1
|
Eggerichs D, Weindorf N, Weddeling HG, Van der Linden IM, Tischler D. Substrate scope expansion of 4-phenol oxidases by rational enzyme selection and sequence-function relations. Commun Chem 2024; 7:123. [PMID: 38831005 PMCID: PMC11148156 DOI: 10.1038/s42004-024-01207-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Accepted: 05/15/2024] [Indexed: 06/05/2024] Open
Abstract
Enzymes are natures' catalysts and will have a lasting impact on (organic) synthesis as they possess unchallenged regio- and stereo selectivity. On the downside, this high selectivity limits enzymes' substrate range and hampers their universal application. Therefore, substrate scope expansion of enzyme families by either modification of known biocatalysts or identification of new members is a key challenge in enzyme-driven catalysis. Here, we present a streamlined approach to rationally select enzymes with proposed functionalities from the ever-increasing amount of available sequence data. In a case study on 4-phenol oxidoreductases, eight enzymes of the oxidase branch were selected from 292 sequences on basis of the properties of first shell residues of the catalytic pocket, guided by the computational tool A2CA. Correlations between these residues and enzyme activity yielded robust sequence-function relations, which were exploited by site-saturation mutagenesis. Application of a peroxidase-independent oxidase screening resulted in 16 active enzyme variants which were up to 90-times more active than respective wildtype enzymes and up to 6-times more active than the best performing natural variants. The results were supported by kinetic experiments and structural models. The newly introduced amino acids confirmed the correlation studies which overall highlights the successful logic of the presented approach.
Collapse
Affiliation(s)
- Daniel Eggerichs
- Microbial Biotechnology, Ruhr University Bochum, Universitätsstr. 150, 44780, Bochum, Germany
| | - Nils Weindorf
- Microbial Biotechnology, Ruhr University Bochum, Universitätsstr. 150, 44780, Bochum, Germany
| | - Heiner G Weddeling
- Microbial Biotechnology, Ruhr University Bochum, Universitätsstr. 150, 44780, Bochum, Germany
| | - Inja M Van der Linden
- Microbial Biotechnology, Ruhr University Bochum, Universitätsstr. 150, 44780, Bochum, Germany
| | - Dirk Tischler
- Microbial Biotechnology, Ruhr University Bochum, Universitätsstr. 150, 44780, Bochum, Germany.
| |
Collapse
|
2
|
Xu Z, Peng B, Kitata RB, Nicora CD, Weitz KK, Pu Y, Shi T, Cort JR, Ragauskas AJ, Yang B. Understanding of bacterial lignin extracellular degradation mechanisms by Pseudomonas putida KT2440 via secretomic analysis. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2022; 15:117. [PMID: 36316752 PMCID: PMC9620641 DOI: 10.1186/s13068-022-02214-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Accepted: 10/12/2022] [Indexed: 11/07/2022]
Abstract
BACKGROUND Bacterial lignin degradation is believed to be primarily achieved by a secreted enzyme system. Effects of such extracellular enzyme systems on lignin structural changes and degradation pathways are still not clearly understood, which remains as a bottleneck in the bacterial lignin bioconversion process. RESULTS This study investigated lignin degradation using an isolated secretome secreted by Pseudomonas putida KT2440 that grew on glucose as the only carbon source. Enzyme assays revealed that the secretome harbored oxidase and peroxidase/Mn2+-peroxidase capacity and reached the highest activity at 120 h of the fermentation time. The degradation rate of alkali lignin was found to be only 8.1% by oxidases, but increased to 14.5% with the activation of peroxidase/Mn2+-peroxidase. Gas chromatography-mass spectrometry (GC-MS) and two-dimensional 1H-13C heteronuclear single-quantum coherence (HSQC) NMR analysis revealed that the oxidases exhibited strong C-C bond (β-β, β-5, and β-1) cleavage. The activation of peroxidases enhanced lignin degradation by stimulating C-O bond (β-O-4) cleavage, resulting in increased yields of aromatic monomers and dimers. Further mass spectrometry-based quantitative proteomics measurements comprehensively identified different groups of enzymes particularly oxidoreductases in P. putida secretome, including reductases, peroxidases, monooxygenases, dioxygenases, oxidases, and dehydrogenases, potentially contributed to the lignin degradation process. CONCLUSIONS Overall, we discovered that bacterial extracellular degradation of alkali lignin to vanillin, vanillic acid, and other lignin-derived aromatics involved a series of oxidative cleavage, catalyzed by active DyP-type peroxidase, multicopper oxidase, and other accessory enzymes. These results will guide further metabolic engineering design to improve the efficiency of lignin bioconversion.
Collapse
Affiliation(s)
- Zhangyang Xu
- grid.451303.00000 0001 2218 3491Bioproducts, Sciences & Engineering Laboratory, Department of Biological Systems Engineering, ashington State University Tri-Cities, Joint Appointment: Pacific Northwest National Laboratory, 2710 Crimson Way, Richland, WA 99354 USA
| | - Bo Peng
- grid.451303.00000 0001 2218 3491Bioproducts, Sciences & Engineering Laboratory, Department of Biological Systems Engineering, ashington State University Tri-Cities, Joint Appointment: Pacific Northwest National Laboratory, 2710 Crimson Way, Richland, WA 99354 USA
| | - Reta Birhanu Kitata
- grid.451303.00000 0001 2218 3491Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352 USA
| | - Carrie D. Nicora
- grid.451303.00000 0001 2218 3491Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352 USA
| | - Karl K. Weitz
- grid.451303.00000 0001 2218 3491Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352 USA
| | - Yunqiao Pu
- grid.135519.a0000 0004 0446 2659Joint Institute for Biological Sciences, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
| | - Tujin Shi
- grid.451303.00000 0001 2218 3491Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352 USA
| | - John R. Cort
- grid.451303.00000 0001 2218 3491Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352 USA
| | - Arthur J. Ragauskas
- grid.135519.a0000 0004 0446 2659Joint Institute for Biological Sciences, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA ,grid.411461.70000 0001 2315 1184Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996 USA ,grid.411461.70000 0001 2315 1184Department of Forestry, Wildlife, and Fisheries, Center for Renewable Carbon, University of Tennessee Institute of Agriculture, Knoxville, TN 37996 USA
| | - Bin Yang
- grid.451303.00000 0001 2218 3491Bioproducts, Sciences & Engineering Laboratory, Department of Biological Systems Engineering, ashington State University Tri-Cities, Joint Appointment: Pacific Northwest National Laboratory, 2710 Crimson Way, Richland, WA 99354 USA ,grid.451303.00000 0001 2218 3491Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352 USA
| |
Collapse
|
3
|
Zhao X, Zhang Y, Jiang H, Zang H, Wang Y, Sun S, Li C. Efficient vanillin biosynthesis by recombinant lignin-degrading bacterium Arthrobacter sp. C2 and its environmental profile via life cycle assessment. BIORESOURCE TECHNOLOGY 2022; 347:126434. [PMID: 34838969 DOI: 10.1016/j.biortech.2021.126434] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 11/21/2021] [Accepted: 11/22/2021] [Indexed: 06/13/2023]
Abstract
Vanillin is a natural flavoring agent that is widely used in the bioengineering industry. To enable sustainable development, joint consideration of bacterial performance and negative environmental impacts are critical to vanillin biosynthesis. In this study, a cold shock protein (csp) gene was upregulated for maintaining stable growth in Arthrobacter sp. C2 responding to vanillin and cold stress. Furthermore, the recombinant strain C2 was constructed by simultaneously deleting the xylC gene encoding benzaldehyde dehydrase and overexpressing the pchF gene encoding vanillyl alcohol oxidase and achieved a maximum vanillin productivity of 0.85 mg/g DCW/h with alkaline lignin as the substrate. Finally, this process generated an environmental impact value of 25.05, which was the lowest environmental impact achieved according to life cycle assessment (LCA). Improvement strategies included reducing electricity consumption and replacing chemicals. This study achieved the development of an effective strategy, and future studies should focus on precise vanillin biosynthesis methods for large-scale application.
Collapse
Affiliation(s)
- Xinyue Zhao
- College of Resource and Environment, Northeast Agricultural University, Harbin 150030, China
| | - Yuting Zhang
- College of Resource and Environment, Northeast Agricultural University, Harbin 150030, China
| | - Hanyi Jiang
- College of Resource and Environment, Northeast Agricultural University, Harbin 150030, China
| | - Hailian Zang
- College of Resource and Environment, Northeast Agricultural University, Harbin 150030, China
| | - Yue Wang
- College of Resource and Environment, Northeast Agricultural University, Harbin 150030, China
| | - Shanshan Sun
- College of Resource and Environment, Northeast Agricultural University, Harbin 150030, China
| | - Chunyan Li
- College of Resource and Environment, Northeast Agricultural University, Harbin 150030, China.
| |
Collapse
|
4
|
Azubuike CC, Allemann MN, Michener JK. Microbial assimilation of lignin-derived aromatic compounds and conversion to value-added products. Curr Opin Microbiol 2021; 65:64-72. [PMID: 34775172 DOI: 10.1016/j.mib.2021.10.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 10/19/2021] [Accepted: 10/21/2021] [Indexed: 11/03/2022]
Abstract
Lignin is an abundant and sustainable source of aromatic compounds that can be converted to value-added products. However, lignin is underutilized, since depolymerization produces a complex mixture of aromatic compounds that is difficult to convert to a single product. Microbial conversion of mixed aromatic substrates provides a potential solution to this conversion challenge. Recent advances have expanded the range of lignin-derived aromatic substrates that can be assimilated and demonstrated efficient conversion via central metabolism to new potential products. The development of additional non-model microbial hosts and genetic tools for these hosts have accelerated engineering efforts. However, yields with real depolymerized lignin are still low, and additional work will be required to achieve viable conversion processes.
Collapse
Affiliation(s)
| | - Marco N Allemann
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
| | - Joshua K Michener
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA.
| |
Collapse
|
5
|
Wang L, Maranas CD. Computationally Prospecting Potential Pathways from Lignin Monomers and Dimers toward Aromatic Compounds. ACS Synth Biol 2021; 10:1064-1076. [PMID: 33877818 DOI: 10.1021/acssynbio.0c00598] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The heterogeneity of the aromatic products originating from lignin catalytic depolymerization remains one of the major challenges associated with lignin valorization. Microbes have evolved catabolic pathways that can funnel heterogeneous intermediates to a few central aromatic products. These aromatic compounds can subsequently undergo intra- or extradiol ring opening to produce value-added chemicals. However, such funneling pathways are only partially characterized for a few organisms such as Sphingobium sp. SYK-6 and Pseudomonas putida KT2440. Herein, we apply the de novo pathway design tool (novoStoic) to computationally prospect possible ways of funneling lignin-derived mono- and biaryls. novoStoic employs reaction rules between molecular moieties to hypothesize de novo conversions by flagging known enzymes that carry out the same biotransformation on the most similar substrate. Both reaction rules and known reactions are then deployed by novoStoic to identify a mass-balanced biochemical network that converts a source to a target metabolite while minimizing the number of de novo steps. We demonstrate the application of novoStoic for (i) designing alternative pathways of funneling S, G, and H lignin monomers, and (ii) exploring cleavage pathways of β-1 and β-β dimers. By exploring the uncharted chemical space afforded by enzyme promiscuity, novoStoic can help predict previously unknown native pathways leveraging enzyme promiscuity and propose new carbon/energy efficient lignin funneling pathways with few heterologous enzymes.
Collapse
Affiliation(s)
- Lin Wang
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Costas D. Maranas
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| |
Collapse
|
6
|
The Hydroxyquinol Degradation Pathway in Rhodococcus jostii RHA1 and Agrobacterium Species Is an Alternative Pathway for Degradation of Protocatechuic Acid and Lignin Fragments. Appl Environ Microbiol 2020; 86:AEM.01561-20. [PMID: 32737130 DOI: 10.1128/aem.01561-20] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 07/27/2020] [Indexed: 12/11/2022] Open
Abstract
Deletion of the pcaHG genes, encoding protocatechuate 3,4-dioxygenase in Rhodococcus jostii RHA1, gives a gene deletion strain still able to grow on protocatechuic acid as the sole carbon source, indicating a second degradation pathway for protocatechuic acid. Metabolite analysis of wild-type R. jostii RHA1 grown on medium containing vanillin or protocatechuic acid indicated the formation of hydroxyquinol (benzene-1,2,4-triol) as a downstream product. Gene cluster ro01857-ro01860 in Rhodococcus jostii RHA1 contains genes encoding hydroxyquinol 1,2-dioxygenase and maleylacetate reductase for degradation of hydroxyquinol but also putative mono-oxygenase (ro01860) and putative decarboxylase (ro01859) genes, and a similar gene cluster is found in the genome of lignin-degrading Agrobacterium species. Recombinant R. jostii mono-oxygenase and decarboxylase enzymes in combination were found to convert protocatechuic acid to hydroxyquinol. Hence, an alternative pathway for degradation of protocatechuic acid via oxidative decarboxylation to hydroxyquinol is proposed.IMPORTANCE There is a well-established paradigm for degradation of protocatechuic acid via the β-ketoadipate pathway in a range of soil bacteria. In this study, we have found the existence of a second pathway for degradation of protocatechuic acid in Rhodococcus jostii RHA1, via hydroxyquinol (benzene-1,2,4-triol), which establishes a metabolic link between protocatechuic acid and hydroxyquinol. The presence of this pathway in a lignin-degrading Agrobacterium sp. strain suggests the involvement of the hydroxyquinol pathway in the metabolism of degraded lignin fragments.
Collapse
|
7
|
Abstract
This review presents a historical outline of the research on vanillyl alcohol oxidase (VAO) from Penicillium simplicissimum, one of the canonical members of the VAO/PCMH flavoprotein family. After describing its discovery and initial biochemical characterization, we discuss the physiological role, substrate scope, and catalytic mechanism of VAO, and review its three-dimensional structure and mechanism of covalent flavinylation. We also explain how protein engineering provided a deeper insight into the role of certain amino acid residues in determining the substrate specificity and enantioselectivity of the enzyme. Finally, we summarize recent computational studies about the migration of substrates and products through the enzyme's structure and the phylogenetic distribution of VAO and related enzymes.
Collapse
Affiliation(s)
- Tom A Ewing
- Wageningen Food & Biobased Research, Wageningen University & Research, Wageningen, The Netherlands
| | - Gudrun Gygli
- Institute for Biological Interfaces, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Marco W Fraaije
- Molecular Enzymology Group, University of Groningen, Groningen, The Netherlands
| | - Willem J H van Berkel
- Laboratory of Food Chemistry, Wageningen University & Research, Wageningen, The Netherlands.
| |
Collapse
|