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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Avalon N, Reis MA, Thornburg CC, Williamson RT, Petras D, Aron AT, Neuhaus GF, Al-Hindy M, Mitrevska J, Ferreira L, Morais J, El Abiead Y, Glukhov E, Alexander KL, Vulpanovici FA, Bertin MJ, Whitner S, Choi H, Spengler G, Blinov K, Almohammadi AM, Shaala LA, Kew WR, Paša-Tolić L, Youssef DTA, Dorrestein PC, Vasconcelos V, Gerwick L, McPhail KL, Gerwick WH. Leptochelins A-C, Cytotoxic Metallophores Produced by Geographically Dispersed Leptothoe Strains of Marine Cyanobacteria. J Am Chem Soc 2024; 146:18626-18638. [PMID: 38918178 PMCID: PMC11240249 DOI: 10.1021/jacs.4c05399] [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] [Received: 04/19/2024] [Revised: 06/10/2024] [Accepted: 06/11/2024] [Indexed: 06/27/2024]
Abstract
Metals are important cofactors in the metabolic processes of cyanobacteria, including photosynthesis, cellular respiration, DNA replication, and the biosynthesis of primary and secondary metabolites. In adaptation to the marine environment, cyanobacteria use metallophores to acquire trace metals when necessary as well as to reduce potential toxicity from excessive metal concentrations. Leptochelins A-C were identified as structurally novel metallophores from three geographically dispersed cyanobacteria of the genus Leptothoe. Determination of the complex structures of these metabolites presented numerous challenges, but they were ultimately solved using integrated data from NMR, mass spectrometry and deductions from the biosynthetic gene cluster. The leptochelins are comprised of halogenated linear NRPS-PKS hybrid products with multiple heterocycles that have potential for hexadentate and tetradentate coordination with metal ions. The genomes of the three leptochelin producers were sequenced, and retrobiosynthetic analysis revealed one candidate biosynthetic gene cluster (BGC) consistent with the structure of leptochelin. The putative BGC is highly homologous in all three Leptothoe strains, and all possess genetic signatures associated with metallophores. Postcolumn infusion of metals using an LC-MS metabolomics workflow performed with leptochelins A and B revealed promiscuous binding of iron, copper, cobalt, and zinc, with greatest preference for copper. Iron depletion and copper toxicity experiments support the hypothesis that leptochelin metallophores may play key ecological roles in iron acquisition and in copper detoxification. In addition, the leptochelins possess significant cytotoxicity against several cancer cell lines.
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Affiliation(s)
- Nicole
E. Avalon
- Center
for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, United States
| | - Mariana A. Reis
- CIIMAR/CIMAR,
Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Matosinhos 4450-208, Portugal
| | | | - R. Thomas Williamson
- Department
of Chemistry and Biochemistry, University
of North Carolina Wilmington, Wilmington, North Carolina 28403, United States
| | - Daniel Petras
- Skaggs
School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California 92093, United States
- Department
of Biochemistry, University of California
Riverside, Riverside, California 92507, United States
- CMFI Cluster
of Excellence, University of Tuebingen, Tuebingen 72706, Germany
| | - Allegra T. Aron
- Skaggs
School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California 92093, United States
- Department
of Chemistry and Biochemistry, University
of Denver, Denver, Colorado 80210, United States
| | - George F. Neuhaus
- College
of Pharmacy, Oregon State University, Corvallis, Oregon 97331, United States
| | - Momen Al-Hindy
- Center
for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, United States
| | - Jana Mitrevska
- Center
for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, United States
| | - Leonor Ferreira
- CIIMAR/CIMAR,
Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Matosinhos 4450-208, Portugal
| | - João Morais
- CIIMAR/CIMAR,
Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Matosinhos 4450-208, Portugal
| | - Yasin El Abiead
- Skaggs
School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California 92093, United States
| | - Evgenia Glukhov
- Center
for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, United States
| | - Kelsey L. Alexander
- Center
for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, United States
- Department
of Chemistry and Biochemistry, University
of California San Diego, La Jolla, California 92093, United States
| | | | - Matthew J. Bertin
- Center
for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, United States
| | - Syrena Whitner
- Center
for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, United States
| | - Hyukjae Choi
- College
of Pharmacy, Yeungnam University, Gyeongsan, Gyeong-buk 38541, South Korea
| | - Gabriella Spengler
- Department
of Medical Microbiology, Albert Szent-Györgyi Health Center
and Albert Szent-Györgyi Medical School, University of Szeged, Szeged 6725, Hungary
| | - Kirill Blinov
- Molecule
Apps, LLC, Corvallis, Oregon 97330, United States
| | - Ameen M. Almohammadi
- Department
of Pharmacy Practice, Faculty of Pharmacy, King Abdulaziz University, Jeddah 21589, Kingdom
of Saudi Arabia
| | - Lamiaa A. Shaala
- Suez Canal
University Hospital, Suez Canal University, Ismailia 41522, Egypt
| | - William R. Kew
- Environmental
Molecular Sciences Laboratory, Pacific Northwest
National Laboratory, Richland, Washington 99354, United States
| | - Ljiljana Paša-Tolić
- Environmental
Molecular Sciences Laboratory, Pacific Northwest
National Laboratory, Richland, Washington 99354, United States
| | - Diaa T. A. Youssef
- Department
of Natural Products, Faculty of Pharmacy, King Abdulaziz University, Jeddah 21589, Kingdom
of Saudi Arabia
- Department
of Pharmacognosy, Faculty of Pharmacy, Suez
Canal University, Ismailia 41522, Egypt
| | - Pieter C. Dorrestein
- Skaggs
School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California 92093, United States
| | - Vitor Vasconcelos
- CIIMAR/CIMAR,
Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Matosinhos 4450-208, Portugal
| | - Lena Gerwick
- Center
for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, United States
| | - Kerry L. McPhail
- College
of Pharmacy, Oregon State University, Corvallis, Oregon 97331, 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
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3
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Dai L, Li H, Dai S, Zhang Q, Zheng H, Hu Y, Guo RT, Chen CC. Structural and functional insights into the self-sufficient flavin-dependent halogenase. Int J Biol Macromol 2024; 260:129312. [PMID: 38216020 DOI: 10.1016/j.ijbiomac.2024.129312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Revised: 12/27/2023] [Accepted: 01/05/2024] [Indexed: 01/14/2024]
Abstract
Flavin-dependent halogenases (FDHs) have tremendous applications in synthetic chemistry. A single-component FDH, AetF, exhibits both halogenase and reductase activities in a continuous polypeptide chain. AetF exhibits broad substrate promiscuity and catalyzes the two-step bromination of l-tryptophan (l-Trp) to produce 5-bromotryptophan (5-Br-Trp) and 5,7-dibromo-l-tryptophan (5,7-di-Br-Trp). To elucidate the mechanism of action of AetF, we solved its crystal structure in complex with FAD, FAD/NADP+, FAD/l-Trp, and FAD/5-Br-Trp at resolutions of 1.92-2.23 Å. The obtained crystal structures depict the unprecedented topology of single-component FDH. Structural analysis revealed that the substrate flexibility and dibromination capability of AetF could be attributed to its spacious substrate-binding pocket. In addition, highly-regulated interaction networks between the substrate-recognizing residues and 5-Br-Trp are crucial for the dibromination activity of AetF. Several Ala variants underwent monobromination with >98 % C5-regioselectivity toward l-Trp. These results reveal the catalytic mechanism of single-component FDH for the first time and contribute to efficient FDH protein engineering for biocatalytic halogenation.
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Affiliation(s)
- Longhai Dai
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Hongshan Laboratory, Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan 430062, PR China
| | - Hao Li
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Hongshan Laboratory, Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan 430062, PR China
| | - Si Dai
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Hongshan Laboratory, Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan 430062, PR China
| | - Qishan Zhang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Hongshan Laboratory, Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan 430062, PR China
| | - Haibin Zheng
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Hongshan Laboratory, Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan 430062, PR China
| | - Yumei Hu
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Hongshan Laboratory, Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan 430062, PR China
| | - Rey-Ting Guo
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Hongshan Laboratory, Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan 430062, PR China; Department of Immunology and Pathogen Biology, School of Basic Medical Sciences, Hangzhou Normal University, Hangzhou 311121, PR China.
| | - Chun-Chi Chen
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Hongshan Laboratory, Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan 430062, PR China; Department of Immunology and Pathogen Biology, School of Basic Medical Sciences, Hangzhou Normal University, Hangzhou 311121, PR China.
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4
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Yu K, Zhang K, Jakob RP, Maier T, Ward TR. An artificial nickel chlorinase based on the biotin-streptavidin technology. Chem Commun (Camb) 2024; 60:1944-1947. [PMID: 38277163 PMCID: PMC10863421 DOI: 10.1039/d3cc05847f] [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] [Received: 12/01/2023] [Accepted: 01/17/2024] [Indexed: 01/27/2024]
Abstract
Herein, we report on an artificial nickel chlorinase (ANCase) resulting from anchoring a biotinylated nickel-based cofactor within streptavidin (Sav). The resulting ANCase was efficient for the chlorination of diverse C(sp3)-H bonds. Guided by the X-ray analysis of the ANCase, the activity of the artificial chlorinase could be significantly improved. This approach opens interesting perspectives for late-stage functionalization of organic intermediates as it complements biocatalytic chlorination strategies.
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Affiliation(s)
- Kun Yu
- Department of Chemistry, University of Basel, Mattenstrasse 22, Basel, CH-4058, Switzerland.
| | - Kailin Zhang
- Department of Chemistry, University of Basel, Mattenstrasse 22, Basel, CH-4058, Switzerland.
| | - Roman P Jakob
- Biozentrum, University of Basel, Spitalstrasse 41, Basel, CH-4056, Switzerland
| | - Timm Maier
- Biozentrum, University of Basel, Spitalstrasse 41, Basel, CH-4056, Switzerland
| | - Thomas R Ward
- Department of Chemistry, University of Basel, Mattenstrasse 22, Basel, CH-4058, Switzerland.
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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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Abstract
The ability to site-selectively modify equivalent functional groups in a molecule has the potential to streamline syntheses and increase product yields by lowering step counts. Enzymes catalyze site-selective transformations throughout primary and secondary metabolism, but leveraging this capability for non-native substrates and reactions requires a detailed understanding of the potential and limitations of enzyme catalysis and how these bounds can be extended by protein engineering. In this review, we discuss representative examples of site-selective enzyme catalysis involving functional group manipulation and C-H bond functionalization. We include illustrative examples of native catalysis, but our focus is on cases involving non-native substrates and reactions often using engineered enzymes. We then discuss the use of these enzymes for chemoenzymatic transformations and target-oriented synthesis and conclude with a survey of tools and techniques that could expand the scope of non-native site-selective enzyme catalysis.
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Affiliation(s)
- Dibyendu Mondal
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Harrison M Snodgrass
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Christian A Gomez
- 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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Peh G, Gunawan GA, Tay T, Tiong E, Tan LL, Jiang S, Goh YL, Ye S, Wong J, Brown CJ, Zhao H, Ang EL, Wong FT, Lim YH. Further Characterization of Fungal Halogenase RadH and Its Homologs. Biomolecules 2023; 13:1081. [PMID: 37509117 PMCID: PMC10377541 DOI: 10.3390/biom13071081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 06/27/2023] [Accepted: 06/29/2023] [Indexed: 07/30/2023] Open
Abstract
RadH is one of the flavin-dependent halogenases that has previously exhibited promising catalytic activity towards hydroxycoumarin, hydroxyisoquinoline, and phenolic derivatives. Here, we evaluated new functional homologs of RadH and expanded its specificities for the halogenation of non-tryptophan-derived, heterocyclic scaffolds. Our investigation revealed that RadH could effectively halogenate hydroxyquinoline and hydroxybenzothiophene. Assay optimization studies revealed the need to balance the various co-factor concentrations and where a GDHi co-factor recycling system most significantly improves the conversion and efficiency of the reaction. A crystal structure of RadH was also obtained with a resolution of 2.4 Å, and docking studies were conducted to pinpoint the binding and catalytic sites for substrates.
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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), 8 Biomedical Grove, Neuros #07-01, Singapore 138665, Singapore; (G.P.); (G.A.G.); (Y.L.G.); (S.Y.); (J.W.)
| | - Gregory A. Gunawan
- Institute of Sustainability for Chemicals, Energy and Environment (ISCE2), Agency for Science, Technology and Research (A*STAR), 8 Biomedical Grove, Neuros #07-01, Singapore 138665, Singapore; (G.P.); (G.A.G.); (Y.L.G.); (S.Y.); (J.W.)
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), 61 Biopolis Dr, Proteos #07-01, Singapore 138673, Singapore; (E.T.); (L.L.T.)
| | - Terence Tay
- Singapore Institute of Food and Biotechnology Innovation (SIFBI), Agency for Science, Technology and Research (A*STAR), 31 Biopolis Way, Nanos #01-02, Singapore 138669, Singapore; (T.T.); (H.Z.)
| | - Elaine Tiong
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), 61 Biopolis Dr, Proteos #07-01, Singapore 138673, Singapore; (E.T.); (L.L.T.)
| | - Lee Ling Tan
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), 61 Biopolis Dr, Proteos #07-01, Singapore 138673, Singapore; (E.T.); (L.L.T.)
| | - Shimin Jiang
- Disease Intervention Technology Laboratory, Institute of Molecular and Cellular Biology, Agency for Science, Technology and Research (A*STAR), 8A Biomedical Grove, Neuros/Immunos #06-04/05, Singapore 138648, Singapore; (S.J.); (C.J.B.)
| | - Yi Ling Goh
- Institute of Sustainability for Chemicals, Energy and Environment (ISCE2), Agency for Science, Technology and Research (A*STAR), 8 Biomedical Grove, Neuros #07-01, Singapore 138665, Singapore; (G.P.); (G.A.G.); (Y.L.G.); (S.Y.); (J.W.)
| | - Suming Ye
- Institute of Sustainability for Chemicals, Energy and Environment (ISCE2), Agency for Science, Technology and Research (A*STAR), 8 Biomedical Grove, Neuros #07-01, Singapore 138665, Singapore; (G.P.); (G.A.G.); (Y.L.G.); (S.Y.); (J.W.)
| | - Joel Wong
- Institute of Sustainability for Chemicals, Energy and Environment (ISCE2), Agency for Science, Technology and Research (A*STAR), 8 Biomedical Grove, Neuros #07-01, Singapore 138665, Singapore; (G.P.); (G.A.G.); (Y.L.G.); (S.Y.); (J.W.)
| | - Christopher J. Brown
- Disease Intervention Technology Laboratory, Institute of Molecular and Cellular Biology, Agency for Science, Technology and Research (A*STAR), 8A Biomedical Grove, Neuros/Immunos #06-04/05, Singapore 138648, Singapore; (S.J.); (C.J.B.)
| | - Huimin Zhao
- Singapore Institute of Food and Biotechnology Innovation (SIFBI), Agency for Science, Technology and Research (A*STAR), 31 Biopolis Way, Nanos #01-02, Singapore 138669, Singapore; (T.T.); (H.Z.)
- Department of Chemical and Biomolecular Engineering, Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Ee Lui Ang
- Singapore Institute of Food and Biotechnology Innovation (SIFBI), Agency for Science, Technology and Research (A*STAR), 31 Biopolis Way, Nanos #01-02, Singapore 138669, Singapore; (T.T.); (H.Z.)
- Synthetic Biology Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Drive, Singapore 117597, Singapore
| | - Fong Tian Wong
- Institute of Sustainability for Chemicals, Energy and Environment (ISCE2), Agency for Science, Technology and Research (A*STAR), 8 Biomedical Grove, Neuros #07-01, Singapore 138665, Singapore; (G.P.); (G.A.G.); (Y.L.G.); (S.Y.); (J.W.)
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), 61 Biopolis Dr, Proteos #07-01, Singapore 138673, Singapore; (E.T.); (L.L.T.)
| | - Yee Hwee Lim
- Institute of Sustainability for Chemicals, Energy and Environment (ISCE2), Agency for Science, Technology and Research (A*STAR), 8 Biomedical Grove, Neuros #07-01, Singapore 138665, Singapore; (G.P.); (G.A.G.); (Y.L.G.); (S.Y.); (J.W.)
- Synthetic Biology Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Drive, Singapore 117597, Singapore
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8
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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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9
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Combining OSMAC, metabolomic and genomic methods for the production and annotation of halogenated azaphilones and ilicicolins in termite symbiotic fungi. Sci Rep 2022; 12:17310. [PMID: 36243836 PMCID: PMC9569342 DOI: 10.1038/s41598-022-22256-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 10/12/2022] [Indexed: 01/10/2023] Open
Abstract
We gathered a collection of termite mutualistic strains from French Guiana to explore the metabolites of symbiotic microorganisms. Molecular networks reconstructed from a metabolomic analysis using LC-ESI-MS/MS methodology led us to identify two families of chlorinated polyketides, i.e., azaphilones from Penicillium sclerotiorum and ilicicolins from Neonectria discophora. To define the biosynthetic pathways related to these two types of scaffolds, we used a whole genome sequencing approach followed by hybrid assembly from short and long reads. We found two biosynthetic gene clusters, including two FAD-dependent halogenases. To exploit the enzymatic promiscuity of the two identified FAD halogenases, we sought to biosynthesize novel halogenated metabolites. An OSMAC strategy was used and resulted in the production of brominated analogs of ilicicolins and azaphilones as well as iodinated analogs of azaphilones.
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10
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Genetic and Biochemical Characterization of Halogenation and Drug Transportation Genes Encoded in the Albofungin Biosynthetic Gene Cluster. Appl Environ Microbiol 2022; 88:e0080622. [PMID: 36000868 PMCID: PMC9469721 DOI: 10.1128/aem.00806-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Albofungin, a hexacyclic aromatic natural product, exhibits broad-spectrum antimicrobial activity. Its biosynthesis, regulation, and resistance remain elusive. Here, we report the albofungin (abf) biosynthetic gene cluster (BGC) from its producing strain Streptomyces tumemacerans JCM5050. The nascent abf BGC encodes 70 putative genes, including regulators, transporters, type II polyketide synthases (PKSs), oxidoreductase, and tailoring enzymes. To validate the intactness and functionality of the BGC, we developed an Escherichia coli-Streptomyces shuttle bacterial artificial chromosome system, whereby the abf BGC was integrated into the genome of a nonproducing host via heterologous conjugation, wherefrom albofungin can be produced, confirming that the BGC is in effect. We then delimited the boundaries of the BGC by means of in vitro CRISPR-Cas9 DNA editing, concluding a minimal but essential 60-kb abf BGC ranging from orfL to abf58. The orfA gene encoding a reduced flavin adenine dinucleotide (FADH2)-dependent halogenase was examined and is capable of transforming albofungin to halogen-substituted congeners in vivo and in vitro. The orfL gene encoding a transporter was examined in vivo. The presence/absence of orfA or orfL demonstrated that the MIC of albofungin is subject to alteration when an extracellular polysaccharide intercellular adhesin was formed. Despite that halogenation of albofungin somewhat increases binding affinity to transglycosylase (TGase), albofungin with/without a halogen substituent manifests similar in vitro antimicrobial activity. Halogenation, however, limits overall dissemination and effectiveness given a high secretion rate, weak membrane permeability, and high hydrophobicity of the resulting products, whereby the functions of orfA and orfL are correlated with drug detoxification/resistance for the first time. IMPORTANCE Albofungin, a natural product produced from Streptomycetes, exhibits bioactivities against bacteria, fungi, and tumor cells. The biosynthetic logic, regulations, and resistance of albofungin remain yet to be addressed. Herein, the minimal albofungin (abf) biosynthetic gene cluster (BGC) from the producing strain Streptomyces tumemacerans JCM5050 was precisely delimited using the Escherichia coli-Streptomyces shuttle bacterial artificial chromosome system, of which the gene essentiality was established in vivo and in vitro. Next, we characterized two genes orfA and orfL encoded in the abf BGC, which act as a reduced flavin adenine dinucleotide (FADH2)-dependent halogenase and an albofungin-congeners transporter, respectively. While each testing microorganism exhibited different sensitivities to albofungins, the MIC values of albofungins against testing strains with/without orfA and/or orfL were subject to considerable changes. Halogen-substituted albofungins mediated by OrfA manifested overall compromised dissemination and effectiveness, revealing for the first time that two functionally distinct proteins OrfA and OrfL are associated together, exerting a novel “belt and braces” mechanism in antimicrobial detoxification/resistance.
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11
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Yin L. Crystal structure determination of the halogenase CtcP from Streptomyces aureofaciens. Acta Crystallogr F Struct Biol Commun 2022; 78:270-275. [PMID: 35787554 PMCID: PMC9254895 DOI: 10.1107/s2053230x22006586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 06/24/2022] [Indexed: 11/10/2022] Open
Abstract
Chlortetracycline (CTC), a derivative of tetracycline (TC), is a broadly used antibiotic that inhibits the synthesis of bacterial proteins by competing with the A-site tRNA on ribosomes. A recent study showed that during the biosynthesis of CTC in Streptomyces aureofaciens, the halogenase CtcP catalyzes the final chlorination reaction and transforms TC into CTC. However, the structure of this fundamental enzyme is still lacking. Here, selenomethionine-derivatized CtcP from S. aureofaciens was overexpressed and purified and its structure was determined at 2.7 Å resolution. The structure of CtcP reveals the conserved monooxygenase domain shared by all flavin-dependent halogenases and a unique C-terminal domain. Although FAD was not observed in the structure, the monooxygenase domain has a conserved FAD-binding pocket and active center. The C-terminal domain displays an α-helical bundle fold, which could contribute to substrate specificity. This work provides a molecular basis for enzyme engineering to improve the industrial production of CTC.
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Affiliation(s)
- Lijuan Yin
- Department of Pathology, Changhai Hospital, The Second Military Medical University, 168 Changhai Road, Shanghai 200433, People’s Republic of China
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12
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Li RN, Chen SL. Mechanism for the Halogenation and Azidation of Lysine Catalyzed by Non-heme Iron BesD Enzyme. Chem Asian J 2022; 17:e202200438. [PMID: 35763338 DOI: 10.1002/asia.202200438] [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: 04/26/2022] [Revised: 06/23/2022] [Indexed: 11/09/2022]
Abstract
Selective halogenation is important in synthetic chemistry. BesD, a new member of the non-heme Fe(II)/α-ketoglutarate (αKG)-dependent halogenase family, can activate the sp3 C-H bond and halogenate lysine, in particular without a carrier protein. Using the density functional calculations, a chlorination mechanism in BesD has been proposed, mainly including the formation of Cl-Fe(IV)=O through the αKG decarboxylation, the isomerization of Cl-Fe(IV)=O, the substrate hydrogen abstraction by Fe(IV)=O, and the rebound of chloro to the substrate carbon radical. The hydrogen abstraction is rate-limiting. The isomerization of Cl-Fe(IV)=O is essential for the hydrogen abstraction and the chiral selectivity. The BesD-catalyzed bromination and azidation of lysine adopt the same mechanism as the chlorination. The hardly-changed overall barriers indicate that the introduced ligands (X) do not affect the reaction rate significantly, implying that the X-introduced reactions catalyzed by BesD may be extended to other X anions.
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Affiliation(s)
- Rui-Ning Li
- Beijing Institute of Technology, School of Chemistry and Chemical Engineering, 100081, Beijing, CHINA
| | - Shi-Lu Chen
- Beijing Institute of Technology, School of Chemistry and Chemical Engineering, 5th, ZhongGuanCun South Street, 100081, Beijing, CHINA
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13
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Yi D, Niroula D, Gutekunst WR, Loper JE, Yan Q, Agarwal V. A Nonfunctional Halogenase Masquerades as an Aromatizing Dehydratase in Biosynthesis of Pyrrolic Polyketides by Type I Polyketide Synthases. ACS Chem Biol 2022; 17:1351-1356. [PMID: 35675261 DOI: 10.1021/acschembio.2c00288] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The bacterial modular type I polyketide synthases (PKSs) typically furnish nonaromatic lactone and lactam natural products. Here, by the complete in vitro enzymatic production of the polyketide antibiotic pyoluteorin, we describe the biosynthetic mechanism for the construction of an aromatic resorcylic ring by a type I PKS. We find that the pyoluteorin type I PKS does not produce an aromatic product, rather furnishing an alicyclic dihydrophloroglucinol that is later enzymatically dehydrated and aromatized. The aromatizing dehydratase is encoded in the pyoluteorin biosynthetic gene cluster (BGC), and its presence is conserved in other BGCs encoding production of pyrrolic polyketides. Sequence similarity and mutational analysis demonstrates that the overall structure and position of the active site for the aromatizing dehydratase is shared with flavin-dependent halogenases albeit with a loss in ability to perform redox catalysis. We demonstrate that the post-PKS dehydrative aromatization is critical for the antibiotic activity of pyoluteorin.
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Affiliation(s)
- Dongqi Yi
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Dhirendra Niroula
- Department of Plant Sciences and Plant Pathology, Montana State University, Bozeman, Montana 59717, United States
| | - Will R Gutekunst
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.,School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Joyce E Loper
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331, United States.,USDA-Agricultural Research Service, Corvallis, Oregon 97330, United States
| | - Qing Yan
- Department of Plant Sciences and Plant Pathology, Montana State University, Bozeman, Montana 59717, United States.,Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331, United States
| | - Vinayak Agarwal
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.,School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
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14
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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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15
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16
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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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17
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Abt K, Castelo-Branco R, Leão PN. Biosynthesis of Chlorinated Lactylates in Sphaerospermopsis sp. LEGE 00249. JOURNAL OF NATURAL PRODUCTS 2021; 84:278-286. [PMID: 33444023 PMCID: PMC7923214 DOI: 10.1021/acs.jnatprod.0c00950] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Indexed: 05/14/2023]
Abstract
Lactylates are an important group of molecules in the food and cosmetic industries. A series of natural halogenated 1-lactylates, chlorosphaerolactylates (1-4), were recently reported from Sphaerospermopsis sp. LEGE 00249. Here, we identify the cly biosynthetic gene cluster, containing all the necessary functionalities for the biosynthesis of the natural lactylates, based on in silico analyses. Using a combination of stable isotope incorporation experiments and bioinformatic analysis, we propose that dodecanoic acid and pyruvate are the key building blocks in the biosynthesis of 1-4. We additionally report minor analogues of these molecules with varying alkyl chains. This work paves the way to accessing industrially relevant lactylates through pathway engineering.
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Affiliation(s)
- Kathleen Abt
- Interdisciplinary
Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, Avenida General Norton de Matos, s/n, 4450-208 Matosinhos, Portugal
- Institute
of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal
| | - Raquel Castelo-Branco
- Interdisciplinary
Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, Avenida General Norton de Matos, s/n, 4450-208 Matosinhos, Portugal
| | - Pedro N. Leão
- Interdisciplinary
Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, Avenida General Norton de Matos, s/n, 4450-208 Matosinhos, Portugal
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18
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Scheide MR, Nicoleti CR, Martins GM, Braga AL. Electrohalogenation of organic compounds. Org Biomol Chem 2021; 19:2578-2602. [DOI: 10.1039/d0ob02459g] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this review we target sp, sp2 and sp3 carbon fluorination, chlorination, bromination and iodination reactions using electrolysis as a redox medium. Mechanistic insights and substrate reactivity are also discussed.
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Affiliation(s)
- Marcos R. Scheide
- Departamento de Química
- Universidade Federal de Santa Catarina – UFSC
- Florianópolis
- Brazil
| | - Celso R. Nicoleti
- Departamento de Química
- Universidade Federal de Santa Catarina – UFSC
- Florianópolis
- Brazil
| | - Guilherme M. Martins
- Departamento de Química
- Universidade Federal de Santa Catarina – UFSC
- Florianópolis
- Brazil
| | - Antonio L. Braga
- Departamento de Química
- Universidade Federal de Santa Catarina – UFSC
- Florianópolis
- Brazil
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19
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Phintha A, Prakinee K, Jaruwat A, Lawan N, Visitsatthawong S, Kantiwiriyawanitch C, Songsungthong W, Trisrivirat D, Chenprakhon P, Mulholland A, van Pée KH, Chitnumsub P, Chaiyen P. Dissecting the low catalytic capability of flavin-dependent halogenases. J Biol Chem 2021; 296:100068. [PMID: 33465708 PMCID: PMC7948982 DOI: 10.1074/jbc.ra120.016004] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 11/11/2020] [Accepted: 11/13/2020] [Indexed: 12/11/2022] Open
Abstract
Although flavin-dependent halogenases (FDHs) are attractive biocatalysts, their practical applications are limited because of their low catalytic efficiency. Here, we investigated the reaction mechanisms and structures of tryptophan 6-halogenase (Thal) from Streptomyces albogriseolus using stopped-flow, rapid-quench flow, quantum/mechanics molecular mechanics calculations, crystallography, and detection of intermediate (hypohalous acid [HOX]) liberation. We found that the key flavin intermediate, C4a-hydroperoxyflavin (C4aOOH-FAD), formed by Thal and other FDHs (tryptophan 7-halogenase [PrnA] and tryptophan 5-halogenase [PyrH]), can react with I-, Br-, and Cl- but not F- to form C4a-hydroxyflavin and HOX. Our experiments revealed that I- reacts with C4aOOH-FAD the fastest with the lowest energy barrier and have shown for the first time that a significant amount of the HOX formed leaks out as free HOX. This leakage is probably a major cause of low product coupling ratios in all FDHs. Site-saturation mutagenesis of Lys79 showed that changing Lys79 to any other amino acid resulted in an inactive enzyme. However, the levels of liberated HOX of these variants are all similar, implying that Lys79 probably does not form a chloramine or bromamine intermediate as previously proposed. Computational calculations revealed that Lys79 has an abnormally lower pKa compared with other Lys residues, implying that the catalytic Lys may act as a proton donor in catalysis. Analysis of new X-ray structures of Thal also explains why premixing of FDHs with reduced flavin adenine dinucleotide generally results in abolishment of C4aOOH-FAD formation. These findings reveal the hidden factors restricting FDHs capability which should be useful for future development of FDHs applications.
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Affiliation(s)
- Aisaraphon Phintha
- Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology, Faculty of Science, Mahidol University, Bangkok, Thailand; School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, Thailand
| | - Kridsadakorn Prakinee
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, Thailand
| | - Aritsara Jaruwat
- Biomolecular Analysis and Application Research Team, National Center for Genetic Engineering and Biotechnology, Klong Luang, Pathumthani, Thailand
| | - Narin Lawan
- Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand
| | - Surawit Visitsatthawong
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, Thailand
| | - Chadaporn Kantiwiriyawanitch
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, Thailand
| | - Warangkhana Songsungthong
- Biomolecular Analysis and Application Research Team, National Center for Genetic Engineering and Biotechnology, Klong Luang, Pathumthani, Thailand
| | - Duangthip Trisrivirat
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, Thailand
| | - Pirom Chenprakhon
- Institute for Innovative Learning, Mahidol University, Nakhon Pathom, Thailand
| | - Adrian Mulholland
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol, UK
| | - Karl-Heinz van Pée
- General Biochemistry, Faculty of Chemistry and Food Chemistry, Technical University of Dresden, Dresden, Germany
| | - Penchit Chitnumsub
- Biomolecular Analysis and Application Research Team, National Center for Genetic Engineering and Biotechnology, Klong Luang, Pathumthani, Thailand.
| | - Pimchai Chaiyen
- Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology, Faculty of Science, Mahidol University, Bangkok, Thailand; School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, Thailand.
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20
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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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21
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Flavin Adenine Dinucleotide-Dependent Halogenase XanH and Engineering of Multifunctional Fusion Halogenases. Appl Environ Microbiol 2020; 86:AEM.01225-20. [PMID: 32651204 DOI: 10.1128/aem.01225-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 07/02/2020] [Indexed: 12/19/2022] Open
Abstract
Xantholipin (compound 1), a polycyclic xanthone antibiotic, exhibited strong antibacterial activities and showed potent cytotoxicity. The biosynthetic gene cluster of compound 1 has been identified in our previous work, and the construction of xanthone nucleus has been well demonstrated. However, limited information of the halogenation involved in compound 1 biosynthesis is available. In this study, based on the genetic manipulation and biochemical assay, we characterized XanH as an indispensable flavin adenine dinucleotide (FAD)-dependent halogenase (FDH) for the biosynthesis of compound 1. XanH was found to be a bifunctional protein capable of flavin reduction and chlorination and exclusively used the NADH. However, the reduced flavin could not be fully and effectively utilized, and the presence of an extra flavin reductase (FDR) and chemical-reducing agent could promote the halogenation. XanH accepted its natural free-standing substrate with angular fused polycyclic aromatic systems. Meanwhile, it exhibited moderate halogenation activity and possessed high substrate specificity. The requirement of extra FDR for higher halogenation activity is tedious for future engineering. To facilitate efforts in engineering XanH derivative proteins, we constructed the self-sufficient FDR-XanH fusion proteins. The fusion protein E1 with comparable activities to that of XanH could be used as a good alternative for future protein engineering. Taken together, these findings reported here not only improve the understanding of polycyclic xanthones biosynthesis but also expand the substrate scope of FDH and pave the way for future engineering of biocatalysts for new active substance synthesis.IMPORTANCE Halogenation is important in medicinal chemistry and plays an essential role in the biosynthesis of active secondary metabolites. Halogenases have evolved to catalyze reactions with high efficiency and selectivity, and engineering efforts have been made to engage the selective reactivity in natural product biosynthesis. The enzymatic halogenations are an environmentally friendly approach with high regio- and stereoselectivity, which make it a potential complement to organic synthesis. FDHs constitute one of the most extensively elucidated class of halogenases; however, the inventory awaits to be expanded for biotechnology applications and for the generation of halogenated natural product analogues. In this study, XanH was found to reduce flavin and halogenated the freely diffusing natural substrate with an angular fused hexacyclic scaffold, findings which were different from those for the exclusively studied FDHs. Moreover, the FDR-XanH fusion protein E1 with comparable reactivity to that of XanH serves as a successful example of genetic fusions and sets an important stage for future protein engineering.
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22
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Liu M, Zhang Z, Liu H, Wu T, Han B. Dehydroxyalkylative halogenation of C(aryl)-C bonds of aryl alcohols. Chem Commun (Camb) 2020; 56:7120-7123. [PMID: 32458843 DOI: 10.1039/d0cc02306j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We herein report Cu mediated side-directed dehydroxyalkylative halogenation of aryl alcohols. C(aryl)-C bonds of aryl alcohols were effectively cleaved, affording the corresponding aryl chlorides, bromides and iodides in excellent yields. Aryl alcohols could serve as both aromatic electrophilic and radical synthetic equivalents during the reaction.
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Affiliation(s)
- Mingyang Liu
- Beijing National Laboratory for Molecular Science, CAS Key Laboratory of Colloid and Interface and Thermodynamics, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
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23
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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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24
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Chevrette MG, Gutiérrez-García K, Selem-Mojica N, Aguilar-Martínez C, Yañez-Olvera A, Ramos-Aboites HE, Hoskisson PA, Barona-Gómez F. Evolutionary dynamics of natural product biosynthesis in bacteria. Nat Prod Rep 2019; 37:566-599. [PMID: 31822877 DOI: 10.1039/c9np00048h] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Covering: 2008 up to 2019The forces of biochemical adaptive evolution operate at the level of genes, manifesting in complex phenotypes and the global biodiversity of proteins and metabolites. While evolutionary histories have been deciphered for some other complex traits, the origins of natural product biosynthesis largely remain a mystery. This fundamental knowledge gap is surprising given the many decades of research probing the genetic, chemical, and biophysical mechanisms of bacterial natural product biosynthesis. Recently, evolutionary thinking has begun to permeate this otherwise mechanistically dominated field. Natural products are now sometimes referred to as 'specialized' rather than 'secondary' metabolites, reinforcing the importance of their biological and ecological functions. Here, we review known evolutionary mechanisms underlying the overwhelming chemical diversity of bacterial secondary metabolism, focusing on enzyme promiscuity and the evolution of enzymatic domains that enable metabolic traits. We discuss the mechanisms that drive the assembly of natural product biosynthetic gene clusters and propose formal definitions for 'specialized' and 'secondary' metabolism. We further explore how biosynthetic gene clusters evolve to synthesize related molecular species, and in turn how the biological and ecological roles that emerge from metabolic diversity are acted on by selection. Finally, we reconcile chemical, functional, and genetic data into an evolutionary model, the dynamic chemical matrix evolutionary hypothesis, in which the relationships between chemical distance, biomolecular activity, and relative fitness shape adaptive landscapes.
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Affiliation(s)
- Marc G Chevrette
- Wisconsin Institute for Discovery, Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, USA.
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25
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Recent Advances in Flavin-Dependent Halogenase Biocatalysis: Sourcing, Engineering, and Application. Catalysts 2019. [DOI: 10.3390/catal9121030] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The introduction of a halogen atom into a small molecule can effectively modulate its properties, yielding bioactive substances of agrochemical and pharmaceutical interest. Consequently, the development of selective halogenation strategies is of high technological value. Besides chemical methodologies, enzymatic halogenations have received increased interest as they allow the selective installation of halogen atoms in molecular scaffolds of varying complexity under mild reaction conditions. Today, a comprehensive library of aromatic halogenases exists, and enzyme as well as reaction engineering approaches are being explored to broaden this enzyme family’s biocatalytic application range. In this review, we highlight recent developments in the sourcing, engineering, and application of flavin-dependent halogenases with a special focus on chemoenzymatic and coupled biosynthetic approaches.
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26
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Gkotsi DS, Ludewig H, Sharma SV, Connolly JA, Dhaliwal J, Wang Y, Unsworth WP, Taylor RJK, McLachlan MMW, Shanahan S, Naismith JH, Goss RJM. A marine viral halogenase that iodinates diverse substrates. Nat Chem 2019; 11:1091-1097. [PMID: 31611633 PMCID: PMC6875430 DOI: 10.1038/s41557-019-0349-z] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Accepted: 09/09/2019] [Indexed: 11/23/2022]
Abstract
Oceanic cyanobacteria are the most abundant oxygen-generating phototrophs on our planet, and therefore, important to life. These organisms are infected by viruses called cyanophages, recently shown to encode metabolic genes that modulate host photosynthesis, phosphorus cycling and nucleotide metabolism. Herein, we report the characterisation of a wild type flavin-dependent viral halogenase (VirX1) from a cyanophage. Notably, halogenases have been previously associated with secondary metabolism, tailoring natural products. Exploration of this viral halogenase reveals it capable of regioselective halogenation of a diverse range of substrates, with a preference for forming aryl iodide species; this has potential implications for the metabolism of the infected host. Until recently, a flavin-dependent halogenase (FDH) capable of iodination in vitro had not been reported. VirX1 is interesting from a biocatalytic perspective showing strikingly broad substrate flexibility, and a clear preference for iodination, as illustrated by kinetic analysis. These factors together render it an attractive tool for synthesis.
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Affiliation(s)
- Danai S Gkotsi
- School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, UK.,Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, UK
| | - Hannes Ludewig
- School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, UK.,Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, UK
| | - Sunil V Sharma
- School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, UK.,Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, UK
| | - Jack A Connolly
- School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, UK.,Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, UK
| | - Jagwinder Dhaliwal
- School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, UK.,Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, UK
| | - Yunpeng Wang
- School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, UK.,Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, UK
| | | | | | - Matthew M W McLachlan
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire, UK.,QEDDI, The University of Queensland, Brisbane, Queensland, Australia
| | - Stephen Shanahan
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire, UK
| | - James H Naismith
- Division of Structural Biology, Wellcome Trust Centre of Human Genomics, Oxford, UK.,Research Complex at Harwell, Rutherford Laboratory, Didcot, UK.,The Rosalind Franklin Institute, Didcot, UK
| | - Rebecca J M Goss
- School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, UK. .,Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, UK.
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