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Wilson RH, Chatterjee S, Smithwick ER, Damodaran AR, Bhagi-Damodaran A. Controllable multi-halogenation of a non-native substrate by SyrB2 iron halogenase. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.08.593161. [PMID: 38766225 PMCID: PMC11100670 DOI: 10.1101/2024.05.08.593161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Geminal, multi-halogenated functional groups are widespread in natural products and pharmaceuticals, yet no synthetic methodologies exist that enable selective multi-halogenation of unactivated C-H bonds. Biocatalysts are powerful tools for late-stage C-H functionalization, as they operate with high degrees of regio-, chemo-, and stereoselectivity. 2-oxoglutarate (2OG)-dependent non-heme iron halogenases chlorinate and brominate aliphatic C-H bonds offering a solution for achieving these challenging transformations. Here, we describe the ability of a non-heme iron halogenase, SyrB2, to controllably halogenate non-native substrate alpha-aminobutyric acid (Aba) to yield mono-chlorinated, di-chlorinated, and tri-chlorinated products. These chemoselective outcomes are achieved by controlling the loading of 2OG cofactor and SyrB2 biocatalyst. By using a ferredoxin-based biological reductant for electron transfer to the catalytic center of SyrB2, we demonstrate order-of-magnitude enhancement in the yield of tri-chlorinated product that were previously inaccessible using any single halogenase enzyme. We also apply these strategies to broaden SyrB2's reactivity scope to include multi-bromination and demonstrate chemoenzymatic conversion of the ethyl side chain in Aba to an ethylyne functional group. We show how steric hindrance induced by the successive addition of halogen atoms on Aba's C4 carbon dictates the degree of multi-halogenation by hampering C3-C4 bond rotation within SyrB2's catalytic pocket. Overall, our work showcases the synthetic potential of iron halogenases to facilitate multi-C-H functionalization chemistry.
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Affiliation(s)
- R Hunter Wilson
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN, 55455, United States
| | - Sourav Chatterjee
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN, 55455, United States
| | - Elizabeth R Smithwick
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN, 55455, United States
| | - Anoop R Damodaran
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN, 55455, United States
| | - Ambika Bhagi-Damodaran
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN, 55455, United States
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Zhou L, Awakawa T, Ushimaru R, Kanaida M, Abe I. Characterization of Aziridine-Forming α-Ketoglutarate-Dependent Oxygenase in l-Isovaline Biosynthesis. Org Lett 2024; 26:724-727. [PMID: 38227980 DOI: 10.1021/acs.orglett.3c04185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2024]
Abstract
l-Isovaline biosynthesis by TqaLFM-ti from Tolypocladium inflatum was demonstrated in vitro. The biochemical analysis of the α-ketoglutarate-dependent oxygenase TqaL-ti revealed that it produces (2S,3S)-3-ethyl-3-methylaziridine-2-carboxylic acid from l-isoleucine, thus exhibiting a stereoselectivity different from those of the reported homologues. Remarkably, a single mutation on I295 in TqaL-ti completely exchanged its stereoselectivity to produce the C-3 stereoisomer. TqaFM-ti generates d-isovaline from (2S,3R)-aziridine-2-carboxylic acid, suggesting that the stereochemistry of the TqaL product defines that of isovaline.
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Affiliation(s)
- Lu Zhou
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
- RIKEN Center for Sustainable Resource Science, 2-1, Hirosawa, Wako, Saitama 351-0198, Japan
| | - Takayoshi Awakawa
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
- RIKEN Center for Sustainable Resource Science, 2-1, Hirosawa, Wako, Saitama 351-0198, Japan
| | - Richiro Ushimaru
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Masahiro Kanaida
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Ikuro Abe
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
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Ushimaru R. Three-membered ring formation catalyzed by α-ketoglutarate-dependent nonheme iron enzymes. J Nat Med 2024; 78:21-32. [PMID: 37980694 PMCID: PMC10764440 DOI: 10.1007/s11418-023-01760-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 10/25/2023] [Indexed: 11/21/2023]
Abstract
Epoxides, aziridines, and cyclopropanes are found in various medicinal natural products, including polyketides, terpenes, peptides, and alkaloids. Many classes of biosynthetic enzymes are involved in constructing these ring structures during their biosynthesis. This review summarizes our current knowledge regarding how α-ketoglutarate-dependent nonheme iron enzymes catalyze the formation of epoxides, aziridines, and cyclopropanes in nature, with a focus on enzyme mechanisms.
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Affiliation(s)
- Richiro Ushimaru
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, 113-0033, Japan.
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, 113-8657, Japan.
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Hopiavuori A, McKinnie SMK. Algal Kainoid Synthases Exhibit Substrate-Dependent Hydroxylation and Cyclization Activities. ACS Chem Biol 2023; 18:2457-2463. [PMID: 38047879 PMCID: PMC10728896 DOI: 10.1021/acschembio.3c00596] [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: 09/26/2023] [Revised: 11/28/2023] [Accepted: 11/29/2023] [Indexed: 12/05/2023]
Abstract
FeII/α-ketoglutarate-dependent dioxygenases (Fe/αKG) make up a large enzyme family that functionalize C-H bonds on diverse organic substrates. Although Fe/αKG homologues catalyze an array of chemically useful reactions, hydroxylation typically predominates. Microalgal DabC uniquely forms a novel C-C bond to construct the bioactive pyrrolidine ring in domoic acid biosynthesis; however, we have identified that this kainoid synthase exclusively performs a stereospecific hydroxylation reaction on its cis substrate regioisomer. Mechanistic and kinetic analyses with native and alternative substrates identified a 20-fold rate increase in DabC radical cyclization over β-hydroxylation with no observable 1,5-hydrogen atom transfer. Moreover, this dual activity was conserved among macroalgal RadC1 and KabC homologues and provided insight into substrate recognition and reactivity trends. Investigation of this substrate-dependent chemistry improves our understanding of kainoid synthases and their biocatalytic application.
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Affiliation(s)
- Austin
R. Hopiavuori
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, California 95064, United States
| | - Shaun M. K. McKinnie
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, California 95064, United States
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Ushimaru R, Cha L, Shimo S, Li X, Paris JC, Mori T, Miyamoto K, Coffer L, Uchiyama M, Guo Y, Chang WC, Abe I. Mechanistic Analysis of Stereodivergent Nitroalkane Cyclopropanation Catalyzed by Nonheme Iron Enzymes. J Am Chem Soc 2023; 145:24210-24217. [PMID: 37874539 PMCID: PMC10725191 DOI: 10.1021/jacs.3c08413] [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: 10/25/2023]
Abstract
BelL and HrmJ are α-ketoglutarate-dependent nonheme iron enzymes that catalyze the oxidative cyclization of 6-nitronorleucine, resulting in the formation of two diastereomeric 3-(2-nitrocyclopropyl)alanine (Ncpa) products containing trans-cyclopropane rings with (1'R,2'R) and (1'S,2'S) configurations, respectively. Herein, we investigate the catalytic mechanism and stereodivergency of the cyclopropanases. The results suggest that the nitroalkane moiety of the substrate is first deprotonated to produce the nitronate form. Spectroscopic analyses and biochemical assays with substrates and analogues indicate that an iron(IV)-oxo species abstracts proS-H from C4 to initiate intramolecular C-C bond formation. A hydroxylation intermediate is unlikely to be involved in the cyclopropanation reaction. Additionally, a genome mining approach is employed to discover new homologues that perform the cyclopropanation of 6-nitronorleucine to generate cis-configured Ncpa products with (1'R,2'S) or (1'S,2'R) stereochemistries. Sequence and structure comparisons of these cyclopropanases enable us to determine the amino acid residues critical for controlling the stereoselectivity of cyclopropanation.
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Affiliation(s)
- Richiro Ushimaru
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo 113-8657, Japan
| | - Lide Cha
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Shotaro Shimo
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Xiaojun Li
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Jared C Paris
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Takahiro Mori
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo 113-8657, Japan
- PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
| | - Kazunori Miyamoto
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Lindsay Coffer
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Masanobu Uchiyama
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
- Research Initiative for Supra-Materials, Shinshu University, Nagano 380-8553, Japan
| | - Yisong Guo
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Wei-Chen Chang
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Ikuro Abe
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo 113-8657, Japan
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Adak S, Ye N, Calderone LA, Schäfer RJB, Lukowski AL, Pandelia ME, Drennan CL, Moore BS. Oxidative rearrangement of tryptophan to indole nitrile by a single diiron enzyme. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.03.551874. [PMID: 37577561 PMCID: PMC10418191 DOI: 10.1101/2023.08.03.551874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Nitriles are uncommon in nature and are typically constructed from oximes via the oxidative decarboxylation of amino acid substrates or from the derivatization of carboxylic acids. Here we report a third strategy of nitrile biosynthesis featuring the cyanobacterial nitrile synthase AetD. During the biosynthesis of the 'eagle-killing' neurotoxin, aetokthonotoxin, AetD converts the alanyl side chain of 5,7-dibromo-L-tryptophan to a nitrile. Employing a combination of structural, biochemical, and biophysical techniques, we characterized AetD as a non-heme diiron enzyme that belongs to the emerging Heme Oxygenase-like Diiron Oxidase and Oxygenase (HDO) superfamily. High-resolution crystal structures of AetD together with the identification of catalytically relevant products provide mechanistic insights into how AetD affords this unique transformation that we propose proceeds via an aziridine intermediate. Our work presents a new paradigm for nitrile biogenesis and portrays a substrate binding and metallocofactor assembly mechanism that may be shared among other HDO enzymes.
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Affiliation(s)
- Sanjoy Adak
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, United States
| | - Naike Ye
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 01239, United States
| | - Logan A. Calderone
- Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02453, United States
| | - Rebecca J. B. Schäfer
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, United States
| | - April L. Lukowski
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, United States
| | - Maria-Eirini Pandelia
- Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02453, United States
| | - Catherine L. Drennan
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 01239, United States
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 01239, United States
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 01239, United States
| | - Bradley S. Moore
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, United States
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California at San Diego, La Jolla, California 92093, United States
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