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Purwani NN, Rozeboom HJ, Willers VP, Wijma HJ, Fraaije MW. Discovery of a new class of bacterial heme-containing CC cleaving oxygenases. N Biotechnol 2024; 83:82-90. [PMID: 39053683 DOI: 10.1016/j.nbt.2024.07.002] [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: 02/14/2024] [Revised: 07/11/2024] [Accepted: 07/22/2024] [Indexed: 07/27/2024]
Abstract
Previously, some bacteria were shown to harbour enzymes capable of catalysing the oxidative cleavage of the double bond of t-anethole and related compounds. The cofactor dependence of these enzymes remained enigmatic due to a lack of biochemical information. We report on catalytic and structural details of a representative of this group of oxidative enzymes: t-anethole oxygenase from Stenotrophomonas maltophilia (TAOSm). The bacterial enzyme could be recombinantly expressed and purified, enabling a detailed biochemical study that has settled the dispute on its cofactor dependence. We have established that TAOSm contains a tightly bound b-type heme and merely depends on dioxygen for catalysis. It was found to accept t-anethole, isoeugenol and O-methyl isoeugenol as substrates, all being converted into the corresponding aromatic aldehydes without the need of any cofactor regeneration. The elucidated crystal structure of TAOSm has revealed that it contains a unique active site architecture that is conserved for this distinct class of heme-containing bacterial oxygenases. Similar to other hemoproteins, TAOSm has a histidine (His121) as proximal ligand. Yet, unique for TAOs, an arginine (Arg89) is located at the distal axial position. Site directed mutagenesis confirmed crucial roles for these heme-liganding residues and other residues that form the substrate binding pocket. In conclusion, the results reported here reveal a new class of bacterial heme-containing oxygenases that can be used for the cleavage of alkene double bonds, analogous to ozonolysis in organic chemistry.
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Affiliation(s)
- Ni Nyoman Purwani
- Molecular Enzymology, University of Groningen, Nijenborgh 4, Groningen 9747AG, the Netherlands; Department of Health, Faculty of Vocational Studies, Kampus B Universitas Airlangga, Surabaya, East Java 60286, Indonesia
| | - Henriette J Rozeboom
- Molecular Enzymology, University of Groningen, Nijenborgh 4, Groningen 9747AG, the Netherlands
| | - Vivian P Willers
- Molecular Enzymology, University of Groningen, Nijenborgh 4, Groningen 9747AG, the Netherlands
| | - Hein J Wijma
- Molecular Enzymology, University of Groningen, Nijenborgh 4, Groningen 9747AG, the Netherlands
| | - Marco W Fraaije
- Molecular Enzymology, University of Groningen, Nijenborgh 4, Groningen 9747AG, the Netherlands.
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2
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Bopp C, Bernet NM, Meyer F, Khan R, Robinson SL, Kohler HPE, Buller R, Hofstetter TB. Elucidating the Role of O 2 Uncoupling for the Adaptation of Bacterial Biodegradation Reactions Catalyzed by Rieske Oxygenases. ACS ENVIRONMENTAL AU 2024; 4:204-218. [PMID: 39035869 PMCID: PMC11258757 DOI: 10.1021/acsenvironau.4c00016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 04/26/2024] [Accepted: 04/26/2024] [Indexed: 07/23/2024]
Abstract
Oxygenation of aromatic and aliphatic hydrocarbons by Rieske oxygenases is the initial step of various biodegradation pathways for environmental organic contaminants. Microorganisms carrying Rieske oxygenases are able to quickly adapt their substrate spectra to alternative carbon and energy sources that are structurally related to the original target substrate, yet the molecular events responsible for this rapid adaptation are not well understood. Here, we evaluated the hypothesis that reactive oxygen species (ROS) generated by unproductive activation of O2, the so-called O2 uncoupling, in the presence of the alternative substrate exert a selective pressure on the bacterium for increasing the oxygenation efficiency of Rieske oxygenases. To that end, we studied wild-type 2-nitrotoluene dioxygenase from Acidovorax sp. strain JS42 and five enzyme variants that have evolved from adaptive laboratory evolution experiments with 3- and 4-nitrotoluene as alternative growth substrates. The enzyme variants showed a substantially increased oxygenation efficiency toward the new target substrates concomitant with a reduction of ROS production, while mechanisms and kinetics of enzymatic O2 activation remained unchanged. Structural analyses and docking studies suggest that amino acid substitutions in enzyme variants occurred at residues lining both substrate and O2 transport tunnels, enabling tighter binding of the target substrates in the active site. Increased oxygenation efficiencies measured in vitro for the various enzyme (variant)-substrate combinations correlated linearly with in vivo changes in growth rates for evolved Acidovorax strains expressing the variants. Our data suggest that the selective pressure from oxidative stress toward more efficient oxygenation by Rieske oxygenases was most notable when O2 uncoupling exceeded 60%.
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Affiliation(s)
- Charlotte
E. Bopp
- Eawag,
Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
- Institute
of Biogeochemistry and Pollutant Dynamics (IBP), ETH Zürich, 8092 Zürich, Switzerland
| | - Nora M. Bernet
- Eawag,
Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
- Institute
of Biogeochemistry and Pollutant Dynamics (IBP), ETH Zürich, 8092 Zürich, Switzerland
| | - Fabian Meyer
- Competence
Center for Biocatalysis, Institute of Chemistry and Biotechnology, Zürich University of Applied Sciences, 8820 Wädenswil, Switzerland
| | - Riyaz Khan
- Eawag,
Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
| | - Serina L. Robinson
- Eawag,
Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
| | - Hans-Peter E. Kohler
- Eawag,
Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
| | - Rebecca Buller
- Competence
Center for Biocatalysis, Institute of Chemistry and Biotechnology, Zürich University of Applied Sciences, 8820 Wädenswil, Switzerland
| | - Thomas B. Hofstetter
- Eawag,
Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
- Institute
of Biogeochemistry and Pollutant Dynamics (IBP), ETH Zürich, 8092 Zürich, Switzerland
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3
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Hunter Wilson R, Damodaran AR, Bhagi-Damodaran A. Machine learning guided rational design of a non-heme iron-based lysine dioxygenase improves its total turnover number. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.04.597480. [PMID: 38895203 PMCID: PMC11185610 DOI: 10.1101/2024.06.04.597480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Highly selective C-H functionalization remains an ongoing challenge in organic synthetic methodologies. Biocatalysts are robust tools for achieving these difficult chemical transformations. Biocatalyst engineering has often required directed evolution or structure-based rational design campaigns to improve their activities. In recent years, machine learning has been integrated into these workflows to improve the discovery of beneficial enzyme variants. In this work, we combine a structure-based machine-learning algorithm with classical molecular dynamics simulations to down select mutations for rational design of a non-heme iron-dependent lysine dioxygenase, LDO. This approach consistently resulted in functional LDO mutants and circumvents the need for extensive study of mutational activity before-hand. Our rationally designed single mutants purified with up to 2-fold higher yields than WT and displayed higher total turnover numbers (TTN). Combining five such single mutations into a pentamutant variant, LPNYI LDO, leads to a 40% improvement in the TTN (218±3) as compared to WT LDO (TTN = 160±2). Overall, this work offers a low-barrier approach for those seeking to synergize machine learning algorithms with pre-existing protein engineering strategies.
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Affiliation(s)
- R Hunter Wilson
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN, 55455
| | - Anoop R Damodaran
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN, 55455
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4
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Wolf ME, Lalande AT, Newman BL, Bleem AC, Palumbo CT, Beckham GT, Eltis LD. The catabolism of lignin-derived p-methoxylated aromatic compounds by Rhodococcus jostii RHA1. Appl Environ Microbiol 2024; 90:e0215523. [PMID: 38380926 PMCID: PMC10952524 DOI: 10.1128/aem.02155-23] [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: 11/30/2023] [Accepted: 01/23/2024] [Indexed: 02/22/2024] Open
Abstract
Emergent strategies to valorize lignin, an abundant but underutilized aromatic biopolymer, include tandem processes that integrate chemical depolymerization and biological catalysis. To date, aromatic monomers from C-O bond cleavage of lignin have been converted to bioproducts, but the presence of recalcitrant C-C bonds in lignin limits the product yield. A promising chemocatalytic strategy that overcomes this limitation involves phenol methyl protection and autoxidation. Incorporating this into a tandem process requires microbial cell factories able to transform the p-methoxylated products in the resulting methylated lignin stream. In this study, we assessed the ability of Rhodococcus jostii RHA1 to catabolize the major aromatic products in a methylated lignin stream and elucidated the pathways responsible for this catabolism. RHA1 grew on a methylated pine lignin stream, catabolizing the major aromatic monomers: p-methoxybenzoate (p-MBA), veratrate, and veratraldehyde. Bioinformatic analyses suggested that a cytochrome P450, PbdA, and its cognate reductase, PbdB, are involved in p-MBA catabolism. Gene deletion studies established that both pbdA and pbdB are essential for growth on p-MBA and several derivatives. Furthermore, a deletion mutant of a candidate p-hydroxybenzoate (p-HBA) hydroxylase, ΔpobA, did not grow on p-HBA. Veratraldehyde and veratrate catabolism required both vanillin dehydrogenase (Vdh) and vanillate O-demethylase (VanAB), revealing previously unknown roles of these enzymes. Finally, a ΔpcaL strain grew on neither p-MBA nor veratrate, indicating they are catabolized through the β-ketoadipate pathway. This study expands our understanding of the bacterial catabolism of aromatic compounds and facilitates the development of biocatalysts for lignin valorization.IMPORTANCELignin, an abundant aromatic polymer found in plant biomass, is a promising renewable replacement for fossil fuels as a feedstock for the chemical industry. Strategies for upgrading lignin include processes that couple the catalytic fractionation of biomass and biocatalytic transformation of the resulting aromatic compounds with a microbial cell factory. Engineering microbial cell factories for this biocatalysis requires characterization of bacterial pathways involved in catabolizing lignin-derived aromatic compounds. This study identifies new pathways for lignin-derived aromatic degradation in Rhodococcus, a genus of bacteria well suited for biocatalysis. Additionally, we describe previously unknown activities of characterized enzymes on lignin-derived compounds, expanding their utility. This work advances the development of strategies to replace fossil fuel-based feedstocks with sustainable alternatives.
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Affiliation(s)
- Megan E. Wolf
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, Canada
| | - Anne T. Lalande
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, Canada
| | - Brianne L. Newman
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, Canada
| | - Alissa C. Bleem
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA
| | - Chad T. Palumbo
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA
| | - Gregg T. Beckham
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA
| | - Lindsay D. Eltis
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, Canada
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5
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Kim SM, Kang SH, Jeon BW, Kim YH. Tunnel engineering of gas-converting enzymes for inhibitor retardation and substrate acceleration. BIORESOURCE TECHNOLOGY 2024; 394:130248. [PMID: 38158090 DOI: 10.1016/j.biortech.2023.130248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 12/20/2023] [Accepted: 12/21/2023] [Indexed: 01/03/2024]
Abstract
Carbon monoxide dehydrogenase (CODH), formate dehydrogenase (FDH), hydrogenase (H2ase), and nitrogenase (N2ase) are crucial enzymatic catalysts that facilitate the conversion of industrially significant gases such as CO, CO2, H2, and N2. The tunnels in the gas-converting enzymes serve as conduits for these low molecular weight gases to access deeply buried catalytic sites. The identification of the substrate tunnels is imperative for comprehending the substrate selectivity mechanism underlying these gas-converting enzymes. This knowledge also holds substantial value for industrial applications, particularly in addressing the challenges associated with separation and utilization of byproduct gases. In this comprehensive review, we delve into the emerging field of tunnel engineering, presenting a range of approaches and analyses. Additionally, we propose methodologies for the systematic design of enzymes, with the ultimate goal of advancing protein engineering strategies.
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Affiliation(s)
- Suk Min Kim
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan 44919, Republic of Korea.
| | - Sung Heuck Kang
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan 44919, Republic of Korea
| | - Byoung Wook Jeon
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan 44919, Republic of Korea
| | - Yong Hwan Kim
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan 44919, Republic of Korea; Graduate School of Carbon Neutrality, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan 44919, Republic of Korea.
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6
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Tian J, Boggs DG, Donnan PH, Barroso GT, Garcia AA, Dowling DP, Buss JA, Bridwell-Rabb J. The NADH recycling enzymes TsaC and TsaD regenerate reducing equivalents for Rieske oxygenase chemistry. J Biol Chem 2023; 299:105222. [PMID: 37673337 PMCID: PMC10579966 DOI: 10.1016/j.jbc.2023.105222] [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: 05/27/2023] [Revised: 08/22/2023] [Accepted: 08/31/2023] [Indexed: 09/08/2023] Open
Abstract
Many microorganisms use both biological and nonbiological molecules as sources of carbon and energy. This resourcefulness means that some microorganisms have mechanisms to assimilate pollutants found in the environment. One such organism is Comamonas testosteroni, which metabolizes 4-methylbenzenesulfonate and 4-methylbenzoate using the TsaMBCD pathway. TsaM is a Rieske oxygenase, which in concert with the reductase TsaB consumes a molar equivalent of NADH. Following this step, the annotated short-chain dehydrogenase/reductase and aldehyde dehydrogenase enzymes TsaC and TsaD each regenerate a molar equivalent of NADH. This co-occurrence ameliorates the need for stoichiometric addition of reducing equivalents and thus represents an attractive strategy for integration of Rieske oxygenase chemistry into biocatalytic applications. Therefore, in this work, to overcome the lack of information regarding NADH recycling enzymes that function in partnership with Rieske non-heme iron oxygenases (Rieske oxygenases), we solved the X-ray crystal structure of TsaC to a resolution of 2.18 Å. Using this structure, a series of substrate analog and protein variant combination reactions, and differential scanning fluorimetry experiments, we identified active site features involved in binding NAD+ and controlling substrate specificity. Further in vitro enzyme cascade experiments demonstrated the efficient TsaC- and TsaD-mediated regeneration of NADH to support Rieske oxygenase chemistry. Finally, through in-depth bioinformatic analyses, we illustrate the widespread co-occurrence of Rieske oxygenases with TsaC-like enzymes. This work thus demonstrates the utility of these NADH recycling enzymes and identifies a library of short-chain dehydrogenase/reductase enzyme prospects that can be used in Rieske oxygenase pathways for in situ regeneration of NADH.
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Affiliation(s)
- Jiayi Tian
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA
| | - David G Boggs
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA
| | - Patrick H Donnan
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA
| | - Gage T Barroso
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA
| | | | - Daniel P Dowling
- Department of Chemistry, University of Massachusetts Boston, Boston, Massachusetts, USA
| | - Joshua A Buss
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA
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7
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Tian J, Liu J, Knapp M, Donnan PH, Boggs DG, Bridwell-Rabb J. Custom tuning of Rieske oxygenase reactivity. Nat Commun 2023; 14:5858. [PMID: 37730711 PMCID: PMC10511449 DOI: 10.1038/s41467-023-41428-x] [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: 11/13/2022] [Accepted: 08/27/2023] [Indexed: 09/22/2023] Open
Abstract
Rieske oxygenases use a Rieske-type [2Fe-2S] cluster and a mononuclear iron center to initiate a range of chemical transformations. However, few details exist regarding how this catalytic scaffold can be predictively tuned to catalyze divergent reactions. Therefore, in this work, using a combination of structural analyses, as well as substrate and rational protein-based engineering campaigns, we elucidate the architectural trends that govern catalytic outcome in the Rieske monooxygenase TsaM. We identify structural features that permit a substrate to be functionalized by TsaM and pinpoint active-site residues that can be targeted to manipulate reactivity. Exploiting these findings allowed for custom tuning of TsaM reactivity: substrates are identified that support divergent TsaM-catalyzed reactions and variants are created that exclusively catalyze dioxygenation or sequential monooxygenation chemistry. Importantly, we further leverage these trends to tune the reactivity of additional monooxygenase and dioxygenase enzymes, and thereby provide strategies to custom tune Rieske oxygenase reaction outcomes.
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Affiliation(s)
- Jiayi Tian
- Department of Chemistry, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Jianxin Liu
- Department of Chemistry, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Madison Knapp
- Department of Chemistry, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Patrick H Donnan
- Department of Chemistry, University of Michigan, Ann Arbor, MI, 48109, USA
| | - David G Boggs
- Department of Chemistry, University of Michigan, Ann Arbor, MI, 48109, USA
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8
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Smithwick ER, Wilson RH, Chatterjee S, Pu Y, Dalluge JJ, Damodaran AR, Bhagi-Damodaran A. Electrostatically regulated active site assembly governs reactivity in non-heme iron halogenases. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.25.542349. [PMID: 37292651 PMCID: PMC10245910 DOI: 10.1101/2023.05.25.542349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Non-heme iron halogenases (NHFe-Hals) catalyze the direct insertion of a chloride/bromide ion at an unactivated carbon position using a high-valent haloferryl intermediate. Despite more than a decade of structural and mechanistic characterization, how NHFe-Hals preferentially bind specific anions and substrates for C-H functionalization remains unknown. Herein, using lysine halogenating BesD and HalB enzymes as model systems, we demonstrate strong positive cooperativity between anion and substrate binding to the catalytic pocket. Detailed computational investigations indicate that a negatively charged glutamate hydrogen-bonded to iron's equatorial-aqua ligand acts as an electrostatic lock preventing both lysine and anion binding in the absence of the other. Using a combination of UV-Vis spectroscopy, binding affinity studies, stopped-flow kinetics investigations, and biochemical assays, we explore the implication of such active site assembly towards chlorination, bromination, and azidation reactivities. Overall, our work highlights previously unknown features regarding how anion-substrate pair binding govern reactivity of iron halogenases that are crucial for engineering next-generation C-H functionalization biocatalysts.
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Affiliation(s)
- Elizabeth R. Smithwick
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN 55455, USA
| | - R. Hunter Wilson
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN 55455, USA
| | - Sourav Chatterjee
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN 55455, USA
| | - Yu Pu
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN 55455, USA
| | - Joseph J. Dalluge
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN 55455, USA
| | - Anoop Rama Damodaran
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN 55455, USA
| | - Ambika Bhagi-Damodaran
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN 55455, USA
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