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Calvey CH, Sànchez I Nogué V, White AM, Kneucker CM, Woodworth SP, Alt HM, Eckert CA, Johnson CW. Improving growth of Cupriavidus necator H16 on formate using adaptive laboratory evolution-informed engineering. Metab Eng 2023; 75:78-90. [PMID: 36368470 DOI: 10.1016/j.ymben.2022.10.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 10/28/2022] [Accepted: 10/30/2022] [Indexed: 11/11/2022]
Abstract
Conversion of CO2 to value-added products presents an opportunity to reduce GHG emissions while generating revenue. Formate, which can be generated by the electrochemical reduction of CO2, has been proposed as a promising intermediate compound for microbial upgrading. Here we present progress towards improving the soil bacterium Cupriavidus necator H16, which is capable of growing on formate as its sole source of carbon and energy using the Calvin-Benson-Bassham (CBB) cycle, as a host for formate utilization. Using adaptive laboratory evolution, we generated several isolates that exhibited faster growth rates on formate. The genomes of these isolates were sequenced, and resulting mutations were systematically reintroduced by metabolic engineering, to identify those that improved growth. The metabolic impact of several mutations was investigated further using RNA-seq transcriptomics. We found that deletion of a transcriptional regulator implicated in quorum sensing, PhcA, reduced expression of several operons and led to improved growth on formate. Growth was also improved by deleting large genomic regions present on the extrachromosomal megaplasmid pHG1, particularly two hydrogenase operons and the megaplasmid CBB operon, one of two copies present in the genome. Based on these findings, we generated a rationally engineered ΔphcA and megaplasmid-deficient strain that exhibited a 24% faster maximum growth rate on formate. Moreover, this strain achieved a 7% growth rate improvement on succinate and a 19% increase on fructose, demonstrating the broad utility of microbial genome reduction. This strain has the potential to serve as an improved microbial chassis for biological conversion of formate to value-added products.
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Affiliation(s)
- Christopher H Calvey
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Violeta Sànchez I Nogué
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Aleena M White
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Colin M Kneucker
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Sean P Woodworth
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Hannah M Alt
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Carrie A Eckert
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Christopher W Johnson
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA.
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Pavan M, Reinmets K, Garg S, Mueller AP, Marcellin E, Köpke M, Valgepea K. Advances in systems metabolic engineering of autotrophic carbon oxide-fixing biocatalysts towards a circular economy. Metab Eng 2022; 71:117-141. [DOI: 10.1016/j.ymben.2022.01.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 01/24/2022] [Accepted: 01/25/2022] [Indexed: 12/16/2022]
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Pan H, Wang J, Wu H, Li Z, Lian J. Synthetic biology toolkit for engineering Cupriviadus necator H16 as a platform for CO 2 valorization. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:212. [PMID: 34736496 PMCID: PMC8570001 DOI: 10.1186/s13068-021-02063-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Accepted: 10/25/2021] [Indexed: 06/09/2023]
Abstract
BACKGROUND CO2 valorization is one of the effective methods to solve current environmental and energy problems, in which microbial electrosynthesis (MES) system has proved feasible and efficient. Cupriviadus necator (Ralstonia eutropha) H16, a model chemolithoautotroph, is a microbe of choice for CO2 conversion, especially with the ability to be employed in MES due to the presence of genes encoding [NiFe]-hydrogenases and all the Calvin-Benson-Basham cycle enzymes. The CO2 valorization strategy will make sense because the required hydrogen can be produced from renewable electricity independently of fossil fuels. MAIN BODY In this review, synthetic biology toolkit for C. necator H16, including genetic engineering vectors, heterologous gene expression elements, platform strain and genome engineering, and transformation strategies, is firstly summarized. Then, the review discusses how to apply these tools to make C. necator H16 an efficient cell factory for converting CO2 to value-added products, with the examples of alcohols, fatty acids, and terpenoids. The review is concluded with the limitation of current genetic tools and perspectives on the development of more efficient and convenient methods as well as the extensive applications of C. necator H16. CONCLUSIONS Great progress has been made on genetic engineering toolkit and synthetic biology applications of C. necator H16. Nevertheless, more efforts are expected in the near future to engineer C. necator H16 as efficient cell factories for the conversion of CO2 to value-added products.
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Affiliation(s)
- Haojie Pan
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Jia Wang
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Haoliang Wu
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Zhongjian Li
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Jiazhang Lian
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, China.
- Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, 310027, China.
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Hakobyan A, Zhu J, Glatter T, Paczia N, Liesack W. Hydrogen utilization by Methylocystis sp. strain SC2 expands the known metabolic versatility of type IIa methanotrophs. Metab Eng 2020; 61:181-196. [PMID: 32479801 DOI: 10.1016/j.ymben.2020.05.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 03/20/2020] [Accepted: 05/01/2020] [Indexed: 12/19/2022]
Abstract
Methane, a non-expensive natural substrate, is used by Methylocystis spp. as a sole source of carbon and energy. Here, we assessed whether Methylocystis sp. strain SC2 is able to also utilize hydrogen as an energy source. The addition of 2% H2 to the culture headspace had the most significant positive effect on the growth yield under CH4 (6%) and O2 (3%) limited conditions. The SC2 biomass yield doubled from 6.41 (±0.52) to 13.82 (±0.69) mg cell dry weight per mmol CH4, while CH4 consumption was significantly reduced. Regardless of H2 addition, CH4 utilization was increasingly redirected from respiration to fermentation-based pathways with decreasing O2/CH4 mixing ratios. Theoretical thermodynamic calculations confirmed that hydrogen utilization under oxygen-limited conditions doubles the maximum biomass yield compared to fully aerobic conditions without H2 addition. Hydrogen utilization was linked to significant changes in the SC2 proteome. In addition to hydrogenase accessory proteins, the production of Group 1d and Group 2b hydrogenases was significantly increased in both short- and long-term incubations. Both long-term incubation with H2 (37 d) and treatments with chemical inhibitors revealed that SC2 growth under hydrogen-utilizing conditions does not require the activity of complex I. Apparently, strain SC2 has the metabolic capacity to channel hydrogen-derived electrons into the quinone pool, which provides a link between hydrogen oxidation and energy production. In summary, H2 may be a promising alternative energy source in biotechnologically oriented methanotroph projects that aim to maximize biomass yield from CH4, such as the production of high-quality feed protein.
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Affiliation(s)
- Anna Hakobyan
- Research Group "Methanotrophic Bacteria and Environmental Genomics/Transcriptomics", Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Jing Zhu
- Research Group "Methanotrophic Bacteria and Environmental Genomics/Transcriptomics", Max Planck Institute for Terrestrial Microbiology, Marburg, Germany; Institute of Environmental Science and Technology, Zhejiang University, Hangzhou, China
| | - Timo Glatter
- Core Facility for Mass Spectrometry and Proteomics, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Nicole Paczia
- Core Facility for Metabolomics and Small Molecule Mass Spectrometry, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Werner Liesack
- Research Group "Methanotrophic Bacteria and Environmental Genomics/Transcriptomics", Max Planck Institute for Terrestrial Microbiology, Marburg, Germany; Center for Synthetic Microbiology (SYNMIKRO), Philipps-Universität Marburg, Marburg, Germany.
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Inactivation of the uptake hydrogenase in the purple non-sulfur photosynthetic bacterium Rubrivivax gelatinosus CBS enables a biological water–gas shift platform for H2 production. ACTA ACUST UNITED AC 2019; 46:993-1002. [DOI: 10.1007/s10295-019-02173-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 04/03/2019] [Indexed: 10/27/2022]
Abstract
Abstract
Biological H2 production has potential to address energy security and environmental concerns if produced from renewable or waste sources. The purple non-sulfur photosynthetic bacterium Rubrivivax gelatinosus CBS produces H2 while oxidizing CO, a component of synthesis gas (Syngas). CO-linked H2 production is facilitated by an energy-converting hydrogenase (Ech), while a subsequent H2 oxidation reaction is catalyzed by a membrane-bound hydrogenase (MBH). Both hydrogenases contain [NiFe] active sites requiring 6 maturation factors (HypA-F) for assembly, but it is unclear which of the two annotated sets of hyp genes are required for each in R. gelatinosus CBS. Herein, we report correlated expression of hyp1 genes with Ech genes and hyp2 expression with MBH genes. Moreover, we find that while Ech H2 evolving activity is only delayed when hyp1 is deleted, hyp2 deletion completely disrupts MBH H2 uptake, providing a platform for a biologically driven water–gas shift reaction to produce H2 from CO.
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Nangle SN, Sakimoto KK, Silver PA, Nocera DG. Biological-inorganic hybrid systems as a generalized platform for chemical production. Curr Opin Chem Biol 2017; 41:107-113. [DOI: 10.1016/j.cbpa.2017.10.023] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 10/16/2017] [Accepted: 10/20/2017] [Indexed: 12/16/2022]
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Jugder BE, Chen Z, Ping DTT, Lebhar H, Welch J, Marquis CP. An analysis of the changes in soluble hydrogenase and global gene expression in Cupriavidus necator (Ralstonia eutropha) H16 grown in heterotrophic diauxic batch culture. Microb Cell Fact 2015; 14:42. [PMID: 25880663 PMCID: PMC4377017 DOI: 10.1186/s12934-015-0226-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 03/12/2015] [Indexed: 12/20/2022] Open
Abstract
Background Soluble hydrogenases (SH) are enzymes that catalyse the oxidation of molecular hydrogen. The SH enzyme from Cupriavidus necator H16 is relatively oxygen tolerant and makes an attractive target for potential application in biochemical hydrogen fuel cells. Expression of the enzyme can be mediated by derepression of the hox promoter system under heterotrophic conditions. However, the overall impact of hox derepression, from a transcriptomic perspective, has never been previously reported. Results Derepression of hydrogenase gene expression upon fructose depletion was confirmed in replicate experiments. Using qRT-PCR, hoxF was 4.6-fold up-regulated, hypF2 was up-regulated in the cells grown 2.2-fold and the regulatory gene hoxA was up-regulated by a mean factor of 4.5. A full transcriptomic evaluation revealed a substantial shift in the global pattern of gene expression. In addition to up-regulation of genes associated with hydrogenase expression, significant changes were observed in genes associated with energy transduction, amino acid metabolism, transcription and translation (and regulation thereof), genes associated with cell stress, lipid and cell wall biogenesis and other functions, including cell motility. Conclusions We report the first full transcriptome analysis of C. necator H16 grown heterotrophically on fructose and glycerol in diauxic batch culture, which permits expression of soluble hydrogenase under heterotrophic conditions. The data presented deepens our understanding of the changes in global gene expression patterns that occur during the switch to growth on glycerol and suggests that energy deficit is a key driver for induction of hydrogenase expression in this organism. Electronic supplementary material The online version of this article (doi:10.1186/s12934-015-0226-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Bat-Erdene Jugder
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, 2052, Australia.
| | - Zhiliang Chen
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, 2052, Australia. .,Systems Biology Initiative, University of New South Wales, Sydney, 2052, Australia.
| | - Darren Tan Tek Ping
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, 2052, Australia.
| | - Helene Lebhar
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, 2052, Australia.
| | - Jeffrey Welch
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, 2052, Australia.
| | - Christopher P Marquis
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, 2052, Australia.
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Greening C, Cook GM. Integration of hydrogenase expression and hydrogen sensing in bacterial cell physiology. Curr Opin Microbiol 2014; 18:30-8. [PMID: 24607643 DOI: 10.1016/j.mib.2014.02.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 02/05/2014] [Indexed: 12/20/2022]
Abstract
Hydrogenases are ubiquitous in ecosystems and widespread in microorganisms. In bacteria, hydrogen metabolism is a facultative trait that is tightly regulated in response to both external factors (e.g. gas concentrations) and internal factors (e.g. redox state). Here we consider how environmental and pathogenic bacteria regulate [NiFe]-hydrogenases to adapt to chemical changes and meet physiological needs. We introduce this concept by exploring how Ralstonia eutropha switches between heterotrophic and lithotrophic growth modes by sensing hydrogen and electron availability. The regulation and integration of hydrogen metabolism in the virulence of Salmonella enterica and Helicobacter pylori, persistence of mycobacteria and streptomycetes, and differentiation of filamentous cyanobacteria are subsequently discussed. We also consider how these findings are extendable to other systems.
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Affiliation(s)
- Chris Greening
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand.
| | - Gregory M Cook
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand.
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9
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Grostern A, Alvarez-Cohen L. RubisCO-based CO2 fixation and C1 metabolism in the actinobacterium Pseudonocardia dioxanivorans CB1190. Environ Microbiol 2013; 15:3040-53. [PMID: 23663433 DOI: 10.1111/1462-2920.12144] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 04/12/2013] [Indexed: 01/01/2023]
Abstract
Pseudonocardia is an actinobacterial genus of interest due to its potential biotechnological, medical and environmental remediation applications, as well as for the ecologically relevant symbiotic relationships it forms with attine ants. Some Pseudonocardia spp. can grow autotrophically, but the genetic basis of this capability has not previously been reported. In this study, we examined autotrophy in Pseudonocardia dioxanivorans CB1190, which can grow using H2 and CO2, as well as heterotrophically. Genomic and transcriptomic analysis of CB1190 cells grown with H2/bicarbonate implicated the Calvin-Benson-Bassham (CBB) cycle in growth-supporting CO2 fixation, as well as a [NiFe] hydrogenase-encoding gene cluster in H2 oxidation. The CBB cycle genes are evolutionarily most related to actinobacterial homologues, although synteny has not been maintained. Ribulose-1,5-bisphosphate carboxylase activity was confirmed in H2/bicarbonate-grown CB1190 cells and was detected in cells grown with the C1 compounds formate, methanol and carbon monoxide. We also demonstrated the upregulation of CBB cycle genes upon exposure of CB1190 to these C1 substrates, and identified genes putatively involved in generating CO2 from the C1 substrates by using RT-qPCR. Finally, the potential for autotrophic growth of other Pseudonocardia spp. was explored, and the ecological implications of autotrophy in attine ant- and plant root-associated Pseudonocardia discussed.
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Affiliation(s)
- Ariel Grostern
- Department of Civil and Environmental Engineering, UC Berkeley, Berkeley, CA, USA.
| | - Lisa Alvarez-Cohen
- Department of Civil and Environmental Engineering, UC Berkeley, Berkeley, CA, USA.,Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
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10
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Schwartz E, Voigt B, Zühlke D, Pohlmann A, Lenz O, Albrecht D, Schwarze A, Kohlmann Y, Krause C, Hecker M, Friedrich B. A proteomic view of the facultatively chemolithoautotrophic lifestyle of Ralstonia eutropha
H16. Proteomics 2009; 9:5132-42. [DOI: 10.1002/pmic.200900333] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Valdés J, Pedroso I, Quatrini R, Dodson RJ, Tettelin H, Blake R, Eisen JA, Holmes DS. Acidithiobacillus ferrooxidans metabolism: from genome sequence to industrial applications. BMC Genomics 2008; 9:597. [PMID: 19077236 PMCID: PMC2621215 DOI: 10.1186/1471-2164-9-597] [Citation(s) in RCA: 315] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Accepted: 12/11/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Acidithiobacillus ferrooxidans is a major participant in consortia of microorganisms used for the industrial recovery of copper (bioleaching or biomining). It is a chemolithoautrophic, gamma-proteobacterium using energy from the oxidation of iron- and sulfur-containing minerals for growth. It thrives at extremely low pH (pH 1-2) and fixes both carbon and nitrogen from the atmosphere. It solubilizes copper and other metals from rocks and plays an important role in nutrient and metal biogeochemical cycling in acid environments. The lack of a well-developed system for genetic manipulation has prevented thorough exploration of its physiology. Also, confusion has been caused by prior metabolic models constructed based upon the examination of multiple, and sometimes distantly related, strains of the microorganism. RESULTS The genome of the type strain A. ferrooxidans ATCC 23270 was sequenced and annotated to identify general features and provide a framework for in silico metabolic reconstruction. Earlier models of iron and sulfur oxidation, biofilm formation, quorum sensing, inorganic ion uptake, and amino acid metabolism are confirmed and extended. Initial models are presented for central carbon metabolism, anaerobic metabolism (including sulfur reduction, hydrogen metabolism and nitrogen fixation), stress responses, DNA repair, and metal and toxic compound fluxes. CONCLUSION Bioinformatics analysis provides a valuable platform for gene discovery and functional prediction that helps explain the activity of A. ferrooxidans in industrial bioleaching and its role as a primary producer in acidic environments. An analysis of the genome of the type strain provides a coherent view of its gene content and metabolic potential.
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Affiliation(s)
- Jorge Valdés
- Center for Bioinformatics and Genome Biology, Fundación Ciencia para la Vida, Facultad de Ciencias de la Salud, Universidad Andres Bello, Santiago, Chile.
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Lenz O, Gleiche A, Strack A, Friedrich B. Requirements for heterologous production of a complex metalloenzyme: the membrane-bound [NiFe] hydrogenase. J Bacteriol 2005; 187:6590-5. [PMID: 16159796 PMCID: PMC1236620 DOI: 10.1128/jb.187.18.6590-6595.2005] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
By taking advantage of the tightly clustered genes for the membrane-bound [NiFe] hydrogenase of Ralstonia eutropha H16, broad-host-range recombinant plasmids were constructed carrying the entire membrane-bound hydrogenase (MBH) operon encompassing 21 genes. We demonstrate that the complex MBH biosynthetic apparatus is actively produced in hydrogenase-free hosts yielding fully assembled and functional MBH protein.
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Affiliation(s)
- Oliver Lenz
- Institut für Biologie, Humboldt-Universität zu Berlin, Chausseestrasse 117, D-10115 Berlin, Germany
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Karig D, Weiss R. Signal-amplifying genetic circuit enables in vivo observation of weak promoter activation in the Rhl quorum sensing system. Biotechnol Bioeng 2005; 89:709-18. [PMID: 15641095 DOI: 10.1002/bit.20371] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Small changes in transcriptional activity often significantly affect phenotype but are not detectable in vivo by conventional means. To address this problem, we present a technique for detecting weak transcriptional responses using signal-amplifying genetic circuits. We apply this technique to reveal previously undetectable log phase responses of several Rhl quorum sensing controlled (qsc) promoters from Pseudomonas aeruginosa. Genetic circuits with Rhl promoters and transcriptional amplification components were built and tested in Escherichia coli. This enabled us to isolate the behavior of the promoters under study from Las and quinolone interactions. To amplify qsc promoter responses to acyl-homoserine lactones (AHL), the highly efficient lambda repressor gene was placed downstream of several Rhl promoters and coupled to a fluorescent reporter under the control of the lambda P(R) promoter. With amplification, up to approximately 100-fold differences in fluorescence levels between AHL induced and noninduced cultures were observed for promoters whose responses were otherwise not detectable. In addition, the combination of using signal amplification and performing experiments in E. coli simplified the analysis of AHL signal crosstalk. For example, we discovered that while a C4HSL/RhlR complex activates both qscrhlA and qscphzA1, a 3OC12HSL/RhlR complex activates qscphzA1 but not qscrhlA in our system. This crosstalk information is particularly important since one of the potential uses of amplification constructs is for the detection of specific quorum sensing signals in environmental and clinical isolates. Furthermore, the process of decomposing networks into basic parts, isolating these components in a well-defined background, and using amplification to characterize both crosstalk and cognate signal responses embodies an important approach to understanding complex genetic networks.
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Affiliation(s)
- David Karig
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
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Martínez M, Brito B, Imperial J, Ruiz-Argüeso T. Characterization of a new internal promoter (P3) for Rhizobium leguminosarum hydrogenase accessory genes hupGHIJ. Microbiology (Reading) 2004; 150:665-675. [PMID: 14993316 DOI: 10.1099/mic.0.26623-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Synthesis of the Rhizobium leguminosarum [NiFe] hydrogenase requires the participation of 16 accessory genes (hupCDEFGHIJKhypABFCDEX) besides the genes encoding the structural proteins (hupSL). Transcription of hupSL is controlled by a -24/-12-type promoter (P(1)), located upstream of hupS and regulated by NifA. In this work, a second -24/-12-type promoter (P(3)), located upstream of the hupG gene and transcribing hupGHIJ genes in R. leguminosarum pea (Pisum sativum L.) bacteroids, has been identified in the hup gene cluster. Promoter P(3) was also active in R. leguminosarum free-living cells, as evidenced by genetic complementation of hydrogenase mutants. Both NifA and NtrC activated P(3) expression in the heterologous host Klebsiella pneumoniae. Also, P(3) activity was highly stimulated by K. pneumoniae NifA in Escherichia coli. This NifA activation of P(3) expression only required the sigma(54)-binding site, and it was independent of any cis-acting element upstream of the sigma(54) box, which suggests a direct interaction of free NifA with the RNA polymerase holoenzyme. P(3)-dependent hupGHIJ expression in pea nodules started in interzone II/III, spanned through nitrogen-fixing zone III, and was coincident with the NifA-dependent nifH expression pattern. However, P(3) was dispensable for hupGHIJ transcription and hydrogenase activity in pea bacteroids due to transcription initiated at P(1). This fact and the lack of an activator recruitment system suggest that P(3) plays a secondary role in symbiotic hupGHIJ expression.
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Affiliation(s)
- Marta Martínez
- Departamento de Biotecnología, E. T. S. de Ingenieros Agrónomos, Universidad Politécnica de Madrid, 28040 Madrid, Spain
| | - Belén Brito
- Departamento de Biotecnología, E. T. S. de Ingenieros Agrónomos, Universidad Politécnica de Madrid, 28040 Madrid, Spain
| | - Juan Imperial
- Consejo Superior de Investigaciones Científicas (C.S.I.C.), 28040 Madrid, Spain
| | - Tomás Ruiz-Argüeso
- Departamento de Biotecnología, E. T. S. de Ingenieros Agrónomos, Universidad Politécnica de Madrid, 28040 Madrid, Spain
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Schwartz E, Henne A, Cramm R, Eitinger T, Friedrich B, Gottschalk G. Complete nucleotide sequence of pHG1: a Ralstonia eutropha H16 megaplasmid encoding key enzymes of H(2)-based ithoautotrophy and anaerobiosis. J Mol Biol 2003; 332:369-83. [PMID: 12948488 DOI: 10.1016/s0022-2836(03)00894-5] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The self-transmissible megaplasmid pHG1 carries essential genetic information for the facultatively lithoautotrophic and facultatively anaerobic lifestyles of its host, the Gram-negative soil bacterium Ralstonia eutropha H16. We have determined the complete nucleotide sequence of pHG1. This megaplasmid is 452,156 bp in size and carries 429 potential genes. Groups of functionally related genes form loose clusters flanked by mobile elements. The largest functional group consists of lithoautotrophy-related genes. These include a set of 41 genes for the biosynthesis of the three previously identified hydrogenases and of a fourth, novel hydrogenase. Another large cluster carries the genetic information for denitrification. In addition to a dissimilatory nitrate reductase, both specific and global regulators were identified. Also located in the denitrification region is a set of genes for cytochrome c biosynthesis. Determinants for several enzymes involved in the mineralization of aromatic compounds were found. The genes for conjugative plasmid transfer predict that R.eutropha forms two types of pili. One of them is related to the type IV pili of pathogenic enterobacteria. pHG1 also carries an extensive "junkyard" region encompassing 17 remnants of mobile elements and 22 partial or intact genes for phage-type integrase. Among the mobile elements is a novel member of the IS5 family, in which the transposase gene is interrupted by a group II intron.
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Affiliation(s)
- Edward Schwartz
- Institut für Biologie, Mikrobiologie, Humboldt-Universität zu Berlin, Chausseestr. 117, 10115 Berlin, Germany.
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Brito B, Palacios JM, Imperial J, Ruiz-Argüeso T. Engineering the Rhizobium leguminosarum bv. viciae hydrogenase system for expression in free-living microaerobic cells and increased symbiotic hydrogenase activity. Appl Environ Microbiol 2002; 68:2461-7. [PMID: 11976122 PMCID: PMC127565 DOI: 10.1128/aem.68.5.2461-2467.2002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rhizobium leguminosarum bv. viciae UPM791 induces hydrogenase activity in pea (Pisum sativum L.) bacteroids but not in free-living cells. The symbiotic induction of hydrogenase structural genes (hupSL) is mediated by NifA, the general regulator of the nitrogen fixation process. So far, no culture conditions have been found to induce NifA-dependent promoters in vegetative cells of this bacterium. This hampers the study of the R. leguminosarum hydrogenase system. We have replaced the native NifA-dependent hupSL promoter with the FnrN-dependent fixN promoter, generating strain SPF25, which expresses the hup system in microaerobic free-living cells. SPF25 reaches levels of hydrogenase activity in microaerobiosis similar to those induced in UPM791 bacteroids. A sixfold increase in hydrogenase activity was detected in merodiploid strain SPF25(pALPF1). A time course induction of hydrogenase activity in microaerobic free-living cells of SPF25(pALPF1) shows that hydrogenase activity is detected after 3 h of microaerobic incubation. Maximal hydrogen uptake activity was observed after 10 h of microaerobiosis. Immunoblot analysis of microaerobically induced SPF25(pALPF1) cell fractions indicated that the HupL active form is located in the membrane, whereas the unprocessed protein remains in the soluble fraction. Symbiotic hydrogenase activity of strain SPF25 was not impaired by the promoter replacement. Moreover, bacteroids from pea plants grown in low-nickel concentrations induced higher levels of hydrogenase activity than the wild-type strain and were able to recycle all hydrogen evolved by nodules. This constitutes a new strategy to improve hydrogenase activity in symbiosis.
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Affiliation(s)
- B Brito
- Laboratorio de Microbiología, E. T. S. Ingenieros Agrónomos, Universidad Politécnica de Madrid, 28040 Madrid, Spain
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Fodor B, Rákhely G, Kovács KL. Transposon mutagenesis in purple sulfur photosynthetic bacteria: identification of hypF, encoding a protein capable of processing [NiFe] hydrogenases in alpha, beta, and gamma subdivisions of the proteobacteria. Appl Environ Microbiol 2001; 67:2476-83. [PMID: 11375153 PMCID: PMC92897 DOI: 10.1128/aem.67.6.2476-2483.2001] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A random transposon-based mutagenesis system was optimized for the purple sulfur phototrophic bacterium Thiocapsa roseopersicina BBS. Screening for hydrogenase-deficient phenotypes resulted in the isolation of six independent mutants in a mini-Tn5 library. One of the mutations was in a gene showing high amino acid sequence similarity to HypF proteins in other organisms. Inactivation of hydrogen uptake activity in the hypF-deficient mutant resulted in a dramatic increase in the hydrogen evolution capacity of T. roseopersicina under nitrogen-fixing conditions. This mutant is therefore a promising candidate for use in practical biohydrogen-producing systems. The reconstructed hypF gene was able to complement the hypF-deficient mutant of T. roseopersicina BBS. Heterologous complementation experiments, using hypF mutant strains of T. roseopersicina, Escherichia coli, and Ralstonia eutropha and various hypF genes, were performed. They were successful in all of the cases tested, although for E. coli, the regulatory region of the foreign gene had to be replaced in order to achieve partial complementation. RT-PCR data suggested that HypF has no effect on the transcriptional regulation of the structural genes of hydrogenases in this organism.
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Affiliation(s)
- B Fodor
- Institute of Biophysics, Biological Research Center, Hungarian Academy of Sciences, and Department of Biotechnology, University of Szeged, H-6726 Szeged, Hungary
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Hansel A, Axelsson R, Lindberg P, Troshina OY, Wünschiers R, Lindblad P. Cloning and characterisation of a hyp gene cluster in the filamentous cyanobacterium Nostoc sp. strain PCC 73102. FEMS Microbiol Lett 2001; 201:59-64. [PMID: 11445168 DOI: 10.1111/j.1574-6968.2001.tb10733.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Maturation of [NiFe]-hydrogenases requires the action of several groups of accessory genes. Homologues of one group of these genes, the so-called hyp genes, putatively encoding proteins participating in the formation of an active uptake hydrogenase in the filamentous, heterocyst-forming cyanobacterium Nostoc PCC 73102, were cloned. The cluster, consisting of hypF, hypC, hypD, hypE, hypA, and hypB, is located 3.8 kb upstream from the uptake hydrogenase-encoding hupSL. Gene expression analyses show that these hyp genes are, like hupL, transcribed under N(2)-fixing but not under non-N(2)-fixing growth conditions. Furthermore, the six hyp genes are transcribed together with an open reading frame upstream of hypF, as a single mRNA. Analysis of the DNA region upstream of the experimentally determined transcriptional start site revealed putative -10 and -35 sequence elements and putative binding sites for the global nitrogen regulator NtcA.
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Affiliation(s)
- A Hansel
- Department of Physiological Botany, EBC, Uppsala University, Sweden
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Kleihues L, Lenz O, Bernhard M, Buhrke T, Friedrich B. The H(2) sensor of Ralstonia eutropha is a member of the subclass of regulatory [NiFe] hydrogenases. J Bacteriol 2000; 182:2716-24. [PMID: 10781538 PMCID: PMC101976 DOI: 10.1128/jb.182.10.2716-2724.2000] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two energy-generating hydrogenases enable the aerobic hydrogen bacterium Ralstonia eutropha (formerly Alcaligenes eutrophus) to use molecular hydrogen as the sole energy source. The complex synthesis of the nickel-iron-containing enzymes has to be efficiently regulated in response to H(2), which is available in low amounts in aerobic environments. H(2) sensing in R. eutropha is achieved by a hydrogenase-like protein which controls the hydrogenase gene expression in concert with a two-component regulatory system. In this study we show that the H(2) sensor of R. eutropha is a cytoplasmic protein. Although capable of H(2) oxidation with redox dyes as electron acceptors, the protein did not support lithoautotrophic growth in the absence of the energy-generating hydrogenases. A specifically designed overexpression system for R. eutropha provided the basis for identifying the H(2) sensor as a nickel-containing regulatory protein. The data support previous results which showed that the sensor has an active site similar to that of prototypic [NiFe] hydrogenases (A. J. Pierik, M. Schmelz, O. Lenz, B. Friedrich, and S. P. J. Albracht, FEBS Lett. 438:231-235, 1998). It is demonstrated that in addition to the enzymatic activity the regulatory function of the H(2) sensor is nickel dependent. The results suggest that H(2) sensing requires an active [NiFe] hydrogenase, leaving the question open whether only H(2) binding or subsequent H(2) oxidation and electron transfer processes are necessary for signaling. The regulatory role of the H(2)-sensing hydrogenase of R. eutropha, which has also been investigated in other hydrogen-oxidizing bacteria, is intimately correlated with a set of typical structural features. Thus, the family of H(2) sensors represents a novel subclass of [NiFe] hydrogenases denoted as the "regulatory hydrogenases."
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Affiliation(s)
- L Kleihues
- Institut für Biologie, Humboldt-Universität zu Berlin, 10115 Berlin, Germany
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