains appears to be an intrinsic feature of both V- and F-ATPases.
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Affiliation(s)
- Takeshi Murata
- Medical Research Council Dunn Human Nutrition Unit, Hills Road, Cambridge CB2 2XY, United Kingdom
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38
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Stahlberg H, Engel A, Philippsen A. Assessing the structure of membrane proteins: combining different methods gives the full picture. Biochem Cell Biol 2003; 80:563-8. [PMID: 12440697 DOI: 10.1139/o02-160] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The rotor stoichiometry of F-ATPases has been revealed by the combined approaches of X-ray diffraction (XRD), electron crystallography, and atomic force microscopy (AFM). XRD showed the rotor from the yeast mitochondrial F-ATPase to contain 10 subunits. AFM was used to visualize the tetradecameric chloroplast rotors, and electron crystallography and AFM together revealed the rotors from Ilyobacter tartaricus to be composed of 11 subunits. While biochemical methods had determined an approximate stoichiometric value, precise measurements and new insights into a species-dependent rotor stoichiometry became available by applying the three structural tools together. The structures of AQP1, a water channel, and G1pF, a glycerol channel, were determined by electron crystallography and XRD. The combination of both of these structural tools with molecular dynamics simulations gave a differentiated description of the mechanisms determining the selectivity of water and glycerol channels. This illustrates that the combination of different methods in structural biology reveals more than each method alone.
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39
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Turina P, Samoray D, Gräber P. H+/ATP ratio of proton transport-coupled ATP synthesis and hydrolysis catalysed by CF0F1-liposomes. EMBO J 2003; 22:418-26. [PMID: 12554643 PMCID: PMC140756 DOI: 10.1093/emboj/cdg073] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The H(+)/ATP ratio and the standard Gibbs free energy of ATP synthesis were determined with a new method using a chemiosmotic model system. The purified H(+)-translocating ATP synthase from chloroplasts was reconstituted into phosphatidylcholine/phosphatidic acid liposomes. During reconstitution, the internal phase was equilibrated with the reconstitution medium, and thereby the pH of the internal liposomal phase, pH(in), could be measured with a conventional glass electrode. The rates of ATP synthesis and hydrolysis were measured with the luciferin/luciferase assay after an acid-base transition at different [ATP]/([ADP][P(i)]) ratios as a function of deltapH, analysing the range from the ATP synthesis to the ATP hydrolysis direction and the deltapH at equilibrium, deltapH (eq) (zero net rate), was determined. The analysis of the [ATP]/([ADP][P(i)]) ratio as a function of deltapH (eq) and of the transmembrane electrochemical potential difference, delta micro approximately (H)(+) (eq), resulted in H(+)/ATP ratios of 3.9 +/- 0.2 at pH 8.45 and 4.0 +/- 0.3 at pH 8.05. The standard Gibbs free energies of ATP synthesis were determined to be 37 +/- 2 kJ/mol at pH 8.45 and 36 +/- 3 kJ/mol at pH 8.05.
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Affiliation(s)
| | - Dietrich Samoray
- Laboratory of Biochemistry and Biophysics, Department of Biology, University of Bologna, Via Irnerio 42, I-40126 Bologna, Italy and
Institut für Physikalische Chemie, Universität Freiburg, Albertstraße 23a, D-79104 Freiburg, Germany Corresponding author e-mail:
| | - Peter Gräber
- Laboratory of Biochemistry and Biophysics, Department of Biology, University of Bologna, Via Irnerio 42, I-40126 Bologna, Italy and
Institut für Physikalische Chemie, Universität Freiburg, Albertstraße 23a, D-79104 Freiburg, Germany Corresponding author e-mail:
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40
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Junge W, Pänke O, Cherepanov DA, Gumbiowski K, Müller M, Engelbrecht S. Inter-subunit rotation and elastic power transmission in F0F1-ATPase. FEBS Lett 2001; 504:152-60. [PMID: 11532447 DOI: 10.1016/s0014-5793(01)02745-4] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
ATP synthase (F-ATPase) produces ATP at the expense of ion-motive force or vice versa. It is composed from two motor/generators, the ATPase (F1) and the ion translocator (F0), which both are rotary steppers. They are mechanically coupled by 360 degrees rotary motion of subunits against each other. The rotor, subunits gamma(epsilon)C10-14, moves against the stator, (alphabeta)3delta(ab2). The enzyme copes with symmetry mismatch (C3 versus C10-14) between its two motors, and it operates robustly in chimeric constructs or with drastically modified subunits. We scrutinized whether an elastic power transmission accounts for these properties. We used the curvature of fluorescent actin filaments, attached to the rotating c ring, as a spring balance (flexural rigidity of 8.10(-26) N x m2) to gauge the angular profile of the output torque at F0 during ATP hydrolysis by F1. The large average output torque (56 pN nm) proved the absence of any slip. Angular variations of the torque were small, so that the output free energy of the loaded enzyme decayed almost linearly over the angular reaction coordinate. Considering the three-fold stepping and high activation barrier (>40 kJ/mol) of the driving motor (F1) itself, the rather constant output torque seen by F0 implied a soft elastic power transmission between F1 and F0. It is considered as essential, not only for the robust operation of this ubiquitous enzyme under symmetry mismatch, but also for a high turnover rate under load of the two counteracting and stepping motors/generators.
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Affiliation(s)
- W Junge
- Division of Biophysics, University of Osnabrück, D-49069, Osnabrück, Germany.
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41
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Schultz BE, Chan SI. Structures and proton-pumping strategies of mitochondrial respiratory enzymes. ANNUAL REVIEW OF BIOPHYSICS AND BIOMOLECULAR STRUCTURE 2001; 30:23-65. [PMID: 11340051 DOI: 10.1146/annurev.biophys.30.1.23] [Citation(s) in RCA: 192] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Enzymes of the mitochondrial respiratory chain serve as proton pumps, using the energy made available from electron transfer reactions to transport protons across the inner mitochondrial membrane and create an electrochemical gradient used for the production of ATP. The ATP synthase enzyme is reversible and can also serve as a proton pump by coupling ATP hydrolysis to proton translocation. Each of the respiratory enzymes uses a different strategy for performing proton pumping. In this work, the strategies are described and the structural bases for the action of these proteins are discussed in light of recent crystal structures of several respiratory enzymes. The mechanisms and efficiency of proton translocation are also analyzed in terms of the thermodynamics of the substrate transformations catalyzed by these enzymes.
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Affiliation(s)
- B E Schultz
- Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125, USA
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42
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Abstract
In recent years, structural information on the F(1) sector of the ATP synthase has provided an insight into the molecular mechanism of ATP catalysis. The structure strongly supports the proposal that the ATP synthase works as a rotary molecular motor. Insights into the membrane domain have just started to emerge but more detailed structural information is needed if the molecular mechanism of proton translocation coupled to ATP synthesis is to be understood. This review will focus mainly on the ion translocating rotor in the membrane domain of the F-type ATPase, and the related vacuolar and archaeal relatives.
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Affiliation(s)
- I Arechaga
- The Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, CB2 2XY, Cambridge, UK.
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43
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Stahlberg H, Müller DJ, Suda K, Fotiadis D, Engel A, Meier T, Matthey U, Dimroth P. Bacterial Na(+)-ATP synthase has an undecameric rotor. EMBO Rep 2001; 2:229-33. [PMID: 11266365 PMCID: PMC1083843 DOI: 10.1093/embo-reports/kve047] [Citation(s) in RCA: 158] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2000] [Revised: 01/11/2001] [Accepted: 01/15/2001] [Indexed: 11/12/2022] Open
Abstract
Synthesis of adenosine triphosphate (ATP) by the F(1)F(0) ATP synthase involves a membrane-embedded rotary engine, the F(0) domain, which drives the extra-membranous catalytic F(1) domain. The F(0) domain consists of subunits a(1)b(2) and a cylindrical rotor assembled from 9-14 alpha-helical hairpin-shaped c-subunits. According to structural analyses, rotors contain 10 c-subunits in yeast and 14 in chloroplast ATP synthases. We determined the rotor stoichiometry of Ilyobacter tartaricus ATP synthase by atomic force microscopy and cryo-electron microscopy, and show the cylindrical sodium-driven rotor to comprise 11 c-subunits.
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Affiliation(s)
- H Stahlberg
- M.E. Müller Institute for Structural Biology, Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland
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Tsunoda SP, Aggeler R, Yoshida M, Capaldi RA. Rotation of the c subunit oligomer in fully functional F1Fo ATP synthase. Proc Natl Acad Sci U S A 2001; 98:898-902. [PMID: 11158567 PMCID: PMC14681 DOI: 10.1073/pnas.98.3.898] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The F(1)F(o)-type ATP synthase is the smallest motor enzyme known. Previous studies had established that the central gamma and epsilon subunits of the F(1) part rotate relative to a stator of alpha(3)beta(3) and delta subunits during catalysis. We now show that the ring of c subunits in the F(o) part moves along with the gamma and epsilon subunits. This was demonstrated by linking the three rotor subunits with disulfide bridges between cysteine residues introduced genetically at the interfaces between the gamma, epsilon, and c subunits. Essentially complete cross-linking of the gamma, epsilon, and c subunits was achieved by using CuCl(2) to induce oxidation. This fixing of the three subunits together had no significant effect on ATP hydrolysis, proton translocation, or ATP synthesis, and each of these functions retained inhibitor sensitivity. These results unequivocally place the c subunit oligomer in the rotor part of this molecular machine.
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Affiliation(s)
- S P Tsunoda
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403-1229, USA
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45
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Rotation of the c subunit oligomer in fully functional F1Fo ATP synthase. Proc Natl Acad Sci U S A 2001. [PMID: 11158567 PMCID: PMC14681 DOI: 10.1073/pnas.031564198] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The F(1)F(o)-type ATP synthase is the smallest motor enzyme known. Previous studies had established that the central gamma and epsilon subunits of the F(1) part rotate relative to a stator of alpha(3)beta(3) and delta subunits during catalysis. We now show that the ring of c subunits in the F(o) part moves along with the gamma and epsilon subunits. This was demonstrated by linking the three rotor subunits with disulfide bridges between cysteine residues introduced genetically at the interfaces between the gamma, epsilon, and c subunits. Essentially complete cross-linking of the gamma, epsilon, and c subunits was achieved by using CuCl(2) to induce oxidation. This fixing of the three subunits together had no significant effect on ATP hydrolysis, proton translocation, or ATP synthesis, and each of these functions retained inhibitor sensitivity. These results unequivocally place the c subunit oligomer in the rotor part of this molecular machine.
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46
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Metzler DE, Metzler CM, Sauke DJ. Electron Transport, Oxidative Phosphorylation, and Hydroxylation. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50021-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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47
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Sacksteder CA, Kanazawa A, Jacoby ME, Kramer DM. The proton to electron stoichiometry of steady-state photosynthesis in living plants: A proton-pumping Q cycle is continuously engaged. Proc Natl Acad Sci U S A 2000; 97:14283-8. [PMID: 11121034 PMCID: PMC18910 DOI: 10.1073/pnas.97.26.14283] [Citation(s) in RCA: 133] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2000] [Accepted: 10/23/2000] [Indexed: 11/18/2022] Open
Abstract
A noninvasive technique is introduced with which relative proton to electron stoichiometries (H(+)/e(-) ratios) for photosynthetic electron transfer can be obtained from leaves of living plants under steady-state illumination. Both electron and proton transfer fluxes were estimated by a modification of our previously reported dark-interval relaxation kinetics (DIRK) analysis, in which processes that occur upon rapid shuttering of the actinic light are analyzed. Rates of turnover of linear electron transfer through the cytochrome (cyt) b(6)f complex were estimated by measuring the DIRK signals associated with reduction of cyt f and P(700). The rates of proton pumping through the electron transfer chain and the CF(O)-CF(1) ATP synthase (ATPase) were estimated by measuring the DIRK signals associated with the electrochromic shifting of pigments in the light-harvesting complexes. Electron transfer fluxes were also estimated by analysis of saturation pulse-induced changes in chlorophyll a fluorescence yield. It was shown that the H(+)/e(-) ratio, with respect to both cyt b(6)f complex and photosystem (PS) II turnover, was constant under low to saturating illumination in intact tobacco leaves. Because a H(+)/e(-) ratio of 3 at a low light is generally accepted, we infer that this ratio is maintained under conditions of normal (unstressed) photosynthesis, implying a continuously engaged, proton-pumping Q cycle at the cyt b(6)f complex.
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Affiliation(s)
- C A Sacksteder
- Institute of Biological Chemistry, Washington State University, 289 Clark Hall, Pullman, WA 99164-6340, USA
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48
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Abstract
The F(0)F(1) ATP synthase functions as a rotary motor where subunit rotation driven by a current of protons flowing through F(0) drives the binding changes in F(1) that are required for net ATP synthesis. Recent work that has led to the identification of components of the rotor and stator is reviewed. In addition, a model is proposed to describe the transmission of energy from four proton transport steps to the synthesis of one ATP. Finally, some of the requirements for efficient energy coupling by a rotary binding change mechanism are considered.
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Affiliation(s)
- R L Cross
- Department of Biochemistry and Molecular Biology, State University of New York, Health Science Center, Syracuse, NY 13210, USA.
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Deckers-Hebestreit G, Greie J, Stalz W, Altendorf K. The ATP synthase of Escherichia coli: structure and function of F(0) subunits. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1458:364-73. [PMID: 10838051 DOI: 10.1016/s0005-2728(00)00087-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
In this review we discuss recent work from our laboratory concerning the structure and/or function of the F(0) subunits of the proton-translocating ATP synthase of Escherichia coli. For the topology of subunit a a brief discussion gives (i) a detailed picture of the C-terminal two-thirds of the protein with four transmembrane helices and the C terminus exposed to the cytoplasm and (ii) an evaluation of the controversial results obtained for the localization of the N-terminal region of subunit a including its consequences on the number of transmembrane helices. The structure of membrane-bound subunit b has been determined by circular dichroism spectroscopy to be at least 75% alpha-helical. For this purpose a method was developed, which allows the determination of the structure composition of membrane proteins in proteoliposomes. Subunit b was purified to homogeneity by preparative SDS gel electrophoresis, precipitated with acetone, and redissolved in cholate-containing buffer, thereby retaining its native conformation as shown by functional coreconstitution with an ac subcomplex. Monoclonal antibodies, which have their epitopes located within the hydrophilic loop region of subunit c, and the F(1) part are bound simultaneously to the F(0) complex without an effect on the function of F(0), indicating that not all c subunits are involved in F(1) interaction. Consequences on the coupling mechanism between ATP synthesis/hydrolysis and proton translocation are discussed.
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Affiliation(s)
- G Deckers-Hebestreit
- Abteilung Mikrobiologie, Fachbereich Biologie/Chemie, Universität Osnabrück, D-49069, Osnabrück, Germany.
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50
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Bond DR, Russell JB. Protonmotive force regulates the membrane conductance of Streptococcus bovis in a non-ohmic fashion. MICROBIOLOGY (READING, ENGLAND) 2000; 146 ( Pt 3):687-694. [PMID: 10746772 DOI: 10.1099/00221287-146-3-687] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Because the DCCD (dicyclohexylcarbodiimide)-sensitive, F-ATPase-mediated, futile ATP hydrolysis of non-growing Streptococcus bovis JB1 cells was not affected by sodium or potassium, ATP hydrolysis appeared to be dependent only upon the rate of proton flux across the cell membrane. However, available estimates of bacterial proton conductance were too low to account for the rate of ATP turnover observed in S. bovis. When de-energized cells were subjected to large pH gradients (2.75 units, or -170 mV), internal pH declined at a rate of 0.15 pH units s(-1). Based on an estimated cellular buffering capacity of 200 nmol H+ (mg protein)(-1) per pH unit, H+ flux across the cell membrane (at -170 mV) was 108 mmol (g protein)(-1) h(-1). When potassium-loaded cells were treated with valinomycin in low-potassium buffers, initial K+ efflux generated membrane potentials in close agreement with values predicted by the Nernst equation. These artificial membrane potentials drove H+ uptake, and H+ influx was counterbalanced by a further loss of cellular K+. Flame photometry indicated that the rate of K+ loss was 215 (+/-26) mmol K+ (g protein)(-1) h(-1) at -170 mV, but the potassium-sensitive fluorescent compound CD222 indicated that this rate was only 110 (+/-44) mmol K+ (g protein)(-1) h(-1). As pH gradients or membrane potentials were reduced, the rate of H+ flux declined in a non-ohmic fashion, and all rates were <25 mmol (g protein)(-1) h(-1) at a driving force of -80 mV. Previous estimates of bacterial proton flux were based on low and unphysiological protonmotive forces, and the assumption that H+ influx rate would be ohmic. Rates of H+ influx into S. bovis cells [as high as 9x10(-11) mol H+ (cm membrane)(-2) s(-1)] were similar to rates reported for respiring mitochondria, but were at least 20-fold greater than any rate previously reported in lactic acid bacteria.
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Affiliation(s)
- Daniel R Bond
- Section of Microbiology, Cornell University1, and Agricultural Research Service, USDA2, Ithaca, NY 14853, USA
| | - James B Russell
- Section of Microbiology, Cornell University1, and Agricultural Research Service, USDA2, Ithaca, NY 14853, USA
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