1
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Zhou J, Huang M. Navigating the landscape of enzyme design: from molecular simulations to machine learning. Chem Soc Rev 2024; 53:8202-8239. [PMID: 38990263 DOI: 10.1039/d4cs00196f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/12/2024]
Abstract
Global environmental issues and sustainable development call for new technologies for fine chemical synthesis and waste valorization. Biocatalysis has attracted great attention as the alternative to the traditional organic synthesis. However, it is challenging to navigate the vast sequence space to identify those proteins with admirable biocatalytic functions. The recent development of deep-learning based structure prediction methods such as AlphaFold2 reinforced by different computational simulations or multiscale calculations has largely expanded the 3D structure databases and enabled structure-based design. While structure-based approaches shed light on site-specific enzyme engineering, they are not suitable for large-scale screening of potential biocatalysts. Effective utilization of big data using machine learning techniques opens up a new era for accelerated predictions. Here, we review the approaches and applications of structure-based and machine-learning guided enzyme design. We also provide our view on the challenges and perspectives on effectively employing enzyme design approaches integrating traditional molecular simulations and machine learning, and the importance of database construction and algorithm development in attaining predictive ML models to explore the sequence fitness landscape for the design of admirable biocatalysts.
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Affiliation(s)
- Jiahui Zhou
- School of Chemistry and Chemical Engineering, Queen's University, David Keir Building, Stranmillis Road, Belfast BT9 5AG, Northern Ireland, UK.
| | - Meilan Huang
- School of Chemistry and Chemical Engineering, Queen's University, David Keir Building, Stranmillis Road, Belfast BT9 5AG, Northern Ireland, UK.
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2
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Lewis JC. Identifying and Engineering Flavin Dependent Halogenases for Selective Biocatalysis. Acc Chem Res 2024; 57:2067-2079. [PMID: 39038085 PMCID: PMC11309780 DOI: 10.1021/acs.accounts.4c00172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/24/2024]
Abstract
ConspectusOrganohalogen compounds are extensively used as building blocks, intermediates, pharmaceuticals, and agrochemicals due to their unique chemical and biological properties. Installing halogen substituents, however, frequently requires functionalized starting materials and multistep functional group interconversion. Several classes of halogenases evolved in nature to enable halogenation of a different classes of substrates; for example, site-selective halogenation of electron rich aromatic compounds is catalyzed by flavin-dependent halogenases (FDHs). Mechanistic studies have shown that these enzymes use FADH2 to reduce O2 to water with concomitant oxidation of X- to HOX (X = Cl, Br, I). This species travels through a tunnel within the enzyme to access the FDH active site. Here, it is believed to interact with an active site lysine proximal to bound substrate, enabling electrophilic halogenation with selectivity imparted via molecular recognition, rather than directing groups or strong electronic activation.The unique selectivity of FDHs led to several early biocatalysis efforts, preparative halogenation was rare, and the hallmark catalyst-controlled selectivity of FDHs did not translate to non-native substrates. FDH engineering was limited to site-directed mutagenesis, which resulted in modest changes in site-selectivity or substrate preference. To address these limitations, we optimized expression conditions for the FDH RebH and its cognate flavin reductase (FRed), RebF. We then showed that RebH could be used for preparative halogenation of non-native substrates with catalyst-controlled selectivity. We reported the first examples in which the stability, substrate scope, and site selectivity of a FDH were improved to synthetically useful levels via directed evolution. X-ray crystal structures of evolved FDHs and reversion mutations showed that random mutations throughout the RebH structure were critical to achieving high levels of activity and selectivity on diverse aromatic substrates, and these data were used in combination with molecular dynamics simulations to develop predictive model for FDH selectivity. Finally, we used family wide genome mining to identify a diverse set of FDHs with novel substrate scope and complementary regioselectivity on large, three-dimensionally complex compounds.The diversity of our evolved and mined FDHs allowed us to pursue synthetic applications beyond simple aromatic halogenation. For example, we established that FDHs catalyze enantioselective reactions involving desymmetrization, atroposelective halogenation, and halocyclization. These results highlight the ability of FDH active sites to tolerate different substrate topologies. This utility was further expanded by our recent studies on the single component FDH/FRed, AetF. While we were initially drawn to AetF because it does not require a separate FRed, we found that it halogenates substrates that are not halogenated efficiently or at all by other FDHs and provides high enantioselectivity for reactions that could only be achieved using RebH variants after extensive mutagenesis. Perhaps most notably, AetF catalyzes site-selective aromatic iodination and enantioselective iodoetherification. Together, these studies highlight the origins of FDH engineering, the utility and limitations of the enzymes developed to date, and the promise of FDHs for an ever-expanding range of biocatalytic halogenation reactions.
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Affiliation(s)
- Jared C Lewis
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
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3
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Prakinee K, Lawan N, Phintha A, Visitsatthawong S, Chitnumsub P, Jitkaroon W, Chaiyen P. On the Mechanisms of Hypohalous Acid Formation and Electrophilic Halogenation by Non-Native Halogenases. Angew Chem Int Ed Engl 2024; 63:e202403858. [PMID: 38606607 DOI: 10.1002/anie.202403858] [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: 02/24/2024] [Revised: 03/29/2024] [Accepted: 04/10/2024] [Indexed: 04/13/2024]
Abstract
Enzymatic electrophilic halogenation is a mild tool for functionalization of diverse organic compounds. Only a few groups of native halogenases are capable of catalyzing such a reaction. In this study, we used a mechanism-guided strategy to discover the electrophilic halogenation activity catalyzed by non-native halogenases. As the ability to form a hypohalous acid (HOX) is key for halogenation, flavin-dependent monooxygenases/oxidases capable of forming C4a-hydroperoxyflavin (FlC4a-OOH), such as dehalogenase, hydroxylases, luciferase and pyranose-2-oxidase (P2O), and flavin reductase capable of forming H2O2 were explored for their abilities to generate HOX in situ. Transient kinetic analyses using stopped-flow spectrophotometry/fluorometry and product analysis indicate that FlC4a-OOH in dehalogenases, selected hydroxylases and luciferases, but not in P2O can form HOX; however, the HOX generated from FlC4a-OOH cannot halogenate their substrates. Remarkably, in situ H2O2 generated by P2O can form HOI and also iodinate various compounds. Because not all enzymes capable of forming FlC4a-OOH can react with halides to form HOX, QM/MM calculations, site-directed mutagenesis and structural analysis were carried out to elucidate the mechanism underlying HOX formation and characterize the active site environment. Our findings shed light on identifying new halogenase scaffolds besides the currently known enzymes and have invoked a new mode of chemoenzymatic halogenation.
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Affiliation(s)
- Kridsadakorn Prakinee
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC) Wangchan Valley, Rayong, 21210, Thailand
| | - Narin Lawan
- Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Aisaraphon Phintha
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC) Wangchan Valley, Rayong, 21210, Thailand
| | - Surawit Visitsatthawong
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC) Wangchan Valley, Rayong, 21210, Thailand
| | - Penchit Chitnumsub
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC) Wangchan Valley, Rayong, 21210, Thailand
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA) Thailand Science Park, Pathum Thani, 12120, Thailand
| | - Watcharapa Jitkaroon
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC) Wangchan Valley, Rayong, 21210, Thailand
| | - Pimchai Chaiyen
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC) Wangchan Valley, Rayong, 21210, Thailand
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4
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Nguyen NA, Vidya FNU, Yennawar NH, Wu H, McShan AC, Agarwal V. Disordered regions in proteusin peptides guide post-translational modification by a flavin-dependent RiPP brominase. Nat Commun 2024; 15:1265. [PMID: 38341413 PMCID: PMC10858898 DOI: 10.1038/s41467-024-45593-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 01/29/2024] [Indexed: 02/12/2024] Open
Abstract
To biosynthesize ribosomally synthesized and post-translationally modified peptides (RiPPs), enzymes recognize and bind to the N-terminal leader region of substrate peptides which enables catalytic modification of the C-terminal core. Our current understanding of RiPP leaders is that they are short and largely unstructured. Proteusins are RiPP precursor peptides that defy this characterization as they possess unusually long leaders. Proteusin peptides have not been structurally characterized, and we possess scant understanding of how these atypical leaders engage with modifying enzymes. Here, we determine the structure of a proteusin peptide which shows that unlike other RiPP leaders, proteusin leaders are preorganized into a rigidly structured region and a smaller intrinsically disordered region. With residue level resolution gained from NMR titration experiments, the intermolecular peptide-protein interactions between proteusin leaders and a flavin-dependent brominase are mapped onto the disordered region, leaving the rigidly structured region of the proteusin leader to be functionally dispensable. Spectroscopic observations are biochemically validated to identify a binding motif in proteusin peptides that is conserved among other RiPP leaders as well. This study provides a structural characterization of the proteusin peptides and extends the paradigm of RiPP modification enzymes using not only unstructured peptides, but also structured proteins as substrates.
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Affiliation(s)
- Nguyet A Nguyen
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - F N U Vidya
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Neela H Yennawar
- The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, 16802, USA
| | - Hongwei Wu
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Andrew C McShan
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
| | - Vinayak Agarwal
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
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5
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Peh G, Tay T, Tan LL, Tiong E, Bi J, Goh YL, Ye S, Lin F, Tan CJX, Tan YZ, Wong J, Zhao H, Wong FT, Ang EL, Lim YH. Site-selective chlorination of pyrrolic heterocycles by flavin dependent enzyme PrnC. Commun Chem 2024; 7:7. [PMID: 38182798 PMCID: PMC10770391 DOI: 10.1038/s42004-023-01083-1] [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: 04/07/2023] [Accepted: 12/06/2023] [Indexed: 01/07/2024] Open
Abstract
Halogenation of pyrrole requires strong electrophilic reagents and often leads to undesired polyhalogenated products. Biocatalytic halogenation is a highly attractive approach given its chemoselectivity and benign reaction conditions. While there are several reports of enzymatic phenol and indole halogenation in organic synthesis, corresponding reports on enzymatic pyrrole halogenation have been lacking. Here we describe the in vitro functional and structural characterization of PrnC, a flavin-dependent halogenase that can act on free-standing pyrroles. Computational modeling and site mutagenesis studies identified three key residues in the catalytic pocket. A moderate resolution map using single-particle cryogenic electron microscopy reveals PrnC to be a dimer. This native PrnC can halogenate a library of structurally diverse pyrrolic heterocycles in a site-selective manner and be applied in the chemoenzymatic synthesis of a chlorinated analog of the agrochemical fungicide Fludioxonil.
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Affiliation(s)
- GuangRong Peh
- Institute of Sustainability for Chemicals, Energy and Environment (ISCE2), Agency for Science, Technology and Research (A*STAR), Singapore, Republic of Singapore
| | - Terence Tay
- Singapore Institute of Food and Biotechnology Innovation (SIFBI), Agency for Science, Technology and Research (A*STAR), Singapore, Republic of Singapore
| | - Lee Ling Tan
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), Singapore, Republic of Singapore
| | - Elaine Tiong
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), Singapore, Republic of Singapore
| | - Jiawu Bi
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), Singapore, Republic of Singapore
| | - Yi Ling Goh
- Institute of Sustainability for Chemicals, Energy and Environment (ISCE2), Agency for Science, Technology and Research (A*STAR), Singapore, Republic of Singapore
| | - Suming Ye
- Institute of Sustainability for Chemicals, Energy and Environment (ISCE2), Agency for Science, Technology and Research (A*STAR), Singapore, Republic of Singapore
| | - Fu Lin
- Singapore Institute of Food and Biotechnology Innovation (SIFBI), Agency for Science, Technology and Research (A*STAR), Singapore, Republic of Singapore
| | - Cheryl Jia Xin Tan
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Yong Zi Tan
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), Singapore, Republic of Singapore
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
- Disease Intervention Technology Laboratory (DITL), Agency for Science, Technology and Research (A*STAR), Singapore, Republic of Singapore
| | - Joel Wong
- Institute of Sustainability for Chemicals, Energy and Environment (ISCE2), Agency for Science, Technology and Research (A*STAR), Singapore, Republic of Singapore
| | - Huimin Zhao
- Singapore Institute of Food and Biotechnology Innovation (SIFBI), Agency for Science, Technology and Research (A*STAR), Singapore, Republic of Singapore
- Department of Chemical and Biomolecular Engineering, Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Fong Tian Wong
- Institute of Sustainability for Chemicals, Energy and Environment (ISCE2), Agency for Science, Technology and Research (A*STAR), Singapore, Republic of Singapore.
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), Singapore, Republic of Singapore.
| | - Ee Lui Ang
- Singapore Institute of Food and Biotechnology Innovation (SIFBI), Agency for Science, Technology and Research (A*STAR), Singapore, Republic of Singapore.
- Synthetic Biology Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Republic of Singapore.
| | - Yee Hwee Lim
- Institute of Sustainability for Chemicals, Energy and Environment (ISCE2), Agency for Science, Technology and Research (A*STAR), Singapore, Republic of Singapore.
- Synthetic Biology Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Republic of Singapore.
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6
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Besse C, Niemann HH, Sewald N. Increasing the Stability of Flavin-Dependent Halogenases by Disulfide Engineering. Chembiochem 2024; 25:e202300700. [PMID: 37917145 DOI: 10.1002/cbic.202300700] [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: 10/13/2023] [Revised: 10/27/2023] [Accepted: 11/02/2023] [Indexed: 11/03/2023]
Abstract
Flavin-dependent halogenases allow halogenation of electron-rich aromatic compounds under mild reaction conditions even at electronically unfavored positions with high regioselectivity. In order to expand the application of halogenases, the enzymes need to be improved in terms of stability and efficiency. A previous study with the tryptophan 6-halogenase Thal demonstrated that thermostable Thal variants tend to form dimers in solution while the wild type is present as a monomer. Based on this a dimeric Thal variant was generated that is covalently linked by disulfide bonds. Introducing two cysteine residues at the dimer interface resulted in the variant Thal CC with significantly increased thermostability (▵T50 =15.7 K) and stability over time at elevated temperature compared to the wild type. By introducing the homologous mutations into the tryptophan 5-halogenase PyrH, we were able to show that the stabilization by covalent dimerization can also be transferred to other halogenases. Moreover, it was possible to further increase the thermostability of PyrH by inserting cysteine mutations at alternative sites of the dimer interface.
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Affiliation(s)
- Caroline Besse
- Organic and Bioorganic Chemistry, Department of Chemistry, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Hartmut H Niemann
- Structural Biochemistry, Department of Chemistry, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Norbert Sewald
- Organic and Bioorganic Chemistry, Department of Chemistry, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany
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7
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Phintha A, Chaiyen P. Unifying and versatile features of flavin-dependent monooxygenases: Diverse catalysis by a common C4a-(hydro)peroxyflavin. J Biol Chem 2023; 299:105413. [PMID: 37918809 PMCID: PMC10696468 DOI: 10.1016/j.jbc.2023.105413] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 10/18/2023] [Accepted: 10/22/2023] [Indexed: 11/04/2023] Open
Abstract
Flavin-dependent monooxygenases (FDMOs) are known for their remarkable versatility and for their crucial roles in various biological processes and applications. Extensive research has been conducted to explore the structural and functional relationships of FDMOs. The majority of reported FDMOs utilize C4a-(hydro)peroxyflavin as a reactive intermediate to incorporate an oxygen atom into a wide range of compounds. This review discusses and analyzes recent advancements in our understanding of the structural and mechanistic features governing the enzyme functions. State-of-the-art discoveries related to common and distinct structural properties governing the catalytic versatility of the C4a-(hydro)peroxyflavin intermediate in selected FDMOs are discussed. Specifically, mechanisms of hydroxylation, dehalogenation, halogenation, and light-emitting reactions by FDMOs are highlighted. We also provide new analysis based on the structural and mechanistic features of these enzymes to gain insights into how the same intermediate can be harnessed to perform a wide variety of reactions. Challenging questions to obtain further breakthroughs in the understanding of FDMOs are also proposed.
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Affiliation(s)
- Aisaraphon Phintha
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Wangchan Valley, Rayong, Thailand
| | - Pimchai Chaiyen
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Wangchan Valley, Rayong, Thailand.
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8
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Montua N, Sewald N. Extended Biocatalytic Halogenation Cascades Involving a Single-Polypeptide Regeneration System for Diffusible FADH 2. Chembiochem 2023; 24:e202300478. [PMID: 37549375 DOI: 10.1002/cbic.202300478] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 08/07/2023] [Accepted: 08/07/2023] [Indexed: 08/09/2023]
Abstract
Flavin-dependent halogenases have attracted increasing interest for aryl halogenation at unactivated C-H positions because they are characterised by high regioselectivity, while requiring only FADH2 , halide salts, and O2 . Their use in combined crosslinked enzyme aggregates (combiCLEAs) together with an NADH-dependent flavin reductase and an NADH-regeneration system for the preparative halogenation of tryptophan and indole derivatives has been previously described. However, multiple cultivations and protein purification steps are necessary for their production. We present a bifunctional regeneration enzyme for two-step catalytic flavin regeneration using phosphite as an inexpensive sacrificial substrate. This fusion protein proved amenable to co-expression with various flavin-dependent Trp-halogenases and enables carrier-free immobilisation as combiCLEAs from a single cultivation for protein production and the preparative synthesis of halotryptophan. The scalability of this system was demonstrated by fed-batch fermentation in bench-top bioreactors on a 2.5 L scale. Furthermore, the inclusion of a 6-halotryptophan-specific dioxygenase into the co-expression strain further converts the halogenation product to the kynurenine derivative. This reaction cascade enables the one-pot synthesis of l-4-Cl-kynurenine and its brominated analogue on a preparative scale.
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Affiliation(s)
- Nicolai Montua
- Organic and Bioorganic Chemistry, Department of Chemistry, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Norbert Sewald
- Organic and Bioorganic Chemistry, Department of Chemistry, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany
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9
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Lukowski AL, Hubert FM, Ngo TE, Avalon NE, Gerwick WH, Moore BS. Enzymatic Halogenation of Terminal Alkynes. J Am Chem Soc 2023; 145:18716-18721. [PMID: 37594919 PMCID: PMC10486310 DOI: 10.1021/jacs.3c05750] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/20/2023]
Abstract
The biosynthetic installation of halogen atoms is largely performed by oxidative halogenases that target a wide array of electron-rich substrates, including aromatic compounds and conjugated systems. Halogenated alkyne-containing molecules are known to occur in Nature; however, halogen atom installation on the terminus of an alkyne has not been demonstrated in enzyme catalysis. Herein, we report the discovery and characterization of an alkynyl halogenase in natural product biosynthesis. We show that the flavin-dependent halogenase from the jamaicamide biosynthetic pathway, JamD, is not only capable of terminal alkyne halogenation on a late-stage intermediate en route to the final natural product but also has broad substrate tolerance for simple to complex alkynes. Furthermore, JamD is specific for terminal alkynes over other electron-rich aromatic substrates and belongs to a newly identified family of halogenases from marine cyanobacteria, indicating its potential as a chemoselective biocatalyst for the formation of haloalkynes.
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Affiliation(s)
- April L Lukowski
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, United States
| | - Felix M Hubert
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, United States
| | - Thuan-Ethan Ngo
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, United States
| | - Nicole E Avalon
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, United States
| | - William H Gerwick
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, United States
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California 92093, United States
| | - Bradley S Moore
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, United States
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California 92093, United States
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10
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Abstract
A survey of protein databases indicates that the majority of enzymes exist in oligomeric forms, with about half of those found in the UniProt database being homodimeric. Understanding why many enzymes are in their dimeric form is imperative. Recent developments in experimental and computational techniques have allowed for a deeper comprehension of the cooperative interactions between the subunits of dimeric enzymes. This review aims to succinctly summarize these recent advancements by providing an overview of experimental and theoretical methods, as well as an understanding of cooperativity in substrate binding and the molecular mechanisms of cooperative catalysis within homodimeric enzymes. Focus is set upon the beneficial effects of dimerization and cooperative catalysis. These advancements not only provide essential case studies and theoretical support for comprehending dimeric enzyme catalysis but also serve as a foundation for designing highly efficient catalysts, such as dimeric organic catalysts. Moreover, these developments have significant implications for drug design, as exemplified by Paxlovid, which was designed for the homodimeric main protease of SARS-CoV-2.
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Affiliation(s)
- Ke-Wei Chen
- Lab of Computional Chemistry and Drug Design, State Key Laboratory of Chemical Oncogenomics, Peking University Shenzhen Graduate School, Shenzhen 518055, China
| | - Tian-Yu Sun
- Shenzhen Bay Laboratory, Shenzhen 518132, China
| | - Yun-Dong Wu
- Lab of Computional Chemistry and Drug Design, State Key Laboratory of Chemical Oncogenomics, Peking University Shenzhen Graduate School, Shenzhen 518055, China
- Shenzhen Bay Laboratory, Shenzhen 518132, China
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11
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Ashaduzzaman M, Lingkon K, De Silva AJ, Bellizzi JJ. Crystallographic and thermodynamic evidence of negative cooperativity of flavin and tryptophan binding in the flavin-dependent halogenases AbeH and BorH. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.22.554356. [PMID: 37662313 PMCID: PMC10473636 DOI: 10.1101/2023.08.22.554356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
The flavin-dependent halogenase AbeH produces 5-chlorotryptophan in the biosynthetic pathway of the chlorinated bisindole alkaloid BE-54017. We report that in vitro, AbeH (assisted by the flavin reductase AbeF) can chlorinate and brominate tryptophan as well as other indole derivatives and substrates with phenyl and quinoline groups. We solved the X-ray crystal structures of AbeH alone and complexed with FAD, as well as crystal structures of the tryptophan-6-halogenase BorH alone, in complex with 6-chlorotryptophan, and in complex with FAD and tryptophan. Partitioning of FAD and tryptophan into different chains of BorH and failure to incorporate tryptophan into AbeH/FAD crystals suggested that flavin and tryptophan binding are negatively coupled in both proteins. ITC and fluorescence quenching experiments confirmed the ability of both AbeH and BorH to form binary complexes with FAD or tryptophan and the inability of tryptophan to bind to AbeH/FAD or BorH/FAD complexes. FAD could not bind to BorH/tryptophan complexes, but FAD appears to displace tryptophan from AbeH/tryptophan complexes in an endothermic entropically-driven process.
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Affiliation(s)
- Md Ashaduzzaman
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo OH 43606
| | - Kazi Lingkon
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo OH 43606
| | - Aravinda J De Silva
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo OH 43606
| | - John J Bellizzi
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo OH 43606
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12
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Jiang Y, Lewis JC. Asymmetric catalysis by flavin-dependent halogenases. Chirality 2023; 35:452-460. [PMID: 36916449 PMCID: PMC11301518 DOI: 10.1002/chir.23550] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 02/15/2023] [Accepted: 02/16/2023] [Indexed: 03/16/2023]
Abstract
In nature, flavin-dependent halogenases (FDHs) catalyze site-selective chlorination and bromination of aromatic natural products. This ability has led to extensive efforts to engineer FDHs for selective chlorination, bromination, and iodination of electron rich aromatic compounds. On the other hand, FDHs are unique among halogenases and haloperoxidases that exhibit catalyst-controlled site selectivity in that no examples of enantioselective FDH catalysis in natural product biosynthesis have been characterized. Over the past several years, our group has established that FDHs can catalyze enantioselective reactions involving desymmetrization, atroposelective halogenation, and halocyclization. Achieving high activity and selectivity for these reactions has required extensive mutagenesis and mitigation of problems resulting from hypohalous acid generated during FDH catalysis. The single-component flavin reductase/FDH AetF is unique among the wild type enzyme we have studied in that it provides high activity and selectivity toward several asymmetric transformations. These results highlight the ability of FDH active sites to tolerate different substrate topologies and suggest that they could be useful for a broad range of oxidative halogenations.
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Affiliation(s)
- Yuhua Jiang
- Department of Chemistry, Indiana University, Bloomington, Indiana, USA
| | - Jared C Lewis
- Department of Chemistry, Indiana University, Bloomington, Indiana, USA
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13
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Xiao S, Wang Z, Wang B, Hou B, Cheng J, Bai T, Zhang Y, Wang W, Yan L, Zhang J. Expanding the application of tryptophan: Industrial biomanufacturing of tryptophan derivatives. Front Microbiol 2023; 14:1099098. [PMID: 37032885 PMCID: PMC10076799 DOI: 10.3389/fmicb.2023.1099098] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 03/08/2023] [Indexed: 04/11/2023] Open
Abstract
Tryptophan derivatives are various aromatic compounds produced in the tryptophan metabolic pathway, such as 5-hydroxytryptophan, 5-hydroxytryptamine, melatonin, 7-chloro-tryptophan, 7-bromo-tryptophan, indigo, indirubin, indole-3-acetic acid, violamycin, and dexoyviolacein. They have high added value, widely used in chemical, food, polymer and pharmaceutical industry and play an important role in treating diseases and improving life. At present, most tryptophan derivatives are synthesized by biosynthesis. The biosynthesis method is to combine metabolic engineering with synthetic biology and system biology, and use the tryptophan biosynthesis pathway of Escherichia coli, Corynebacterium glutamicum and other related microorganisms to reconstruct the artificial biosynthesis pathway, and then produce various tryptophan derivatives. In this paper, the characteristics, applications and specific biosynthetic pathways and methods of these derivatives were reviewed, and some strategies to increase the yield of derivatives and reduce the production cost on the basis of biosynthesis were introduced in order to make some contributions to the development of tryptophan derivatives biosynthesis industry.
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Affiliation(s)
- Shujian Xiao
- Meat Processing Key Laboratory of Sichuan Province, College of Food and Biological Engineering, Chengdu University, Chengdu, China
| | - Zhen Wang
- College of Science and Technology, Hebei Agricultural University, Cangzhou, China
| | - Bangxu Wang
- Meat Processing Key Laboratory of Sichuan Province, College of Food and Biological Engineering, Chengdu University, Chengdu, China
| | - Bo Hou
- Meat Processing Key Laboratory of Sichuan Province, College of Food and Biological Engineering, Chengdu University, Chengdu, China
| | - Jie Cheng
- Meat Processing Key Laboratory of Sichuan Province, College of Food and Biological Engineering, Chengdu University, Chengdu, China
- *Correspondence: Jie Cheng, ; Lixiu Yan, ; Jiamin Zhang,
| | - Ting Bai
- Meat Processing Key Laboratory of Sichuan Province, College of Food and Biological Engineering, Chengdu University, Chengdu, China
| | - Yin Zhang
- Meat Processing Key Laboratory of Sichuan Province, College of Food and Biological Engineering, Chengdu University, Chengdu, China
| | - Wei Wang
- Meat Processing Key Laboratory of Sichuan Province, College of Food and Biological Engineering, Chengdu University, Chengdu, China
| | - Lixiu Yan
- Chongqing Academy of Metrology and Quality Inspection, Chongqing, China
- *Correspondence: Jie Cheng, ; Lixiu Yan, ; Jiamin Zhang,
| | - Jiamin Zhang
- Meat Processing Key Laboratory of Sichuan Province, College of Food and Biological Engineering, Chengdu University, Chengdu, China
- *Correspondence: Jie Cheng, ; Lixiu Yan, ; Jiamin Zhang,
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14
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Jiang Y, Snodgrass HM, Zubi YS, Roof CV, Guan Y, Mondal D, Honeycutt NH, Lee JW, Lewis RD, Martinez CA, Lewis JC. The Single-Component Flavin Reductase/Flavin-Dependent Halogenase AetF is a Versatile Catalyst for Selective Bromination and Iodination of Arenes and Olefins. Angew Chem Int Ed Engl 2022; 61:e202214610. [PMID: 36282507 PMCID: PMC9772203 DOI: 10.1002/anie.202214610] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Indexed: 11/05/2022]
Abstract
Flavin-dependent halogenases (FDHs) natively catalyze selective halogenation of electron rich aromatic and enolate groups. Nearly all FDHs reported to date require a separate flavin reductase to supply them with FADH2 , which complicates biocatalysis applications. In this study, we establish that the single component flavin reductase/flavin dependent halogenase AetF catalyzes halogenation of a diverse set of substrates using a commercially available glucose dehydrogenase to drive its halogenase activity. High site selectivity, activity on relatively unactivated substrates, and high enantioselectivity for atroposelective bromination and bromolactonization was demonstrated. Site-selective iodination and enantioselective cycloiodoetherification was also possible using AetF. The substrate and reaction scope of AetF suggest that it has the potential to greatly improve the utility of biocatalytic halogenation.
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Affiliation(s)
- Yuhua Jiang
- Department of ChemistryIndiana UniversityBloomingtonIN 47405USA
| | | | - Yasmine S. Zubi
- Department of ChemistryIndiana UniversityBloomingtonIN 47405USA
| | - Caitlin V. Roof
- Department of ChemistryIndiana UniversityBloomingtonIN 47405USA
| | - Yanfei Guan
- Chemical Research & DevelopmentPfizer Worldwide Research & DevelopmentGrotonConnecticut 06340USA
| | - Dibyendu Mondal
- Department of ChemistryIndiana UniversityBloomingtonIN 47405USA
- Kalsec Inc.3713W. Main St.KalamazooMichigan 49006USA
| | | | - Johnny W. Lee
- Chemical Research & DevelopmentPfizer Worldwide Research & DevelopmentGrotonConnecticut 06340USA
| | - Russell D. Lewis
- Chemical Research & DevelopmentPfizer Worldwide Research & DevelopmentGrotonConnecticut 06340USA
| | - Carlos A. Martinez
- Chemical Research & DevelopmentPfizer Worldwide Research & DevelopmentGrotonConnecticut 06340USA
| | - Jared C. Lewis
- Department of ChemistryIndiana UniversityBloomingtonIN 47405USA
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15
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Barker RD, Yu Y, De Maria L, Johannissen LO, Scrutton NS. Mechanism of Action of Flavin-Dependent Halogenases. ACS Catal 2022; 12:15352-15360. [PMID: 36570077 PMCID: PMC9764358 DOI: 10.1021/acscatal.2c05231] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Revised: 11/12/2022] [Indexed: 12/05/2022]
Abstract
To rationally engineer the substrate scope and selectivity of flavin-dependent halogenases (FDHs), it is essential to first understand the reaction mechanism and substrate interactions in the active site. FDHs have long been known to achieve regioselectivity through an electrophilic aromatic substitution at C7 of the natural substrate Trp, but the precise role of a key active-site Lys residue remains ambiguous. Formation of hypochlorous acid (HOCl) at the cofactor-binding site is achieved by the direct reaction of molecular oxygen and a single chloride ion with reduced FAD and flavin hydroxide, respectively. HOCl is then guided 10 Å into the halogenation active site. Lys79, located in this site, has been proposed to direct HOCl toward Trp C7 through hydrogen bonding or a direct reaction with HOCl to form an -NH2Cl+ intermediate. Here, we present the most likely mechanism for halogenation based on molecular dynamics (MD) simulations and active-site density functional theory "cluster" models of FDH PrnA in complex with its native substrate l-tryptophan, hypochlorous acid, and the FAD cofactor. MD simulations with different protonation states for key active-site residues suggest that Lys79 directs HOCl through hydrogen bonding, which is confirmed by calculations of the reaction profiles for both proposed mechanisms.
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Affiliation(s)
- Rhys D. Barker
- Manchester
Institute of Biotechnology, The University
of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | - Yuqi Yu
- Manchester
Institute of Biotechnology, The University
of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | - Leonardo De Maria
- Research
and Early Development, Respiratory & Immunology, BioPharmaceuticals
R&D, AstraZeneca, Gothenburg 43283, Sweden
| | - Linus O. Johannissen
- Manchester
Institute of Biotechnology, The University
of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.,
| | - Nigel S. Scrutton
- Manchester
Institute of Biotechnology, The University
of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.,
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16
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Andorfer MC, Evans D, Yang S, He CQ, Girlich AM, Vergara-Coll J, Sukumar N, Houk KN, Lewis JC. Analysis of Laboratory-Evolved Flavin-Dependent Halogenases Affords a Computational Model for Predicting Halogenase Site Selectivity. CHEM CATALYSIS 2022; 2:2658-2674. [PMID: 36569427 PMCID: PMC9784200 DOI: 10.1016/j.checat.2022.07.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Flavin-dependent halogenases (FDHs) catalyze selective halogenation of electron-rich aromatic compounds without the need for harsh oxidants required by conventional oxidative halogenation reactions. Predictive models for halogenase site selectivity could greatly improve their utility for chemical synthesis. Toward this end, we analyzed the structures and selectivity of three halogenase variants evolved to halogenate tryptamine with orthogonal selectivity. Crystal structures and reversion mutations revealed key residues involved in altering halogenase selectivity. Density functional theory calculations and molecular dynamics simulations are both consistent with hypohalous acid as the active halogenating species in FDH catalysis. This model was used to accurately predict the site selectivity of halogenase variants toward different synthetic substrates, providing a valuable tool for implementing halogenases in biocatalysis efforts.
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Affiliation(s)
- Mary C. Andorfer
- Department of Chemistry, University of Chicago, Chicago, IL 60637, USA
- Present address: Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
- These authors contributed equally
| | - Declan Evans
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
- These authors contributed equally
| | - Song Yang
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Present address: Merck Research Laboratories, South San Francisco, CA, USA
| | - Cyndi Qixin He
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Present address: Merck Research Laboratories, Kenilworth, NJ, USA
| | - Anna M. Girlich
- Department of Chemistry, University of Chicago, Chicago, IL 60637, USA
| | | | - Narayanasami Sukumar
- NE-CAT and Department of Chemistry and Chemical Biology, Cornell University, Argonne National Laboratory, Building 436E, Argonne, IL 60439, USA
| | - K. N. Houk
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Jared C. Lewis
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
- Lead contact
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17
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Lee J, Kim J, Kim H, Park H, Kim JY, Kim EJ, Yang YH, Choi KY, Kim BG. Constructing multi-enzymatic cascade reactions for selective production of 6-bromoindirubin from tryptophan in Escherichia coli. Biotechnol Bioeng 2022; 119:2938-2949. [PMID: 35876239 DOI: 10.1002/bit.28188] [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: 05/26/2022] [Revised: 07/04/2022] [Accepted: 07/17/2022] [Indexed: 11/06/2022]
Abstract
6-Bromoindirubin (6BrIR), found in Murex sea snails, is a precursor of indirubin-derivatives anticancer drugs. However, its synthesis remains limited due to uncharacterized biosynthetic pathways and difficulties in site-specific bromination and oxidation at indole ring. Here, we present an efficient 6BrIR production strategy in E. coli by using four enzymes, i.e., tryptophan 6-halogenase fused with flavin reductase Fre (Fre-L3-SttH), tryptophanase (TnaA), toluene 4-monooxygenase (PmT4MO) and flavin-containing monooxygenase (MaFMO). Although most indole oxygenases preferentially oxygenate the electronically active C3 position of indole, PmT4MO was newly characterized to perform C2 oxygenation of 6-bromoindole with 45 % yield to produce 6-bromo-2-oxindole. In addition, 6BrIR was selectively generated without indigo and indirubin byproducts by controlling the reducing power of cysteine and oxygen supply during the MaFMO reaction. These approaches led to 34.1 mg/L 6BrIR productions, making it possible to produce the critical precursor of the anticancer drugs only from natural ingredients such as tryptophan, NaBr and oxygen. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Jeongchan Lee
- School of Chemical and Biological Engineering, Seoul National University, Seoul, Republic of Korea.,Institute of Molecular Biology and Genetics, Seoul National University, Seoul, Republic of Korea.,Bio-MAX Institute, Seoul National University, Seoul, Republic of Korea
| | - Joonwon Kim
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, USA
| | - Hyun Kim
- School of Chemical and Biological Engineering, Seoul National University, Seoul, Republic of Korea
| | - HyunA Park
- Department of Environmental Engineering, Ajou University, Suwon, Republic of Korea
| | - Jin Young Kim
- Interdisciplinary Program in Bioengineering, Seoul National University, Seoul, Republic of Korea
| | - Eun-Jung Kim
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul, Republic of Korea.,Bio-MAX Institute, Seoul National University, Seoul, Republic of Korea
| | - Yung-Hun Yang
- Department of Biological Engineering, Konkuk University, Seoul, Republic of Korea
| | - Kwon-Young Choi
- Department of Environmental Engineering, Ajou University, Suwon, Republic of Korea
| | - Byung-Gee Kim
- School of Chemical and Biological Engineering, Seoul National University, Seoul, Republic of Korea.,Institute of Molecular Biology and Genetics, Seoul National University, Seoul, Republic of Korea.,Bio-MAX Institute, Seoul National University, Seoul, Republic of Korea.,Interdisciplinary Program in Bioengineering, Seoul National University, Seoul, Republic of Korea.,Institute of Engineering Research, Seoul National University, Seoul, Republic of Korea
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18
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Mechanism-guided tunnel engineering to increase the efficiency of a flavin-dependent halogenase. Nat Catal 2022. [DOI: 10.1038/s41929-022-00800-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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19
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Crowe C, Molyneux S, Sharma SV, Zhang Y, Gkotsi DS, Connaris H, Goss RJM. Halogenases: a palette of emerging opportunities for synthetic biology-synthetic chemistry and C-H functionalisation. Chem Soc Rev 2021; 50:9443-9481. [PMID: 34368824 PMCID: PMC8407142 DOI: 10.1039/d0cs01551b] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Indexed: 12/14/2022]
Abstract
The enzymatic generation of carbon-halogen bonds is a powerful strategy used by both nature and synthetic chemists to tune the bioactivity, bioavailability and reactivity of compounds, opening up the opportunity for selective C-H functionalisation. Genes encoding halogenase enzymes have recently been shown to transcend all kingdoms of life. These enzymes install halogen atoms into aromatic and less activated aliphatic substrates, achieving selectivities that are often challenging to accomplish using synthetic methodologies. Significant advances in both halogenase discovery and engineering have provided a toolbox of enzymes, enabling the ready use of these catalysts in biotransformations, synthetic biology, and in combination with chemical catalysis to enable late stage C-H functionalisation. With a focus on substrate scope, this review outlines the mechanisms employed by the major classes of halogenases, while in parallel, it highlights key advances in the utilisation of the combination of enzymatic halogenation and chemical catalysis for C-H activation and diversification.
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Affiliation(s)
- Charlotte Crowe
- School of Chemistry, and BSRC, University of St Andrews, North HaughSt Andrews KY16 9STUK
| | - Samuel Molyneux
- School of Chemistry, and BSRC, University of St Andrews, North HaughSt Andrews KY16 9STUK
| | - Sunil V. Sharma
- School of Chemistry, and BSRC, University of St Andrews, North HaughSt Andrews KY16 9STUK
| | - Ying Zhang
- School of Chemistry, and BSRC, University of St Andrews, North HaughSt Andrews KY16 9STUK
| | - Danai S. Gkotsi
- School of Chemistry, and BSRC, University of St Andrews, North HaughSt Andrews KY16 9STUK
| | - Helen Connaris
- School of Chemistry, and BSRC, University of St Andrews, North HaughSt Andrews KY16 9STUK
| | - Rebecca J. M. Goss
- School of Chemistry, and BSRC, University of St Andrews, North HaughSt Andrews KY16 9STUK
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20
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Abstract
We report the development of a chemoenzymatic approach toward fasamycin A, a halogenated naphthacenoid that exhibits activities against methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecalis. The synthesis was accomplished in a convergent manner: two fragments were combined together in a Sammes annulation to afford a dimethylnaphthacenone system. Finally, an enzymatic halogenation was employed to introduce the requisite chlorine substituent of the natural product at a late stage.
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Affiliation(s)
- Jian Li
- The Scripps Research Institute, Department of Chemistry, 130 Scripps Way, Jupiter, Florida 33458 United States
| | - Hans Renata
- The Scripps Research Institute, Department of Chemistry, 130 Scripps Way, Jupiter, Florida 33458 United States
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21
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Pimviriyakul P, Jaruwat A, Chitnumsub P, Chaiyen P. Structural insights into a flavin-dependent dehalogenase HadA explain catalysis and substrate inhibition via quadruple π-stacking. J Biol Chem 2021; 297:100952. [PMID: 34252455 PMCID: PMC8342789 DOI: 10.1016/j.jbc.2021.100952] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 06/24/2021] [Accepted: 07/08/2021] [Indexed: 12/20/2022] Open
Abstract
HadA is a flavin-dependent monooxygenase catalyzing hydroxylation plus dehalogenation/denitration, which is useful for biodetoxification and biodetection. In this study, the X-ray structure of wild-type HadA (HadAWT) co-complexed with reduced FAD (FADH-) and 4-nitrophenol (4NP) (HadAWT-FADH--4NP) was solved at 2.3-Å resolution, providing the first full package (with flavin and substrate bound) structure of a monooxygenase of this type. Residues Arg101, Gln158, Arg161, Thr193, Asp254, Arg233, and Arg439 constitute a flavin-binding pocket, whereas the 4NP-binding pocket contains the aromatic side chain of Phe206, which provides π-π stacking and also is a part of the hydrophobic pocket formed by Phe155, Phe286, Thr449, and Leu457. Based on site-directed mutagenesis and stopped-flow experiments, Thr193, Asp254, and His290 are important for C4a-hydroperoxyflavin formation with His290, also serving as a catalytic base for hydroxylation. We also identified a novel structural motif of quadruple π-stacking (π-π-π-π) provided by two 4NP and two Phe441 from two subunits. This motif promotes 4NP binding in a nonproductive dead-end complex, which prevents C4a-hydroperoxy-FAD formation when HadA is premixed with aromatic substrates. We also solved the structure of the HadAPhe441Val-FADH--4NP complex at 2.3-Å resolution. Although 4NP can still bind to this variant, the quadruple π-stacking motif was disrupted. All HadAPhe441 variants lack substrate inhibition behavior, confirming that quadruple π-stacking is a main cause of dead-end complex formation. Moreover, the activities of these HadAPhe441 variants were improved by ⁓20%, suggesting that insights gained from the flavin-dependent monooxygenases illustrated here should be useful for future improvement of HadA's biocatalytic applications.
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Affiliation(s)
- Panu Pimviriyakul
- Department of Biochemistry, Faculty of Science, Kasetsart University, Bangkok, Thailand
| | - Aritsara Jaruwat
- National Center for Genetic Engineering and Biotechnology, Pathumthani, Thailand
| | - Penchit Chitnumsub
- National Center for Genetic Engineering and Biotechnology, Pathumthani, Thailand.
| | - Pimchai Chaiyen
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, Thailand.
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22
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Flavin-dependent halogenases catalyze enantioselective olefin halocyclization. Nat Commun 2021; 12:3268. [PMID: 34075034 PMCID: PMC8169660 DOI: 10.1038/s41467-021-23503-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 04/27/2021] [Indexed: 11/17/2022] Open
Abstract
Halocyclization of alkenes is a powerful bond-forming tool in synthetic organic chemistry and a key step in natural product biosynthesis, but catalyzing halocyclization with high enantioselectivity remains a challenging task. Identifying suitable enzymes that catalyze enantioselective halocyclization of simple olefins would therefore have significant synthetic value. Flavin-dependent halogenases (FDHs) catalyze halogenation of arene and enol(ate) substrates. Herein, we reveal that FDHs engineered to catalyze site-selective aromatic halogenation also catalyze non-native bromolactonization of olefins with high enantioselectivity and near-native catalytic proficiency. Highly selective halocyclization is achieved by characterizing and mitigating the release of HOBr from the FDH active site using a combination of reaction optimization and protein engineering. The structural origins of improvements imparted by mutations responsible for the emergence of halocyclase activity are discussed. This expansion of FDH catalytic activity presages the development of a wide range of biocatalytic halogenation reactions. Catalytic enantioselective halocyclization of alkenes is an important bond forming tool and a key step in natural product biosynthesis, but so far no examples of the enzymatic counterpart of this reaction on simple achiral olefins have been reported. Here, the authors describe examples of engineered flavin-dependent halogenases that catalyze halolactonization of olefins with high enantioselectivity and near-native catalytic activity.
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