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Witkowska M, Jedrzejczak RP, Joachimiak A, Cavdar O, Malankowska A, Skowron PM, Zylicz-Stachula A. Promising approaches for the assembly of the catalytically active, recombinant Desulfomicrobium baculatum hydrogenase with substitutions at the active site. Microb Cell Fact 2023; 22:134. [PMID: 37479997 PMCID: PMC10362691 DOI: 10.1186/s12934-023-02127-w] [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: 03/22/2023] [Accepted: 06/17/2023] [Indexed: 07/23/2023] Open
Abstract
BACKGROUND Hydrogenases (H2ases) are metalloenzymes capable of the reversible conversion of protons and electrons to molecular hydrogen. Exploiting the unique enzymatic activity of H2ases can lead to advancements in the process of biohydrogen evolution and green energy production. RESULTS Here we created of a functional, optimized operon for rapid and robust production of recombinant [NiFe] Desulfomicrobium baculatum hydrogenase (Dmb H2ase). The conversion of the [NiFeSe] Dmb H2ase to [NiFe] type was performed on genetic level by site-directed mutagenesis. The native dmb operon includes two structural H2ase genes, coding for large and small subunits, and an additional gene, encoding a specific maturase (protease) that is essential for the proper maturation of the enzyme. Dmb, like all H2ases, needs intricate bio-production machinery to incorporate its crucial inorganic ligands and cofactors. Strictly anaerobic, sulfate reducer D. baculatum bacteria are distinct, in terms of their biology, from E. coli. Thus, we introduced a series of alterations within the native dmb genes. As a result, more than 100 elements, further compiled into 32 operon variants, were constructed. The initial requirement for a specific maturase was omitted by the artificial truncation of the large Dmb subunit. The assembly of the produced H2ase subunit variants was investigated both, in vitro and in vivo. This approach resulted in 4 recombinant [NiFe] Dmb enzyme variants, capable of H2 evolution. The aim of this study was to overcome the gene expression, protein biosynthesis, maturation and ligand loading bottlenecks for the easy, fast, and cost-effective delivery of recombinant [NiFe] H2ase, using a commonly available E. coli strains. CONCLUSION The optimized genetic constructs together with the developed growth and purification procedures appear to be a promising platform for further studies toward fully-active and O2 tolerant, recombinant [NiFeSe] Dmb H2ase, resembling the native Dmb enzyme. It could likely be achieved by selective cysteine to selenocysteine substitution within the active site of the [NiFe] Dmb variant.
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Affiliation(s)
- Malgorzata Witkowska
- Department of Molecular Biotechnology, Faculty of Chemistry, University of Gdansk, Wita Stwosza 63, Gdansk, 80-308, Poland
| | - Robert P Jedrzejczak
- Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - Andrzej Joachimiak
- Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - Onur Cavdar
- Department of Environmental Technology, Faculty of Chemistry, University of Gdansk, Wita Stwosza 63, Gdansk, 80-308, Poland
| | - Anna Malankowska
- Department of Environmental Technology, Faculty of Chemistry, University of Gdansk, Wita Stwosza 63, Gdansk, 80-308, Poland
| | - Piotr M Skowron
- Department of Molecular Biotechnology, Faculty of Chemistry, University of Gdansk, Wita Stwosza 63, Gdansk, 80-308, Poland
| | - Agnieszka Zylicz-Stachula
- Department of Molecular Biotechnology, Faculty of Chemistry, University of Gdansk, Wita Stwosza 63, Gdansk, 80-308, Poland.
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Benoit SL, Maier RJ, Sawers RG, Greening C. Molecular Hydrogen Metabolism: a Widespread Trait of Pathogenic Bacteria and Protists. Microbiol Mol Biol Rev 2020; 84:e00092-19. [PMID: 31996394 PMCID: PMC7167206 DOI: 10.1128/mmbr.00092-19] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Pathogenic microorganisms use various mechanisms to conserve energy in host tissues and environmental reservoirs. One widespread but often overlooked means of energy conservation is through the consumption or production of molecular hydrogen (H2). Here, we comprehensively review the distribution, biochemistry, and physiology of H2 metabolism in pathogens. Over 200 pathogens and pathobionts carry genes for hydrogenases, the enzymes responsible for H2 oxidation and/or production. Furthermore, at least 46 of these species have been experimentally shown to consume or produce H2 Several major human pathogens use the large amounts of H2 produced by colonic microbiota as an energy source for aerobic or anaerobic respiration. This process has been shown to be critical for growth and virulence of the gastrointestinal bacteria Salmonella enterica serovar Typhimurium, Campylobacter jejuni, Campylobacter concisus, and Helicobacter pylori (including carcinogenic strains). H2 oxidation is generally a facultative trait controlled by central regulators in response to energy and oxidant availability. Other bacterial and protist pathogens produce H2 as a diffusible end product of fermentation processes. These include facultative anaerobes such as Escherichia coli, S Typhimurium, and Giardia intestinalis, which persist by fermentation when limited for respiratory electron acceptors, as well as obligate anaerobes, such as Clostridium perfringens, Clostridioides difficile, and Trichomonas vaginalis, that produce large amounts of H2 during growth. Overall, there is a rich literature on hydrogenases in growth, survival, and virulence in some pathogens. However, we lack a detailed understanding of H2 metabolism in most pathogens, especially obligately anaerobic bacteria, as well as a holistic understanding of gastrointestinal H2 transactions overall. Based on these findings, we also evaluate H2 metabolism as a possible target for drug development or other therapies.
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Affiliation(s)
- Stéphane L Benoit
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
| | - Robert J Maier
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
| | - R Gary Sawers
- Institute of Microbiology, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Chris Greening
- School of Biological Sciences, Monash University, Clayton, VIC, Australia
- Department of Microbiology, Monash Biomedicine Discovery Institute, Clayton, VIC, Australia
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3
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Land H, Ceccaldi P, Mészáros LS, Lorenzi M, Redman HJ, Senger M, Stripp ST, Berggren G. Discovery of novel [FeFe]-hydrogenases for biocatalytic H 2-production. Chem Sci 2019; 10:9941-9948. [PMID: 32055351 PMCID: PMC6984386 DOI: 10.1039/c9sc03717a] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Accepted: 09/23/2019] [Indexed: 11/21/2022] Open
Abstract
A semi-synthetic screening method for mining the biodiversity of [FeFe]-hydrogenases, expanding the toolbox for biocatalytic H2-gas production.
A new screening method for [FeFe]-hydrogenases is described, circumventing the need for specialized expression conditions as well as protein purification for initial characterization. [FeFe]-hydrogenases catalyze the formation and oxidation of molecular hydrogen at rates exceeding 103 s–1, making them highly promising for biotechnological applications. However, the discovery of novel [FeFe]-hydrogenases is slow due to their oxygen sensitivity and dependency on a structurally unique cofactor, complicating protein expression and purification. Consequently, only a very limited number have been characterized, hampering their implementation. With the purpose of increasing the throughput of [FeFe]-hydrogenase discovery, we have developed a screening method that allows for rapid identification of novel [FeFe]-hydrogenases as well as their characterization with regards to activity (activity assays and protein film electrochemistry) and spectroscopic properties (electron paramagnetic resonance and Fourier transform infrared spectroscopy). The method is based on in vivo artificial maturation of [FeFe]-hydrogenases in Escherichia coli and all procedures are performed on either whole cells or non-purified cell lysates, thereby circumventing extensive protein purification. The screening was applied on eight putative [FeFe]-hydrogenases originating from different structural sub-classes and resulted in the discovery of two new active [FeFe]-hydrogenases. The [FeFe]-hydrogenase from Solobacterium moorei shows high H2-gas production activity, while the enzyme from Thermoanaerobacter mathranii represents a hitherto uncharacterized [FeFe]-hydrogenase sub-class. This latter enzyme is a putative sensory hydrogenase and our in vivo spectroscopy study reveals distinct differences compared to the well established H2 producing HydA1 hydrogenase from Chlamydomonas reinhardtii.
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Affiliation(s)
- Henrik Land
- Molecular Biomimetics , Department of Chemistry - Ångström Laboratory , Uppsala University , Box 523 , Uppsala , SE-75120 , Sweden .
| | - Pierre Ceccaldi
- Molecular Biomimetics , Department of Chemistry - Ångström Laboratory , Uppsala University , Box 523 , Uppsala , SE-75120 , Sweden .
| | - Lívia S Mészáros
- Molecular Biomimetics , Department of Chemistry - Ångström Laboratory , Uppsala University , Box 523 , Uppsala , SE-75120 , Sweden .
| | - Marco Lorenzi
- Molecular Biomimetics , Department of Chemistry - Ångström Laboratory , Uppsala University , Box 523 , Uppsala , SE-75120 , Sweden .
| | - Holly J Redman
- Molecular Biomimetics , Department of Chemistry - Ångström Laboratory , Uppsala University , Box 523 , Uppsala , SE-75120 , Sweden .
| | - Moritz Senger
- Institute of Experimental Physics, Experimental Molecular Biophysics , Freie Universität Berlin , Arnimallee 14 , Berlin , DE-14195 , Germany
| | - Sven T Stripp
- Institute of Experimental Physics, Experimental Molecular Biophysics , Freie Universität Berlin , Arnimallee 14 , Berlin , DE-14195 , Germany
| | - Gustav Berggren
- Molecular Biomimetics , Department of Chemistry - Ångström Laboratory , Uppsala University , Box 523 , Uppsala , SE-75120 , Sweden .
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4
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Rowe SF, Le Gall G, Ainsworth EV, Davies JA, Lockwood CWJ, Shi L, Elliston A, Roberts IN, Waldron KW, Richardson DJ, Clarke TA, Jeuken LJC, Reisner E, Butt JN. Light-Driven H2 Evolution and C═C or C═O Bond Hydrogenation by Shewanella oneidensis: A Versatile Strategy for Photocatalysis by Nonphotosynthetic Microorganisms. ACS Catal 2017. [DOI: 10.1021/acscatal.7b02736] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sam F. Rowe
- School
of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Gwénaëlle Le Gall
- Quadram
Institute for Bioscience, Norwich Research Park, Norwich NR4 7UA, U.K
| | - Emma V. Ainsworth
- School
of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Jonathan A. Davies
- School
of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Colin W. J. Lockwood
- School
of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Liang Shi
- Department
of Biological Sciences and Technology, China University of Geoscience in Wuhan, Wuhan 430074, People’s Republic of China
| | - Adam Elliston
- Quadram
Institute for Bioscience, Norwich Research Park, Norwich NR4 7UA, U.K
| | - Ian N. Roberts
- Quadram
Institute for Bioscience, Norwich Research Park, Norwich NR4 7UA, U.K
| | - Keith W. Waldron
- Quadram
Institute for Bioscience, Norwich Research Park, Norwich NR4 7UA, U.K
| | - David J. Richardson
- School
of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Thomas A. Clarke
- School
of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Lars J. C. Jeuken
- School
of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, U.K
| | - Erwin Reisner
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
| | - Julea N. Butt
- School
of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
- School
of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
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5
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Cheng J, Liu M, Song W, Ding L, Liu J, Zhang L, Cen K. Enhanced hydrogen production of Enterobacter aerogenes mutated by nuclear irradiation. BIORESOURCE TECHNOLOGY 2017; 227:50-55. [PMID: 28013136 DOI: 10.1016/j.biortech.2016.12.033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 12/08/2016] [Accepted: 12/09/2016] [Indexed: 06/06/2023]
Abstract
Nuclear irradiation was used for the first time to generate efficient mutants of hydrogen-producing bacteria Enterobacter aerogenes, which were screened with larger colour circles of more fermentative acid by-products. E. aerogenes cells were mutated by nuclear irradiation of 60Co γ-rays. The screened E. aerogenes ZJU1 mutant with larger colour circles enhanced the hydrogenase activity from 89.8 of the wild strain to 157.4mLH2/(gDWh). The hereditary stability of the E. aerogenes ZJU1 mutant was certified after over ten generations of cultivation. The hydrogen yield of 301mLH2/gglucose with the mutant was higher by 81.8% than that of 166mL/gglucose with the wild strain. The peak hydrogen production rate of 27.2mL/(L·h) with the mutant was higher by 40.9% compared with that of 19.3mL/(L·h) with the wild strain. The mutant produced more acetate and butyrate but less ethanol compared with the wild strain during hydrogen fermentation.
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Affiliation(s)
- Jun Cheng
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China.
| | - Min Liu
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
| | - Wenlu Song
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China; Department of Life Science and Engineering, Jining University, Jining 273155, China
| | - Lingkan Ding
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
| | - Jianzhong Liu
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
| | - Li Zhang
- Shandong Botong New Energy Company, Jining 272000, China
| | - Kefa Cen
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
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6
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Lacasse MJ, Douglas CD, Zamble DB. Mechanism of Selective Nickel Transfer from HypB to HypA, Escherichia coli [NiFe]-Hydrogenase Accessory Proteins. Biochemistry 2016; 55:6821-6831. [PMID: 27951644 DOI: 10.1021/acs.biochem.6b00706] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
[NiFe]-hydrogenase enzymes catalyze the reversible reduction of protons to molecular hydrogen and serve as a vital component of the metabolism of many pathogens. The synthesis of the bimetallic catalytic center requires a suite of accessory proteins, and the penultimate step, nickel insertion, is facilitated by the metallochaperones HypA and HypB. In Escherichia coli, nickel moves from a site in the GTPase domain of HypB to HypA in a process accelerated by GDP. To determine how the transfer of nickel is controlled, the impacts of HypA and nucleotides on the properties of HypB were examined. Integral to this work was His2Gln HypA, a mutant with attenuated nickel affinity that does not support hydrogenase production in E. coli. This mutation inhibits the translocation of nickel from HypB. H2Q-HypA does not modulate the apparent metal affinity of HypB, but the stoichiometry and stability of the HypB-nickel complex are modulated by the nucleotide. Furthermore, the HypA-HypB interaction was detected by gel filtration chromatography if HypB was loaded with GDP, but not a GTP analogue, and the protein complex dissociated upon binding of nickel to His2 of HypA. In contrast, a nucleotide does not modulate the binding of zinc to HypB, and loading zinc into the GTPase domain of HypB inhibits formation of the complex with HypA. These results demonstrate that GTP hydrolysis controls both metal binding and protein-protein interactions, conferring selective and directional nickel transfer during [NiFe]-hydrogenase biosynthesis.
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Affiliation(s)
- Michael J Lacasse
- Department of Chemistry, University of Toronto , Toronto, Ontario, Canada M5S 3H6
| | - Colin D Douglas
- Department of Chemistry, University of Toronto , Toronto, Ontario, Canada M5S 3H6
| | - Deborah B Zamble
- Department of Chemistry, University of Toronto , Toronto, Ontario, Canada M5S 3H6.,Department of Biochemistry, University of Toronto , Toronto, Ontario, Canada M5S 1A8
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7
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Abstract
A simple, functional mimic of [NiFe] hydrogenases based on a nickel-substituted rubredoxin (NiRd) protein is reported. NiRd is capable of light-initiated and solution-phase hydrogen production and demonstrates high electrocatalytic activity using protein film voltammetry. The catalytic voltammograms are modeled using analytical expressions developed for hydrogenase enzymes, revealing maximum turnover frequencies of approximately 20-100 s(-1) at 4 °C with an overpotential of 540 mV. These rates are directly comparable to those observed for [NiFe] hydrogenases under similar conditions. Like the native enzymes, the proton reduction activity of NiRd is strongly inhibited by carbon monoxide. This engineered rubredoxin-based enzyme is chemically and thermally robust, easily accessible, and highly tunable. These results have implications for understanding the enzymatic mechanisms of native hydrogenases, and, using NiRd as a scaffold, it will be possible to optimize this catalyst for application in sustainable fuel generation.
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Affiliation(s)
- Jeffrey W Slater
- Department of Chemistry and Biochemistry and Ohio State Biochemistry Program, The Ohio State University , 100 W 18th Avenue, Columbus, Ohio 43210, United States
| | - Hannah S Shafaat
- Department of Chemistry and Biochemistry and Ohio State Biochemistry Program, The Ohio State University , 100 W 18th Avenue, Columbus, Ohio 43210, United States
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8
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Identification, cloning and heterologous expression of active [NiFe]-hydrogenase 2 from Citrobacter sp. SG in Escherichia coli. J Biotechnol 2015; 199:1-8. [DOI: 10.1016/j.jbiotec.2015.01.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 01/27/2015] [Accepted: 01/29/2015] [Indexed: 11/22/2022]
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9
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Douglas CD, Ngu TT, Kaluarachchi H, Zamble DB. Metal transfer within the Escherichia coli HypB-HypA complex of hydrogenase accessory proteins. Biochemistry 2013; 52:6030-9. [PMID: 23899293 DOI: 10.1021/bi400812r] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The maturation of [NiFe]-hydrogenase in Escherichia coli is a complex process involving many steps and multiple accessory proteins. The two accessory proteins HypA and HypB interact with each other and are thought to cooperate to insert nickel into the active site of the hydrogenase-3 precursor protein. Both of these accessory proteins bind metal individually, but little is known about the metal-binding activities of the proteins once they assemble together into a functional complex. In this study, we investigate how complex formation modulates metal binding to the E. coli proteins HypA and HypB. This work lead to a re-evaluation of the HypA nickel affinity, revealing a KD on the order of 10(-8) M. HypA can efficiently remove nickel, but not zinc, from the metal-binding site in the GTPase domain of HypB, a process that is less efficient when complex formation between HypA and HypB is disrupted. Furthermore, nickel release from HypB to HypA is specifically accelerated when HypB is loaded with GDP, but not GTP. These results are consistent with the HypA-HypB complex serving as a transfer step in the relay of nickel from membrane transporter to its final destination in the hydrogenase active site and suggest that this complex contributes to the metal fidelity of this pathway.
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Affiliation(s)
- Colin D Douglas
- Department of Chemistry, University of Toronto , 80 St. George St., Toronto, Ontario M5S 3H6, Canada
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10
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Zeng J, Zhang M, Sun X. Molecular hydrogen is involved in phytohormone signaling and stress responses in plants. PLoS One 2013; 8:e71038. [PMID: 23951075 PMCID: PMC3741361 DOI: 10.1371/journal.pone.0071038] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Accepted: 06/27/2013] [Indexed: 12/31/2022] Open
Abstract
Molecular hydrogen (H2) metabolism in bacteria and algae has been well studied from an industrial perspective because H2 is viewed as a potential future energy source. A number of clinical trials have recently reported that H2 is a therapeutic antioxidant and signaling molecule. Although H2 metabolism in higher plants was reported in some early studies, its biological effects remain unclear. In this report, the biological effects of H2 and its involvement in plant hormone signaling pathways and stress responses were determined. Antioxidant enzyme activity was found to be increased and the transcription of corresponding genes altered when the effects of H2 on the germination of mung bean seeds treated with phytohormones was investigated. In addition, upregulation of several phytohormone receptor genes and genes that encode a few key factors involved in plant signaling pathways was detected in rice seedlings treated with HW. The transcription of putative rice hydrogenase genes, hydrogenase activity, and endogenous H2 production were also determined. H2 production was found to be induced by abscisic acid, ethylene, and jasmonate acid, salt, and drought stress and was consistent with hydrogenase activity and the expression of putative hydrogenase genes in rice seedlings. Together, these results suggest that H2 may have an effect on rice stress tolerance by modulating the output of hormone signaling pathways.
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Affiliation(s)
- Jiqing Zeng
- Key Laboratory of South China Agricultural Plant Genetics and Breeding, Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
- * E-mail: (JQZ); (MYZ)
| | - Mingyong Zhang
- Key Laboratory of South China Agricultural Plant Genetics and Breeding, Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
- * E-mail: (JQZ); (MYZ)
| | - Xuejun Sun
- Department of Diving Medicine, Second Military Medical University, Shanghai, China
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11
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Zhu H, Song N, Lv H, Hill CL, Lian T. Near Unity Quantum Yield of Light-Driven Redox Mediator Reduction and Efficient H2 Generation Using Colloidal Nanorod Heterostructures. J Am Chem Soc 2012; 134:11701-8. [DOI: 10.1021/ja303698e] [Citation(s) in RCA: 213] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Haiming Zhu
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Nianhui Song
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Hongjin Lv
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Craig L. Hill
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Tianquan Lian
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
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12
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Stapleton JA, Swartz JR. Development of an in vitro compartmentalization screen for high-throughput directed evolution of [FeFe] hydrogenases. PLoS One 2010; 5:e15275. [PMID: 21151915 PMCID: PMC2997796 DOI: 10.1371/journal.pone.0015275] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Accepted: 11/03/2010] [Indexed: 01/10/2023] Open
Abstract
Background [FeFe] hydrogenase enzymes catalyze the formation and dissociation of molecular hydrogen with the help of a complex prosthetic group composed of common elements. The development of energy conversion technologies based on these renewable catalysts has been hindered by their extreme oxygen sensitivity. Attempts to improve the enzymes by directed evolution have failed for want of a screening platform capable of throughputs high enough to adequately sample heavily mutated DNA libraries. In vitro compartmentalization (IVC) is a powerful method capable of screening for multiple-turnover enzymatic activity at very high throughputs. Recent advances have allowed [FeFe] hydrogenases to be expressed and activated in the cell-free protein synthesis reactions on which IVC is based; however, IVC is a demanding technique with which many enzymes have proven incompatible. Methodology/Principal Findings Here we describe an extremely high-throughput IVC screen for oxygen-tolerant [FeFe] hydrogenases. We demonstrate that the [FeFe] hydrogenase CpI can be expressed and activated within emulsion droplets, and identify a fluorogenic substrate that links activity after oxygen exposure to the generation of a fluorescent signal. We present a screening protocol in which attachment of mutant genes and the proteins they encode to the surfaces of microbeads is followed by three separate emulsion steps for amplification, expression, and evaluation of hydrogenase mutants. We show that beads displaying active hydrogenase can be isolated by fluorescence-activated cell-sorting, and we use the method to enrich such beads from a mock library. Conclusions/Significance [FeFe] hydrogenases are the most complex enzymes to be produced by cell-free protein synthesis, and the most challenging targets to which IVC has yet been applied. The technique described here is an enabling step towards the development of biocatalysts for a biological hydrogen economy.
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Affiliation(s)
- James A. Stapleton
- Department of Chemical Engineering, Stanford University, Stanford, California, United States of America
| | - James R. Swartz
- Department of Chemical Engineering, Stanford University, Stanford, California, United States of America
- Department of Bioengineering, Stanford University, Stanford, California, United States of America
- * E-mail:
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13
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Saint-Martin P, Lespinat PA, Fauque G, Berlier Y, Legall J, Moura I, Teixeira M, Xavier AV, Moura JJ. Hydrogen production and deuterium-proton exchange reactions catalyzed by Desulfovibrio nickel(II)-substituted rubredoxins. Proc Natl Acad Sci U S A 2010; 85:9378-80. [PMID: 16594005 PMCID: PMC282755 DOI: 10.1073/pnas.85.24.9378] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The nickel tetrahedral sulfur-coordinated core formed upon metal replacement of the native iron in Desulfovibrio sp. rubredoxins is shown to mimic the reactivity pattern of nickel-containing hydrogenases with respect to hydrogen production, deuterium-proton exchange, and inhibition by carbon monoxide.
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Affiliation(s)
- P Saint-Martin
- L'Association pour la Recherche en Bioenergie Solaire, Section Enzymologie et Biochimie Bactérienne, Centre d'Etudes Nucleaires, Cadarache, 13108 Saint-Paul-lez-Durance Cedex, France
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14
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Yagi T. Separation of hydrogenase-catalyzed hydrogen-evolution system from electron-donating system by means of enzymic electric cell technique. Proc Natl Acad Sci U S A 2010; 73:2947-9. [PMID: 16592344 PMCID: PMC430887 DOI: 10.1073/pnas.73.9.2947] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
An enzymic electric cell was constructed in which the anode was composed of a zinc plate inserted in aqueous NH(4)Cl solution and the cathode was composed of an electrode made of a glassy carbon stick inserted in a reaction mixture containing cytochrome c(3) hydrogenase (H(2):ferricytochrome c(3) oxidoreductase, EC 1.12.2.1) and methylviologen under an atmosphere of N(2). When the circuit was closed, the electric cell formulated as [Formula: see text] was composed, and hydrogenase-catalyzed H(2)-evolution was observed in the cathode of the cell with concomitant flow of an electric current. Thus, the hydrogenase-catalyzed reaction and the electron-donating reaction proceeded at different parts of the cell. This enables us to protect the hydrogenase from the byproducts of the electron-donating system, which might be hazardous to the enzyme.
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Affiliation(s)
- T Yagi
- Department of Chemistry, School of Education, Shizuoka University, Oya, Shizuoka 422, Japan
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Schubert KR, Evans HJ. Hydrogen evolution: A major factor affecting the efficiency of nitrogen fixation in nodulated symbionts. Proc Natl Acad Sci U S A 2010; 73:1207-11. [PMID: 16592307 PMCID: PMC430231 DOI: 10.1073/pnas.73.4.1207] [Citation(s) in RCA: 198] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nitrogenase-dependent hydrogen evolution from detached legume nodules and from reaction mixtures containing cell-free nitrogenase has been well established, but the overall effect of hydrogen evolution on the efficiency of nitrogen fixation in vivo has not been critically assessed. This paper describes a survey which revealed that hydrogen evolution is a general phenomenon associated with nitrogen fixation by many nodulated nitrogen-fixing symbionts. An evaluation of the magnitude of energy loss in terms of the efficiency of electron transfer to nitrogen, via nitrogenase, in excised nodules suggested that hydrogen production may severely reduce nitrogen fixation in many legumes where photosynthate supply is a factor limiting fixation. With most symbionts, including soybeans, only 40-60% of the electron flow to nitrogenase was transferred to nitrogen. The remainder was lost through hydrogen evolution. In situ measurements of hydrogen evolution and acetylene reduction by nodulated soybeans confirmed the results obtained with excised nodules. In an atmosphere of air, a major portion of the total electron flux available for the reduction of atmospheric nitrogen by either excised nodules or intact nodulated plants was utilized in the production of hydrogen gas. Some non-leguminous symbionts, such as Alnus rubra, and a few legumes (i.e., Vigna sinensis) apparently have evolved mechanisms of minimizing net hydrogen production, thus increasing their efficiency of electron transfer to nitrogen. Our results indicate that the extent of hydrogen evolution during nitrogen reduction is a major factor affecting the efficiency of nitrogen fixation by many agronomically important legumes.
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Affiliation(s)
- K R Schubert
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oreg. 97331
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16
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Stapleton JA, Swartz JR. A cell-free microtiter plate screen for improved [FeFe] hydrogenases. PLoS One 2010; 5:e10554. [PMID: 20479937 PMCID: PMC2866662 DOI: 10.1371/journal.pone.0010554] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2010] [Accepted: 04/09/2010] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND [FeFe] hydrogenase enzymes catalyze the production and dissociation of H(2), a potential renewable fuel. Attempts to exploit these catalysts in engineered systems have been hindered by the biotechnologically inconvenient properties of the natural enzymes, including their extreme oxygen sensitivity. Directed evolution has been used to improve the characteristics of a range of natural catalysts, but has been largely unsuccessful for [FeFe] hydrogenases because of a lack of convenient screening platforms. METHODOLOGY/PRINCIPAL FINDINGS Here we describe an in vitro screening technology for oxygen-tolerant and highly active [FeFe] hydrogenases. Despite the complexity of the protocol, we demonstrate a level of reproducibility that allows moderately improved mutants to be isolated. We have used the platform to identify a mutant of the Chlamydomonas reinhardtii [FeFe] hydrogenase HydA1 with a specific activity approximately 4 times that of the wild-type enzyme. CONCLUSIONS/SIGNIFICANCE Our results demonstrate the feasibility of using the screen presented here for large-scale efforts to identify improved biocatalysts for energy applications. The system is based on our ability to activate these complex enzymes in E. coli cell extracts, which allows unhindered access to the protein maturation and assay environment.
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Affiliation(s)
- James A. Stapleton
- Department of Chemical Engineering, Stanford University, Stanford, California, United States of America
| | - James R. Swartz
- Department of Chemical Engineering, Stanford University, Stanford, California, United States of America
- Department of Bioengineering, Stanford University, Stanford, California, United States of America
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Yanke LJ, Bryant RD, Laishley EJ. Hydrogenase I of Clostridium pasteurianum functions as a novel selenite reductase. Anaerobe 2007; 1:61-7. [PMID: 16887509 DOI: 10.1016/s1075-9964(95)80457-9] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/17/1994] [Indexed: 11/26/2022]
Abstract
Clostridium pasteurianum's hydrogenase I, an important constitutive metabolic enzyme, has been shown to function as a 'novel selenite reductase'. Selenite reductase activity was found to co-purify with hydrogenase I activity; the fold purification and specific activities for these two activities paralleled each other throughout the purification steps. The highly purified hydrogenase I apparent K(m) for the selenite substrate was 0.2 mM. The stoichiometry for the enzymatic reduction of SeO3(2-) to Se(0) via H2 oxidation, was determined to be 2.3:1 (H2:Se(0)), very close to the theoretical ratio of 2:1 for this reduction reaction. Known electron carriers required for hydrogenase I activity were also found to couple its selenite reductase activity, the most efficient one being ferredoxin. The purified hydrogenase I not only reduced selenite but also tellurite, and its selenite activity was completely inhibited by O2 and CuSO4, potent inhibitors of hydrogenase I activity.
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Affiliation(s)
- L J Yanke
- Agriculture Canada Research Station, Lethbridge, Alberta, Canada T1J 4B1, Canada
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18
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McGlynn SE, Ruebush SS, Naumov A, Nagy LE, Dubini A, King PW, Broderick JB, Posewitz MC, Peters JW. In vitro activation of [FeFe] hydrogenase: new insights into hydrogenase maturation. J Biol Inorg Chem 2007; 12:443-7. [PMID: 17372774 DOI: 10.1007/s00775-007-0224-z] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2006] [Accepted: 02/22/2007] [Indexed: 10/23/2022]
Abstract
The in vitro activation of the [FeFe] hydrogenase is accomplished by combining Escherichia coli cell extracts containing the heterologously expressed inactive HydA with extracts in which hydrogenase-specific maturation proteins HydE, HydF, and HydG are expressed in concert. Interestingly, the process of HydA activation occurs rapidly and in the absence of potential substrates, which suggests that the hydrogenase accessory proteins synthesize an H-cluster precursor that can be quickly transferred to the hydrogenase enzyme to affect activation. HydA activity is observed to be dependent on the protein fraction containing all three accessory proteins expressed in concert and cannot be accomplished with addition of heat-treated extract or extract filtrate, suggesting that the activation of the hydrogenase structural protein is mediated by interaction with the accessory assembly protein(s). These results represent the first important step in understanding the process of H-cluster assembly and provide significant insights into hydrogenase maturation.
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Affiliation(s)
- Shawn E McGlynn
- Department of Chemistry and Biochemistry, Montana State University Bozeman, Bozeman, MT 59717, USA
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19
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Valente FMA, Almeida CC, Pacheco I, Carita J, Saraiva LM, Pereira IAC. Selenium is involved in regulation of periplasmic hydrogenase gene expression in Desulfovibrio vulgaris Hildenborough. J Bacteriol 2006; 188:3228-35. [PMID: 16621815 PMCID: PMC1447438 DOI: 10.1128/jb.188.9.3228-3235.2006] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Desulfovibrio vulgaris Hildenborough is a good model organism to study hydrogen metabolism in sulfate-reducing bacteria. Hydrogen is a key compound for these organisms, since it is one of their major energy sources in natural habitats and also an intermediate in the energy metabolism. The D. vulgaris Hildenborough genome codes for six different hydrogenases, but only three of them, the periplasmic-facing [FeFe], [FeNi]1, and [FeNiSe] hydrogenases, are usually detected. In this work, we studied the synthesis of each of these enzymes in response to different electron donors and acceptors for growth as well as in response to the availability of Ni and Se. The formation of the three hydrogenases was not very strongly affected by the electron donors or acceptors used, but the highest levels were observed after growth with hydrogen as electron donor and lowest with thiosulfate as electron acceptor. The major effect observed was with inclusion of Se in the growth medium, which led to a strong repression of the [FeFe] and [NiFe]1 hydrogenases and a strong increase in the [NiFeSe] hydrogenase that is not detected in the absence of Se. Ni also led to increased formation of the [NiFe]1 hydrogenase, except for growth with H2, where its synthesis is very high even without Ni added to the medium. Growth with H2 results in a strong increase in the soluble forms of the [NiFe]1 and [NiFeSe] hydrogenases. This study is an important contribution to understanding why D. vulgaris Hildenborough has three periplasmic hydrogenases. It supports their similar physiological role in H2 oxidation and reveals that element availability has a strong influence in their relative expression.
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Affiliation(s)
- Filipa M A Valente
- Instituto de Tecnologia Química e Biológica, Apt. 127, 2781-901 Oeiras, Portugal
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20
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Peck HD. THE ATP-DEPENDENT REDUCTION OF SULFATE WITH HYDROGEN IN EXTRACTS OF DESULFOVIBRIO DESULFURICANS. Proc Natl Acad Sci U S A 2006; 45:701-8. [PMID: 16590430 PMCID: PMC222620 DOI: 10.1073/pnas.45.5.701] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- H D Peck
- BIOLOGY DIVISION, OAK RIDGE NATIONAL LABORATORY
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21
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Valente FMA, Oliveira ASF, Gnadt N, Pacheco I, Coelho AV, Xavier AV, Teixeira M, Soares CM, Pereira IAC. Hydrogenases in Desulfovibrio vulgaris Hildenborough: structural and physiologic characterisation of the membrane-bound [NiFeSe] hydrogenase. J Biol Inorg Chem 2005; 10:667-82. [PMID: 16187073 DOI: 10.1007/s00775-005-0022-4] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2005] [Accepted: 08/11/2005] [Indexed: 10/25/2022]
Abstract
The genome of Desulfovibrio vulgaris Hildenborough (DvH) encodes for six hydrogenases (Hases), making it an interesting organism to study the role of these proteins in sulphate respiration. In this work we address the role of the [NiFeSe] Hase, found to be the major Hase associated with the cytoplasmic membrane. The purified enzyme displays interesting catalytic properties, such as a very high H(2) production activity, which is dependent on the presence of phospholipids or detergent, and resistance to oxygen inactivation since it is isolated aerobically in a Ni(II) oxidation state. Evidence was obtained that the [NiFeSe] Hase is post-translationally modified to include a hydrophobic group bound to the N-terminal, which is responsible for its membrane association. Cleavage of this group originates a soluble, less active form of the enzyme. Sequence analysis shows that [NiFeSe] Hases from Desulfovibrionacae form a separate family from the [NiFe] enzymes of these organisms, and are more closely related to [NiFe] Hases from more distant bacterial species that have a medial [4Fe4S](2+/1+) cluster, but not a selenocysteine. The interaction of the [NiFeSe] Hase with periplasmic cytochromes was investigated and is similar to the [NiFe](1) Hase, with the Type I cytochrome c (3) as the preferred electron acceptor. A model of the DvH [NiFeSe] Hase was generated based on the structure of the Desulfomicrobium baculatum enzyme. The structures of the two [NiFeSe] Hases are compared with the structures of [NiFe] Hases, to evaluate the consensual structural differences between the two families. Several conserved residues close to the redox centres were identified, which may be relevant to the higher activity displayed by [NiFeSe] Hases.
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Affiliation(s)
- Filipa M A Valente
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
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22
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Gu W, Jacquamet L, Patil DS, Wang HX, Evans DJ, Smith MC, Millar M, Koch S, Eichhorn DM, Latimer M, Cramer SP. Refinement of the nickel site structure in Desulfovibrio gigas hydrogenase using range-extended EXAFS spectroscopy. J Inorg Biochem 2003; 93:41-51. [PMID: 12538051 DOI: 10.1016/s0162-0134(02)00494-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We have reexamined the Ni EXAFS of oxidized, inactive (as-isolated) and H(2) reduced Desulfovibrio gigas hydrogenase. Better spatial resolution was achieved by analyzing the data over a 50% wider k-range than was previously available. A lower k(min) was obtained using the FEFF code for phase shifts and amplitudes. A higher k(max) was obtained by removing an interfering Cu signal from the raw spectra using multiple energy fluorescence detection. The larger k-range allowed us to better resolve the Ni-S bond lengths and to define more accurately the Ni-O and Ni-Fe bond lengths. We find that as-isolated, hydrogenase has two Ni-S bonds at approximately 2.2 A, but also 1-2 Ni-S bonds in the 2.35+/-0.05 A range. A Ni-O interaction is evident at 1.91 A. The as-isolated Ni-Fe distance cannot be unambiguously determined. Upon H(2) reduction, two short Ni-S bonds persist at approximately 2.2 A, but the remaining Ni-S bonds lengthen to 2.47+/-0.05 A. Good simulations are obtained with a Ni-Fe distance at 2.52 A, in agreement with crystal structures of the reduced enzyme. Although not evident in the crystal structures, an improvement in the fit is obtained by inclusion of one Ni-O interaction at 2.03 A. Implications of these distances for the spin-state of H(2) reduced H(2)ase are discussed.
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Affiliation(s)
- Weiwei Gu
- Department of Applied Science, University of California, 1 Shields Ave, Davis, CA 95616, USA
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23
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Desvaux M, Guedon E, Petitdemange H. Carbon flux distribution and kinetics of cellulose fermentation in steady-state continuous cultures of Clostridium cellulolyticum on a chemically defined medium. J Bacteriol 2001; 183:119-30. [PMID: 11114908 PMCID: PMC94857 DOI: 10.1128/jb.183.1.119-130.2001] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2000] [Accepted: 10/06/2000] [Indexed: 11/20/2022] Open
Abstract
The metabolic characteristics of Clostridium cellulolyticum, a mesophilic cellulolytic nonruminal bacterium, were investigated and characterized kinetically for the fermentation of cellulose by using chemostat culture analysis. Since with C. cellulolyticum (i) the ATP/ADP ratio is lower than 1, (ii) the production of lactate at low specific growth rate (mu) is low, and (iii) there is a decrease of the NADH/NAD(+) ratio and q(NADH produced)/ q(NADH used) ratio as the dilution rate (D) increases in carbon-limited conditions, the chemostats used were cellulose-limited continuously fed cultures. Under all conditions, ethanol and acetate were the main end products of catabolism. There was no shift from an acetate-ethanol fermentation to a lactate-ethanol fermentation as previously observed on cellobiose as mu increased (E. Guedon, S. Payot, M. Desvaux, and H. Petitdemange, J. Bacteriol. 181:3262-3269, 1999). The acetate/ethanol ratio was always higher than 1 but decreased with D. On cellulose, glucose 6-phosphate and glucose 1-phosphate are important branch points since the longer the soluble beta-glucan uptake is, the more glucose 1-phosphate will be generated. The proportion of carbon flowing toward phosphoglucomutase remained constant (around 59.0%), while the carbon surplus was dissipated through exopolysaccharide and glycogen synthesis. The percentage of carbon metabolized via pyruvate-ferredoxin oxidoreductase decreased with D. Acetyl coenzyme A was mainly directed toward the acetate formation pathway, which represented a minimum of 27.1% of the carbon substrate. Yet the proportion of carbon directed through biosynthesis (i.e., biomass, extracellular proteins, and free amino acids) and ethanol increased with D, reaching 27.3 and 16.8%, respectively, at 0.083 h(-1). Lactate and extracellular pyruvate remained low, representing up to 1.5 and 0.2%, respectively, of the original carbon uptake. The true growth yield obtained on cellulose was higher, [50.5 g of cells (mol of hexose eq)(-1)] than on cellobiose, a soluble cellodextrin [36.2 g of cells (mol of hexose eq)(-1)]. The rate of cellulose utilization depended on the solid retention time and was first order, with a rate constant of 0.05 h(-1). Compared to cellobiose, substrate hydrolysis by cellulosome when bacteria are grown on cellulose fibers introduces an extra means for regulation of the entering carbon flow. This led to a lower mu, and so metabolism was not as distorted as previously observed with a soluble substrate. From these results, C. cellulolyticum appeared well adapted and even restricted to a cellulolytic lifestyle.
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Affiliation(s)
- M Desvaux
- Laboratoire de Biochimie des Bactéries Gram +, Domaine Scientifique Victor Grignard, Faculté des Sciences, Université Henri Poincaré, 54506 Vandouvre-lès-Nancy Cédex, France
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24
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Magnani P, Doussiere J, Lissolo T. Diphenylene iodonium as an inhibitor for the hydrogenase complex of Rhodobacter capsulatus. Evidence for two distinct electron donor sites. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1459:169-78. [PMID: 10924909 DOI: 10.1016/s0005-2728(00)00145-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The photosynthetic bacterium Rhodobacter capsulatus synthesises a membrane-bound [NiFe] hydrogenase encoded by the H2 uptake hydrogenase (hup)SLC structural operon. The hupS and hupL genes encode the small and large subunits of hydrogenase, respectively; hupC encodes a membrane electron carrier protein which may be considered as the third subunit of the uptake hydrogenase. In Wolinella succinogenes, the hydC gene, homologous to hupC, has been shown to encode a low potential cytochrome b which mediates electron transfer from H2 to the quinone pool of the bacterial membrane. In whole cells of R. capsulatus or intact membrane preparation of the wild type strain B10, methylene blue but not benzyl viologen can be used as acceptor of the electrons donated by H2 to hydrogenase; on the other hand, membranes of B10 treated with Triton X-100 or whole cells of a HupC- mutant exhibit both benzyl viologen and methylene blue reductase activities. We report the effect of diphenylene iodonium (Ph2I), a known inhibitor of mitochondrial complex I and of various monooxygenases on R. capsulatus hydrogenase activity. With H2 as electron donor, Ph2I inhibited partially the methylene blue reductase activity in an uncompetitive manner, and totally benzyl viologen reductase activity in a competitive manner. Furthermore, with benzyl viologen as electron acceptor, Ph2I increased dramatically the observed lagtime for dye reduction. These results suggest that two different sites exist on the electron donor side of the membrane-bound [NiFe] hydrogenase of R. capsulatus, both located on the small subunit. A low redox potential site which reduces benzyl viologen, binds Ph2I and could be located on the distal [Fe4S4] cluster. A higher redox potential site which can reduce methylene blue in vitro could be connected to the high potential [Fe3S4] cluster and freely accessible from the periplasm.
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Affiliation(s)
- P Magnani
- Laboratoire TEPE, ESIGEC, Université de Savoie, Le Bourget Du Lac, France
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26
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ORMEROD JG, GEST H. Symposium on metabolism of inorganic compounds. IV. Hydrogen photosynthesis and alternative metabolic pathways in photosynthetic bacteria. BACTERIOLOGICAL REVIEWS 1998; 26:51-66. [PMID: 14482327 PMCID: PMC441136 DOI: 10.1128/br.26.1.51-66.1962] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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SADANA JC, MOREY AV. Purification and properties of the hydrogenase of Desulfovibrio desulfuricans. ACTA ACUST UNITED AC 1998; 50:153-63. [PMID: 13745271 DOI: 10.1016/0006-3002(61)91072-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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AKAGI JM, CAMPBELL LL. Studies on thermophilic sulfate-reducing bacteria. II. Hydrogenase activity of Clostridium nigrificans. J Bacteriol 1998; 82:927-32. [PMID: 13859876 PMCID: PMC279278 DOI: 10.1128/jb.82.6.927-932.1961] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Akagi, J. M. (Western Reserve University, Cleveland, Ohio) and L. Leon Campbell. Studies on thermophilic sulfate-reducing bacteria. II. Hydrogenase activity of Clostridium nigrificans. J. Bacteriol. 82:927-932. 1961.-The hydrogenase of Clostridium nigrificans has been found to be associated with the cell-free particulate fraction which can be sedimented at 105,000 x g in 1 hr. The specific activity of this fraction was increased 2 to 3 fold over that of the crude extract. It was not found possible to liberate the enzyme from the particulate fraction by methods of enzymatic digestion, chemical extraction, or physical disruption. The optimum temperature for H(2) utilization using benzyl viologen as an electron acceptor was found to be 55 C, and the optimum pH range was 7 to 8. Employing metal complexing agents it was found that the enzyme required Fe(++) ions for H(2) utilization. In contrast, Fe(++) ions were not required to catalyze the evolution of H(2) from reduced methyl viologen. The role of Fe(++) ions in the hydrogenase activity of this organism is discussed.
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WOOLFOLK CA. Reduction of inorganic compounds with molecular hydrogen by Micrococcus lactilyticus. II. Stoichiometry with inorganic sulfur compounds. J Bacteriol 1998; 84:659-68. [PMID: 14001843 PMCID: PMC277941 DOI: 10.1128/jb.84.4.659-668.1962] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Woolfolk, C. A. (University of Washington, Seattle). Reduction of inorganic compounds with molecular hydrogen by Micrococcus lactilyticus. II. Stoichiometry with inorganic sulfur compounds. J. Bacteriol. 84:659-668. 1962.-Extracts of Micrococcus lactilyticus (Veillonella alcalescens) are capable of utilizing molecular hydrogen for the reduction of metabisulfite (pyrosulfite) to thiosulfate via dithionite as an intermediate. The first step of metabisulfite reduction (i.e., to dithionite) is reversible, and, when dithionite is added as a substrate, there is an evolution of molecular hydrogen accompanied by the formation of equilibrium concentrations of metabisulfite. Kinetic studies indicate that dithionite may be directly reduced to thiosulfate without the formation of sulfoxylate as an intermediate. Although tetrathionate is reduced to thiosulfate with an uptake of hydrogen, polythionates probably are not formed as intermediates in the reduction of metabisulfite to thiosulfate.
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Abstract
Grau, F. H. (University of Wisconsin, Madison) and P. W. Wilson. Physiology of nitrogen fixation by Bacillus polymyxa. J. Bacteriol. 83:490-496. 1962.-Of 17 strains of Bacillus polymyxa tested for fixation of molecular nitrogen, 15 fixed considerable quantities (30 to 150 mug N/ml). Two strains of the closely related B. macerans did not use N(2), but possibly other members of this species may do so. Confirmation of fixation was obtained by showing incorporation of N(15) into cell material. Both iron and molybdenum are specifically required for fixation; without the addition of these metals to the nitrogen-free medium, the growth rate and the total nitrogen fixed were reduced about 30 to 50%. No requirement for added molybdenum could be shown when ammonia was the nitrogen source, and the absence of iron caused only a slight decrease in growth. Washed-cell suspensions of B. polymyxa containing an active hydrogenase readily incorporated N(15) into cell materials when provided with mannitol, glucose, or pyruvate but not when formate was the substrate. Hydrogen is a specific inhibitor of fixation, reducing both the rate and final amount of nitrogen fixed; it did not reduce growth on ammonia. Fixation was strictly anaerobic, 1% oxygen in the gas phase being sufficient to stop fixation. Arsenate is a powerful inhibitor of fixation of N(2) by washed-cell suspensions of B. polymyxa, indicating that high-energy phosphate may be significant for this process.
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Feio MJ, Beech IB, Carepo M, Lopes JM, Cheung CW, Franco R, Guezennec J, Smith JR, Mitchell JI, Moura JJ, Lino AR. Isolation and Characterisation of a Novel Sulphate-reducing Bacterium of theDesulfovibrioGenus. Anaerobe 1998; 4:117-30. [PMID: 16887631 DOI: 10.1006/anae.1997.0142] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/1997] [Accepted: 12/04/1997] [Indexed: 11/22/2022]
Abstract
A novel sulphate-reducing bacterium (Ind 1) was isolated from a biofilm removed from a severely corroded carbon steel structure in a marine environment. Light microscopy observations revealed that cells were Gram-negative, rod shaped and very motile. Partial 16S rRNA gene sequencing and analysis of the fatty acid profile demonstrated a strong similarity between the new species and members from the Desulfovibrio genus. This was confirmed by the results obtained following purification and characterisation of the key proteins involved in the sulphate-reduction pathway. Several metal-containing proteins, such as two periplasmic proteins: hydrogenase and cytochrome c3, and two cytoplasmic proteins: ferredoxin and sulphite reductase, were isolated and purified. The latter proved to be of the desulfoviridin type which is typical of the Desulfovibrio genus. The study of the remaining proteins revealed a high degree of similarity with the homologous proteins isolated from Desulfovibrio gigas. However, the position of the strain within the phylogenetic tree clearly indicates that the bacterium is closely related to Desulfovibrio gabonensis, and these three strains form a separate cluster in the delta subdivision of the Proteobacteria. On the basis of the results obtained, it is suggested that Ind 1 belongs to a new species of the genus Desulfovibrio, and the name Desulfovibrio indonensis is proposed.
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Affiliation(s)
- M J Feio
- School of Biomedical and Pharmaceutical Sciences, University of Portsmouth, Portsmouth, UK
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Romão CV, Pereira IA, Xavier AV, LeGall J, Teixeira M. Characterization of the [NiFe] hydrogenase from the sulfate reducer Desulfovibrio vulgaris Hildenborough. Biochem Biophys Res Commun 1997; 240:75-9. [PMID: 9367885 DOI: 10.1006/bbrc.1997.7598] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The [NiFe] hydrogenase from Desulfovibrio vulgaris Hildenborough was isolated from the cytoplasmic membranes and characterized by EPR spectroscopy. It has a total molecular mass of 98.7 kDa (subunits of 66.4 and 32.3 kDa), and contains 1 nickel and 12 Fe atoms per heterodimer. The catalytic activities for hydrogen consumption and production were determined to be 174 and 89 mumol H2.min-1.mg-1, respectively. As isolated, under aerobic conditions, this hydrogenase exhibits EPR signals characteristic of the nickel centers in [NiFe] hydrogenases (Ni-A signal at gx,y,z = 2.32, 2.23 and approximately 2.0 and Ni-B signal at gx,y,z = 2.33, 2.16 and approximately 2.0) as well as an intense quasi-isotropic signal centered at g = 2.02 due to the oxidized [3Fe-4S] center. The redox profile under hydrogen atmosphere is remarkably similar to that of other [NiFe] hydrogenases. The signals observed for the oxidized state disappear, first being substituted by the Ni-C type signal (gx,y,z = 2.19, 2.14, approximately 2.01), which upon long incubation under hydrogen yields the split Ni-C signal due to interaction with the reduced [4Fe-4S] centers.
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Affiliation(s)
- C V Romão
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
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Abstract
Centifanto, Ysolina M. (University of Florida, Gainesville), and Warren S. Silver. Leafnodule symbiosis. I. Endophyte of Psychotria bacteriophila. J. Bacteriol. 88:776-781. 1964.-The leaf-nodule endophyte of Psychotria bacteriophila has been repeatedly isolated in pure culture from germinating seedlings and young leaves on a nitrogen-free mineral agar. Its morphological, serological, and cultural characteristics place it within the Klebsiella-Aerobacter group. The endophyte has been provisionally named Klebsiella rubiacearum. Pure cultures fix N(2) under anaerobic conditions with good efficiency (4.54 mug of N fixed/mg of glucose utilized in 3 days). Nitrogen fixation by pure cultures is intimately related to pyruvate and hydrogen metabolism.
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BACHOFEN R, BUCHANAN BB, ARNON DI. FERREDOXIN AS A REDUCTANT IN PYRUVATE SYNTHESIS BY A BACTERIAL EXTRACT. Proc Natl Acad Sci U S A 1996; 51:690-4. [PMID: 14166776 PMCID: PMC300141 DOI: 10.1073/pnas.51.4.690] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Abstract
Wilder, Martin (University of Kansas, Lawrence), R. C. Valentine, and J. M. Akagi. Ferredoxin of Clostridium thermosaccharolyticum. J. Bacteriol. 86:861-865. 1963.-An electron-transferring agent has been isolated from Clostridium thermosaccharolyticum. This factor was found to participate as an electron carrier in the phosphoroclastic reaction of pyruvate, with the subsequent formation of acetyl phosphate and molecular hydrogen. It can be employed interchangeably with the ferredoxin of C. pasteurianum in various reactions. Thermal-stability studies indicated that this factor from C. thermosaccharolyticum was comparatively more heat-resistant than the carrier obtained from C. pasteurianum. It was concluded that this carrier was ferredoxin or a ferredoxin-like substance.
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UPADHYAY J, STOKES JL. TEMPERATURE-SENSITIVE HYDROGENASE AND HYDROGENASE SYNTHESIS IN A PSYCHROPHILIC BACTERIUM. J Bacteriol 1996; 86:992-8. [PMID: 14080812 PMCID: PMC278557 DOI: 10.1128/jb.86.5.992-998.1963] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Upadhyay, J. (Washington State University, Pullman) and J. L. Stokes. Temperature-sensitive hydrogenase and hydrogenase synthesis in a psychrophilic bacterium. J. Bacteriol. 86:992-998. 1963.-Hydrogenase and its synthesis were more heat-sensitive in psychrophilic strain 82 than in mesophilic Escherichia coli. The enzyme was not formed above 20 C by the psychrophile, whereas it was formed by E. coli and other mesophiles at 45 C. Aerobically grown cells of strain 82 do not contain hydrogenase but could be induced to form the enzyme by incubation with glucose and amino acids. Hydrogenase adaptation proceeded best at pH 8.0. The psychrophile hydrogenase was destroyed 50% by exposure to 60 C for 2 hr compared with 25% destruction of mesophile hydrogenase under the same conditions. The psychrophile hydrogenase was most active at pH 9.0, and the mesophile hydrogenase was most active at pH 10.0 or higher.
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38
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Abstract
Valentine, R. C. (University of Illinois, Urbana) and R. S. Wolfe. Role of ferredoxin in the metabolism of molecular hydrogen. J. Bacteriol. 85:1114-1120. 1963.-The metabolism of molecular hydrogen by Clostridium pasteurianum, Micrococcus lactilyticus (Veillonella alcalescens), and several other anaerobic bacteria was studied. Oxidation of hydrogen, using several electron-accepting substrates including triphosphopyridine nucleotide, uric acid, xanthine, nitrite, and hydroxylamine, required ferredoxin in conjunction with hydrogenase. Evolution of hydrogen from pyruvate, alpha-ketoglutarate, hypoxanthine, and dithionite was mediated by ferredoxin. On the basis of these findings, a unitary hypothesis for biological hydrogen evolution is proposed in which ferredoxin plays a key role.
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Abstract
From a general standpoint, the formation of molecular hydrogen can be considered a device for disposal of electrons released in metabolic oxidations. We presume that this means of performing anaerobic oxidations is of ancient origin and that the hydrogen-evolving system of strict anaerobes represents a primitive form of cytochrome oxidase, which in aerobes effects the terminal step of respiration, namely the disposal of electrons by combination with molecular oxygen. We further assume that the original pattern of reactions leading to H(2) production has become modified in various ways (with respect to both mechanisms and functions) during the course of biochemical evolution, and we believe that this point of view suggests profitable approaches for clarifying a number of problems in the intermediary metabolism of microorganisms which produce or utilize H(2). Of special general importance in this connection is the basic problem of defining more precisely the fundamental elements in the regulatory control of anaerobic energy metabolism. Among the more specific aspects awaiting further elucidation are: the relations between formation of H(2) and use of H(2) as a primary reductant for biosynthetic purposes; the various forms of direct and indirect interactions between hydrogenase and N(2) reduction systems; and the transitional stages between anaerobic and aerobic energy-metabolism patterns of facultative organisms.
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41
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Metabolic pathway to propionate of Pectinatus frisingensis, a strictly anaerobic beer-spoilage bacterium. Arch Microbiol 1994. [DOI: 10.1007/bf00282104] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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42
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Mechanism of dissimilatory sulfite reduction by Desulfovibrio desulfuricans: purification of a membrane-bound sulfite reductase and coupling iwth cytochrome c 3 and hydrogenase. Arch Microbiol 1994. [DOI: 10.1007/bf00301847] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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43
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Gest H. A microbiologist's odyssey: Bacterial viruses to photosynthetic bacteria. PHOTOSYNTHESIS RESEARCH 1994; 40:129-146. [PMID: 24311283 DOI: 10.1007/bf00019331] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/1994] [Accepted: 01/13/1994] [Indexed: 06/02/2023]
Abstract
Perspective can be defined as the relationships or relative importance of facts or matters from any special point of view. Thus, my Personal perspective reflects the threads I followed in a 50-year journey of research in the complex tapestry of bioenergetics and various aspects of microbial metabolism. An early interest in biochemical and microbial evolution led to the fertile hunting grounds of anoxygenic photosynthetic bacteria. Viewed as a physiological class, these organisms show remarkable metabolic versatility in that certain individual species are capable of using all the known major types of energy conversion (photosynthetic, respiratory, and fermentative) to support growth. Since such anoxyphototrophs are readily amenable to molecular genetic/biological manipulation, it can be expected that they will eventually provide important clues for unraveling the evolutionary relationships of the several kinds of energy conversion. I gradually came to believe that understanding the evolution of phototrophs would require detailed knowledge not only of how light is converted to chemical energy, but also of a) pathways of monomer production from extracellular sources of carbon and nitrogen and b) mechanisms cells use for integrating ATP regeneration with the energy-requiring biosyntheses of biological macromolecules. Serendipic observation of photoproduction of H2 from organic compounds by Rhodospirillum rubrum in 1949 led to discovery of N2 fixation by anoxyphototrophs, and this capacity was later exploited for the isolation of hitherto unknown species of photosynthetic prokaryotes, including the heliobacteria. Recent studies on the reaction centers of the heliobacteria suggest the possibility that these bacteria are descendents of early phototrophs that gave rise to oxygenic photosynthetic organisms.
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Affiliation(s)
- H Gest
- Photosynthetic Bacteria Group, Department of Biology, Indiana University, 47405, Bloomington, IN, USA
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Katz E, de Lacey AL, Fernandez VM. Covalent binding of viologen to electrode surfaces coated with poly(acrylic acid) prepared by electropolymerization of acrylate ions. J Electroanal Chem (Lausanne) 1993. [DOI: 10.1016/0022-0728(93)80443-l] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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46
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Katz E, de Lacey AL, Fierro JL, Palacios JM, Fernandez VM. Covalent binding of viologen to electrode surfaces coated with poly(acrylic acid) formed by electropolymerization of acrylate ions. J Electroanal Chem (Lausanne) 1993. [DOI: 10.1016/0022-0728(93)80442-k] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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47
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Franco R, Moura I, LeGall J, Peck HD, Huynh BH, Moura JJ. Characterization of D. desulfuricans (ATCC 27774) [NiFe] hydrogenase EPR and redox properties of the native and the dihydrogen reacted states. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1144:302-8. [PMID: 8399280 DOI: 10.1016/0005-2728(93)90115-v] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Redox intermediates of D. desulfuricans ATCC 27774 [NiFe] hydrogenase were generated under dihydrogen. Detailed redox titrations, coupled to EPR measurements, give access to the mid-point redox potentials of the iron-sulfur centers and of the Nickel-B signal that represents the ready form of the enzyme. The interaction between the dihydrogen molecule and the nickel centre was probed by the observation of an isotopic effect on the EPR signals detected in turnover conditions, by comparison of the H2O/H2 and D2O/D2-reacted samples.
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Affiliation(s)
- R Franco
- Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Monte de Caparica, Portugal
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Pierik AJ, Hagen WR, Redeker JS, Wolbert RB, Boersma M, Verhagen MF, Grande HJ, Veeger C, Mutsaers PH, Sands RH. Redox properties of the iron-sulfur clusters in activated Fe-hydrogenase from Desulfovibrio vulgaris (Hildenborough). EUROPEAN JOURNAL OF BIOCHEMISTRY 1992; 209:63-72. [PMID: 1396719 DOI: 10.1111/j.1432-1033.1992.tb17261.x] [Citation(s) in RCA: 120] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The periplasmic Fe-hydrogenase from Desulfovibrio vulgaris (Hildenborough) contains three iron-sulfur prosthetic groups: two putative electron transferring [4Fe-4S] ferredoxin-like cubanes (two F-clusters), and one putative Fe/S supercluster redox catalyst (one H-cluster). Combined elemental analysis by proton-induced X-ray emission, inductively coupled plasma mass spectrometry, instrumental neutron activation analysis, atomic absorption spectroscopy and colorimetry establishes that elements with Z > 21 (except for 12-15 Fe) are present in 0.001-0.1 mol/mol quantities, not correlating with activity. Isoelectric focussing reveals the existence of multiple charge conformers with pI in the range 5.7-6.4. Repeated re-chromatography results in small amounts of enzyme of very high H2-production activity determined under standardized conditions (approximately 7000 U/mg). The enzyme exists in two different catalytic forms: as isolated the protein is 'resting' and O2-insensitive; upon reduction the protein becomes active and O2-sensitive. EPR-monitored redox titrations have been carried out of both the resting and the activated enzyme. In the course of a reductive titration, the resting protein becomes activated and begins to produce molecular hydrogen at the expense of reduced titrant. Therefore, equilibrium potentials are undefined, and previously reported apparent Em and n values [Patil, D. S., Moura, J. J. G., He, S. H., Teixeira, M, Prickril, B. C., DerVartanian, D. V., Peck, H. D. Jr, LeGall, J. & Huynh, B.-H. (1988) J. Biol. Chem. 263, 18,732-18,738] are not thermodynamic quantities. In the activated enzyme an S = 1/2 signal (g = 2.11, 2.05, 2.00; 0.4 spin/protein molecule), attributed to the oxidized H cluster, exhibits a single reduction potential, Em,7 = -307 mV, just above the onset potential of H2 production. The midpoint potential of the two F clusters (2.0 spins/protein molecule) has been determined either by titrating active enzyme with the H2/H+ couple (E,m = -330 mV) or by dithionite-titrating a recombinant protein that lacks the H-cluster active site (Em,7.5 = -340 mV). There is no significant redox interaction between the two F clusters (n approximately 1).
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Affiliation(s)
- A J Pierik
- Department of Biochemistry, Agricultural University, Wageningen, The Netherlands
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49
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Fauque G, Czechowski M, Berlier YM, Lespinat PA, LeGall J, Moura JJ. Partial purification and characterization of the first hydrogenase isolated from a thermophilic sulfate-reducing bacterium. Biochem Biophys Res Commun 1992; 184:1256-60. [PMID: 1317168 DOI: 10.1016/s0006-291x(05)80017-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A soluble [NiFe] hydrogenase has been partially purified from the obligate thermophilic sulfate-reducing bacterium Thermodesulfobacterium mobile. A 17% purification yield was obtained after four chromatographic steps and the hydrogenase presents a purity index (A398 nm/A277 nm) equal to 0.21. This protein appears to be 75% pure on SDS-gel electrophoresis showing two major bands of molecular mass around 55 and 15 kDa. This hydrogenase contains 0.6-0.7 nickel atom and 7-8 iron atoms per mole of enzyme and has a specific activity of 783 in the hydrogen uptake reaction, of 231 in the hydrogen production assay and of 84 in the deuterium-proton exchange reaction. The H2/HD ratio is lower than one in the D2-H+ exchange reaction. The enzyme is very sensitive to NO, relatively little inhibited by CO but unaffected by NO2-. The EPR spectrum of the native hydrogenase shows the presence of a [3Fe-4S] oxidized cluster and of a Ni(III) species.
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Affiliation(s)
- G Fauque
- Centre d'Océanologie de Marseille, Faculté des Sciences de Luminy, France
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50
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Doherty GM, Mayhew SG. The hydrogen-tritium exchange activity of Megasphaera elsdenii hydrogenase. EUROPEAN JOURNAL OF BIOCHEMISTRY 1992; 205:117-26. [PMID: 1555573 DOI: 10.1111/j.1432-1033.1992.tb16758.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The hydrogenase of Megasphaera elsdenii was purified to a specific activity of 350 units/mg. The hydrogen-tritium exchange assay of Hallahan et al. [Hallahan, D.L., Fernandez, V. M., Hatchikian, E. C. and Hall, D. O. (1986) Biochimie (Paris) 68, 49-54] was adapted to allow its use in the study of the M. elsdenii hydrogenase preparation. Under the assay conditions routinely employed, the enzyme's exchange activity was inhibited by Tris/HCl and MgCl2; it was stimulated by ethylene glycol. Maximal activity in this standard assay occurred at pH 7.1. The effect of the concentration of molecular hydrogen (1H2 plus 3H1H) on the exchange activity was studied. The resulting double-reciprocal plot was linear; its slope and its intercepts on the ordinate and abscissa were pH-dependent. The rate equations for a number of models of the exchange activity were derived. Each model gave rise to a linear double-reciprocal plot at constant pH, but none could explain fully the observed effects of varying pH. The experimental data corresponded most closely to the predictions of models in which protons were treated both as substrates and as regulators of the enzyme's activity.
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Affiliation(s)
- G M Doherty
- Department of Biochemistry, University College Dublin, Ireland
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