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Greening C, Kropp A, Vincent K, Grinter R. Developing high-affinity, oxygen-insensitive [NiFe]-hydrogenases as biocatalysts for energy conversion. Biochem Soc Trans 2023; 51:1921-1933. [PMID: 37743798 PMCID: PMC10657181 DOI: 10.1042/bst20230120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 09/13/2023] [Accepted: 09/14/2023] [Indexed: 09/26/2023]
Abstract
The splitting of hydrogen (H2) is an energy-yielding process, which is important for both biological systems and as a means of providing green energy. In biology, this reaction is mediated by enzymes called hydrogenases, which utilise complex nickel and iron cofactors to split H2 and transfer the resulting electrons to an electron-acceptor. These [NiFe]-hydrogenases have received considerable attention as catalysts in fuel cells, which utilise H2 to produce electrical current. [NiFe]-hydrogenases are a promising alternative to the platinum-based catalysts that currently predominate in fuel cells due to the abundance of nickel and iron, and the resistance of some family members to inhibition by gases, including carbon monoxide, which rapidly poison platinum-based catalysts. However, the majority of characterised [NiFe]-hydrogenases are inhibited by oxygen (O2), limiting their activity and stability. We recently reported the isolation and characterisation of the [NiFe]-hydrogenase Huc from Mycobacterium smegmatis, which is insensitive to inhibition by O2 and has an extremely high affinity, making it capable of oxidising H2 in air to below atmospheric concentrations. These properties make Huc a promising candidate for the development of enzyme-based fuel cells (EBFCs), which utilise H2 at low concentrations and in impure gas mixtures. In this review, we aim to provide context for the use of Huc for this purpose by discussing the advantages of [NiFe]-hydrogenases as catalysts and their deployment in fuel cells. We also address the challenges associated with using [NiFe]-hydrogenases for this purpose, and how these might be overcome to develop EBFCs that can be deployed at scale.
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Affiliation(s)
- Chris Greening
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
- Securing Antarctica's Environmental Future, Monash University, Clayton, VIC 3800, Australia
- Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia
- ARC Research Hub for Carbon Utilisation and Recycling, Monash University, Clayton, VIC 3800, Australia
| | - Ashleigh Kropp
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
| | - Kylie Vincent
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, Oxford OX1 3QR, U.K
| | - Rhys Grinter
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
- Centre for Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria 3052, Australia
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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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Opel F, Itzenhäuser MA, Wehner I, Lupacchini S, Lauterbach L, Lenz O, Klähn S. Toward a synthetic hydrogen sensor in cyanobacteria: Functional production of an oxygen-tolerant regulatory hydrogenase in Synechocystis sp. PCC 6803. Front Microbiol 2023; 14:1122078. [PMID: 37032909 PMCID: PMC10073562 DOI: 10.3389/fmicb.2023.1122078] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 02/22/2023] [Indexed: 04/11/2023] Open
Abstract
Cyanobacteria have raised great interest in biotechnology, e.g., for the sustainable production of molecular hydrogen (H2) using electrons from water oxidation. However, this is hampered by various constraints. For example, H2-producing enzymes compete with primary metabolism for electrons and are usually inhibited by molecular oxygen (O2). In addition, there are a number of other constraints, some of which are unknown, requiring unbiased screening and systematic engineering approaches to improve the H2 yield. Here, we introduced the regulatory [NiFe]-hydrogenase (RH) of Cupriavidus necator (formerly Ralstonia eutropha) H16 into the cyanobacterial model strain Synechocystis sp. PCC 6803. In its natural host, the RH serves as a molecular H2 sensor initiating a signal cascade to express hydrogenase-related genes when no additional energy source other than H2 is available. Unlike most hydrogenases, the C. necator enzymes are O2-tolerant, allowing their efficient utilization in an oxygenic phototroph. Similar to C. necator, the RH produced in Synechocystis showed distinct H2 oxidation activity, confirming that it can be properly matured and assembled under photoautotrophic, i.e., oxygen-evolving conditions. Although the functional H2-sensing cascade has not yet been established in Synechocystis yet, we utilized the associated two-component system consisting of a histidine kinase and a response regulator to drive and modulate the expression of a superfolder gfp gene in Escherichia coli. This demonstrates that all components of the H2-dependent signal cascade can be functionally implemented in heterologous hosts. Thus, this work provides the basis for the development of an intrinsic H2 biosensor within a cyanobacterial cell that could be used to probe the effects of random mutagenesis and systematically identify promising genetic configurations to enable continuous and high-yield production of H2 via oxygenic photosynthesis.
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Affiliation(s)
- Franz Opel
- Department of Solar Materials, Helmholtz Centre for Environmental Research – UFZ, Leipzig, Germany
| | | | - Isabel Wehner
- Department of Solar Materials, Helmholtz Centre for Environmental Research – UFZ, Leipzig, Germany
| | - Sara Lupacchini
- Department of Solar Materials, Helmholtz Centre for Environmental Research – UFZ, Leipzig, Germany
| | - Lars Lauterbach
- Institute of Applied Microbiology (iAMB), RWTH Aachen University, Aachen, Germany
| | - Oliver Lenz
- Institute of Chemistry, Technical University of Berlin, Berlin, Germany
| | - Stephan Klähn
- Department of Solar Materials, Helmholtz Centre for Environmental Research – UFZ, Leipzig, Germany
- *Correspondence: Stephan Klähn,
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Fan Q, Waldburger S, Neubauer P, Riedel SL, Gimpel M. Implementation of a high cell density fed-batch for heterologous production of active [NiFe]-hydrogenase in Escherichia coli bioreactor cultivations. Microb Cell Fact 2022; 21:193. [PMID: 36123684 PMCID: PMC9484157 DOI: 10.1186/s12934-022-01919-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 09/07/2022] [Indexed: 11/13/2022] Open
Abstract
Background O2-tolerant [NiFe]-hydrogenases offer tremendous potential for applications in H2-based technology. As these metalloenzymes undergo a complicated maturation process that requires a dedicated set of multiple accessory proteins, their heterologous production is challenging, thus hindering their fundamental understanding and the development of related applications. Taking these challenges into account, we selected the comparably simple regulatory [NiFe]-hydrogenase (RH) from Cupriavidus necator as a model for the development of bioprocesses for heterologous [NiFe]-hydrogenase production. We already reported recently on the high-yield production of catalytically active RH in Escherichia coli by optimizing the culture conditions in shake flasks. Results In this study, we further increase the RH yield and ensure consistent product quality by a rationally designed high cell density fed-batch cultivation process. Overall, the bioreactor cultivations resulted in ˃130 mg L−1 of catalytically active RH which is a more than 100-fold increase compared to other RH laboratory bioreactor scale processes with C. necator. Furthermore, the process shows high reproducibility of the previously selected optimized conditions and high productivity. Conclusions This work provides a good opportunity to readily supply such difficult-to-express complex metalloproteins economically and at high concentrations to meet the demand in basic and applied studies. Supplementary Information The online version contains supplementary material available at 10.1186/s12934-022-01919-w.
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Affiliation(s)
- Qin Fan
- Chair of Bioprocess Engineering, Technische Universität Berlin, Ackerstr. 76, ACK24, D-13355, Berlin, Germany
| | - Saskia Waldburger
- Chair of Bioprocess Engineering, Technische Universität Berlin, Ackerstr. 76, ACK24, D-13355, Berlin, Germany
| | - Peter Neubauer
- Chair of Bioprocess Engineering, Technische Universität Berlin, Ackerstr. 76, ACK24, D-13355, Berlin, Germany
| | - Sebastian L Riedel
- Chair of Bioprocess Engineering, Technische Universität Berlin, Ackerstr. 76, ACK24, D-13355, Berlin, Germany
| | - Matthias Gimpel
- Chair of Bioprocess Engineering, Technische Universität Berlin, Ackerstr. 76, ACK24, D-13355, Berlin, Germany.
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