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Strauss J, Wilkinson C, Vidilaseris K, de Castro Ribeiro OM, Liu J, Hillier J, Wichert M, Malinen AM, Gehl B, Jeuken LJ, Pearson AR, Goldman A. Functional and structural asymmetry suggest a unifying principle for catalysis in membrane-bound pyrophosphatases. EMBO Rep 2024; 25:853-875. [PMID: 38182815 PMCID: PMC10897367 DOI: 10.1038/s44319-023-00037-x] [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: 08/24/2023] [Revised: 11/27/2023] [Accepted: 12/01/2023] [Indexed: 01/07/2024] Open
Abstract
Membrane-bound pyrophosphatases (M-PPases) are homodimeric primary ion pumps that couple the transport of Na+- and/or H+ across membranes to the hydrolysis of pyrophosphate. Their role in the virulence of protist pathogens like Plasmodium falciparum makes them an intriguing target for structural and functional studies. Here, we show the first structure of a K+-independent M-PPase, asymmetric and time-dependent substrate binding in time-resolved structures of a K+-dependent M-PPase and demonstrate pumping-before-hydrolysis by electrometric studies. We suggest how key residues in helix 12, 13, and the exit channel loops affect ion selectivity and K+-activation due to a complex interplay of residues that are involved in subunit-subunit communication. Our findings not only explain ion selectivity in M-PPases but also why they display half-of-the-sites reactivity. Based on this, we propose, for the first time, a unified model for ion-pumping, hydrolysis, and energy coupling in all M-PPases, including those that pump both Na+ and H+.
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Affiliation(s)
- Jannik Strauss
- Astbury Centre for Structural and Molecular Biology, University of Leeds, LS2 9JT, Leeds, UK
- Numaferm GmbH, Düsseldorf, Germany
| | - Craig Wilkinson
- Astbury Centre for Structural and Molecular Biology, University of Leeds, LS2 9JT, Leeds, UK
| | - Keni Vidilaseris
- Molecular and Integrative Biosciences, Biological and Environmental Sciences, University of Helsinki, 00100, Helsinki, Finland
| | - Orquidea M de Castro Ribeiro
- Molecular and Integrative Biosciences, Biological and Environmental Sciences, University of Helsinki, 00100, Helsinki, Finland
| | - Jianing Liu
- Molecular and Integrative Biosciences, Biological and Environmental Sciences, University of Helsinki, 00100, Helsinki, Finland
| | - James Hillier
- Astbury Centre for Structural and Molecular Biology, University of Leeds, LS2 9JT, Leeds, UK
- Bio-Rad Laboratories Ltd., Watford, UK
| | - Maximilian Wichert
- Leiden Institute of Chemistry, University Leiden, PO Box 9502, 2300 RA, Leiden, The Netherlands
| | - Anssi M Malinen
- Department of Life Technologies, University of Turku, FIN-20014, Turku, Finland
| | - Bernadette Gehl
- Molecular and Integrative Biosciences, Biological and Environmental Sciences, University of Helsinki, 00100, Helsinki, Finland
- Department of Applied Physics, Aalto University, FI-00076, AALTO, Espoo, Finland
| | - Lars Jc Jeuken
- Leiden Institute of Chemistry, University Leiden, PO Box 9502, 2300 RA, Leiden, The Netherlands
| | - Arwen R Pearson
- Institute for Nanostructure and Solid State Physics, Hamburg Centre for Ultrafast Imaging, Universität Hamburg, 22761, Hamburg, Germany
| | - Adrian Goldman
- Astbury Centre for Structural and Molecular Biology, University of Leeds, LS2 9JT, Leeds, UK.
- Molecular and Integrative Biosciences, Biological and Environmental Sciences, University of Helsinki, 00100, Helsinki, Finland.
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2
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Daley SR, Gallanosa PM, Sparling R. Kinetic characterization of annotated glycolytic enzymes present in cellulose-fermenting Clostridium thermocellum suggests different metabolic roles. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:112. [PMID: 37438781 DOI: 10.1186/s13068-023-02362-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 06/27/2023] [Indexed: 07/14/2023]
Abstract
BACKGROUND The efficient production of sustainable biofuels is important for the reduction of greenhouse gas emissions. Clostridium thermocellum ATCC 27405 is a candidate for ethanol production from lignocellulosic biomass using consolidated bioprocessing. Fermentation of cellulosic biomass goes through an atypical glycolytic pathway in this thermophilic bacterium, with various glycolytic enzymes capable of utilizing different phosphate donors, including GTP and inorganic pyrophosphate (PPi), in addition to or in place of the usual ATP. C. thermocellum contains three annotated phosphofructokinases (PFK) genes, the expression of which have all been detected through proteomics and transcriptomics. Pfp (Cthe_0347) was previously characterized as pyrophosphate dependent with fructose-6-phosphate (F6P) as its substrate. RESULTS We now demonstrate that this enzyme can also phosphorylate sedoheptulose-7-phosphate (an intermediate in the pentose phosphate pathway), with the Vmax and Km of F6P being approximately 15 folds higher and 43 folds lower, respectively, in comparison to sedoheptulose-7-phosphate. Purified PfkA shows preference for GTP as the phosphate donor as opposed to ATP with a 12.5-fold difference in Km values while phosphorylating F6P. Allosteric regulation is a factor at play in PfkA activity, with F6P exhibiting positive cooperativity, and an apparent requirement for ammonium ions to attain maximal activity. Phosphoenolpyruvate and PPi were the only inhibitors for PfkA determined from the study, which corroborates what is known about enzymes from this subfamily. The activation or inhibition by these ligands lends support to the argument that glycolysis is regulated by metabolites such as PPi and NH4+ in the organism. PfkB, showed no activity with F6P, but had significant activity with fructose, while utilizing either ATP or GTP, making it a fructokinase. Rounding out the upper glycolysis pathway, the identity of the fructose-1,6-bisphosphate aldolase in the genome was verified and reported to have substantial activity with fructose-1,6-bisphosphate, in the presence of the divalent ion, Zn2+. CONCLUSION These findings along with previous proteomic data suggest that Pfp, plays a role in both glycolysis and the pentose phosphate pathway, while PfkA and PfkB may phosphorylate sugars in glycolysis but is responsible for sugar metabolism elsewhere under conditions outside of growth on sufficient cellobiose.
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Affiliation(s)
- Steve R Daley
- Department of Microbiology, University of Manitoba, 213 Buller Building, Winnipeg, MB, R3T 2N2, Canada
| | - Patricia Mae Gallanosa
- Department of Microbiology, University of Manitoba, 213 Buller Building, Winnipeg, MB, R3T 2N2, Canada
| | - Richard Sparling
- Department of Microbiology, University of Manitoba, 213 Buller Building, Winnipeg, MB, R3T 2N2, Canada.
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3
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Obiol A, López-Escardó D, Salomaki ED, Wiśniewska MM, Forn I, Sà E, Vaqué D, Kolísko M, Massana R. Gene expression dynamics of natural assemblages of heterotrophic flagellates during bacterivory. MICROBIOME 2023; 11:134. [PMID: 37322519 PMCID: PMC10268365 DOI: 10.1186/s40168-023-01571-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 05/12/2023] [Indexed: 06/17/2023]
Abstract
BACKGROUND Marine heterotrophic flagellates (HF) are dominant bacterivores in the ocean, where they represent the trophic link between bacteria and higher trophic levels and participate in the recycling of inorganic nutrients for regenerated primary production. Studying their activity and function in the ecosystem is challenging since most of the HFs in the ocean are still uncultured. In the present work, we investigated gene expression of natural HF communities during bacterivory in four unamended seawater incubations. RESULTS The most abundant species growing in our incubations belonged to the taxonomic groups MAST-4, MAST-7, Chrysophyceae, and Telonemia. Gene expression dynamics were similar between incubations and could be divided into three states based on microbial counts, each state displaying distinct expression patterns. The analysis of samples where HF growth was highest revealed some highly expressed genes that could be related to bacterivory. Using available genomic and transcriptomic references, we identified 25 species growing in our incubations and used those to compare the expression levels of these specific genes. Video Abstract CONCLUSIONS: Our results indicate that several peptidases, together with some glycoside hydrolases and glycosyltransferases, are more expressed in phagotrophic than in phototrophic species, and thus could be used to infer the process of bacterivory in natural assemblages.
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Affiliation(s)
- Aleix Obiol
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar (ICM-CSIC), Passeig Marítim de la Barceloneta 37-49, Barcelona, Catalonia, 08003, Spain.
| | - David López-Escardó
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar (ICM-CSIC), Passeig Marítim de la Barceloneta 37-49, Barcelona, Catalonia, 08003, Spain
| | - Eric D Salomaki
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
| | - Monika M Wiśniewska
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Irene Forn
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar (ICM-CSIC), Passeig Marítim de la Barceloneta 37-49, Barcelona, Catalonia, 08003, Spain
| | - Elisabet Sà
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar (ICM-CSIC), Passeig Marítim de la Barceloneta 37-49, Barcelona, Catalonia, 08003, Spain
| | - Dolors Vaqué
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar (ICM-CSIC), Passeig Marítim de la Barceloneta 37-49, Barcelona, Catalonia, 08003, Spain
| | - Martin Kolísko
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Ramon Massana
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar (ICM-CSIC), Passeig Marítim de la Barceloneta 37-49, Barcelona, Catalonia, 08003, Spain.
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Russell MJ. A self-sustaining serpentinization mega-engine feeds the fougerite nanoengines implicated in the emergence of guided metabolism. Front Microbiol 2023; 14:1145915. [PMID: 37275164 PMCID: PMC10236563 DOI: 10.3389/fmicb.2023.1145915] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 03/22/2023] [Indexed: 06/07/2023] Open
Abstract
The demonstration by Ivan Barnes et al. that the serpentinization of fresh Alpine-type ultramafic rocks results in the exhalation of hot alkaline fluids is foundational to the submarine alkaline vent theory (AVT) for life's emergence to its 'improbable' thermodynamic state. In AVT, such alkaline fluids ≤ 150°C, bearing H2 > CH4 > HS--generated and driven convectively by a serpentinizing exothermic mega-engine operating in the ultramafic crust-exhale into the iron-rich, CO2> > > NO3--bearing Hadean ocean to result in hydrothermal precipitate mounds comprising macromolecular ferroferric-carbonate oxyhydroxide and minor sulfide. As the nanocrystalline minerals fougerite/green rust and mackinawite (FeS), they compose the spontaneously precipitated inorganic membranes that keep the highly contrasting solutions apart, thereby maintaining redox and pH disequilibria. They do so in the form of fine chimneys and chemical gardens. The same disequilibria drive the reduction of CO2 to HCOO- or CO, and the oxidation of CH4 to a methyl group-the two products reacting to form acetate in a sequence antedating the 'energy-producing' acetyl coenzyme-A pathway. Fougerite is a 2D-layered mineral in which the hydrous interlayers themselves harbor 2D solutions, in effect constricted to ~ 1D by preferentially directed electron hopping/tunneling, and proton Gröthuss 'bucket-brigading' when subject to charge. As a redox-driven nanoengine or peristaltic pump, fougerite forces the ordered reduction of nitrate to ammonium, the amination of pyruvate and oxalate to alanine and glycine, and their condensation to short peptides. In turn, these peptides have the flexibility to sequester the founding inorganic iron oxyhydroxide, sulfide, and pyrophosphate clusters, to produce metal- and phosphate-dosed organic films and cells. As the feed to the hydrothermal mound fails, the only equivalent sustenance on offer to the first autotrophs is the still mildly serpentinizing upper crust beneath. While the conditions here are very much less bountiful, they do offer the similar feed and disequilibria the survivors are accustomed to. Sometime during this transition, a replicating non-ribosomal guidance system is discovered to provide the rules to take on the incrementally changing surroundings. The details of how these replicating apparatuses emerged are the hard problem, but by doing so the progenote archaea and bacteria could begin to colonize what would become the deep biosphere. Indeed, that the anaerobic nitrate-respiring methanotrophic archaea and the deep-branching Acetothermia presently comprise a portion of that microbiome occupying serpentinizing rocks offers circumstantial support for this notion. However, the inescapable, if jarring conclusion is drawn that, absent fougerite/green rust, there would be no structured channelway to life.
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Affiliation(s)
- Michael J. Russell
- Dipartimento di Chimica, Università degli Studi di Torino, Torino, Italy
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5
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Huang XY, Wang CK, Zhao YW, Sun CH, Hu DG. Mechanisms and regulation of organic acid accumulation in plant vacuoles. HORTICULTURE RESEARCH 2021; 8:227. [PMID: 34697291 PMCID: PMC8546024 DOI: 10.1038/s41438-021-00702-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 09/09/2021] [Accepted: 09/24/2021] [Indexed: 06/13/2023]
Abstract
In fleshy fruits, organic acids are the main source of fruit acidity and play an important role in regulating osmotic pressure, pH homeostasis, stress resistance, and fruit quality. The transport of organic acids from the cytosol to the vacuole and their storage are complex processes. A large number of transporters carry organic acids from the cytosol to the vacuole with the assistance of various proton pumps and enzymes. However, much remains to be explored regarding the vacuolar transport mechanism of organic acids as well as the substances involved and their association. In this review, recent advances in the vacuolar transport mechanism of organic acids in plants are summarized from the perspectives of transporters, channels, proton pumps, and upstream regulators to better understand the complex regulatory networks involved in fruit acid formation.
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Affiliation(s)
- Xiao-Yu Huang
- National Key Laboratory of Crop Biology; Shandong Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production; College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an, Shandong, 271018, China
| | - Chu-Kun Wang
- National Key Laboratory of Crop Biology; Shandong Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production; College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an, Shandong, 271018, China
| | - Yu-Wen Zhao
- National Key Laboratory of Crop Biology; Shandong Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production; College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an, Shandong, 271018, China
| | - Cui-Hui Sun
- National Key Laboratory of Crop Biology; Shandong Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production; College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an, Shandong, 271018, China.
| | - Da-Gang Hu
- National Key Laboratory of Crop Biology; Shandong Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production; College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an, Shandong, 271018, China.
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6
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Pyrophosphate as an alternative energy currency in plants. Biochem J 2021; 478:1515-1524. [PMID: 33881486 DOI: 10.1042/bcj20200940] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 03/20/2021] [Accepted: 03/23/2021] [Indexed: 02/07/2023]
Abstract
In the conditions of [Mg2+] elevation that occur, in particular, under low oxygen stress and are the consequence of the decrease in [ATP] and increase in [ADP] and [AMP], pyrophosphate (PPi) can function as an alternative energy currency in plant cells. In addition to its production by various metabolic pathways, PPi can be synthesized in the combined reactions of pyruvate, phosphate dikinase (PPDK) and pyruvate kinase (PK) by so-called PK/PPDK substrate cycle, and in the reverse reaction of membrane-bound H+-pyrophosphatase, which uses the energy of electrochemical gradients generated on tonoplast and plasma membrane. The PPi can then be consumed in its active forms of MgPPi and Mg2PPi by PPi-utilizing enzymes, which require an elevated [Mg2+]. This ensures a continuous operation of glycolysis in the conditions of suppressed ATP synthesis, keeping metabolism energy efficient and less dependent on ATP.
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7
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Massana R, Labarre A, López-Escardó D, Obiol A, Bucchini F, Hackl T, Fischer MG, Vandepoele K, Tikhonenkov DV, Husnik F, Keeling PJ. Gene expression during bacterivorous growth of a widespread marine heterotrophic flagellate. ISME JOURNAL 2020; 15:154-167. [PMID: 32920602 PMCID: PMC7852580 DOI: 10.1038/s41396-020-00770-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Revised: 08/19/2020] [Accepted: 09/02/2020] [Indexed: 11/17/2022]
Abstract
Phagocytosis is a fundamental process in marine ecosystems by which prey organisms are consumed and their biomass incorporated in food webs or remineralized. However, studies searching for the genes underlying this key ecological process in free-living phagocytizing protists are still scarce, in part due to the lack of appropriate ecological models. Our reanalysis of recent molecular datasets revealed that the cultured heterotrophic flagellate Cafeteria burkhardae is widespread in the global oceans, which prompted us to design a transcriptomics study with this species, grown with the cultured flavobacterium Dokdonia sp. We compared the gene expression between exponential and stationary phases, which were complemented with three starvation by dilution phases that appeared as intermediate states. We found distinct expression profiles in each condition and identified 2056 differentially expressed genes between exponential and stationary samples. Upregulated genes at the exponential phase were related to DNA duplication, transcription and translational machinery, protein remodeling, respiration and phagocytosis, whereas upregulated genes in the stationary phase were involved in signal transduction, cell adhesion, and lipid metabolism. We identified a few highly expressed phagocytosis genes, like peptidases and proton pumps, which could be used to target this ecologically relevant process in marine ecosystems.
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Affiliation(s)
- Ramon Massana
- Institut de Ciències del Mar (CSIC), Passeig Marítim de la Barceloneta 37-49, ES-08003, Barcelona, Catalonia, Spain.
| | - Aurelie Labarre
- Institut de Ciències del Mar (CSIC), Passeig Marítim de la Barceloneta 37-49, ES-08003, Barcelona, Catalonia, Spain
| | - David López-Escardó
- Institut de Ciències del Mar (CSIC), Passeig Marítim de la Barceloneta 37-49, ES-08003, Barcelona, Catalonia, Spain
| | - Aleix Obiol
- Institut de Ciències del Mar (CSIC), Passeig Marítim de la Barceloneta 37-49, ES-08003, Barcelona, Catalonia, Spain
| | - François Bucchini
- Department of Plant Systems Biology, VIB, B-9052, Ghent, Belgium.,Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052, Ghent, Belgium
| | - Thomas Hackl
- Max Planck Institute for Medical Research, 69120, Heidelberg, Germany
| | | | - Klaas Vandepoele
- Department of Plant Systems Biology, VIB, B-9052, Ghent, Belgium.,Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052, Ghent, Belgium
| | - Denis V Tikhonenkov
- Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences, Borok, 152742, Russia
| | - Filip Husnik
- University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
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8
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Primo C, Pizzio GA, Yang J, Gaxiola RA, Scholz-Starke J, Hirschi KD. Plant proton pumping pyrophosphatase: the potential for its pyrophosphate synthesis activity to modulate plant growth. PLANT BIOLOGY (STUTTGART, GERMANY) 2019; 21:989-996. [PMID: 31081197 DOI: 10.1111/plb.13007] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 05/09/2019] [Indexed: 05/25/2023]
Abstract
Cellular pyrophosphate (PPi) homeostasis is vital for normal plant growth and development. Plant proton-pumping pyrophosphatases (H+ -PPases) are enzymes with different tissue-specific functions related to the regulation of PPi homeostasis. Enhanced expression of plant H+ -PPases increases biomass and yield in different crop species. Here, we emphasise emerging studies utilising heterologous expression in yeast and plant vacuole electrophysiology approaches, as well as phylogenetic relationships and structural analysis, to showcase that the H+ -PPases possess a PPi synthesis function. We postulate this synthase activity contributes to modulating and promoting plant growth both in H+ -PPase-engineered crops and in wild-type plants. We propose a model where the PPi synthase activity of H+ -PPases maintains the PPi pool when cells adopt PPi-dependent glycolysis during high energy demands and/or low oxygen environments. We conclude by proposing experiments to further investigate the H+ -PPase-mediated PPi synthase role in plant growth.
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Affiliation(s)
- C Primo
- Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX, USA
| | - G A Pizzio
- Center for Research in Agricultural Genomics, Consejo Superior de Investigaciones Científicas, Barcelona, Spain
| | - J Yang
- Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX, USA
| | - R A Gaxiola
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - J Scholz-Starke
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Genova, Italy
| | - K D Hirschi
- Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX, USA
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9
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Duval S, Baymann F, Schoepp-Cothenet B, Trolard F, Bourrié G, Grauby O, Branscomb E, Russell MJ, Nitschke W. Fougerite: the not so simple progenitor of the first cells. Interface Focus 2019; 9:20190063. [PMID: 31641434 DOI: 10.1098/rsfs.2019.0063] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/09/2019] [Indexed: 12/22/2022] Open
Abstract
We here review the extraordinary mineralogical properties of green rusts and their naturally occurring form, fougerite, and discuss the pertinence of these properties within the alkaline hydrothermal vent (AHV) hypothesis for life's emergence. We put forward an extended version of the AHV scenario which enhances the conformity between extant life and its earliest progenitor by extensively making use of fougerite's mechanistic and catalytic particularities.
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Affiliation(s)
- Simon Duval
- Aix Marseille Université, CNRS, BIP (UMR 7281), Marseille, France
| | - Frauke Baymann
- Aix Marseille Université, CNRS, BIP (UMR 7281), Marseille, France
| | | | | | | | - Olivier Grauby
- Aix Marseille Université, CINaM (UMR 7325), Luminy, France
| | - Elbert Branscomb
- Carl R. Woese Institute for Genomic Biology, and Department of Physics, University of Illinois, Urbana, IL 61801, USA
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10
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Wang Q, Barge LM, Steinbock O. Microfluidic Production of Pyrophosphate Catalyzed by Mineral Membranes with Steep pH Gradients. Chemistry 2019; 25:4732-4739. [DOI: 10.1002/chem.201805950] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 02/05/2019] [Indexed: 12/27/2022]
Affiliation(s)
- Qingpu Wang
- Department of Chemistry and BiochemistryFlorida State University Tallahassee Florida 32306-4390 USA
| | - Laura M. Barge
- NASA Jet Propulsion LaboratoryCalifornia Institute of Technology Pasadena California 91109 USA
| | - Oliver Steinbock
- Department of Chemistry and BiochemistryFlorida State University Tallahassee Florida 32306-4390 USA
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11
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Russell MJ. Green Rust: The Simple Organizing 'Seed' of All Life? Life (Basel) 2018; 8:E35. [PMID: 30150570 PMCID: PMC6161180 DOI: 10.3390/life8030035] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 06/28/2018] [Accepted: 08/14/2018] [Indexed: 01/18/2023] Open
Abstract
Korenaga and coworkers presented evidence to suggest that the Earth's mantle was dry and water filled the ocean to twice its present volume 4.3 billion years ago. Carbon dioxide was constantly exhaled during the mafic to ultramafic volcanic activity associated with magmatic plumes that produced the thick, dense, and relatively stable oceanic crust. In that setting, two distinct and major types of sub-marine hydrothermal vents were active: ~400 °C acidic springs, whose effluents bore vast quantities of iron into the ocean, and ~120 °C, highly alkaline, and reduced vents exhaling from the cooler, serpentinizing crust some distance from the heads of the plumes. When encountering the alkaline effluents, the iron from the plume head vents precipitated out, forming mounds likely surrounded by voluminous exhalative deposits similar to the banded iron formations known from the Archean. These mounds and the surrounding sediments, comprised micro or nano-crysts of the variable valence FeII/FeIII oxyhydroxide known as green rust. The precipitation of green rust, along with subsidiary iron sulfides and minor concentrations of nickel, cobalt, and molybdenum in the environment at the alkaline springs, may have established both the key bio-syntonic disequilibria and the means to properly make use of them-the elements needed to effect the essential inanimate-to-animate transitions that launched life. Specifically, in the submarine alkaline vent model for the emergence of life, it is first suggested that the redox-flexible green rust micro- and nano-crysts spontaneously precipitated to form barriers to the complete mixing of carbonic ocean and alkaline hydrothermal fluids. These barriers created and maintained steep ionic disequilibria. Second, the hydrous interlayers of green rust acted as engines that were powered by those ionic disequilibria and drove essential endergonic reactions. There, aided by sulfides and trace elements acting as catalytic promoters and electron transfer agents, nitrate could be reduced to ammonia and carbon dioxide to formate, while methane may have been oxidized to methyl and formyl groups. Acetate and higher carboxylic acids could then have been produced from these C1 molecules and aminated to amino acids, and thence oligomerized to offer peptide nests to phosphate and iron sulfides, and secreted to form primitive amyloid-bounded structures, leading conceivably to protocells.
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Affiliation(s)
- Michael J Russell
- Planetary Chemistry and Astrobiology, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099, USA.
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12
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Branscomb E, Russell MJ. Frankenstein or a Submarine Alkaline Vent: Who is Responsible for Abiogenesis? Bioessays 2018; 40:e1700182. [DOI: 10.1002/bies.201700182] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 04/26/2018] [Indexed: 12/18/2022]
Affiliation(s)
- Elbert Branscomb
- Department of Physics; Carl R. Woese Institute for Genomic Biology; University of Illinois; Urbana IL 61801 USA
| | - Michael J. Russell
- Planetary Chemistry and Astrobiology; Sec. 3225 MS:183-301; Jet Propulsion Laboratory; California Institute of Technology; Pasadena CA 91109-8099 USA
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Huang XL. Hydrolysis of Phosphate Esters Catalyzed by Inorganic Iron Oxide Nanoparticles Acting as Biocatalysts. ASTROBIOLOGY 2018; 18:294-310. [PMID: 29489387 DOI: 10.1089/ast.2016.1628] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Phosphorus ester hydrolysis is one of the key chemical processes in biological systems, including signaling, free-energy transaction, protein synthesis, and maintaining the integrity of genetic material. Hydrolysis of this otherwise kinetically stable phosphoester and/or phosphoanhydride bond is induced by enzymes such as purple acid phosphatase. Here, I report that, as in previously reported aged inorganic iron ion solutions, the iron oxide nanoparticles in the solution, which are trapped in a dialysis membrane tube filled with the various iron oxides, significantly promote the hydrolysis of the various phosphate esters, including the inorganic polyphosphates, with enzyme-like kinetics. This observation, along with those of recent studies of iron oxide, vanadium pentoxide, and molybdenum trioxide nanoparticles that behave as mimics of peroxidase, bromoperoxidase, and sulfite oxidase, respectively, indicates that the oxo-metal bond in the oxide nanoparticles is critical for the function of these corresponding natural metalloproteins. These inorganic biocatalysts challenge the traditional concept of replicator-first scenarios and support the metabolism-first hypothesis. As biocatalysts, these inorganic nanoparticles with enzyme-like activity may work in natural terrestrial environments and likely were at work in early Earth environments as well. They may have played an important role in the C, H, O, S, and P metabolic pathway with regard to the emergence and early evolution of life. Key Words: Enzyme-Hydrolysis-Iron oxide-Nanoparticles-Origin of life-Phosphate ester. Astrobiology 18, 294-310.
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Whitham JM, Moon JW, Rodriguez M, Engle NL, Klingeman DM, Rydzak T, Abel MM, Tschaplinski TJ, Guss AM, Brown SD. Clostridium thermocellum LL1210 pH homeostasis mechanisms informed by transcriptomics and metabolomics. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:98. [PMID: 29632556 PMCID: PMC5887222 DOI: 10.1186/s13068-018-1095-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2017] [Accepted: 03/24/2018] [Indexed: 05/21/2023]
Abstract
BACKGROUND Clostridium (Ruminiclostridium) thermocellum is a model fermentative anaerobic thermophile being studied and engineered for consolidated bioprocessing of lignocellulosic feedstocks into fuels and chemicals. Engineering efforts have resulted in significant improvements in ethanol yields and titers although further advances are required to make the bacterium industry-ready. For instance, fermentations at lower pH could enable co-culturing with microbes that have lower pH optima, augment productivity, and reduce buffering cost. C. thermocellum is typically grown at neutral pH, and little is known about its pH limits or pH homeostasis mechanisms. To better understand C. thermocellum pH homeostasis we grew strain LL1210 (C. thermocellum DSM1313 Δhpt ΔhydG Δldh Δpfl Δpta-ack), currently the highest ethanol producing strain of C. thermocellum, at different pH values in chemostat culture and applied systems biology tools. RESULTS Clostridium thermocellum LL1210 was found to be growth-limited below pH 6.24 at a dilution rate of 0.1 h-1. F1F0-ATPase gene expression was upregulated while many ATP-utilizing enzymes and pathways were downregulated at pH 6.24. These included most flagella biosynthesis genes, genes for chemotaxis, and other motility-related genes (> 50) as well as sulfate transport and reduction, nitrate transport and nitrogen fixation, and fatty acid biosynthesis genes. Clustering and enrichment of differentially expressed genes at pH values 6.48, pH 6.24 and pH 6.12 (washout conditions) compared to pH 6.98 showed inverse differential expression patterns between the F1F0-ATPase and genes for other ATP-utilizing enzymes. At and below pH 6.24, amino acids including glutamate and valine; long-chain fatty acids, their iso-counterparts and glycerol conjugates; glycolysis intermediates 3-phosphoglycerate, glucose 6-phosphate, and glucose accumulated intracellularly. Glutamate was 267 times more abundant in cells at pH 6.24 compared to pH 6.98, and intercellular concentration reached 1.8 μmol/g pellet at pH 5.80 (stopped flow). CONCLUSIONS Clostridium thermocellum LL1210 can grow under slightly acidic conditions, similar to limits reported for other strains. This foundational study provides a detailed characterization of a relatively acid-intolerant bacterium and provides genetic targets for strain improvement. Future studies should examine adding gene functions used by more acid-tolerant bacteria for improved pH homeostasis at acidic pH values.
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Affiliation(s)
- Jason M. Whitham
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
- BioEnergy Science Center, National Laboratory, Oak Ridge, TN USA
| | - Ji-Won Moon
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
| | - Miguel Rodriguez
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
- BioEnergy Science Center, National Laboratory, Oak Ridge, TN USA
| | - Nancy L. Engle
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
- BioEnergy Science Center, National Laboratory, Oak Ridge, TN USA
| | - Dawn M. Klingeman
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
- BioEnergy Science Center, National Laboratory, Oak Ridge, TN USA
| | - Thomas Rydzak
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
- BioEnergy Science Center, National Laboratory, Oak Ridge, TN USA
- Present Address: Department of Biological Science, University of Calgary, Calgary, AB T2N 1N4 Canada
| | - Malaney M. Abel
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
- BioEnergy Science Center, National Laboratory, Oak Ridge, TN USA
| | - Timothy J. Tschaplinski
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
- BioEnergy Science Center, National Laboratory, Oak Ridge, TN USA
| | - Adam M. Guss
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
- BioEnergy Science Center, National Laboratory, Oak Ridge, TN USA
| | - Steven D. Brown
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
- BioEnergy Science Center, National Laboratory, Oak Ridge, TN USA
- Present Address: LanzaTech, Inc., Skokie, IL USA
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He R, Yu G, Han X, Han J, Li W, Wang B, Huang S, Cheng X. ThPP1 gene, encodes an inorganic pyrophosphatase in Thellungiella halophila, enhanced the tolerance of the transgenic rice to alkali stress. PLANT CELL REPORTS 2017; 36:1929-1942. [PMID: 29030650 DOI: 10.1007/s00299-017-2208-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Accepted: 09/12/2017] [Indexed: 05/14/2023]
Abstract
An inorganic pyrophosphorylase gene, ThPP1 , modulated the accumulations of phosphate and osmolytes by up-regulating the differentially expression genes, thus enhancing the tolerance of the transgenic rice to alkali stress (AS). Inorganic pyrophosphorylase is essential in catalyzing the hydrolysis of pyrophosphate to inorganic phosphate during plant growth. Here, we report the changes of physiological osmolytes and differentially expression genes in the transgenic rice overexpressing a soluble inorganic pyrophosphatase gene ThPP1 of Thellungiella halophila in response to AS. Analyses showed that the ThPP1 gene was a PPase family I member which is located to the cytoplasm. Data showed that the transgenic lines revealed an enhanced tolerance to AS compared to the wild type, and effectively increased the accumulations of inorganic phosphate and organic small molecules starch, sucrose, proline and chlorophyll, and maintained the balance of osmotic potential by modulating the ratio of Na+/K+ in plant cells. Under AS, total 379 of differentially expression genes were up-regulated in the leaves of the transgenic line compared with control, and the enhanced tolerance of the transgenic rice to the AS seemed to be associated with the up-regulations of the osmotic stress-related genes such as the L-type lectin-domain containing receptor kinase (L-type LecRK), the cation/H+ antiporter gene and the vacuolar cation/proton exchanger 1 gene (CAX1), which conferred the involvements in the biosynthesis and metabolic pathways. Protein interaction showed that the ThPP1 protein specifically interacted with a 16# target partner of the photosystem II light-harvesting-Chl-binding protein. This study suggested that the ThPP1 gene plays an important regulatory role in conferring the tolerance of the transgenic rice to AS, and is an effective candidate in molecular breeding for crop cultivation of the alkali tolerance.
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Affiliation(s)
- Rui He
- College of Land and Environment, Shenyang Agricultural University, No. 120 Dongling Road, Shenyang, 110866, Liaoning, People's Republic of China
- Key Lab of Plant Nutrition and Fertilizers, Ministry of Agriculture, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, No. 12 South Street, Zhongguancun, Beijing, 100081, People's Republic of China
| | - Guohong Yu
- Key Lab of Plant Nutrition and Fertilizers, Ministry of Agriculture, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, No. 12 South Street, Zhongguancun, Beijing, 100081, People's Republic of China
| | - Xiaori Han
- College of Land and Environment, Shenyang Agricultural University, No. 120 Dongling Road, Shenyang, 110866, Liaoning, People's Republic of China
| | - Jiao Han
- Key Lab of Plant Nutrition and Fertilizers, Ministry of Agriculture, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, No. 12 South Street, Zhongguancun, Beijing, 100081, People's Republic of China
- College of Life Science, Shanxi Normal University, No. 1 Gongyue Street, Yaodu Area, Linfen, 0410004, Shanxi, People's Republic of China
| | - Wei Li
- Key Lab of Plant Nutrition and Fertilizers, Ministry of Agriculture, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, No. 12 South Street, Zhongguancun, Beijing, 100081, People's Republic of China
| | - Bing Wang
- Key Lab of Plant Nutrition and Fertilizers, Ministry of Agriculture, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, No. 12 South Street, Zhongguancun, Beijing, 100081, People's Republic of China
| | - Shengcai Huang
- Key Lab of Plant Nutrition and Fertilizers, Ministry of Agriculture, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, No. 12 South Street, Zhongguancun, Beijing, 100081, People's Republic of China
| | - Xianguo Cheng
- Key Lab of Plant Nutrition and Fertilizers, Ministry of Agriculture, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, No. 12 South Street, Zhongguancun, Beijing, 100081, People's Republic of China.
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Russell MJ, Nitschke W. Methane: Fuel or Exhaust at the Emergence of Life? ASTROBIOLOGY 2017; 17:1053-1066. [PMID: 28949766 PMCID: PMC5655419 DOI: 10.1089/ast.2016.1599] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 03/20/2017] [Indexed: 05/28/2023]
Abstract
As many of the methanogens first encountered at hydrothermal vents were thermophilic to hyperthermophilic and comprised one of the lower roots of the evolutionary tree, it has been assumed that methanogenesis was one of the earliest, if not the earliest, pathway to life. It being well known that hydrothermal springs associated with serpentinization also bore abiotic methane, it had been further assumed that emergent biochemistry merely adopted and quickened this supposed serpentinization reaction. Yet, recent hydrothermal experiments simulating serpentinization have failed to generate methane so far, thus casting doubt on this assumption. The idea that the inverse view is worthy of debate, that is, that methanotrophy was the earlier, is stymied by the "fact" that methanotrophy itself has been termed "reverse methanogenesis," so allotting the methanogens the founding pedigree. Thus, attempting to suggest instead that methanogenesis might be termed reverse methanotrophy would require "unlearning"-a challenge to the subconscious! Here we re-examine the "impossibility" of methanotrophy predating methanogenesis as in what we have termed the "denitrifying methanotrophic acetogenic pathway." Advantages offered by such thinking are that methane would not only be a fuel but also a ready source of reduced carbon to combine with formate or carbon monoxide-available in hydrothermal fluids-to generate acetate, a target molecule of the first autotrophs. And the nitrate/nitrite required for the putative oxidation of methane with activated NO would also be a ready source of fixed nitrogen for amination reactions. Theoretical conditions for such a putative pathway would be met in a hydrothermal green rust-bearing exhalative pile and associated chimneys subject to proton and electron counter gradients. This hypothesis could be put to test in a high-pressure hydrothermal reaction chamber in which a cool carbonate/nitrate/nitrite-bearing early acidulous ocean simulant is juxtaposed across a precipitate membrane to an alkaline solution of hydrogen and methane. Key Words: Green rust-Methanotrophy-Nitrate reduction-Emergence of life. Astrobiology 17, 1053-1066.
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Affiliation(s)
- Michael J. Russell
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
| | - Wolfgang Nitschke
- CNRS/Aix-Marseille University, BIP UMR 7281, IMM FR 3479, Marseille, France
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Taillefer M, Sparling R. Glycolysis as the Central Core of Fermentation. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2017; 156:55-77. [PMID: 26907549 DOI: 10.1007/10_2015_5003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The increasing concerns of greenhouse gas emissions have increased the interest in dark fermentation as a means of productions for industrial chemicals, especially from renewable cellulosic biomass. However, the metabolism, including glycolysis, of many candidate organisms for cellulosic biomass conversion through consolidated bioprocessing is still poorly understood and the genomes have only recently been sequenced. Because a variety of industrial chemicals are produced directly from sugar metabolism, the careful understanding of glycolysis from a genomic and biochemical point of view is essential in the development of strategies for increasing product yields and therefore increasing industrial potential. The current review discusses the different pathways available for glycolysis along with unexpected variations from traditional models, especially in the utilization of alternate energy intermediates (GTP, pyrophosphate). This reinforces the need for a careful description of interactions between energy metabolites and glycolysis enzymes for understanding carbon and electron flux regulation.
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Affiliation(s)
- M Taillefer
- Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada, R3T 2N2
| | - R Sparling
- Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada, R3T 2N2.
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Daouda MP, Bouchra EK, Roman PCJ, Aurelio SD, Abdelaziz S. Inorganic Pyrophosphatases: Study of Interest. ACTA ACUST UNITED AC 2017. [DOI: 10.4236/abb.2017.810028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Two independent evolutionary routes to Na+/H+ cotransport function in membrane pyrophosphatases. Biochem J 2016; 473:3099-111. [DOI: 10.1042/bcj20160529] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2016] [Accepted: 08/03/2016] [Indexed: 11/17/2022]
Abstract
Membrane-bound pyrophosphatases (mPPases) hydrolyze pyrophosphate (PPi) to transport H+, Na+ or both and help organisms to cope with stress conditions, such as high salinity or limiting nutrients. Recent elucidation of mPPase structure and identification of subfamilies that have fully or partially switched from Na+ to H+ pumping have established mPPases as versatile models for studying the principles governing the mechanism, specificity and evolution of cation transporters. In the present study, we constructed an accurate phylogenetic map of the interface of Na+-transporting PPases (Na+-PPases) and Na+- and H+-transporting PPases (Na+,H+-PPases), which guided our experimental exploration of the variations in PPi hydrolysis and ion transport activities during evolution. Surprisingly, we identified two mPPase lineages that independently acquired physiologically significant Na+ and H+ cotransport function. Na+,H+-PPases of the first lineage transport H+ over an extended [Na+] range, but progressively lose H+ transport efficiency at high [Na+]. In contrast, H+-transport by Na+,H+-PPases of the second lineage is not inhibited by up to 100 mM Na+. With the identification of Na+,H+-PPase subtypes, the mPPases protein superfamily appears as a continuum, ranging from monospecific Na+ transporters to transporters with tunable levels of Na+ and H+ cotransport and further to monospecific H+ transporters. Our results lend credence to the concept that Na+ and H+ are transported by similar mechanisms, allowing the relative efficiencies of Na+ and H+ transport to be modulated by minor changes in protein structure during the course of adaptation to a changing environment.
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Role of H(+)-pyrophosphatase activity in the regulation of intracellular pH in a scuticociliate parasite of turbot: Physiological effects. Exp Parasitol 2016; 169:59-68. [PMID: 27480055 DOI: 10.1016/j.exppara.2016.07.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Revised: 06/04/2016] [Accepted: 07/28/2016] [Indexed: 11/21/2022]
Abstract
The scuticociliatosis is a very serious disease that affects the cultured turbot, and whose causal agent is the anphizoic and marine euryhaline ciliate Philasterides dicentrarchi. Several protozoans possess acidic organelles that contain high concentrations of pyrophosphate (PPi), Ca(2+) and other elements with essential roles in vesicular trafficking, pH homeostasis and osmoregulation. P. dicentrarchi possesses a pyrophosphatase (H(+)-PPase) that pumps H(+) through the membranes of vacuolar and alveolar sacs. These compartments share common features with the acidocalcisomes described in other parasitic protozoa (e.g. acid content and Ca(2+) storage). We evaluated the effects of Ca(2+) and ATP on H (+)-PPase activity in this ciliate and analyzed their role in maintaining intracellular pH homeostasis and osmoregulation, by the addition of PPi and inorganic molecules that affect osmolarity. Addition of PPi led to acidification of the intracellular compartments, while the addition of ATP, CaCl2 and bisphosphonates analogous of PPi and Ca(2+) metabolism regulators led to alkalinization and a decrease in H(+)-PPase expression in trophozoites. Addition of NaCl led to proton release, intracellular Ca(2+) accumulation and downregulation of H(+)-PPase expression. We conclude that the regulation of the acidification of intracellular compartments may be essential for maintaining the intracellular pH homeostasis necessary for survival of ciliates and their adaptation to salt stress, which they will presumably face during the endoparasitic phase, in which the salinity levels are lower than in their natural environment.
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Presence of an isoform of H+-pyrophosphatase located in the alveolar sacs of a scuticociliate parasite of turbot: physiological consequences. Parasitology 2016; 143:576-87. [DOI: 10.1017/s0031182015001997] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
SUMMARYH+-pyrophosphatases (H+-PPases) are integral membrane proteins that couple pyrophosphate energy to an electrochemical gradient across biological membranes and promote the acidification of cellular compartments. Eukaryotic organisms, essentially plants and protozoan parasites, contain various types of H+-PPases associated with vacuoles, plasma membrane and acidic Ca+2storage organelles called acidocalcisomes. We used Lysotracker Red DND-99 staining to identify two acidic cellular compartments in trophozoites of the marine scuticociliate parasitePhilasterides dicentrarchi: the phagocytic vacuoles and the alveolar sacs. The membranes of these compartments also contain H+-PPase, which may promote acidification of these cell structures. We also demonstrated for the first time that theP. dicentrarchiH+-PPase has two isoforms: H+-PPase 1 and 2. Isoform 2, which is probably generated by splicing, is located in the membranes of the alveolar sacs and has an amino acid motif recognized by the H+-PPase-specific antibody PABHK. The amino acid sequences of different isolates of this ciliate are highly conserved. Gene and protein expression in this isoform are significantly regulated by variations in salinity, indicating a possible physiological role of this enzyme and the alveolar sacs in osmoregulation and salt tolerance inP. dicentrarchi.
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Mallo N, Lamas J, DeFelipe AP, Sueiro RA, Fontenla F, Leiro JM. Enzymes Involved in Pyrophosphate and Calcium Metabolism as Targets for Anti-scuticociliate Chemotherapy. J Eukaryot Microbiol 2016; 63:505-15. [DOI: 10.1111/jeu.12294] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Revised: 12/18/2015] [Accepted: 01/05/2016] [Indexed: 12/20/2022]
Affiliation(s)
- Natalia Mallo
- Departamento de Microbiología y Parasitología; Instituto de Investigación y Análisis Alimentarios; Universidad de Santiago de Compostela; Santiago de Compostela Spain
| | - Jesús Lamas
- Departamento de Biología Celular y Ecología; Facultad de Biología; Instituto de Acuicultura; Universidad de Santiago de Compostela; Santiago de Compostela Spain
| | - Ana-Paula DeFelipe
- Departamento de Microbiología y Parasitología; Instituto de Investigación y Análisis Alimentarios; Universidad de Santiago de Compostela; Santiago de Compostela Spain
| | - Rosa-Ana Sueiro
- Departamento de Microbiología y Parasitología; Instituto de Investigación y Análisis Alimentarios; Universidad de Santiago de Compostela; Santiago de Compostela Spain
- Departamento de Biología Celular y Ecología; Facultad de Biología; Instituto de Acuicultura; Universidad de Santiago de Compostela; Santiago de Compostela Spain
| | - Francisco Fontenla
- Departamento de Biología Celular y Ecología; Facultad de Biología; Instituto de Acuicultura; Universidad de Santiago de Compostela; Santiago de Compostela Spain
| | - José-Manuel Leiro
- Departamento de Microbiología y Parasitología; Instituto de Investigación y Análisis Alimentarios; Universidad de Santiago de Compostela; Santiago de Compostela Spain
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Chen YW, Lee CH, Huang YT, Pan YJ, Lin SM, Lo YY, Lee CH, Huang LK, Huang YF, Hsu YD, Pan RL. Functional and fluorescence analyses of tryptophan residues in H+-pyrophosphatase of Clostridium tetani. J Bioenerg Biomembr 2015; 46:127-34. [PMID: 24121937 DOI: 10.1007/s10863-013-9532-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Accepted: 10/01/2013] [Indexed: 10/26/2022]
Abstract
Homodimeric proton-translocating pyrophosphatase (H+-PPase; EC 3.6.1.1) maintains the cytoplasmic pH homeostasis of many bacteria and higher plants by coupling pyrophosphate (PPi) hydrolysis and proton translocation. H+-PPase accommodates several essential motifs involved in the catalytic mechanism, including the PPi binding motif and Acidic I and II motifs. In this study, 3 intrinsic tryptophan residues, Trp-75, Trp-365, and Trp-602, in H+-PPase from Clostridium tetani were used as internal probes to monitor the local conformational state of the periplasm domain, transmembrane region, and cytoplasmic domain, respectively. Upon binding of the substrate analog Mg-imidodiphosphate (Mg-IDP), local structural changes prevented the modification of tryptophan residues by N-bromosuccinimide (NBS), especially at Trp-602. Following Mg-Pi binding, Trp-75 and Trp-365, but not Trp-602, were slightly protected from structural modifications by NBS. These results reveal the conformation of H+-PPase is distinct in the presence of different ligands. Moreover, analyses of the Stern-Volmer relationship and steady-state fluorescence anisotropy also indicate that the local structure around Trp-602 is more exposed to solvent and varied under different environments. In addition, Trp-602 was identified to be a crucial residue in the H+-PPase that may potentially be involved in stabilizing the structure of the catalytic region by site-directed mutagenesis analysis.
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Presence of a plant-like proton-translocating pyrophosphatase in a scuticociliate parasite and its role as a possible drug target. Parasitology 2014; 142:449-62. [DOI: 10.1017/s0031182014001267] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
SUMMARYThe proton-translocating inorganic pyrophosphatases (H+-PPases) are primary electrogenic H+ pumps that derive energy from the hydrolysis of inorganic pyrophosphate (PPi). They are widely distributed among most land plants and have also been found in several species of protozoan parasites. Here we describe, for the first time, the molecular cloning and functional characterization of a gene encoding an H+-pyrophosphatase in the protozoan scuticociliate parasite Philasterides dicentrarchi, which infects turbot. The predicted P. dicentrarchi PPase (PdPPase) consists of 587 amino acids of molecular mass 61·7 kDa and an isoelectric point of 5·0. Several motifs characteristic of plant vacuolar H+-PPases (V–H+-PPases) were also found in the PdPPase, which contains all the sequence motifs of the prototypical type I V–H+-PPase from Arabidopsis thaliana vacuolar pyrophosphatase type I (AVP1) plant. The PdPPase has a characteristic residue that determines strict K+-dependence, but unlike AVP1, PdPPase contains an N-terminal signal peptide (SP) sequence. Antibodies generated by vaccination of mice with a genetic or recombinant protein containing a partial sequence of the PdPPase and a common motif with the polyclonal antibody PABHK specific to AVP1 recognized a single band of about 62 kDa in western blots. These antibodies specifically stained both vacuole and the alveolar membranes of trophozoites of P. dicentrarchi. H+ transport was partially inhibited by the bisphosphonate pamidronate (PAM) and completely inhibited by NaF. The bisphosphonate PAM inhibited both H+-translocation and gene expression. PdPPase and PAM also inhibited in vitro growth of the ciliates. The apparent lack of V–H+-PPases in vertebrates and the parasite sensitivity to PPI analogues may provide a molecular target for developing new drugs to control scuticociliatosis.
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Proton/sodium pumping pyrophosphatases: the last of the primary ion pumps. Curr Opin Struct Biol 2014; 27:38-47. [DOI: 10.1016/j.sbi.2014.03.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2014] [Revised: 03/18/2014] [Accepted: 03/25/2014] [Indexed: 11/24/2022]
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Liu J, Pace D, Dou Z, King TP, Guidot D, Li ZH, Carruthers VB, Moreno SNJ. A vacuolar-H(+) -pyrophosphatase (TgVP1) is required for microneme secretion, host cell invasion, and extracellular survival of Toxoplasma gondii. Mol Microbiol 2014; 93:698-712. [PMID: 24975633 DOI: 10.1111/mmi.12685] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/19/2014] [Indexed: 01/17/2023]
Abstract
The vacuolar proton pyrophosphatase (H(+) -PPase) of Toxoplasma gondii (TgVP1), a membrane proton pump, localizes to acidocalcisomes and a novel lysosome-like compartment termed plant-like vacuole (PLV) or vacuolar compartment (VAC). We report the characterization of a T. gondii null mutant for the TgVP1 gene. Propagation of these mutants decreased significantly because of deficient attachment and invasion of host cells, which correlated with deficient microneme secretion. Processing of cathepsin L (CPL) in these mutants was deficient only when the parasites were incubated in the presence of low concentrations of the vacuolar H(+) -ATPase (V-H(+) -ATPase) inhibitor bafilomycin A1 , suggesting that either TgVP1 or the T. gondii V-H(+) -ATPase (TgVATPase) are sufficient to support CPL processing. The lack of TgVP1 did not affect processing of micronemal proteins, indicating that it does not contribute to proMIC maturations. The TgVP1 null mutants were more sensitive to extracellular conditions and were less virulent in mice. We demonstrate that T. gondii tachyzoites possess regulatory volume decrease capability during hypo-osmotic stress and this ability is impaired in TgVP1 null mutants implicating TgVP1 in osmoregulation. We hypothesize that osmoregulation is needed for host cell invasion and that TgVP1 plays a role during the normal lytic cycle of T. gondii.
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Affiliation(s)
- Jing Liu
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, GA, 30602-7400, USA; College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China
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Russell MJ, Barge LM, Bhartia R, Bocanegra D, Bracher PJ, Branscomb E, Kidd R, McGlynn S, Meier DH, Nitschke W, Shibuya T, Vance S, White L, Kanik I. The drive to life on wet and icy worlds. ASTROBIOLOGY 2014; 14:308-43. [PMID: 24697642 PMCID: PMC3995032 DOI: 10.1089/ast.2013.1110] [Citation(s) in RCA: 129] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 02/02/2014] [Indexed: 05/22/2023]
Abstract
This paper presents a reformulation of the submarine alkaline hydrothermal theory for the emergence of life in response to recent experimental findings. The theory views life, like other self-organizing systems in the Universe, as an inevitable outcome of particular disequilibria. In this case, the disequilibria were two: (1) in redox potential, between hydrogen plus methane with the circuit-completing electron acceptors such as nitrite, nitrate, ferric iron, and carbon dioxide, and (2) in pH gradient between an acidulous external ocean and an alkaline hydrothermal fluid. Both CO2 and CH4 were equally the ultimate sources of organic carbon, and the metal sulfides and oxyhydroxides acted as protoenzymatic catalysts. The realization, now 50 years old, that membrane-spanning gradients, rather than organic intermediates, play a vital role in life's operations calls into question the idea of "prebiotic chemistry." It informs our own suggestion that experimentation should look to the kind of nanoengines that must have been the precursors to molecular motors-such as pyrophosphate synthetase and the like driven by these gradients-that make life work. It is these putative free energy or disequilibria converters, presumably constructed from minerals comprising the earliest inorganic membranes, that, as obstacles to vectorial ionic flows, present themselves as the candidates for future experiments. Key Words: Methanotrophy-Origin of life. Astrobiology 14, 308-343. The fixation of inorganic carbon into organic material (autotrophy) is a prerequisite for life and sets the starting point of biological evolution. (Fuchs, 2011 ) Further significant progress with the tightly membrane-bound H(+)-PPase family should lead to an increased insight into basic requirements for the biological transport of protons through membranes and its coupling to phosphorylation. (Baltscheffsky et al., 1999 ).
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Characterization of the pyrophosphate-dependent 6-phosphofructokinase from Xanthomonas campestris pv. campestris. Arch Biochem Biophys 2014; 546:53-63. [DOI: 10.1016/j.abb.2014.01.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Revised: 01/23/2014] [Accepted: 01/26/2014] [Indexed: 01/01/2023]
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Eamens AL, Smith NA, Dennis ES, Wassenegger M, Wang MB. In Nicotiana species, an artificial microRNA corresponding to the virulence modulating region of Potato spindle tuber viroid directs RNA silencing of a soluble inorganic pyrophosphatase gene and the development of abnormal phenotypes. Virology 2014; 450-451:266-77. [PMID: 24503090 DOI: 10.1016/j.virol.2013.12.019] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Revised: 12/08/2013] [Accepted: 12/15/2013] [Indexed: 11/26/2022]
Abstract
Potato spindle tuber viroid (PSTVd) is a small non-protein-coding RNA pathogen that can induce disease symptoms in a variety of plant species. How PSTVd induces disease symptoms is a long standing question. It has been suggested that PSTVd-derived small RNAs (sRNAs) could direct RNA silencing of a targeted host gene(s) resulting in symptom development. To test this, we expressed PSTVd sequences as artificial microRNAs (amiRNAs) in Nicotiana tabacum and Nicotiana benthamiana. One amiRNA, amiR46 that corresponds to sequences within the PSTVd virulence modulating region (VMR), induced abnormal phenotypes in both Nicotiana species that closely resemble those displayed by PSTVd infected plants. In N. tabacum amiR46 plants, phenotype severity correlated with amiR46 accumulation and expression down-regulation of the bioinformatically-identified target gene, a Nicotiana soluble inorganic pyrophosphatase (siPPase). Taken together, our phenotypic and molecular analyses suggest that disease symptom development in Nicotiana species following PSTVd infection results from sRNA-directed RNA silencing of the host gene, siPPase.
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Affiliation(s)
- Andrew L Eamens
- CSIRO Plant Industry, Clunies Ross Street, Canberra, ACT 2601, Australia
| | - Neil A Smith
- CSIRO Plant Industry, Clunies Ross Street, Canberra, ACT 2601, Australia
| | - Elizabeth S Dennis
- CSIRO Plant Industry, Clunies Ross Street, Canberra, ACT 2601, Australia
| | - Michael Wassenegger
- RLP AgroScience GmbH, AIPlanta-Institute for Plant Research, Neustadt, Germany; Centre for Organisational Studies (COS) Heidelberg, University of Heidelberg, Heidelberg, Germany
| | - Ming-Bo Wang
- CSIRO Plant Industry, Clunies Ross Street, Canberra, ACT 2601, Australia.
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On an Early Gene for Membrane-Integral Inorganic Pyrophosphatase in the Genome of an Apparently Pre-LUCA Extremophile, the Archaeon Candidatus Korarchaeum cryptofilum. J Mol Evol 2014; 78:140-7. [DOI: 10.1007/s00239-014-9610-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2013] [Accepted: 01/17/2014] [Indexed: 10/25/2022]
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Freitas-Mesquita AL, Fonseca-de-Souza AL, Meyer-Fernandes JR. Leishmania amazonensis: characterization of an ecto-pyrophosphatase activity. Exp Parasitol 2013; 137:8-13. [PMID: 24316462 DOI: 10.1016/j.exppara.2013.11.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 11/22/2013] [Accepted: 11/27/2013] [Indexed: 01/30/2023]
Abstract
Several ecto-enzymatic activities have been described in the plasma membrane of the protozoan Leishmania amazonensis, which is the major etiological agent of diffuse cutaneous leishmaniasis in South America. These enzymes, including ecto-phosphatases, contribute to the survival of the parasite by participating in phosphate metabolism. This work identifies and characterizes the extracellular hydrolysis of inorganic pyrophosphate related to an ecto-pyrophosphatase activity of the promastigote form of L. amazonensis. This ecto-pyrophosphatase activity is insensitive to MnCl2 but is strongly stimulated by MgCl2. This stimulation was not observed during the hydrolysis of p-nitrophenyl phosphate (p-NPP) or β-glycerophosphate, two substrates for different ecto-phosphatases present in the L. amazonensis plasma membrane. Furthermore, extracellular PPi hydrolysis is more efficient at alkaline pHs, while p-NPP hydrolysis occurs mainly at acidic pHs. These results led us to conclude that extracellular PPi is hydrolyzed not by non-specific ecto-phosphatases but rather by a genuine ecto-pyrophosphatase. In the presence of 5mM MgCl2, the ecto-pyrophosphatase activity from L. amazonensis is sensitive to micromolar concentrations of NaF and millimolar concentrations of CaCl2. Moreover, this activity is significantly higher during the first days of L. amazonensis culture, which suggests a possible role for this enzyme in parasite growth.
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Affiliation(s)
- Anita Leocadio Freitas-Mesquita
- Instituto de Bioquímica Médica, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, RJ, Brazil; Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, 21941-590 Rio de Janeiro, RJ, Brazil
| | - André Luiz Fonseca-de-Souza
- Laboratório de Terapia e Fisiologia Celular e Molecular, Centro Universitário Estadual da Zona Oeste, 23070-200 Rio de Janeiro, RJ, Brazil
| | - José Roberto Meyer-Fernandes
- Instituto de Bioquímica Médica, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, RJ, Brazil; Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, 21941-590 Rio de Janeiro, RJ, Brazil.
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Galizzi M, Bustamante JM, Fang J, Miranda K, Soares Medeiros LC, Tarleton RL, Docampo R. Evidence for the role of vacuolar soluble pyrophosphatase and inorganic polyphosphate in Trypanosoma cruzi persistence. Mol Microbiol 2013; 90:699-715. [PMID: 24033456 DOI: 10.1111/mmi.12392] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/02/2013] [Indexed: 11/30/2022]
Abstract
Trypanosoma cruzi infection leads to development of a chronic disease but the mechanisms that the parasite utilizes to establish a persistent infection despite activation of a potent immune response by the host are currently unknown. Unusual characteristics of T. cruzi are that it possesses cellular levels of pyrophosphate (PPi ) at least 10 times higher than those of ATP and molar levels of inorganic polyphosphate (polyP) within acidocalcisomes. We characterized an inorganic soluble EF-hand containing pyrophosphatase from T. cruzi (TcVSP) that, depending on the pH and cofactors, can hydrolyse either pyrophosphate (PPi ) or polyphosphate (polyP). The enzyme is localized to both acidocalcisomes and cytosol. Overexpression of TcVSP (TcVSP-OE) resulted in a significant decrease in cytosolic PPi , and short and long-chain polyP levels. Additionally, the TcVSP-OE parasites showed a significant growth defect in fibroblasts, less responsiveness to hyperosmotic stress, and reduced persistence in tissues of mice, suggesting that PPi and polyP are essential for the parasite to resist the stressful conditions in the host and to maintain a persistent infection.
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Affiliation(s)
- Melina Galizzi
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA, 30602, USA
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Abstract
Life is evolutionarily the most complex of the emergent symmetry-breaking, macroscopically organized dynamic structures in the Universe. Members of this cascading series of disequilibria-converting systems, or engines in Cottrell's terminology, become ever more complicated-more chemical and less physical-as each engine extracts, exploits and generates ever lower grades of energy and resources in the service of entropy generation. Each one of these engines emerges spontaneously from order created by a particular mother engine or engines, as the disequilibrated potential daughter is driven beyond a critical point. Exothermic serpentinization of ocean crust is life's mother engine. It drives alkaline hydrothermal convection and thereby the spontaneous production of precipitated submarine hydrothermal mounds. Here, the two chemical disequilibria directly causative in the emergence of life spontaneously arose across the mineral precipitate membranes separating the acidulous, nitrate-bearing CO2-rich, Hadean sea from the alkaline and CH4/H2-rich serpentinization-generated effluents. Essential redox gradients-involving hydrothermal CH4 and H2 as electron donors, CO2 and nitrate, nitrite, and ferric iron from the ambient ocean as acceptors-were imposed which functioned as the original 'carbon-fixing engine'. At the same time, a post-critical-point (milli)voltage pH potential (proton concentration gradient) drove the condensation of orthophosphate to produce a high energy currency: 'the pyrophosphatase engine'.
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Affiliation(s)
- Michael J Russell
- Planetary Science Section 3225, MS:183-301, Jet Propulsion Laboratory, California Institute of Technology, , 4800 Oak Grove Drive, Pasadena, CA 91109-8099, USA.
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Baykov AA, Malinen AM, Luoto HH, Lahti R. Pyrophosphate-fueled Na+ and H+ transport in prokaryotes. Microbiol Mol Biol Rev 2013; 77:267-76. [PMID: 23699258 PMCID: PMC3668671 DOI: 10.1128/mmbr.00003-13] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In its early history, life appeared to depend on pyrophosphate rather than ATP as the source of energy. Ancient membrane pyrophosphatases that couple pyrophosphate hydrolysis to active H(+) transport across biological membranes (H(+)-pyrophosphatases) have long been known in prokaryotes, plants, and protists. Recent studies have identified two evolutionarily related and widespread prokaryotic relics that can pump Na(+) (Na(+)-pyrophosphatase) or both Na(+) and H(+) (Na(+),H(+)-pyrophosphatase). Both these transporters require Na(+) for pyrophosphate hydrolysis and are further activated by K(+). The determination of the three-dimensional structures of H(+)- and Na(+)-pyrophosphatases has been another recent breakthrough in the studies of these cation pumps. Structural and functional studies have highlighted the major determinants of the cation specificities of membrane pyrophosphatases and their potential use in constructing transgenic stress-resistant organisms.
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Affiliation(s)
- Alexander A. Baykov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Anssi M. Malinen
- Department of Biochemistry and Food Chemistry, University of Turku, Turku, Finland
| | - Heidi H. Luoto
- Department of Biochemistry and Food Chemistry, University of Turku, Turku, Finland
| | - Reijo Lahti
- Department of Biochemistry and Food Chemistry, University of Turku, Turku, Finland
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Abstract
Cofactor specificities of glycolytic enzymes in Clostridium thermocellum were studied with cellobiose-grown cells from batch cultures. Intracellular glucose was phosphorylated by glucokinase using GTP rather than ATP. Although phosphofructokinase typically uses ATP as a phosphoryl donor, we found only pyrophosphate (PPi)-linked activity. Phosphoglycerate kinase used both GDP and ADP as phosphoryl acceptors. In agreement with the absence of a pyruvate kinase sequence in the C. thermocellum genome, no activity of this enzyme could be detected. Also, the annotated pyruvate phosphate dikinase (ppdk) is not crucial for the generation of pyruvate from phosphoenolpyruvate (PEP), as deletion of the ppdk gene did not substantially change cellobiose fermentation. Instead pyruvate formation is likely to proceed via a malate shunt with GDP-linked PEP carboxykinase, NADH-linked malate dehydrogenase, and NADP-linked malic enzyme. High activities of these enzymes were detected in extracts of cellobiose-grown cells. Our results thus show that GTP is consumed while both GTP and ATP are produced in glycolysis of C. thermocellum. The requirement for PPi in this pathway can be satisfied only to a small extent by biosynthetic reactions, in contrast to what is generally assumed for a PPi-dependent glycolysis in anaerobic heterotrophs. Metabolic network analysis showed that most of the required PPi must be generated via ATP or GTP hydrolysis exclusive of that which happens during biosynthesis. Experimental proof for the necessity of an alternative mechanism of PPi generation was obtained by studying the glycolysis in washed-cell suspensions in which biosynthesis was absent. Under these conditions, cells still fermented cellobiose to ethanol.
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Shishova MF, Tankelyun OV, Rudashevskaya EL, Emel’yanov VV, Shakhova NV, Kirpichnikova AA. Alteration of transport activity of proton pumps in coleoptile cells during early development stages of maize seedlings. Russ J Dev Biol 2012. [DOI: 10.1134/s1062360412060070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Branscomb E, Russell MJ. Turnstiles and bifurcators: the disequilibrium converting engines that put metabolism on the road. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1827:62-78. [PMID: 23063910 DOI: 10.1016/j.bbabio.2012.10.003] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Revised: 10/02/2012] [Accepted: 10/03/2012] [Indexed: 10/27/2022]
Abstract
The Submarine Hydrothermal Alkaline Spring Theory for the emergence of life holds that it is the ordered delivery of hydrogen and methane in alkaline hydrothermal solutions at a spontaneously precipitated inorganic osmotic and catalytic membrane to the carbon dioxide and other electron acceptors in the earliest acidulous cool ocean that, through these gradients, drove life into being. That such interactions between hydrothermal fuels and potential oxidants have so far not been accomplished in the lab is because some steps along the necessary metabolic pathways are endergonic and must therefore be driven by being coupled to thermodynamically larger exergonic processes. But coupling of this kind is far from automatic and it is not enough to merely sum the ΔGs of two supposedly coupled reactions and show their combined thermodynamic viability. An exergonic reaction will not drive an endergonic one unless 'forced' to do so by being tied to it mechanistically via an organized "engine" of "Free Energy Conversion" (FEC). Here we discuss the thermodynamics of FEC and advance proposals regarding the nature and roles of the FEC devices that could, in principle, have arisen spontaneously in the alkaline hydrothermal context and have forced the onset of a protometabolism. The key challenge is to divine what these initial engines of life were in physicochemical terms and as part of that, what structures provided the first "turnstile-like" mechanisms needed to couple the partner processes in free energy conversion; in particular to couple the dissipation of geochemically given gradients to, say, the reduction of CO(2) to formate and the generation of a pyrophosphate disequilibrium. This article is part of a Special Issue entitled: The evolutionary aspects of bioenergetic systems.
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Schoepp-Cothenet B, van Lis R, Atteia A, Baymann F, Capowiez L, Ducluzeau AL, Duval S, ten Brink F, Russell MJ, Nitschke W. On the universal core of bioenergetics. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1827:79-93. [PMID: 22982447 DOI: 10.1016/j.bbabio.2012.09.005] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 09/06/2012] [Accepted: 09/07/2012] [Indexed: 01/05/2023]
Abstract
Living cells are able to harvest energy by coupling exergonic electron transfer between reducing and oxidising substrates to the generation of chemiosmotic potential. Whereas a wide variety of redox substrates is exploited by prokaryotes resulting in very diverse layouts of electron transfer chains, the ensemble of molecular architectures of enzymes and redox cofactors employed to construct these systems is stunningly small and uniform. An overview of prominent types of electron transfer chains and of their characteristic electrochemical parameters is presented. We propose that basic thermodynamic considerations are able to rationalise the global molecular make-up and functioning of these chemiosmotic systems. Arguments from palaeogeochemistry and molecular phylogeny are employed to discuss the evolutionary history leading from putative energy metabolisms in early life to the chemiosmotic diversity of extant organisms. Following the Occam's razor principle, we only considered for this purpose origin of life scenarios which are contiguous with extant life. This article is part of a Special Issue entitled: The evolutionary aspects of bioenergetic systems.
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Affiliation(s)
- Barbara Schoepp-Cothenet
- Laboratoire de Bioénergétique et Ingénierie des Protéines UMR 7281 CNRS/AMU, FR3479, F-13402 Marseille Cedex 20, France.
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40
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Kellosalo J, Kajander T, Kogan K, Pokharel K, Goldman A. The structure and catalytic cycle of a sodium-pumping pyrophosphatase. Science 2012; 337:473-6. [PMID: 22837527 DOI: 10.1126/science.1222505] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Membrane-integral pyrophosphatases (M-PPases) are crucial for the survival of plants, bacteria, and protozoan parasites. They couple pyrophosphate hydrolysis or synthesis to Na(+) or H(+) pumping. The 2.6-angstrom structure of Thermotoga maritima M-PPase in the resting state reveals a previously unknown solution for ion pumping. The hydrolytic center, 20 angstroms above the membrane, is coupled to the gate formed by the conserved Asp(243), Glu(246), and Lys(707) by an unusual "coupling funnel" of six α helices. Comparison with our 4.0-angstrom resolution structure of the product complex suggests that helix 12 slides down upon substrate binding to open the gate by a simple binding-change mechanism. Below the gate, four helices form the exit channel. Superimposing helices 3 to 6, 9 to 12, and 13 to 16 suggests that M-PPases arose through gene triplication.
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Affiliation(s)
- Juho Kellosalo
- Structural Biology and Biophysics Program, Institute of Biotechnology, Post Office Box 65, University of Helsinki, FIN-00014, Finland
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McGlynn SE, Kanik I, Russell MJ. Peptide and RNA contributions to iron-sulphur chemical gardens as life's first inorganic compartments, catalysts, capacitors and condensers. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2012; 370:3007-3022. [PMID: 22615473 DOI: 10.1098/rsta.2011.0211] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Hydrothermal chimneys and compartments comprising transition metal sulphides and associated minerals have been proposed as likely locations for the beginnings of life. In laboratory simulations of off-axis alkaline springs, it is shown that the interaction of a simulated alkaline sulphide-bearing submarine vent solution with a primeval anoxic iron-bearing ocean leads to the formation of chimney structures reminiscent of chemical gardens. These chimneys display periodicity in their deposition and exhibit diverse morphologies and mineralogies, affording the possibilities of catalysis and molecular sequestration. The addition of peptides and RNA to the alkaline solution modifies the elemental stoichiometry of the chimneys-perhaps indicating the very initial stage of the organic takeover on the way to living cells by charged organic polymers potentially synthesized in this same environment.
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Affiliation(s)
- Shawn E McGlynn
- Planetary Science Section 3220, MS:183-301, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099, USA
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Barge LM, Doloboff IJ, White LM, Stucky GD, Russell MJ, Kanik I. Characterization of iron-phosphate-silicate chemical garden structures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:3714-3721. [PMID: 22035594 DOI: 10.1021/la203727g] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Chemical gardens form when ferrous chloride hydrate seed crystals are added or concentrated solutions are injected into solutions of sodium silicate and potassium phosphate. Various precipitation morphologies are observed depending on silicate and phosphate concentrations, including hollow plumes, bulbs, and tubes. The growth of precipitates is controlled by the internal osmotic pressure, fluid buoyancy, and membrane strength. Additionally, rapid bubble-led growth is observed when silicate concentrations are high. ESEM/EDX analysis confirms compositional gradients within the membranes, and voltage measurements across the membranes during growth show a final potential of around 150-200 mV, indicating that electrochemical gradients are maintained across the membranes as growth proceeds. The characterization of chemical gardens formed with iron, silicate, and phosphate, three important components of an early earth prebiotic hydrothermal system, can help us understand the properties of analogous structures that likely formed at submarine alkaline hydrothermal vents in the Hadean-structures offering themselves as the hatchery of life.
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Affiliation(s)
- Laura M Barge
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, USA.
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43
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Mielke RE, Robinson KJ, White LM, McGlynn SE, McEachern K, Bhartia R, Kanik I, Russell MJ. Iron-sulfide-bearing chimneys as potential catalytic energy traps at life's emergence. ASTROBIOLOGY 2011; 11:933-950. [PMID: 22111762 DOI: 10.1089/ast.2011.0667] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The concept that life emerged where alkaline hydrogen-bearing submarine hot springs exhaled into the most ancient acidulous ocean was used as a working hypothesis to investigate the nature of precipitate membranes. Alkaline solutions at 25-70°C and pH between 8 and 12, bearing HS(-)±silicate, were injected slowly into visi-jars containing ferrous chloride to partially simulate the early ocean on this or any other wet and icy, geologically active rocky world. Dependent on pH and sulfide content, fine tubular chimneys and geodal bubbles were generated with semipermeable walls 4-100 μm thick that comprised radial platelets of nanometric mackinawite [FeS]±ferrous hydroxide [∼Fe(OH)(2)], accompanied by silica and, at the higher temperature, greigite [Fe(3)S(4)]. Within the chimney walls, these platelets define a myriad of micropores. The interior walls of the chimneys host iron sulfide framboids, while, in cases where the alkaline solution has a pH>11 or relatively low sulfide content, their exteriors exhibit radial flanges with a spacing of ∼4 μm that comprise microdendrites of ferrous hydroxide. We speculate that this pattern results from outward and inward radial flow through the chimney walls. The outer Fe(OH)(2) flanges perhaps precipitate where the highly alkaline flow meets the ambient ferrous iron-bearing fluid, while the intervening troughs signal where the acidulous iron-bearing solutions could gain access to the sulfidic and alkaline interior of the chimneys, thereby leading to the precipitation of the framboids. Addition of soluble pentameric peptides enhances membrane durability and accentuates the crenulations on the chimney exteriors. These dynamic patterns may have implications for acid-base catalysis and the natural proton motive force acting through the matrix of the porous inorganic membrane. Thus, within such membranes, steep redox and pH gradients would bear across the nanometric platelets and separate the two counter-flowing solutions, a condition that may have led to the onset of an autotrophic metabolism through the reduction of carbon dioxide.
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Affiliation(s)
- Randall E Mielke
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
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Pace DA, Fang J, Cintron R, Docampo MD, Moreno SNJ. Overexpression of a cytosolic pyrophosphatase (TgPPase) reveals a regulatory role of PP(i) in glycolysis for Toxoplasma gondii. Biochem J 2011; 440:229-40. [PMID: 21831041 PMCID: PMC4874478 DOI: 10.1042/bj20110641] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PP(i) is a critical element of cellular metabolism as both an energy donor and as an allosteric regulator of several metabolic pathways. The apicomplexan parasite Toxoplasma gondii uses PP(i) in place of ATP as an energy donor in at least two reactions: the glycolytic PP(i)-dependent PFK (phosphofructokinase) and V-H(+)-PPase [vacuolar H(+)-translocating PPase (pyrophosphatase)]. In the present study, we report the cloning, expression and characterization of cytosolic TgPPase (T. gondii soluble PPase). Amino acid sequence alignment and phylogenetic analysis indicates that the gene encodes a family I soluble PPase. Overexpression of the enzyme in extracellular tachyzoites led to a 6-fold decrease in the cytosolic concentration of PP(i) relative to wild-type strain RH tachyzoites. Unexpectedly, this subsequent reduction in PP(i) was associated with a higher glycolytic flux in the overexpressing mutants, as evidenced by higher rates of proton and lactate extrusion. In addition to elevated glycolytic flux, TgPPase-overexpressing tachyzoites also possessed higher ATP concentrations relative to wild-type RH parasites. These results implicate PP(i) as having a significant regulatory role in glycolysis and, potentially, other downstream processes that regulate growth and cell division.
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Affiliation(s)
- Douglas A Pace
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA.
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Luoto HH, Belogurov GA, Baykov AA, Lahti R, Malinen AM. Na+-translocating membrane pyrophosphatases are widespread in the microbial world and evolutionarily precede H+-translocating pyrophosphatases. J Biol Chem 2011; 286:21633-42. [PMID: 21527638 DOI: 10.1074/jbc.m111.244483] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Membrane pyrophosphatases (PPases), divided into K(+)-dependent and K(+)-independent subfamilies, were believed to pump H(+) across cell membranes until a recent demonstration that some K(+)-dependent PPases function as Na(+) pumps. Here, we have expressed seven evolutionarily important putative PPases in Escherichia coli and estimated their hydrolytic, Na(+) transport, and H(+) transport activities as well as their K(+) and Na(+) requirements in inner membrane vesicles. Four of these enzymes (from Anaerostipes caccae, Chlorobium limicola, Clostridium tetani, and Desulfuromonas acetoxidans) were identified as K(+)-dependent Na(+) transporters. Phylogenetic analysis led to the identification of a monophyletic clade comprising characterized and predicted Na(+)-transporting PPases (Na(+)-PPases) within the K(+)-dependent subfamily. H(+)-transporting PPases (H(+)-PPases) are more heterogeneous and form at least three independent clades in both subfamilies. These results suggest that rather than being a curious rarity, Na(+)-PPases predominantly constitute the K(+)-dependent subfamily. Furthermore, Na(+)-PPases possibly preceded H(+)-PPases in evolution, and transition from Na(+) to H(+) transport may have occurred in several independent enzyme lineages. Site-directed mutagenesis studies facilitated the identification of a specific Glu residue that appears to be central in the transport mechanism. This residue is located in the cytoplasm-membrane interface of transmembrane helix 6 in Na(+)-PPases but shifted to within the membrane or helix 5 in H(+)-PPases. These results contribute to the prediction of the transport specificity and K(+) dependence for a particular membrane PPase sequence based on its position in the phylogenetic tree, identity of residues in the K(+) dependence signature, and position of the membrane-located Glu residue.
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Affiliation(s)
- Heidi H Luoto
- Department of Biochemistry and Food Chemistry, University of Turku, FIN-20014 Turku, Finland
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Lee CH, Pan YJ, Huang YT, Liu TH, Hsu SH, Lee CH, Chen YW, Lin SM, Huang LK, Pan RL. Identification of essential lysines involved in substrate binding of vacuolar H+-pyrophosphatase. J Biol Chem 2011; 286:11970-6. [PMID: 21292767 DOI: 10.1074/jbc.m110.190215] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
H+-translocating pyrophosphatase (H+-PPase; EC 3.6.1.1) drives proton transport against an electrochemical potential gradient by hydrolyzing pyrophosphate (PPi) and is found in various endomembranes of higher plants, bacteria, and some protists. H+-PPase contains seven highly conserved lysines. We examined the functional roles of these lysines, which are, for the most part, found in the cytosolic regions of mung bean H+-PPase by site-directed mutagenesis. Construction of mutants that each had a cytosolic and highly conserved lysine substituted with an alanine resulted in dramatic drops in the PPi hydrolytic activity. The effects caused by ions on the activities of WT and mutant H+-PPases suggest that Lys-730 may be in close proximity to the Mg2+-binding site, and the great resistance of the K694A and K695A mutants to fluoride inhibition suggests that these lysines are present in the active site. The modifier fluorescein 5'-isothiocyanate (FITC) labeled a lysine at the H+-PPase active site but did not inhibit the hydrolytic activities of K250A, K250N, K250T, and K250S, which suggested that Lys-250 is essential for substrate binding and may be involved in proton translocation. Analysis of tryptic digests indicated that Lys-711 and Lys-717 help maintain the conformation of the active site. Proteolytic evidence also demonstrated that Lys-250 is the primary target of trypsin and confirmed its crucial role in H+-PPase hydrolysis.
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Affiliation(s)
- Chien-Hsien Lee
- Department of Life Science and Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, Hsin Chu 30043, Taiwan
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Biegel E, Müller V. A Na+-translocating pyrophosphatase in the acetogenic bacterium Acetobacterium woodii. J Biol Chem 2010; 286:6080-4. [PMID: 21173152 DOI: 10.1074/jbc.m110.192823] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The anaerobic acetogenic bacterium Acetobacterium woodii employs a novel type of Na(+)-motive anaerobic respiration, caffeate respiration. However, this respiration is at the thermodynamic limit of energy conservation, and even worse, in the first step, caffeate is activated by caffeyl-CoA synthetase, which hydrolyzes ATP to AMP and pyrophosphate. Here, we have addressed whether or not the energy stored in the anhydride bond of pyrophosphate is conserved by A. woodii. Inverted membrane vesicles of A. woodii have a membrane-bound pyrophosphatase that catalyzes pyrophosphate hydrolysis at a rate of 70-120 milliunits/mg of protein. Pyrophosphatase activity was dependent on the divalent cation Mg(2+). In addition, activity was strictly dependent on Na(+) with a K(m) of 1.1 mM. Hydrolysis of pyrophosphate was accompanied by (22)Na(+) transport into the lumen of the inverted membrane vesicles. Inhibitor studies revealed that (22)Na(+) transport was primary and electrogenic. Next to the Na(+)-motive ferredoxin:NAD(+) oxidoreductase (Fno or Rnf), the Na(+)-pyrophosphatase is the second primary Na(+)-translocating enzyme in A. woodii.
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Affiliation(s)
- Eva Biegel
- Department of Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University Frankfurt/Main, Max-von-Laue-Strasse 9, 60438 Frankfurt, Germany
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George GM, van der Merwe MJ, Nunes-Nesi A, Bauer R, Fernie AR, Kossmann J, Lloyd JR. Virus-induced gene silencing of plastidial soluble inorganic pyrophosphatase impairs essential leaf anabolic pathways and reduces drought stress tolerance in Nicotiana benthamiana. PLANT PHYSIOLOGY 2010; 154:55-66. [PMID: 20605913 PMCID: PMC2938153 DOI: 10.1104/pp.110.157776] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Accepted: 07/02/2010] [Indexed: 05/18/2023]
Abstract
The role of pyrophosphate in primary metabolism is poorly understood. Here, we report on the transient down-regulation of plastid-targeted soluble inorganic pyrophosphatase in Nicotiana benthamiana source leaves. Physiological and metabolic perturbations were particularly evident in chloroplastic central metabolism, which is reliant on fast and efficient pyrophosphate dissipation. Plants lacking plastidial soluble inorganic pyrophosphatase (psPPase) were characterized by increased pyrophosphate levels, decreased starch content, and alterations in chlorophyll and carotenoid biosynthesis, while constituents like amino acids (except for histidine, serine, and tryptophan) and soluble sugars and organic acids (except for malate and citrate) remained invariable from the control. Furthermore, translation of Rubisco was significantly affected, as observed for the amounts of the respective subunits as well as total soluble protein content. These changes were concurrent with the fact that plants with reduced psPPase were unable to assimilate carbon to the same extent as the controls. Furthermore, plants with lowered psPPase exposed to mild drought stress showed a moderate wilting phenotype and reduced vitality, which could be correlated to reduced abscisic acid levels limiting stomatal closure. Taken together, the results suggest that plastidial pyrophosphate dissipation through psPPase is indispensable for vital plant processes.
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Affiliation(s)
| | | | | | | | | | | | - James R. Lloyd
- Institute of Plant Biotechnology, University of Stellenbosch, Matieland 7602, Stellenbosch, South Africa (G.M.G., M.J.v.d.M., R.B., J.K., J.R.L.); Max Planck Institute of Molecular Plant Physiology, D–14476 Potsdam-Golm, Germany (A.N.-N., A.R.F.)
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van der Merwe MJ, Groenewald JH, Stitt M, Kossmann J, Botha FC. Downregulation of pyrophosphate: D-fructose-6-phosphate 1-phosphotransferase activity in sugarcane culms enhances sucrose accumulation due to elevated hexose-phosphate levels. PLANTA 2010; 231:595-608. [PMID: 19957089 PMCID: PMC2806535 DOI: 10.1007/s00425-009-1069-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Accepted: 11/09/2009] [Indexed: 05/19/2023]
Abstract
Analyses of transgenic sugarcane clones with 45-95% reduced cytosolic pyrophosphate: D-fructose-6-phosphate 1-phosphotransferase (PFP, EC 2.7.1.90) activity displayed no visual phenotypical change, but significant changes were evident in in vivo metabolite levels and fluxes during internode development. In three independent transgenic lines, sucrose concentrations increased between three- and sixfold in immature internodes, compared to the levels in the wildtype control. There was an eightfold increase in the hexose-phosphate:triose-phosphate ratio in immature internodes, a significant restriction in the triose phosphate to hexose phosphate cycle and significant increase in sucrose cycling as monitored by (13)C nuclear magnetic resonance. This suggests that an increase in the hexose-phosphate concentrations resulting from a restriction in the conversion of hexose phosphates to triose phosphates drive sucrose synthesis in the young internodes. These effects became less pronounced as the tissue matured. Decreased expression of PFP also resulted in an increase of the ATP/ADP and UTP/UDP ratios, and an increase of the total uridine nucleotide and, at a later stage, the total adenine nucleotide pool, revealing strong interactions between PPi metabolism and general energy metabolism. Finally, decreased PFP leads to a reduction of PPi levels in older internodes indicating that in these developmental stages PFP acts in the gluconeogenic direction. The lowered PPi levels might also contribute to the absence of increases in sucrose contents in the more mature tissues of transgenic sugarcane with reduced PFP activity.
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Affiliation(s)
- Margaretha J van der Merwe
- Institute of Plant Biotechnology, University of Stellenbosch, Merriman Avenue, Stellenbosch 7602, South Africa.
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Liu Q, Zhang Q, Burton RA, Shirley NJ, Atwell BJ. Expression of vacuolar H+-pyrophosphatase (OVP3) is under control of an anoxia-inducible promoter in rice. PLANT MOLECULAR BIOLOGY 2010; 72:47-60. [PMID: 19763843 DOI: 10.1007/s11103-009-9549-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2008] [Accepted: 09/07/2009] [Indexed: 05/08/2023]
Abstract
Vacuolar H(+)-pyrophosphatase (V-PPase) expression increases in a number of abiotic stresses and is thought to play a role in adaptation to abiotic stresses. This paper reports on the regulation of six V-PPase genes in rice (Oryza sativa L.) coleoptiles under anoxia, using flood tolerant and intolerant cultivars to test our hypothesis. Quantitative PCR analysis showed that one vacuolar H(+)-pyrophosphatase (OVP3) was induced by anoxia, particularly in flood-tolerant rice. Regulation of OVP3 expression under anoxia was investigated by analysing putative OVP promoters. The putative OVP3 promoter contained more previously identified anoxia-inducible motifs than the putative promoters of the other five OVP genes. GUS activity in transgenic rice plants containing the OVP3 promoter region linked to the GUS reporter gene was induced only by anoxia. Salt and cold treatments had little effect on OVP3 promoter-driven GUS expression when compared to the anoxic treatment.
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Affiliation(s)
- Qinxiang Liu
- Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia
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