1
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Prout L, Hailes HC, Ward JM. Natural transaminase fusions for biocatalysis. RSC Adv 2024; 14:4264-4273. [PMID: 38298934 PMCID: PMC10829540 DOI: 10.1039/d3ra07081f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 01/23/2024] [Indexed: 02/02/2024] Open
Abstract
Biocatalytic approaches are used widely for the synthesis of amines from abundant or low cost starting materials. This is a fast-developing field where novel enzymes and enzyme combinations emerge quickly to enable the production of new and complex compounds. Natural multifunctional enzymes represent a part of multi-step biosynthetic pathways that ensure a one-way flux of reactants. In vivo, they confer a selective advantage via increased reaction rates and chemical stability or prevention of toxicity from reactive intermediates. Here we report the identification and analysis of a natural transaminase fusion, PP_2782, from Pseudomonas putida KT2440, as well as three of its thermophilic homologs from Thermaerobacter marianensis, Thermaerobacter subterraneus, and Thermincola ferriacetica. Both the fusions and their truncated transaminase-only derivatives showed good activity with unsubstituted aliphatic and aromatic aldehydes and amines, as well as with a range of α-keto acids, and l-alanine, l-glutamate, and l-glutamine. Through structural similarity, the fused domain was recognised as the acyl-[acyl-carrier-protein] reductase that affects reductive chain release. These natural transaminase fusions could have a great potential for industrial applications.
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Affiliation(s)
- Luba Prout
- Department of Biochemical Engineering, University College London London WC1E 6BT UK
| | - Helen C Hailes
- Department of Chemistry, University College London 20 Gordon Street London WC1H 0AJ UK
| | - John M Ward
- Department of Biochemical Engineering, University College London London WC1E 6BT UK
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2
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Han J, Asano K, Matsumoto T, Yamada R, Ogino H. Engineering acyl-ACP reductase with fusion tags enhances alka(e)ne synthesis in Escherichia coli. Enzyme Microb Technol 2023; 168:110262. [PMID: 37224590 DOI: 10.1016/j.enzmictec.2023.110262] [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: 11/25/2022] [Revised: 05/17/2023] [Accepted: 05/18/2023] [Indexed: 05/26/2023]
Abstract
Alka(e)nes are high-value chemicals with a potentially broad range of industrial applications because of their following advantages: (1) chemical and structural resemblance to petroleum hydrocarbons and (2) higher energy density and hydrophobicity than those of other biofuels. The low yield of bio-alka(e)nes, however, hinders their commercial application. The activity and solubility of acyl carrier protein (ACP) reductase (AAR) affect alka(e)ne biosynthesis in cyanobacteria. The enhancement of the activity and concentration of soluble AAR through genetic and process engineering can improve bio-alka(e)ne yield. Although fusion tags are used to enhance the expression or solubility of recombinant proteins, their effectiveness in improving the production of bio-alka(e)nes has not yet been reported. Fusion tags can be used to improve the amount or activity of soluble AAR in Escherichia coli and to increase the yield of alka(e)nes in E. coli cells co-expressing aldehyde deformylating oxygenase (ADO). Hence, in the present study, histidine (His6/His12), thioredoxin (Trx), maltose-binding protein (MBP), and N-utilization substance (NusA) were used as AAR fusion tags. The strain expressing SeAAR with His12 tag and NpADO showed a 7.2-fold higher yield of alka(e)nes than the strain expressing AAR without fusion tag and NpADO. The highest titer of alka(e)nes (194.78 mg/L) was achieved with the His12 tag.
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Affiliation(s)
- Jiahu Han
- Department of Chemical Engineering, Osaka Metropolitan University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
| | - Koki Asano
- Department of Chemical Engineering, Osaka Metropolitan University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
| | - Takuya Matsumoto
- Department of Chemical Engineering, Osaka Metropolitan University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan.
| | - Ryosuke Yamada
- Department of Chemical Engineering, Osaka Metropolitan University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
| | - Hiroyasu Ogino
- Department of Chemical Engineering, Osaka Metropolitan University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
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3
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Hayashi Y, Arai M. Recent advances in the improvement of cyanobacterial enzymes for bioalkane production. Microb Cell Fact 2022; 21:256. [PMID: 36503511 PMCID: PMC9743570 DOI: 10.1186/s12934-022-01981-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 12/01/2022] [Indexed: 12/14/2022] Open
Abstract
The use of biologically produced alkanes has attracted considerable attention as an alternative energy source to petroleum. In 2010, the alkane synthesis pathway in cyanobacteria was found to include two small globular proteins, acyl-(acyl carrier protein [ACP]) reductase (AAR) and aldehyde deformylating oxygenase (ADO). AAR produces fatty aldehydes from acyl-ACPs/CoAs, which are then converted by ADO to alkanes/alkenes equivalent to diesel oil. This discovery has paved the way for alkane production by genetically modified organisms. Since then, many studies have investigated the reactions catalyzed by AAR and ADO. In this review, we first summarize recent findings on structures and catalytic mechanisms of AAR and ADO. We then outline the mechanism by which AAR and ADO form a complex and efficiently transfer the insoluble aldehyde produced by AAR to ADO. Furthermore, we describe recent advances in protein engineering studies on AAR and ADO to improve the efficiency of alkane production in genetically engineered microorganisms such as Escherichia coli and cyanobacteria. Finally, the role of alkanes in cyanobacteria and future perspectives for bioalkane production using AAR and ADO are discussed. This review provides strategies for improving the production of bioalkanes using AAR and ADO in cyanobacteria for enabling the production of carbon-neutral fuels.
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Affiliation(s)
- Yuuki Hayashi
- grid.26999.3d0000 0001 2151 536XDepartment of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902 Japan ,grid.26999.3d0000 0001 2151 536XEnvironmental Science Center, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033 Japan
| | - Munehito Arai
- grid.26999.3d0000 0001 2151 536XDepartment of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902 Japan ,grid.26999.3d0000 0001 2151 536XDepartment of Physics, Graduate School of Science, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902 Japan
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4
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Richardson SM, Marchetti PM, Herrera MA, Campopiano DJ. Coupled Natural Fusion Enzymes in a Novel Biocatalytic Cascade Convert Fatty Acids to Amines. ACS Catal 2022; 12:12701-12710. [PMID: 36313522 PMCID: PMC9594044 DOI: 10.1021/acscatal.2c02954] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Revised: 07/29/2022] [Indexed: 11/28/2022]
Abstract
![]()
Tambjamine YP1 is a pyrrole-containing natural product.
Analysis
of the enzymes encoded in the Pseudoalteromonas tunicata “tam” biosynthetic gene cluster (BGC)
identified a unique di-domain biocatalyst (PtTamH).
Sequence and bioinformatic analysis predicts that PtTamH comprises an N-terminal, pyridoxal 5′-phosphate (PLP)-dependent
transaminase (TA) domain fused to a NADH-dependent C-terminal thioester
reductase (TR) domain. Spectroscopic and chemical analysis revealed
that the TA domain binds PLP, utilizes l-Glu as an amine
donor, accepts a range of fatty aldehydes (C7–C14 with a preference for C12), and produces the
corresponding amines. The previously characterized PtTamA from the “tam” BGC is an ATP-dependent, di-domain
enzyme comprising a class I adenylation domain fused to an acyl carrier
protein (ACP). Since recombinant PtTamA catalyzes
the activation and thioesterification of C12 acid to the holo-ACP domain, we hypothesized that C12 ACP
is the natural substrate for PtTamH. PtTamA and PtTamH were successfully coupled together
in a biocatalytic cascade that converts fatty acids (FAs) to amines
in one pot. Moreover, a structural model of PtTamH
provides insights into how the TA and TR domains are organized. This
work not only characterizes the formation of the tambjamine YP1 tail
but also suggests that PtTamA and PtTamH could be useful biocatalysts for FA to amine functional group
conversion.
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Affiliation(s)
- Shona M. Richardson
- School of Chemistry, The University of Edinburgh, David Brewster Road, EdinburghEH9 3FJ, U.K
| | - Piera M. Marchetti
- School of Chemistry, The University of Edinburgh, David Brewster Road, EdinburghEH9 3FJ, U.K
| | - Michael A. Herrera
- School of Chemistry, The University of Edinburgh, David Brewster Road, EdinburghEH9 3FJ, U.K
| | - Dominic J. Campopiano
- School of Chemistry, The University of Edinburgh, David Brewster Road, EdinburghEH9 3FJ, U.K
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5
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Domergue F, Miklaszewska M. The production of wax esters in transgenic plants:
towards a sustainable source of bio-lubricants. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:2817-2834. [PMID: 35560197 PMCID: PMC9113324 DOI: 10.1093/jxb/erac046] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 02/03/2022] [Indexed: 05/08/2023]
Abstract
Wax esters are high-value compounds used as feedstocks for the production of lubricants, pharmaceuticals, and cosmetics. Currently, they are produced mostly from fossil reserves using chemical synthesis, but this cannot meet increasing demand and has a negative environmental impact. Natural wax esters are also obtained from Simmondsia chinensis (jojoba) but comparably in very low amounts and expensively. Therefore, metabolic engineering of plants, especially of the seed storage lipid metabolism of oil crops, represents an attractive strategy for renewable, sustainable, and environmentally friendly production of wax esters tailored to industrial applications. Utilization of wax ester-synthesizing enzymes with defined specificities and modulation of the acyl-CoA pools by various genetic engineering approaches can lead to obtaining wax esters with desired compositions and properties. However, obtaining high amounts of wax esters is still challenging due to their negative impact on seed germination and yield. In this review, we describe recent progress in establishing non-food-plant platforms for wax ester production and discuss their advantages and limitations as well as future prospects.
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Affiliation(s)
- Frédéric Domergue
- Univ. Bordeaux, CNRS, LBM, UMR 5200, F-33140 Villenave d’Ornon, France
| | - Magdalena Miklaszewska
- Department of Functional and Evolutionary Ecology, Division of Molecular Systems Biology (MOSYS), Faculty of Life Sciences, University of Vienna, Djerassiplatz 1, 1030, Vienna, Austria
- Department of Plant Physiology and Biotechnology, University of Gdańsk, Wita Stwosza 59, 80-308, Gdańsk, Poland
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6
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Banerjee R, Srinivas V, Lebrette H. Ferritin-Like Proteins: A Conserved Core for a Myriad of Enzyme Complexes. Subcell Biochem 2022; 99:109-153. [PMID: 36151375 DOI: 10.1007/978-3-031-00793-4_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Ferritin-like proteins share a common fold, a four α-helix bundle core, often coordinating a pair of metal ions. Although conserved, the ferritin fold permits a diverse set of reactions, and is central in a multitude of macromolecular enzyme complexes. Here, we emphasize this diversity through three members of the ferritin-like superfamily: the soluble methane monooxygenase, the class I ribonucleotide reductase and the aldehyde deformylating oxygenase. They all rely on dinuclear metal cofactors to catalyze different challenging oxygen-dependent reactions through the formation of multi-protein complexes. Recent studies using cryo-electron microscopy, serial femtosecond crystallography at an X-ray free electron laser source, or single-crystal X-ray diffraction, have reported the structures of the active protein complexes, and revealed unprecedented insights into the molecular mechanisms of these three enzymes.
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Affiliation(s)
- Rahul Banerjee
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Vivek Srinivas
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Hugo Lebrette
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, UPS, Université de Toulouse, Toulouse, France.
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7
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Biophysical and structural studies reveal marginal stability of a crucial hydrocarbon biosynthetic enzyme acyl ACP reductase. Sci Rep 2021; 11:12045. [PMID: 34103559 PMCID: PMC8187606 DOI: 10.1038/s41598-021-91232-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Accepted: 05/19/2021] [Indexed: 11/22/2022] Open
Abstract
Acyl-ACP reductase (AAR) is one of the two key cyanobacterial enzymes along with aldehyde deformylating oxygenase (ADO) involved in the synthesis of long-chain alkanes, a drop-in biofuel. The enzyme is prone to aggregation when expressed in Escherichia coli, leading to varying alkane levels. The present work attempts to investigate the crucial structural aspects of AAR protein associated with its stability and folding. Characterization by dynamic light scattering experiment and intact mass spectrometry revealed that recombinantly expressed AAR in E. coli existed in multiple-sized protein particles due to diverse lipidation. Interestingly, while thermal- and urea-based denaturation of AAR showed 2-state unfolding transition in circular dichroism and intrinsic fluorescent spectroscopy, the unfolding process of AAR was a 3-state pathway in GdnHCl solution suggesting that the protein milieu plays a significant role in dictating its folding. Apparent standard free energy \documentclass[12pt]{minimal}
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\begin{document}$$\left( {\Delta {\text{G}}_{{{\text{NU}}}}^{{{\text{H}}_{2} {\text{O}}}} } \right)$$\end{document}ΔGNUH2O of ~ 4.5 kcal/mol for the steady-state unfolding of AAR indicated borderline stability of the protein. Based on these evidences, we propose that the marginal stability of AAR are plausible contributing reasons for aggregation propensity and hence the low catalytic activity of the enzyme when expressed in E. coli for biofuel production. Our results show a path for building superior biocatalyst for higher biofuel production.
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8
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Krishnan A, McNeil BA, Stuart DT. Biosynthesis of Fatty Alcohols in Engineered Microbial Cell Factories: Advances and Limitations. Front Bioeng Biotechnol 2020; 8:610936. [PMID: 33344437 PMCID: PMC7744569 DOI: 10.3389/fbioe.2020.610936] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 11/10/2020] [Indexed: 11/19/2022] Open
Abstract
Concerns about climate change and environmental destruction have led to interest in technologies that can replace fossil fuels and petrochemicals with compounds derived from sustainable sources that have lower environmental impact. Fatty alcohols produced by chemical synthesis from ethylene or by chemical conversion of plant oils have a large range of industrial applications. These chemicals can be synthesized through biological routes but their free forms are produced in trace amounts naturally. This review focuses on how genetic engineering of endogenous fatty acid metabolism and heterologous expression of fatty alcohol producing enzymes have come together resulting in the current state of the field for production of fatty alcohols by microbial cell factories. We provide an overview of endogenous fatty acid synthesis, enzymatic methods of conversion to fatty alcohols and review the research to date on microbial fatty alcohol production. The primary focus is on work performed in the model microorganisms, Escherichia coli and Saccharomyces cerevisiae but advances made with cyanobacteria and oleaginous yeasts are also considered. The limitations to production of fatty alcohols by microbial cell factories are detailed along with consideration to potential research directions that may aid in achieving viable commercial scale production of fatty alcohols from renewable feedstock.
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Affiliation(s)
- Anagha Krishnan
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
| | - Bonnie A McNeil
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
| | - David T Stuart
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
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9
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Structural insights into catalytic mechanism and product delivery of cyanobacterial acyl-acyl carrier protein reductase. Nat Commun 2020; 11:1525. [PMID: 32251275 PMCID: PMC7089970 DOI: 10.1038/s41467-020-15268-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 02/28/2020] [Indexed: 11/10/2022] Open
Abstract
Long-chain alk(a/e)nes represent the major constituents of conventional transportation fuels. Biosynthesis of alkanes is ubiquitous in many kinds of organisms. Cyanobacteria possess two enzymes, acyl-acyl carrier protein (acyl-ACP) reductase (AAR) and aldehyde-deformylating oxygenase (ADO), which function in a two-step alkane biosynthesis pathway. These two enzymes act in series and possibly form a complex that efficiently converts long chain fatty acyl-ACP/fatty acyl-CoA into hydrocarbon. While the structure of ADO has been previously described, structures of both AAR and AAR–ADO complex have not been solved, preventing deeper understanding of this pathway. Here, we report a ligand-free AAR structure, and three AAR–ADO complex structures in which AARs bind various ligands. Our results reveal the binding pattern of AAR with its substrate/cofactor, and suggest a potential aldehyde-transferring channel from AAR to ADO. Based on our structural and biochemical data, we proposed a model for the complete catalytic cycle of AAR. Acyl-acyl carrier protein reductase (AAR) and aldehyde deformylating oxygenase (ADO) are the two enzymes in a cyanobacterial alkane biosynthesis pathway that is of interest for biofuel production. Here the authors provide insights into the catalytic mechanisms of AAR and the coupling between the two enzymes by determining the crystal structures of AAR alone and three AAR–ADO complexes with various bound ligands.
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10
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Triacylglycerol and phytyl ester synthesis in Synechocystis sp. PCC6803. Proc Natl Acad Sci U S A 2020; 117:6216-6222. [PMID: 32123083 DOI: 10.1073/pnas.1915930117] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cyanobacteria are unicellular prokaryotic algae that perform oxygenic photosynthesis, similar to plants. The cells harbor thylakoid membranes composed of lipids related to those of chloroplasts in plants to accommodate the complexes of photosynthesis. The occurrence of storage lipids, including triacylglycerol or wax esters, which are found in plants, animals, and some bacteria, nevertheless remained unclear in cyanobacteria. We show here that the cyanobacterium Synechocystis sp. PCC6803 accumulates both triacylglycerol and wax esters (fatty acid phytyl esters). Phytyl esters accumulate in higher levels under abiotic stress conditions. The analysis of an insertional mutant revealed that the acyltransferase slr2103, with sequence similarity to plant esterase/lipase/thioesterase (ELT) proteins, is essential for triacylglycerol and phytyl ester synthesis in Synechocystis The recombinant slr2103 enzyme showed acyltransferase activity with phytol and diacylglycerol, thus producing phytyl esters and triacylglycerol. Acyl-CoA thioesters were the preferred acyl donors, while acyl-ACP (acyl carrier protein), free fatty acids, or galactolipid-bound fatty acids were poor substrates. The slr2103 protein sequence is unrelated to acyltransferases from bacteria (AtfA) or plants (DGAT1, DGAT2, PDAT), and therefore establishes an independent group of bacterial acyltransferases involved in triacylglycerol and wax ester synthesis. The identification of the gene slr2103 responsible for triacylglycerol synthesis in cyanobacteria opens the possibility of using prokaryotic photosynthetic cells in biotechnological applications.
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11
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Building cell factories for the production of advanced fuels. Biochem Soc Trans 2020; 47:1701-1714. [PMID: 31803925 DOI: 10.1042/bst20190168] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 11/13/2019] [Accepted: 11/15/2019] [Indexed: 12/31/2022]
Abstract
Synthetic biology-based engineering strategies are being extensively employed for microbial production of advanced fuels. Advanced fuels, being comparable in energy efficiency and properties to conventional fuels, have been increasingly explored as they can be directly incorporated into the current fuel infrastructure without the need for reconstructing the pre-existing set-up rendering them economically viable. Multiple metabolic engineering approaches have been used for rewiring microbes to improve existing or develop newly programmed cells capable of efficient fuel production. The primary challenge in using these approaches is improving the product yield for the feasibility of the commercial processes. Some of the common roadblocks towards enhanced fuel production include - limited availability of flux towards precursors and desired pathways due to presence of competing pathways, limited cofactor and energy supply in cells, the low catalytic activity of pathway enzymes, obstructed product transport, and poor tolerance of host cells for end products. Consequently, despite extensive studies on the engineering of microbial hosts, the costs of industrial-scale production of most of these heterologously produced fuel compounds are still too high. Though considerable progress has been made towards successfully producing some of these biofuels, a substantial amount of work needs to be done for improving the titers of others. In this review, we have summarized the different engineering strategies that have been successfully used for engineering pathways into commercial hosts for the production of advanced fuels and different approaches implemented for tuning host strains and pathway enzymes for scaling up production levels.
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12
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Jaroensuk J, Intasian P, Wattanasuepsin W, Akeratchatapan N, Kesornpun C, Kittipanukul N, Chaiyen P. Enzymatic reactions and pathway engineering for the production of renewable hydrocarbons. J Biotechnol 2020; 309:1-19. [DOI: 10.1016/j.jbiotec.2019.12.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 12/14/2019] [Accepted: 12/15/2019] [Indexed: 01/23/2023]
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13
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Kudo H, Hayashi Y, Arai M. Improving hydrocarbon production by engineering cyanobacterial acyl-(acyl carrier protein) reductase. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:291. [PMID: 31890019 PMCID: PMC6916063 DOI: 10.1186/s13068-019-1623-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2019] [Accepted: 11/27/2019] [Indexed: 05/31/2023]
Abstract
BACKGROUND Acyl-(acyl carrier protein (ACP)) reductase (AAR) is a key enzyme for hydrocarbon biosynthesis in cyanobacteria, reducing fatty acyl-ACPs to aldehydes, which are then converted into hydrocarbons by aldehyde-deformylating oxygenase (ADO). Previously, we compared AARs from various cyanobacteria and found that hydrocarbon yield in Escherichia coli coexpressing AAR and ADO was highest for AAR from Synechococcus elongatus PCC 7942 (7942AAR), which has high substrate affinity for 18-carbon fatty acyl-ACP, resulting in production of mainly heptadecene. In contrast, the hydrocarbon yield was lowest for AAR from Synechococcus sp. PCC 7336 (7336AAR), which has a high specificity for 16-carbon substrates, leading to production of mainly pentadecane. However, even the most productive AAR (7942AAR) still showed low activity; thus, residues within AAR that are nonconserved, but may still be important in hydrocarbon production need to be identified to engineer enzymes with improved hydrocarbon yields. Moreover, AAR mutants that favor shorter alkane production will be useful for producing diesel fuels with decreased freezing temperatures. Here, we aimed to identify such residues and design a highly productive and specific enzyme for hydrocarbon biosynthesis in E. coli. RESULTS We introduced single amino acid substitutions into the least productive AAR (7336AAR) to make its amino acid sequence similar to that of the most productive enzyme (7942AAR). From the analysis of 41 mutants, we identified 6 mutations that increased either the activity or amount of soluble AAR, leading to a hydrocarbon yield improvement in E. coli coexpressing ADO. Moreover, by combining these mutations, we successfully created 7336AAR mutants with ~ 70-fold increased hydrocarbon production, especially for pentadecane, when compared with that of wild-type 7336AAR. Strikingly, the hydrocarbon yield was higher in the multiple mutants of 7336AAR than in 7942AAR. CONCLUSIONS We successfully designed AAR mutants that, when coexpressed with ADO in E. coli, are more highly effective in hydrocarbon production, especially for pentadecane, than wild-type AARs. Our results provide a series of highly productive AARs with different substrate specificities, enabling the production of a variety of hydrocarbons in E. coli that may be used as biofuels.
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Affiliation(s)
- Hisashi Kudo
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902 Japan
| | - Yuuki Hayashi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902 Japan
| | - Munehito Arai
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902 Japan
- Department of Physics, Graduate School of Science, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902 Japan
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14
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Chang M, Shimba K, Hayashi Y, Arai M. Electrostatic interactions at the interface of two enzymes are essential for two-step alkane biosynthesis in cyanobacteria. Biosci Biotechnol Biochem 2019; 84:228-237. [PMID: 31601165 DOI: 10.1080/09168451.2019.1677142] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Cyanobacterial alkane biosynthesis is catalyzed by acyl-(acyl carrier protein (ACP)) reductase (AAR) and aldehyde-deformylating oxygenase (ADO) in a two-step reaction. AAR reduces acyl-ACPs to fatty aldehydes, which are then converted by ADO to alkanes, the main components of diesel fuel. Interaction between AAR and ADO allows AAR to efficiently deliver the aldehyde to ADO. However, this interaction is poorly understood. Here, using analytical size-exclusion chromatography (SEC), we show that electrostatic interactions play an important role in the binding of the two enzymes. Alanine-scanning mutagenesis at charged residues around the substrate entry site of ADO revealed that E201A mutation greatly reduced hydrocarbon production. SEC measurement of the mutant demonstrated that E201 of ADO is essential for the AAR-ADO interaction. Our results suggest that AAR binds to the substrate entrance gate of ADO and thereby facilitates the insertion of the reactive and relatively insoluble aldehyde into the hydrophobic channel of ADO.Abbreviations: AAR: acyl-ACP reductase; ACP: acyl carrier protein; ADO: aldehyde-deformylating oxygenase; ASA: solvent accessible surface area; BSA: bovine serum albumin; CD: circular dichroism; DMSO: dimethyl sulfoxide; DTT: dithiothreitol; GC-MS: gas chromatography-mass spectrometer; HPLC: high-performance liquid chromatography; IPTG: isopropyl-β-D-thiogalactoside; MRE: mean residue ellipticity; NpAAR: AAR from Nostoc punctiforme PCC 73102; NpADO: ADO from Nostoc punctiforme PCC 73102; PmADO: ADO from Prochlorococcus marinus MIT 9313; SDS-PAGE: sodium dodecyl sulfate-polyacrylamide gel electrophoresis; SeAAR: AAR from Synechococcus elongatus PCC 7942; SeADO: ADO from Synechococcus elongatus PCC 7942; SEC: size-exclusion chromatography; TeAAR: AAR from Thermosynechococcus elongatus BP-1; TeADO: ADO from Thermosynechococcus elongatus BP-1; UV: ultraviolet.
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Affiliation(s)
- Mari Chang
- Department of Physics, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Keigo Shimba
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Yuuki Hayashi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Munehito Arai
- Department of Physics, Graduate School of Science, The University of Tokyo, Tokyo, Japan.,Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
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15
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Kudo H, Hayashi Y, Arai M. Identification of non-conserved residues essential for improving the hydrocarbon-producing activity of cyanobacterial aldehyde-deformylating oxygenase. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:89. [PMID: 31015863 PMCID: PMC6469105 DOI: 10.1186/s13068-019-1409-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 03/14/2019] [Indexed: 05/25/2023]
Abstract
BACKGROUND Cyanobacteria produce hydrocarbons corresponding to diesel fuels by means of aldehyde-deformylating oxygenase (ADO). ADO catalyzes a difficult and unusual reaction in the conversion of aldehydes to hydrocarbons and has been widely used for biofuel production in metabolic engineering; however, its activity is low. A comparison of the amino acid sequences of highly active and less active ADOs will elucidate non-conserved residues that are essential for improving the hydrocarbon-producing activity of ADOs. RESULTS Here, we measured the activities of ADOs from 10 representative cyanobacterial strains by expressing each of them in Escherichia coli and quantifying the hydrocarbon yield and amount of soluble ADO. We demonstrated that the activity was highest for the ADO from Synechococcus elongatus PCC 7942 (7942ADO). In contrast, the ADO from Gloeobacter violaceus PCC 7421 (7421ADO) had low activity but yielded high amounts of soluble protein, resulting in a high production level of hydrocarbons. By introducing 37 single amino acid substitutions at the non-conserved residues of the less active ADO (7421ADO) to make its sequence more similar to that of the highly active ADO (7942ADO), we found 20 mutations that improved the activity of 7421ADO. In addition, 13 other mutations increased the amount of soluble ADO while maintaining more than 80% of wild-type activity. Correlation analysis showed a solubility-activity trade-off in ADO, in which activity was negatively correlated with solubility. CONCLUSIONS We succeeded in identifying non-conserved residues that are essential for improving ADO activity. Our results may be useful for generating combinatorial mutants of ADO that have both higher activity and higher amounts of the soluble protein in vivo, thereby producing higher yields of biohydrocarbons.
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Affiliation(s)
- Hisashi Kudo
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo, 153-8902 Japan
| | - Yuuki Hayashi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo, 153-8902 Japan
| | - Munehito Arai
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo, 153-8902 Japan
- Department of Physics, Graduate School of Science, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo, 153-8902 Japan
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16
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Synthetic metabolic pathways for photobiological conversion of CO2 into hydrocarbon fuel. Metab Eng 2018; 49:201-211. [DOI: 10.1016/j.ymben.2018.08.008] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 08/20/2018] [Accepted: 08/20/2018] [Indexed: 12/16/2022]
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17
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Arai M, Hayashi Y, Kudo H. Cyanobacterial Enzymes for Bioalkane Production. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1080:119-154. [PMID: 30091094 DOI: 10.1007/978-981-13-0854-3_6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cyanobacterial biosynthesis of alkanes is an attractive way of producing substitutes for petroleum-based fuels. Key enzymes for bioalkane production in cyanobacteria are acyl-ACP reductase (AAR) and aldehyde-deformylating oxygenase (ADO). AAR catalyzes the reduction of the fatty acyl-ACP/CoA substrates to fatty aldehydes, which are then converted into alkanes/alkenes by ADO. These enzymes have been widely used for biofuel production by metabolic engineering of cyanobacteria and other organisms. However, both proteins, particularly ADO, have low enzymatic activities, and their catalytic activities are desired to be improved for use in biofuel production. Recently, progress has been made in the basic sciences and in the application of AAR and ADO in alkane production. This chapter provides an overview of recent advances in the study of the structure and function of AAR and ADO, protein engineering of these enzymes for improving activity and modifying substrate specificities, and examples of metabolic engineering of cyanobacteria and other organisms using AAR and ADO for biofuel production.
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Affiliation(s)
- Munehito Arai
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan.
| | - Yuuki Hayashi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Hisashi Kudo
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
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18
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Bains RK, Miller JJ, van der Roest HK, Qu S, Lute B, Warren JJ. Light-Activated Electron Transfer and Turnover in Ru-Modified Aldehyde Deformylating Oxygenases. Inorg Chem 2018; 57:8211-8217. [PMID: 29939728 DOI: 10.1021/acs.inorgchem.8b00673] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Conversion of biological molecules into fuels or other useful chemicals is an ongoing chemical challenge. One class of enzymes that has received attention for such applications is aldehyde deformylating oxygenase (ADO) enzymes. These enzymes convert aliphatic aldehydes to the alkanes and formate. In this work, we prepared and investigated ADO enzymes modified with RuII(tris-diimine) photosensitizers as a starting point for probing intramolecular electron transfer events. Three variants were prepared, with RuII-modification at the wild type (WT) residue C70, at the R62C site in one mutant ADO, and at both C62 and C70 in a second mutant ADO protein. The single-site modification of WT ADO at C70 using a cysteine-reactive label is an important observation and opens a way forward for new studies of electron flow, mechanism, and redox catalysis in ADO. These Ru-ADO constructs can perform the ADO catalytic cycle in the presence of light and a sacrificial reductant. In this work, the Ru photosensitizer serves as a tethered, artificial reductase that promotes turnover of aldehyde substrates with different carbon chain lengths. Peroxide side products were detected for shorter chain aldehydes, concomitant with less productive turnover. Analysis using semiclassical electron transfer theory supports proposals for hopping pathway for electron flow in WT ADO and in our new Ru-ADO proteins.
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Affiliation(s)
- Rajneesh K Bains
- Department of Chemistry , Simon Fraser University , 8888 University Drive , Burnaby , British Columbia V5A 1S6 , Canada
| | - Jessica J Miller
- Department of Chemistry , Simon Fraser University , 8888 University Drive , Burnaby , British Columbia V5A 1S6 , Canada
| | - Hannah K van der Roest
- Department of Chemistry , Simon Fraser University , 8888 University Drive , Burnaby , British Columbia V5A 1S6 , Canada
| | - Sheng Qu
- Department of Chemistry , Simon Fraser University , 8888 University Drive , Burnaby , British Columbia V5A 1S6 , Canada
| | - Brad Lute
- Department of Chemistry , Simon Fraser University , 8888 University Drive , Burnaby , British Columbia V5A 1S6 , Canada
| | - Jeffrey J Warren
- Department of Chemistry , Simon Fraser University , 8888 University Drive , Burnaby , British Columbia V5A 1S6 , Canada
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Lehtinen T, Efimova E, Santala S, Santala V. Improved fatty aldehyde and wax ester production by overexpression of fatty acyl-CoA reductases. Microb Cell Fact 2018; 17:19. [PMID: 29422050 PMCID: PMC5806253 DOI: 10.1186/s12934-018-0869-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 02/01/2018] [Indexed: 12/31/2022] Open
Abstract
Background Fatty aldehydes are industrially relevant compounds, which also represent a common metabolic intermediate in the microbial synthesis of various oleochemicals, including alkanes, fatty alcohols and wax esters. The key enzymes in biological fatty aldehyde production are the fatty acyl-CoA/ACP reductases (FARs) which reduce the activated acyl molecules to fatty aldehydes. Due to the disparity of FARs, identification and in vivo characterization of reductases with different properties are needed for the construction of tailored synthetic pathways for the production of various compounds. Results Fatty aldehyde production in Acinetobacter baylyi ADP1 was increased by the overexpression of three different FARs: a native A. baylyi FAR Acr1, a cyanobacterial Aar, and a putative, previously uncharacterized dehydrogenase (Ramo) from Nevskia ramosa. The fatty aldehyde production was followed in real-time inside the cells with a luminescence-based tool, and the highest aldehyde production was achieved with Aar. The fate of the overproduced fatty aldehydes was studied by measuring the production of wax esters by a native downstream pathway of A. baylyi, for which fatty aldehyde is a specific intermediate. The wax ester production was improved with the overexpression of Acr1 or Ramo compared to the wild type A. baylyi by more than two-fold, whereas the expression of Aar led to only subtle wax ester production. The overexpression of FARs did not affect the length of the acyl chains of the wax esters. Conclusions The fatty aldehyde production, as well as the wax ester production of A. baylyi, was improved with the overexpression of a key enzyme in the pathway. The wax ester titer (0.45 g/l) achieved with the overexpression of Acr1 is the highest reported without hydrocarbon supplementation to the culture. The contrasting behavior of the different reductases highlight the significance of in vivo characterization of enzymes and emphasizes the possibilities provided by the diversity of FARs for pathway and product modulation. Electronic supplementary material The online version of this article (10.1186/s12934-018-0869-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Tapio Lehtinen
- Department of Chemistry and Bioengineering, Tampere University of Technology, Tampere, Finland.
| | - Elena Efimova
- Department of Chemistry and Bioengineering, Tampere University of Technology, Tampere, Finland
| | - Suvi Santala
- Department of Chemistry and Bioengineering, Tampere University of Technology, Tampere, Finland
| | - Ville Santala
- Department of Chemistry and Bioengineering, Tampere University of Technology, Tampere, Finland
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20
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Luo S, Berges JA, He Z, Young EB. Algal-microbial community collaboration for energy recovery and nutrient remediation from wastewater in integrated photobioelectrochemical systems. ALGAL RES 2017. [DOI: 10.1016/j.algal.2016.10.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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21
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Junne S, Kabisch J. Fueling the future with biomass: Processes and pathways for a sustainable supply of hydrocarbon fuels and biogas. Eng Life Sci 2016; 17:14-26. [PMID: 32624725 DOI: 10.1002/elsc.201600112] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 08/08/2016] [Accepted: 08/23/2016] [Indexed: 12/11/2022] Open
Abstract
Global economic growth, wealth and security rely upon the availability of cheap, mostly fossil-derived energy and chemical compounds. The replacement by sustainable resources is widely discussed. However, the current state of biotechnological processes usually restricts them to be used as a true alternative in terms of economic feasibility and even sustainability. Among the rare examples of bioprocesses applied for the energetic use of biomass are biogas and bioethanol production. Usually, these processes lack in efficiency and they cannot be operated without the support of legislation. Although they represent a first step towards a greater share of bio-based processes for energy provision, there is no doubt that tremendous improvements in strain and process development, feedstock and process flexibility as well as in the integration of these processes into broader supply and production networks, in this review called smart bioproduction grids, are required to make them economically attractive, robust enough, and wider acceptance by society. All this requires an interdisciplinary approach, which includes the use of residues in closed carbon cycles and issues concerning the process safety. This short review aims to depict some of the promising strategies to achieve an improved process performance as a basis for future application.
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Affiliation(s)
- Stefan Junne
- Department of Biotechnology Chair of Bioprocess Engineering Technische Universität Berlin Berlin Germany
| | - Johannes Kabisch
- Institute of Biochemistry Ernst-Moritz-Arndt University Greifswald Greifswald Germany
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22
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Kudo H, Nawa R, Hayashi Y, Arai M. Comparison of aldehyde-producing activities of cyanobacterial acyl-(acyl carrier protein) reductases. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:234. [PMID: 27822307 PMCID: PMC5090900 DOI: 10.1186/s13068-016-0644-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2016] [Accepted: 10/12/2016] [Indexed: 05/04/2023]
Abstract
BACKGROUND Biosynthesis of alkanes is an attractive way of producing substitutes for petroleum-based alkanes. Acyl-[acyl carrier protein (ACP)] reductase (AAR) is a key enzyme for alkane biosynthesis in cyanobacteria and catalyzes the reduction of fatty acyl-ACP to fatty aldehydes, which are then converted into alkanes/alkenes by aldehyde-deformylating oxygenase (ADO). The amino acid sequences of AARs vary among cyanobacteria. However, their differences in catalytic activity, substrate specificity, and solubility are poorly understood. RESULTS We compared the aldehyde-producing activity, substrate specificity, and solubility of AARs from 12 representative cyanobacteria. The activity is the highest for AAR from Synechococcus elongatus PCC 7942, followed by AAR from Prochlorococcus marinus MIT 9313. On the other hand, protein solubility is high for AARs from PCC 7942, Microcystis aeruginosa, Thermosynechococcus elongatus BP-1, Synechococcus sp. RS9917, and Synechococcus sp. CB0205. As a consequence, the amount of alkanes/alkenes produced in Escherichia coli coexpressing AAR and ADO is the highest for AAR from PCC 7942, followed by AARs from BP-1 and MIT 9313. Strikingly, AARs from marine and freshwater cyanobacteria tend to have higher specificity toward the substrates with 16 and 18 carbons in the fatty acyl chain, respectively, suggesting that the substrate specificity of AARs correlates with the type of habitat of host cyanobacteria. Furthermore, mutational analysis identified several residues responsible for the high activity of AAR. CONCLUSIONS We found that the activity, substrate specificity, and solubility are diverse among various AARs. Our results provide a basis for selecting an AAR sequence suitable for metabolic engineering of bioalkane production while regulating carbon chain length.
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Affiliation(s)
- Hisashi Kudo
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902 Japan
| | - Ryota Nawa
- Department of Pure and Applied Sciences, College of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902 Japan
| | - Yuuki Hayashi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902 Japan
- Department of Pure and Applied Sciences, College of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902 Japan
| | - Munehito Arai
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902 Japan
- Department of Pure and Applied Sciences, College of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902 Japan
- Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 Japan
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23
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Ichikawa S, Karita S. Bacterial production and secretion of water-insoluble fuel compounds from cellulose without the supplementation of cellulases. FEMS Microbiol Lett 2015; 362:fnv202. [DOI: 10.1093/femsle/fnv202] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/18/2015] [Indexed: 01/15/2023] Open
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24
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Rajakovich LJ, Nørgaard H, Warui DM, Chang WC, Li N, Booker SJ, Krebs C, Bollinger JM, Pandelia ME. Rapid Reduction of the Diferric-Peroxyhemiacetal Intermediate in Aldehyde-Deformylating Oxygenase by a Cyanobacterial Ferredoxin: Evidence for a Free-Radical Mechanism. J Am Chem Soc 2015; 137:11695-709. [PMID: 26284355 DOI: 10.1021/jacs.5b06345] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Aldehyde-deformylating oxygenase (ADO) is a ferritin-like nonheme-diiron enzyme that catalyzes the last step in a pathway through which fatty acids are converted into hydrocarbons in cyanobacteria. ADO catalyzes conversion of a fatty aldehyde to the corresponding alk(a/e)ne and formate, consuming four electrons and one molecule of O2 per turnover and incorporating one atom from O2 into the formate coproduct. The source of the reducing equivalents in vivo has not been definitively established, but a cyanobacterial [2Fe-2S] ferredoxin (PetF), reduced by ferredoxin-NADP(+) reductase (FNR) using NADPH, has been implicated. We show that both the diferric form of Nostoc punctiforme ADO and its (putative) diferric-peroxyhemiacetal intermediate are reduced much more rapidly by Synechocystis sp. PCC6803 PetF than by the previously employed chemical reductant, 1-methoxy-5-methylphenazinium methyl sulfate. The yield of formate and alkane per reduced PetF approaches its theoretical upper limit when reduction of the intermediate is carried out in the presence of FNR. Reduction of the intermediate by either system leads to accumulation of a substrate-derived peroxyl radical as a result of off-pathway trapping of the C2-alkyl radical intermediate by excess O2, which consequently diminishes the yield of the hydrocarbon product. A sulfinyl radical located on residue Cys71 also accumulates with short-chain aldehydes. The detection of these radicals under turnover conditions provides the most direct evidence to date for a free-radical mechanism. Additionally, our results expose an inefficiency of the enzyme in processing its radical intermediate, presenting a target for optimization of bioprocesses exploiting this hydrocarbon-production pathway.
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Affiliation(s)
- Lauren J Rajakovich
- Department of Biochemistry and Molecular Biology and ‡Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Hanne Nørgaard
- Department of Biochemistry and Molecular Biology and ‡Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Douglas M Warui
- Department of Biochemistry and Molecular Biology and ‡Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Wei-chen Chang
- Department of Biochemistry and Molecular Biology and ‡Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Ning Li
- Department of Biochemistry and Molecular Biology and ‡Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Squire J Booker
- Department of Biochemistry and Molecular Biology and ‡Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Carsten Krebs
- Department of Biochemistry and Molecular Biology and ‡Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - J Martin Bollinger
- Department of Biochemistry and Molecular Biology and ‡Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Maria-Eirini Pandelia
- Department of Biochemistry and Molecular Biology and ‡Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
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25
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Atkins WM. Biological messiness vs. biological genius: Mechanistic aspects and roles of protein promiscuity. J Steroid Biochem Mol Biol 2015; 151:3-11. [PMID: 25218442 PMCID: PMC4920067 DOI: 10.1016/j.jsbmb.2014.09.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 08/28/2014] [Accepted: 09/09/2014] [Indexed: 02/06/2023]
Abstract
In contrast to the traditional biological paradigms focused on 'specificity', recent research and theoretical efforts have focused on functional 'promiscuity' exhibited by proteins and enzymes in many biological settings, including enzymatic detoxication, steroid biochemistry, signal transduction and immune responses. In addition, divergent evolutionary processes are apparently facilitated by random mutations that yield promiscuous enzyme intermediates. The intermediates, in turn, provide opportunities for further evolution to optimize new functions from existing protein scaffolds. In some cases, promiscuity may simply represent the inherent plasticity of proteins resulting from their polymeric nature with distributed conformational ensembles. Enzymes or proteins that bind or metabolize noncognate substrates create 'messiness' or noise in the systems they contribute to. With our increasing awareness of the frequency of these promiscuous behaviors it becomes interesting and important to understand the molecular bases for promiscuous behavior and to distinguish between evolutionarily selected promiscuity and evolutionarily tolerated messiness. This review provides an overview of current understanding of these aspects of protein biochemistry and enzymology.
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Affiliation(s)
- William M Atkins
- Department of Medicinal Chemistry, Box 357610, University of Washington, Seattle, WA 98195-7610, USA.
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26
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27
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Warui DM, Pandelia ME, Rajakovich LJ, Krebs C, Bollinger JM, Booker SJ. Efficient delivery of long-chain fatty aldehydes from the Nostoc punctiforme acyl-acyl carrier protein reductase to its cognate aldehyde-deformylating oxygenase. Biochemistry 2015; 54:1006-15. [PMID: 25496470 DOI: 10.1021/bi500847u] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A two-step pathway consisting of an acyl-acyl carrier protein (ACP) reductase (AAR) and an aldehyde-deformylating oxygenase (ADO) allows various cyanobacteria to convert long-chain fatty acids into hydrocarbons. AAR catalyzes the two-electron, NADPH-dependent reduction of a fatty acid attached to ACP via a thioester linkage to the corresponding fatty aldehyde, while ADO transforms the fatty aldehyde to a Cn-1 hydrocarbon and C1-derived formate. Considering that heptadec(a/e)ne is the most prevalent hydrocarbon produced by cyanobacterial ADOs, the insolubility of its precursor, octadec(a/e)nal, poses a conundrum with respect to its acquisition by ADO. Herein, we report that AAR from the cyanobacterium Nostoc punctiforme is activated almost 20-fold by potassium and other monovalent cations of similar ionic radius, and that AAR and ADO form a tight isolable complex with a Kd of 3 ± 0.3 μM. In addition, we show that when the aldehyde substrate is supplied to ADO by AAR, efficient in vitro turnover is observed in the absence of solubilizing agents. Similarly to studies by Lin et al. with AAR from Synechococcus elongatus [Lin et al. (2013) FEBS J. 280, 4773-4781], we show that catalysis by AAR proceeds via formation of a covalent intermediate involving a cysteine residue that we have identified as Cys294. Moreover, AAR specifically transfers the pro-R hydride of NADPH to the Cys294-thioester intermediate to afford its aldehyde product. Our results suggest that the interaction between AAR and ADO facilitates either direct transfer of the aldehyde product of AAR to ADO or formation of the aldehyde product in a microenvironment allowing for its efficient uptake by ADO.
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Affiliation(s)
- Douglas M Warui
- Department of Biochemistry and Molecular Biology, and ‡Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
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Buer B, Paul B, Das D, Stuckey JA, Marsh ENG. Insights into substrate and metal binding from the crystal structure of cyanobacterial aldehyde deformylating oxygenase with substrate bound. ACS Chem Biol 2014; 9:2584-93. [PMID: 25222710 PMCID: PMC4245163 DOI: 10.1021/cb500343j] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 09/02/2014] [Indexed: 11/28/2022]
Abstract
The nonheme diiron enzyme cyanobacterial aldehyde deformylating oxygenase, cADO, catalyzes the highly unusual deformylation of aliphatic aldehydes to alkanes and formate. We have determined crystal structures for the enzyme with a long-chain water-soluble aldehyde and medium-chain carboxylic acid bound to the active site. These structures delineate a hydrophobic channel that connects the solvent with the deeply buried active site and reveal a mode of substrate binding that is different from previously determined structures with long-chain fatty acids bound. The structures also identify a water channel leading to the active site that could facilitate the entry of protons required in the reaction. NMR studies examining 1-[(13)C]-octanal binding to cADO indicate that the enzyme binds the aldehyde form rather than the hydrated form. Lastly, the fortuitous cocrystallization of the metal-free form of the protein with aldehyde bound has revealed protein conformation changes that are involved in binding iron.
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Affiliation(s)
- Benjamin
C. Buer
- Department of Chemistry, Life Sciences Institute, and Department of Biological
Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Bishwajit Paul
- Department of Chemistry, Life Sciences Institute, and Department of Biological
Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Debasis Das
- Department of Chemistry, Life Sciences Institute, and Department of Biological
Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Jeanne A. Stuckey
- Department of Chemistry, Life Sciences Institute, and Department of Biological
Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - E. Neil G. Marsh
- Department of Chemistry, Life Sciences Institute, and Department of Biological
Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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Waugh MW, Marsh ENG. Solvent isotope effects on alkane formation by cyanobacterial aldehyde deformylating oxygenase and their mechanistic implications. Biochemistry 2014; 53:5537-43. [PMID: 25142631 PMCID: PMC4151702 DOI: 10.1021/bi5005766] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The reaction catalyzed by cyanobacterial aldehyde deformylating oxygenase is of interest both because of its potential application to the production of biofuels and because of the highly unusual nature of the deformylation reaction it catalyzes. Whereas the proton in the product alkane derives ultimately from the solvent, the identity of the proton donor in the active site remains unclear. To investigate the proton transfer step, solvent isotope effect (SIE) studies were undertaken. The rate of alkane formation was found to be maximal at pH 6.8 and to be the same in D2O or H2O within experimental error, implying that proton transfer is not a kinetically significant step. However, when the ratio of protium to deuterium in the product alkane was measured as a function of the mole fraction of D2O, a (D2O)SIEobs of 2.19 ± 0.02 was observed. The SIE was invariant with the mole fraction of D2O, indicating the involvement of a single protic site in the reaction. We interpret this SIE as most likely arising from a reactant state equilibrium isotope effect on a proton donor with an inverse fractionation factor, for which Φ = 0.45. These observations are consistent with an iron-bound water molecule being the proton donor to the alkane in the reaction.
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Affiliation(s)
- Matthew W Waugh
- Department of Chemistry and ‡Department of Biological Chemistry, University of Michigan , Ann Arbor, Michigan 48109, United States
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30
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Rodriguez GM, Tashiro Y, Atsumi S. Expanding ester biosynthesis in Escherichia coli. Nat Chem Biol 2014; 10:259-65. [PMID: 24609358 DOI: 10.1038/nchembio.1476] [Citation(s) in RCA: 137] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 01/14/2014] [Indexed: 11/09/2022]
Abstract
To expand the capabilities of whole-cell biocatalysis, we have engineered Escherichia coli to produce various esters. The alcohol O-acyltransferase (ATF) class of enzyme uses acyl-CoA units for ester formation. The release of free CoA upon esterification with an alcohol provides the free energy to facilitate ester formation. The diversity of CoA molecules found in nature in combination with various alcohol biosynthetic pathways allows for the biosynthesis of a multitude of esters. Small to medium volatile esters have extensive applications in the flavor, fragrance, cosmetic, solvent, paint and coating industries. The present work enables the production of these compounds by designing several ester pathways in E. coli. The engineered pathways generated acetate esters of ethyl, propyl, isobutyl, 2-methyl-1-butyl, 3-methyl-1-butyl and 2-phenylethyl alcohols. In particular, we achieved high-level production of isobutyl acetate from glucose (17.2 g l(-1)). This strategy was expanded to realize pathways for tetradecyl acetate and several isobutyrate esters.
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Affiliation(s)
- Gabriel M Rodriguez
- 1] Department of Chemistry, University of California-Davis, Davis, California, USA. [2]
| | - Yohei Tashiro
- 1] Department of Chemistry, University of California-Davis, Davis, California, USA. [2]
| | - Shota Atsumi
- Department of Chemistry, University of California-Davis, Davis, California, USA
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Das D, Ellington B, Paul B, Marsh ENG. Mechanistic insights from reaction of α-oxiranyl-aldehydes with cyanobacterial aldehyde deformylating oxygenase. ACS Chem Biol 2014; 9:570-7. [PMID: 24313866 DOI: 10.1021/cb400772q] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The biosynthesis of long-chain aliphatic hydrocarbons, which are derived from fatty acids, is widespread in Nature. The last step in this pathway involves the decarbonylation of fatty aldehydes to the corresponding alkanes or alkenes. In cyanobacteria, this is catalyzed by an aldehyde deformylating oxygenase. We have investigated the mechanism of this enzyme using substrates bearing an oxirane ring adjacent to the aldehyde carbon. The enzyme catalyzed the deformylation of these substrates to produce the corresponding oxiranes. Performing the reaction in D2O allowed the facial selectivity of proton addition to be examined by (1)H NMR spectroscopy. The proton is delivered with equal probability to either face of the oxirane ring, indicating the formation of an oxiranyl radical intermediate that is free to rotate during the reaction. Unexpectedly, the enzyme also catalyzes a side reaction in which oxiranyl-aldehydes undergo tandem deformylation to furnish alkanes two carbons shorter. We present evidence that this involves the rearrangement of the intermediate oxiranyl radical formed in the first step, resulting in aldehyde that is further deformylated in a second step. These observations provide support for a radical mechanism for deformylation and, furthermore, allow the lifetime of the radical intermediate to be estimated based on prior measurements of rate constants for the rearrangement of oxiranyl radicals.
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Affiliation(s)
- Debasis Das
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Benjamin Ellington
- Department
of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Bishwajit Paul
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - E. Neil G. Marsh
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department
of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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