1
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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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2
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Ni J, Zhuang J, Shi Y, Chiang YC, Cheng GJ. Discovery and substrate specificity engineering of nucleotide halogenases. Nat Commun 2024; 15:5254. [PMID: 38898020 PMCID: PMC11186838 DOI: 10.1038/s41467-024-49147-7] [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: 09/23/2023] [Accepted: 05/24/2024] [Indexed: 06/21/2024] Open
Abstract
C2'-halogenation has been recognized as an essential modification to enhance the drug-like properties of nucleotide analogs. The direct C2'-halogenation of the nucleotide 2'-deoxyadenosine-5'-monophosphate (dAMP) has recently been achieved using the Fe(II)/α-ketoglutarate-dependent nucleotide halogenase AdaV. However, the limited substrate scope of this enzyme hampers its broader applications. In this study, we report two halogenases capable of halogenating 2'-deoxyguanosine monophosphate (dGMP), thereby expanding the family of nucleotide halogenases. Computational studies reveal that nucleotide specificity is regulated by the binding pose of the phosphate group. Based on these findings, we successfully engineered the substrate specificity of these halogenases by mutating second-sphere residues. This work expands the toolbox of nucleotide halogenases and provides insights into the regulation mechanism of nucleotide specificity.
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Affiliation(s)
- Jie Ni
- Warshel Institute for Computational Biology, School of Medicine, The Chinese University of Hong Kong, Shenzhen, 518172, Guangdong, China
| | - Jingyuan Zhuang
- Warshel Institute for Computational Biology, School of Medicine, The Chinese University of Hong Kong, Shenzhen, 518172, Guangdong, China
| | - Yiming Shi
- Warshel Institute for Computational Biology, School of Medicine, The Chinese University of Hong Kong, Shenzhen, 518172, Guangdong, China
| | - Ying-Chih Chiang
- Kobilka Institute of Innovative Drug Discovery, School of Medicine, The Chinese University of Hong Kong, Shenzhen, 518172, Guangdong, China
| | - Gui-Juan Cheng
- Warshel Institute for Computational Biology, School of Medicine, The Chinese University of Hong Kong, Shenzhen, 518172, Guangdong, China.
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3
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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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4
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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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5
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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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6
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Jiang Y, Mondal D, Lewis JC. Expanding the Reactivity of Flavin-Dependent Halogenases toward Olefins via Enantioselective Intramolecular Haloetherification and Chemoenzymatic Oxidative Rearrangements. ACS Catal 2022. [DOI: 10.1021/acscatal.2c03383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yuhua Jiang
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Dibyendu Mondal
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Jared C. Lewis
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
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7
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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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8
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Snodgrass HM, Mondal D, Lewis JC. Directed Evolution of Flavin-Dependent Halogenases for Site- and Atroposelective Halogenation of 3-Aryl-4(3 H)-Quinazolinones via Kinetic or Dynamic Kinetic Resolution. J Am Chem Soc 2022; 144:16676-16682. [PMID: 36044712 DOI: 10.1021/jacs.2c07422] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
In this study, we engineer a variant of the flavin-dependent halogenase RebH that catalyzes site- and atroposelective halogenation of 3-aryl-4(3H)-quinazolinones via kinetic or dynamic kinetic resolution. The required directed evolution uses a combination of random and site-saturation mutagenesis, substrate walking using two probe substrates, and a two-tiered screening approach involving the analysis of variant conversion and then enantioselectivity of improved variants. The resulting variant, 3-T, provides >99:1 e.r. for the (M)-atropisomer of the major brominated product, 25-fold improved conversion, and 91-fold improved site selectivity relative to the parent enzyme on the probe substrate used in the final rounds of evolution. This high activity and selectivity translate well to several additional substrates with varied steric and electronic properties. Computational modeling and docking simulations are used to rationalize the effects of key mutations on substrate binding. Given the range of substrates that have been used for atroposelective synthesis via electrophilic halogenation in the literature, these results suggest that flavin-dependent halogenases (FDHs) could find many additional applications for atroposelective catalysis. More broadly, this study highlights how RebH can be engineered to accept structurally diverse substrates that enable its use for enantioselective catalysis.
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Affiliation(s)
- Harrison M Snodgrass
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Dibyendu Mondal
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Jared C Lewis
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
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9
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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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10
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Sana B, Ho T, Kannan S, Ke D, Li EHY, Seayad J, Verma CS, Duong HA, Ghadessy FJ. Engineered RebH Halogenase Variants Demonstrating a Specificity Switch from Tryptophan towards Novel Indole Compounds. Chembiochem 2021; 22:2791-2798. [PMID: 34240527 PMCID: PMC8518859 DOI: 10.1002/cbic.202100210] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 07/06/2021] [Indexed: 01/21/2023]
Abstract
Activating industrially important aromatic hydrocarbons by installing halogen atoms is extremely important in organic synthesis and often improves the pharmacological properties of drug molecules. To this end, tryptophan halogenase enzymes are potentially valuable tools for regioselective halogenation of arenes, including various industrially important indole derivatives and similar scaffolds. Although endogenous enzymes show reasonable substrate scope towards indole compounds, their efficacy can often be improved by engineering. Using a structure-guided semi-rational mutagenesis approach, we have developed two RebH variants with expanded biocatalytic repertoires that can efficiently halogenate several novel indole substrates and produce important pharmaceutical intermediates. Interestingly, the engineered enzymes are completely inactive towards their natural substrate tryptophan in spite of their high tolerance to various functional groups in the indole ring. Computational modelling and molecular dynamics simulations provide mechanistic insights into the role of gatekeeper residues in the substrate binding site and the dramatic switch in substrate specificity when these are mutated.
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Affiliation(s)
- Barindra Sana
- Disease Intervention Technology LaboratoryInstitute of Molecular and Cell BiologyAgency for Science Technology and Research (A*STAR)8 A Biomedical Grove, #06-04/05 Neuros/ImmunosSingapore138648Singapore
| | - Timothy Ho
- Institute of Chemical and Engineering SciencesAgency for Science Technology And Research (A*STAR)8 Biomedical Grove, Neuros, #07-01Singapore138665Singapore
| | - Srinivasaraghavan Kannan
- Bioinformatics InstituteAgency for Science Technology And Research (A*STAR)30 Biopolis Street, #07-01 MatrixSingapore138671Singapore
| | - Ding Ke
- Disease Intervention Technology LaboratoryInstitute of Molecular and Cell BiologyAgency for Science Technology and Research (A*STAR)8 A Biomedical Grove, #06-04/05 Neuros/ImmunosSingapore138648Singapore
| | - Eunice H. Y. Li
- Institute of Chemical and Engineering SciencesAgency for Science Technology And Research (A*STAR)8 Biomedical Grove, Neuros, #07-01Singapore138665Singapore
| | - Jayasree Seayad
- Institute of Chemical and Engineering SciencesAgency for Science Technology And Research (A*STAR)8 Biomedical Grove, Neuros, #07-01Singapore138665Singapore
| | - Chandra S. Verma
- Bioinformatics InstituteAgency for Science Technology And Research (A*STAR)30 Biopolis Street, #07-01 MatrixSingapore138671Singapore
- School of Biological SciencesNanyang Technological University60 Nanyang DriveSingapore637551Singapore
- Department of Biological SciencesNational University of Singapore14 Science Drive 4Singapore117558Singapore
| | - Hung A. Duong
- Institute of Chemical and Engineering SciencesAgency for Science Technology And Research (A*STAR)8 Biomedical Grove, Neuros, #07-01Singapore138665Singapore
| | - Farid J. Ghadessy
- Disease Intervention Technology LaboratoryInstitute of Molecular and Cell BiologyAgency for Science Technology and Research (A*STAR)8 A Biomedical Grove, #06-04/05 Neuros/ImmunosSingapore138648Singapore
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11
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Song Y, Wu X, Zhao Y, Jiang X, Wang L. Comparative molecular dynamics simulations identify a salt-sensitive loop responsible for the halotolerant activity of GH5 cellulases. J Biomol Struct Dyn 2021; 40:9522-9529. [PMID: 34043936 DOI: 10.1080/07391102.2021.1930167] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Halotolerant glycoside hydrolases (GH) have broad application potentials in biorefinery industries. Elucidating the structure-activity relationship underlying the halotolerant catalysis is essential to design superior biocatalysts. Here, we performed molecular dynamics simulations to investigate the structural dynamics of two GH5 cellulases, namely the halotolerant Cel5R and non-halotolerant TfCel5A. Through characterizing the physical properties at different salt concentrations, the results revealed that the overall structures of Cel5R and TfCel5A were marginally affected by the increase in salt concentrations. However, a salt-sensitive loop was identified from both Cel5R and TfCel5A based on its significantly increased flexibility at high salt concentrations. Importantly, compared to TfCel5A the salt-sensitive loop of Cel5R engaged more sodium ions and water molecules around the active site of the enzyme. Besides, the unique residue motif of the salt-sensitive loop in Cel5R formed more intramolecular hydrogen bonds, stabilizing the active architecture of Cel5R at high salt concentrations. Collectively, the structural and dynamic differences may contribute to the various catalytic halotolerance of Cel5R and TfCel5A. These findings provide mechanistic insight into the halotolerant catalysis and will guide the ration design of GH5 cellulases with improved catalytic properties.Communicated by Ramaswamy H. Samy.
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Affiliation(s)
- Yuxuan Song
- Taishan College, Shandong University, Qingdao, China
| | - Xiuyun Wu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Yue Zhao
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Xukai Jiang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China.,National Glycoengineering Research Center, Shandong University, Qingdao, China
| | - Lushan Wang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
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12
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Genomic Determinants Encode the Reactivity and Regioselectivity of Flavin-Dependent Halogenases in Bacterial Genomes and Metagenomes. mSystems 2021; 6:e0005321. [PMID: 34042468 PMCID: PMC8269204 DOI: 10.1128/msystems.00053-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Halogenases create diverse natural products by utilizing halide ions and are of great interest in the synthesis of potential pharmaceuticals and agrochemicals. An increasing number of halogenases discovered in microorganisms are annotated as flavin-dependent halogenases (FDHs), but their chemical reactivities are markedly different and the genomic contents associated with such functional distinction have not been revealed yet. Even though the reactivity and regioselectivity of FDHs are essential in the halogenation activity, these FDHs are annotated inaccurately in the protein sequence repositories without characterizing their functional activities. We carried out a comprehensive sequence analysis and biochemical characterization of FDHs. Using a probabilistic model that we built in this study, FDHs were discovered from 2,787 bacterial genomes and 17 sediment metagenomes. We analyzed the essential genomic determinants that are responsible for substrate binding and subsequent reactions: four flavin adenine dinucleotide-binding, one halide-binding, and four tryptophan-binding sites. Compared with previous studies, our study utilizes large-scale genomic information to propose a comprehensive set of sequence motifs that are related to the active sites and regioselectivity. We reveal that the genomic patterns and phylogenetic locations of the FDHs determine the enzymatic reactivities, which was experimentally validated in terms of the substrate scope and regioselectivity. A large portion of publicly available FDHs needs to be reevaluated to designate their correct functions. Our genomic models establish comprehensive links among genotypic information, reactivity, and regioselectivity of FDHs, thereby laying an important foundation for future discovery and classification of novel FDHs. IMPORTANCE Halogenases are playing an important role as tailoring enzymes in biosynthetic pathways. Flavin-dependent tryptophan halogenases (Trp-FDHs) are among the enzymes that have broad substrate scope and high selectivity. From bacterial genomes and metagenomes, we found highly diverse halogenase sequences by using a well-trained profile hidden Markov model built from the experimentally validated halogenases. The characterization of genotype, steady-state activity, substrate scope, and regioselectivity has established comprehensive links between the information encoded in the genomic sequence and reactivity of FDHs reported here. By constructing models for accurate and detailed sequence markers, our work should guide future discovery and classification of novel FDHs.
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13
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Liu M, Ohashi M, Hung YS, Scherlach K, Watanabe K, Hertweck C, Tang Y. AoiQ Catalyzes Geminal Dichlorination of 1,3-Diketone Natural Products. J Am Chem Soc 2021; 143:7267-7271. [PMID: 33957045 PMCID: PMC8434754 DOI: 10.1021/jacs.1c02868] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Enzymes that can perform halogenation of aliphatic carbons are of significant interest to the synthetic and biocatalysis communities. Here we describe the characterization of AoiQ, a single-component flavin-dependent halogenase (FDH) that catalyzes gem-dichlorination of 1,3-diketone substrates in the biosynthesis of dichlorodiaporthin. AoiQ represents the first biochemically reconstituted FDH that can halogenate an enolizable sp3-hybridized carbon atom.
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Affiliation(s)
- Mengting Liu
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, California 90095, USA
- Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030
| | - Masao Ohashi
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, California 90095, USA
| | - Yiu-Sun Hung
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, California 90095, USA
| | - Kirstin Scherlach
- Leibniz Institute for Natural Product Research and Infection Biology – HKI, 07745 Jena, Germany
| | - Kenji Watanabe
- Department of Pharmaceutical Sciences, University of Shizuoka, Shizuoka 422-8526, Japan
| | - Christian Hertweck
- Leibniz Institute for Natural Product Research and Infection Biology – HKI, 07745 Jena, Germany
- Faculty of Biological Sciences, Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Yi Tang
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, California 90095, USA
- Department of Chemistry and Biochemistry University of California, Los Angeles, California 90095, USA
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14
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Two Novel, Flavin-Dependent Halogenases from the Bacterial Consortia of Botryococcus braunii Catalyze Mono- and Dibromination. Catalysts 2021. [DOI: 10.3390/catal11040485] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Halogen substituents often lead to a profound effect on the biological activity of organic compounds. Flavin-dependent halogenases offer the possibility of regioselective halogenation at non-activated carbon atoms, while employing only halide salts and molecular oxygen. However, low enzyme activity, instability, and narrow substrate scope compromise the use of enzymatic halogenation as an economical and environmentally friendly process. To overcome these drawbacks, it is of tremendous interest to identify novel halogenases with high enzymatic activity and novel substrate scopes. Previously, Neubauer et al. developed a new hidden Markov model (pHMM) based on the PFAM tryptophan halogenase model, and identified 254 complete and partial putative flavin-dependent halogenase genes in eleven metagenomic data sets. In the present study, the pHMM was used to screen the bacterial associates of the Botryococcus braunii consortia (PRJEB21978), leading to the identification of several putative, flavin-dependent halogenase genes. Two of these new halogenase genes were found in one gene cluster of the Botryococcus braunii symbiont Sphingomonas sp. In vitro activity tests revealed that both heterologously expressed enzymes are active flavin-dependent halogenases able to halogenate indole and indole derivatives, as well as phenol derivatives, while preferring bromination over chlorination. Interestingly, SpH1 catalyses only monohalogenation, while SpH2 can catalyse both mono- and dihalogenation for some substrates.
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Halogenases: structures and functions. Curr Opin Struct Biol 2020; 65:51-60. [DOI: 10.1016/j.sbi.2020.05.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 05/13/2020] [Accepted: 05/17/2020] [Indexed: 11/23/2022]
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Menon BRK, Richmond D, Menon N. Halogenases for biosynthetic pathway engineering: Toward new routes to naturals and non-naturals. CATALYSIS REVIEWS-SCIENCE AND ENGINEERING 2020. [DOI: 10.1080/01614940.2020.1823788] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Binuraj R. K. Menon
- Warwick Integrative Synthetic Biology Centre, School of Life Sciences, University of Warwick, Coventry, UK
| | - Daniel Richmond
- Warwick Integrative Synthetic Biology Centre, School of Life Sciences, University of Warwick, Coventry, UK
| | - Navya Menon
- Warwick Integrative Synthetic Biology Centre, School of Life Sciences, University of Warwick, Coventry, UK
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Widmann C, Ismail M, Sewald N, Niemann HH. Structure of apo flavin-dependent halogenase Xcc4156 hints at a reason for cofactor-soaking difficulties. Acta Crystallogr D Struct Biol 2020; 76:687-697. [PMID: 32627741 PMCID: PMC7336383 DOI: 10.1107/s2059798320007731] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 06/05/2020] [Indexed: 01/18/2023] Open
Abstract
Flavin-dependent halogenases regioselectively introduce halide substituents into electron-rich substrates under mild reaction conditions. For the enzyme Xcc4156 from Xanthomonas campestris, the structure of a complex with the cofactor flavin adenine dinucleotide (FAD) and a bromide ion would be of particular interest as this enzyme exclusively brominates model substrates in vitro. Apo Xcc4156 crystals diffracted to 1.6 Å resolution. The structure revealed an open substrate-binding site lacking the loop regions that close off the active site and contribute to substrate binding in tryptophan halogenases. Therefore, Xcc4156 might accept larger substrates, possibly even peptides. Soaking of apo Xcc4156 crystals with FAD led to crumbling of the intergrown crystals. Around half of the crystals soaked with FAD did not diffract, while in the others there was no electron density for FAD. The FAD-binding loop, which changes its conformation between the apo and the FAD-bound form in related enzymes, is involved in a crystal contact in the apo Xcc4156 crystals. The conformational change that is predicted to occur upon FAD binding would disrupt this crystal contact, providing a likely explanation for the destruction of the apo crystals in the presence of FAD. Soaking with only bromide did not result in bromide bound to the catalytic halide-binding site. Simultaneous soaking with FAD and bromide damaged the crystals more severely than soaking with only FAD. Together, these latter two observations suggest that FAD and bromide bind to Xcc4156 with positive cooperativity. Thus, apo Xcc4156 crystals provide functional insight into FAD and bromide binding, even though neither the cofactor nor the halide is visible in the structure.
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Affiliation(s)
- Christiane Widmann
- Structural Biochemistry (BCIV), Department of Chemistry, Bielefeld University, Universitaetsstrasse 25, 33615 Bielefeld, Germany
| | - Mohamed Ismail
- Organic and Bioorganic Chemistry (OC III), Department of Chemistry, Bielefeld University, Universitaetsstrasse 25, 33615 Bielefeld, Germany
| | - Norbert Sewald
- Organic and Bioorganic Chemistry (OC III), Department of Chemistry, Bielefeld University, Universitaetsstrasse 25, 33615 Bielefeld, Germany
| | - Hartmut H. Niemann
- Structural Biochemistry (BCIV), Department of Chemistry, Bielefeld University, Universitaetsstrasse 25, 33615 Bielefeld, Germany
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Waheed SO, Ramanan R, Chaturvedi SS, Ainsley J, Evison M, Ames JM, Schofield CJ, Christov CZ, Karabencheva-Christova TG. Conformational flexibility influences structure-function relationships in nucleic acid N-methyl demethylases. Org Biomol Chem 2019; 17:2223-2231. [PMID: 30720838 DOI: 10.1039/c9ob00162j] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
N-Methylation of DNA/RNA bases can be regulatory or damaging and is linked to diseases including cancer and genetic disorders. Bacterial AlkB and human FTO are DNA/RNA demethylases belonging to the Fe(ii) and 2-oxoglutarate oxygenase superfamily. Modelling studies reveal conformational dynamics influence structure-function relationships of AlkB and FTO, e.g. why 1-methyladenine is a better substrate for AlkB than 6-methyladenine. Simulations show that the flexibility of the double stranded DNA substrate in AlkB influences correlated motions, including between the core jelly-roll fold and an active site loop involved in substrate binding. The FTO N- and C-terminal domains move in respect to one another in a manner likely important for substrate binding. Substitutions, including clinically observed ones, influencing catalysis contribute to the network of correlated motions in AlkB and FTO. Overall, the calculations highlight the importance of the overall protein environment and its flexibility to the geometry of the reactant complexes.
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Affiliation(s)
- Sodiq O Waheed
- Department of Chemistry, Michigan Technological University, Houghton, Michigan 49931, USA.
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Ainsley J, Lodola A, Mulholland AJ, Christov CZ, Karabencheva-Christova TG. Combined Quantum Mechanics and Molecular Mechanics Studies of Enzymatic Reaction Mechanisms. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2018; 113:1-32. [PMID: 30149903 DOI: 10.1016/bs.apcsb.2018.07.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The combined quantum mechanics/molecular mechanics (QM/MM) methods have become a valuable tool in computational biochemistry and received versatile applications for studying the reaction mechanisms of enzymes. The approach combines the calculations of the electronic structure of the active site by QM, with modeling of the protein environment using MM force field, which allows the long-range electrostatics and steric effects on the enzyme reactivity to be accounted for. In this review, we review some key theoretical and computational aspects of the method and we also present some applications to particular enzymatic reactions such as tryptophan-7-halogenase, cyclooxygenase-1, and the epidermal growth factor receptor.
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Affiliation(s)
- Jon Ainsley
- Department of Applied Sciences, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom
| | | | - Adrian J Mulholland
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol, United Kingdom
| | - Christo Z Christov
- Department of Chemistry, Michigan Technological University, Houghton, MI, United States.
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