1
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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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2
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Ren D, Lee YH, Wang SA, Liu HW. Characterization of the Oxazinomycin Biosynthetic Pathway Revealing the Key Role of a Nonheme Iron-Dependent Mono-oxygenase. J Am Chem Soc 2022; 144:10968-10977. [PMID: 35687050 DOI: 10.1021/jacs.2c04080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Oxazinomycin is a C-nucleoside natural product with antibacterial and antitumor activities. In addition to the characteristic C-glycosidic linkage shared with other C-nucleosides, oxazinomycin also features a structurally unusual 1,3-oxazine moiety, the biosynthesis of which had previously been unknown. Herein, complete in vitro reconstitution of the oxazinomycin biosynthetic pathway is described. Construction of the C-glycosidic bond between ribose 5-phosphate and an oxygen-labile pyridine heterocycle is catalyzed by the C-glycosidase OzmB and involves formation of an enzyme-substrate Schiff base intermediate. The DUF4243 family protein OzmD is shown to catalyze oxygen insertion and rearrangement of the pyridine C-nucleoside intermediate to generate the 1,3-oxazine moiety along with the elimination of cyanide. Spectroscopic analysis and mutagenesis studies indicate that OzmD is a novel nonheme iron-dependent enzyme in which the catalytic iron center is likely coordinated by four histidine residues. These results provide the first example of 1,3-oxazine biosynthesis catalyzed by an unprecedented iron-dependent mono-oxygenase.
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Affiliation(s)
- Daan Ren
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Yu-Hsuan Lee
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Shao-An Wang
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Hung-Wen Liu
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States.,Division of Chemical Biology & Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712, United States
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3
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L-tyrosine-bound ThiH structure reveals C-C bond break differences within radical SAM aromatic amino acid lyases. Nat Commun 2022; 13:2284. [PMID: 35477710 PMCID: PMC9046217 DOI: 10.1038/s41467-022-29980-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 04/05/2022] [Indexed: 11/08/2022] Open
Abstract
2-iminoacetate synthase ThiH is a radical S-adenosyl-L-methionine (SAM) L-tyrosine lyase and catalyzes the L-tyrosine Cα-Cβ bond break to produce dehydroglycine and p-cresol while the radical SAM L-tryptophan lyase NosL cleaves the L-tryptophan Cα-C bond to produce 3-methylindole-2-carboxylic acid. It has been difficult to understand the features that condition one C-C bond break over the other one because the two enzymes display significant primary structure similarities and presumably similar substrate-binding modes. Here, we report the crystal structure of L-tyrosine bound ThiH from Thermosinus carboxydivorans revealing an unusual protonation state of L-tyrosine upon binding. Structural comparison of ThiH with NosL and computational studies of the respective reactions they catalyze show that substrate activation is eased by tunneling effect and that subtle structural changes between the two enzymes affect, in particular, the hydrogen-atom abstraction by the 5´-deoxyadenosyl radical species, driving the difference in reaction specificity.
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4
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Brimberry MA, Mathew L, Lanzilotta W. Making and breaking carbon-carbon bonds in class C radical SAM methyltransferases. J Inorg Biochem 2022; 226:111636. [PMID: 34717253 PMCID: PMC8667262 DOI: 10.1016/j.jinorgbio.2021.111636] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 10/07/2021] [Accepted: 10/12/2021] [Indexed: 01/03/2023]
Abstract
Radical S-adenosylmethionine (SAM) enzymes utilize a [4Fe-4S]1+ cluster and S-(5'-adenosyl)-L-methionine, (SAM), to generate a highly reactive radical and catalyze what is arguably the most diverse set of chemical reactions for any known enzyme family. At the heart of radical SAM catalysis is a highly reactive 5'-deoxyadenosyl radical intermediate (5'-dAdo●) generated through reductive cleavage of SAM or nucleophilic attack of the unique iron of the [4Fe-4S]+ cluster on the 5' C atom of SAM. Spectroscopic studies reveal the 5'-dAdo● is transiently captured in an FeC bond (Ω species). In the presence of substrate, homolytic scission of this metal‑carbon bond regenerates the 5'-dAdo● for catalytic hydrogen atom abstraction. While reminiscent of the adenosylcobalamin mechanism, radical SAM enzymes appear to encompass greater catalytic diversity. In this review we discuss recent developments for radical SAM enzymes involved in unique chemical rearrangements, specifically regarding class C radical SAM methyltransferases. Illuminating this class of radical SAM enzymes is especially significant as many enzymes have been shown to play critical roles in pathogenesis and the synthesis of novel antimicrobial compounds.
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Affiliation(s)
- Marley A. Brimberry
- Department of Biochemistry and Molecular Biology & Center for Metalloenzyme Studies,,Department of Chemistry University of Georgia, Athens GA 30602
| | - Liju Mathew
- Department of Biochemistry and Molecular Biology & Center for Metalloenzyme Studies,,Department of Chemistry University of Georgia, Athens GA 30602
| | - William Lanzilotta
- Department of Biochemistry and Molecular Biology & Center for Metalloenzyme Studies,,Department of Chemistry University of Georgia, Athens GA 30602.,To whom correspondence should be addressed. Phone, (706) 542-1324; fax, (706) 542-1738;
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5
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Wang B, Silakov A, Booker SJ. Using peptide substrate analogs to characterize a radical intermediate in NosN catalysis. Methods Enzymol 2022; 666:469-487. [DOI: 10.1016/bs.mie.2022.02.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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6
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Yin Y, Ji X, Zhang Q. The Promiscuous Activity of the Radical
SAM
Enzyme
NosL
toward Two Unnatural Substrates. CHINESE J CHEM 2021. [DOI: 10.1002/cjoc.202100304] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Yue Yin
- Department of Chemistry Fudan University Shanghai 200433 China
| | - Xinjian Ji
- Department of Chemistry Fudan University Shanghai 200433 China
| | - Qi Zhang
- Department of Chemistry Fudan University Shanghai 200433 China
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7
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Nguyen NA, Lin Z, Mohanty I, Garg N, Schmidt EW, Agarwal V. An Obligate Peptidyl Brominase Underlies the Discovery of Highly Distributed Biosynthetic Gene Clusters in Marine Sponge Microbiomes. J Am Chem Soc 2021; 143:10221-10231. [PMID: 34213321 DOI: 10.1021/jacs.1c03474] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Marine sponges are prolific sources of bioactive natural products, several of which are produced by bacteria symbiotically associated with the sponge host. Bacteria-derived natural products, and the specialized bacterial symbionts that synthesize them, are not shared among phylogenetically distant sponge hosts. This is in contrast to nonsymbiotic culturable bacteria in which the conservation of natural products and natural product biosynthetic gene clusters (BGCs) is well established. Here, we demonstrate the widespread conservation of a BGC encoding a cryptic ribosomally synthesized and post-translationally modified peptide (RiPP) in microbiomes of phylogenetically and geographically dispersed sponges from the Pacific and Atlantic oceans. Detection of this BGC was enabled by mining for halogenating enzymes in sponge metagenomes, which, in turn, allowed for the description of a broad-spectrum regiospecific peptidyl tryptophan-6-brominase which possessed no chlorination activity. In addition, we demonstrate the cyclodehydrative installation of azoline heterocycles in proteusin RiPPs. This is the first demonstration of halogenation and cyclodehydration for proteusin RiPPs and the enzymes catalyzing these transformations were found to competently interact with other previously described proteusin substrate peptides. Within a sponge microbiome, many different generalized bacterial taxa harbored this BGC with often more than 50 copies of the BGC detected in individual sponge metagenomes. Moreover, the BGC was found in all sponges queried that possess high diversity microbiomes but it was not detected in other marine invertebrate microbiomes. These data shed light on conservation of cryptic natural product biosynthetic potential in marine sponges that was not detected by traditional natural product-to-BGC (meta)genome mining.
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Affiliation(s)
- Nguyet A Nguyen
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Zhenjian Lin
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Ipsita Mohanty
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Neha Garg
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Eric W Schmidt
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah 84112, 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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8
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Manion-Sommerhalter HR, Fedoseyenko D, Joshi S, Begley TP. Menaquinone Biosynthesis: The Mechanism of 5,8-Dihydroxy-2-naphthoate Synthase (MqnD). Biochemistry 2021; 60:1947-1951. [PMID: 34143602 DOI: 10.1021/acs.biochem.1c00257] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
MqnD catalyzes the conversion of cyclic dehypoxanthine futalosine (6) to 5,8-dihydroxy-2-naphthoic acid (7) and an uncharacterized product. This study describes a chemoenzymatic synthesis of 6. This synthesis achieved a 2-fold yield enhancement by using titanium(III) citrate as the reducing agent and another 5-fold yield enhancement using a fluorinated analogue of dehypoxanthine futalosine (5) that was converted to 6 by an ipso substitution mechanism. This synthetic route enabled the synthesis of 6 in sufficient quantity to identify the second reaction product and to determine that the MqnD-catalyzed reaction proceeds by a hemiacetal ring opening-tautomerization-retroaldol sequence.
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Affiliation(s)
| | - Dmytro Fedoseyenko
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, United States
| | - Sumedh Joshi
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, United States
| | - Tadhg P Begley
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, United States
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9
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Lu J, Li Y, Bai Z, Lv H, Wang H. Enzymatic macrocyclization of ribosomally synthesized and posttranslational modified peptides via C-S and C-C bond formation. Nat Prod Rep 2021; 38:981-992. [PMID: 33185226 DOI: 10.1039/d0np00044b] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Covering: 2000 to 2020 Ribosomally synthesized and posttranslational modified peptides (RiPPs) are a rapidly growing class of bioactive natural products. Many members of RiPPs contain macrocyclic structural units constructed by modification enzymes through macrocyclization of linear precursor peptides. In this study, we summarize recent progress in the macrocyclization of RiPPs by C-S and C-C bond formation with a focus on the current understanding of the enzymatic mechanisms.
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Affiliation(s)
- Jingxia Lu
- State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center of Nanjing University, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
| | - Yuqing Li
- State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center of Nanjing University, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
| | - Zengbing Bai
- State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center of Nanjing University, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
| | - Hongmei Lv
- State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center of Nanjing University, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
| | - Huan Wang
- State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center of Nanjing University, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
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10
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Montalbán-López M, Scott TA, Ramesh S, Rahman IR, van Heel AJ, Viel JH, Bandarian V, Dittmann E, Genilloud O, Goto Y, Grande Burgos MJ, Hill C, Kim S, Koehnke J, Latham JA, Link AJ, Martínez B, Nair SK, Nicolet Y, Rebuffat S, Sahl HG, Sareen D, Schmidt EW, Schmitt L, Severinov K, Süssmuth RD, Truman AW, Wang H, Weng JK, van Wezel GP, Zhang Q, Zhong J, Piel J, Mitchell DA, Kuipers OP, van der Donk WA. New developments in RiPP discovery, enzymology and engineering. Nat Prod Rep 2021; 38:130-239. [PMID: 32935693 PMCID: PMC7864896 DOI: 10.1039/d0np00027b] [Citation(s) in RCA: 392] [Impact Index Per Article: 130.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Covering: up to June 2020Ribosomally-synthesized and post-translationally modified peptides (RiPPs) are a large group of natural products. A community-driven review in 2013 described the emerging commonalities in the biosynthesis of RiPPs and the opportunities they offered for bioengineering and genome mining. Since then, the field has seen tremendous advances in understanding of the mechanisms by which nature assembles these compounds, in engineering their biosynthetic machinery for a wide range of applications, and in the discovery of entirely new RiPP families using bioinformatic tools developed specifically for this compound class. The First International Conference on RiPPs was held in 2019, and the meeting participants assembled the current review describing new developments since 2013. The review discusses the new classes of RiPPs that have been discovered, the advances in our understanding of the installation of both primary and secondary post-translational modifications, and the mechanisms by which the enzymes recognize the leader peptides in their substrates. In addition, genome mining tools used for RiPP discovery are discussed as well as various strategies for RiPP engineering. An outlook section presents directions for future research.
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11
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Balty C, Guillot A, Fradale L, Brewee C, Lefranc B, Herrero C, Sandström C, Leprince J, Berteau O, Benjdia A. Biosynthesis of the sactipeptide Ruminococcin C by the human microbiome: Mechanistic insights into thioether bond formation by radical SAM enzymes. J Biol Chem 2020; 295:16665-16677. [PMID: 32972973 PMCID: PMC8188230 DOI: 10.1074/jbc.ra120.015371] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 09/22/2020] [Indexed: 12/17/2022] Open
Abstract
Despite its major importance in human health, the metabolic potential of the human gut microbiota is still poorly understood. We have recently shown that biosynthesis of Ruminococcin C (RumC), a novel ribosomally synthesized and posttranslationally modified peptide (RiPP) produced by the commensal bacterium Ruminococcus gnavus, requires two radical SAM enzymes (RumMC1 and RumMC2) catalyzing the formation of four Cα-thioether bridges. These bridges, which are essential for RumC's antibiotic properties against human pathogens such as Clostridium perfringens, define two hairpin domains giving this sactipeptide (sulfur-to-α-carbon thioether-containing peptide) an unusual architecture among natural products. We report here the biochemical and spectroscopic characterizations of RumMC2. EPR spectroscopy and mutagenesis data support that RumMC2 is a member of the large family of SPASM domain radical SAM enzymes characterized by the presence of three [4Fe-4S] clusters. We also demonstrate that this enzyme initiates its reaction by Cα H-atom abstraction and is able to catalyze the formation of nonnatural thioether bonds in engineered peptide substrates. Unexpectedly, our data support the formation of a ketoimine rather than an α,β-dehydro-amino acid intermediate during Cα-thioether bridge LC-MS/MS fragmentation. Finally, we explored the roles of the leader peptide and of the RiPP precursor peptide recognition element, present in myriad RiPP-modifying enzymes. Collectively, our data support a more complex role for the peptide recognition element and the core peptide for the installation of posttranslational modifications in RiPPs than previously anticipated and suggest a possible reaction intermediate for thioether bond formation.
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Affiliation(s)
- Clémence Balty
- Micalis Institute, ChemSyBio, INRAE, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Alain Guillot
- Micalis Institute, ChemSyBio, INRAE, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Laura Fradale
- Micalis Institute, ChemSyBio, INRAE, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Clémence Brewee
- Micalis Institute, ChemSyBio, INRAE, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Benjamin Lefranc
- INSERM U1239, PRIMACEN, Université de Normandie-Rouen, Rouen, France
| | | | - Corine Sandström
- Department of Molecular Sciences, Uppsala BioCenter, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Jérôme Leprince
- INSERM U1239, PRIMACEN, Université de Normandie-Rouen, Rouen, France
| | - Olivier Berteau
- Micalis Institute, ChemSyBio, INRAE, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France.
| | - Alhosna Benjdia
- Micalis Institute, ChemSyBio, INRAE, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France.
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12
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13
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Revisiting the Mechanism of the Anaerobic Coproporphyrinogen III Oxidase HemN. Angew Chem Int Ed Engl 2019; 58:6235-6238. [DOI: 10.1002/anie.201814708] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Revised: 03/13/2019] [Indexed: 12/26/2022]
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14
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Ruszczycky MW, Zhong A, Liu HW. Following the electrons: peculiarities in the catalytic cycles of radical SAM enzymes. Nat Prod Rep 2019; 35:615-621. [PMID: 29485151 DOI: 10.1039/c7np00058h] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Radical SAM enzymes use S-adenosyl-l-methionine as an oxidant to initiate radical-mediated transformations that would otherwise not be possible with Lewis acid/base chemistry alone. These reactions are either redox neutral or oxidative leading to certain expectations regarding the role of SAM as either a reusable cofactor or the ultimate electron acceptor during each turnover. However, these expectations are frequently not realized resulting in fundamental questions regarding the redox handling and movement of electrons associated with these biological catalysts. Herein we provide a focused perspective on several of these questions and associated hypotheses with an emphasis on recently discovered radical SAM enzymes.
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Affiliation(s)
- Mark W Ruszczycky
- Division of Chemical Biology & Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, USA.
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15
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Wang B, LaMattina JW, Marshall SL, Booker SJ. Capturing Intermediates in the Reaction Catalyzed by NosN, a Class C Radical S-Adenosylmethionine Methylase Involved in the Biosynthesis of the Nosiheptide Side-Ring System. J Am Chem Soc 2019; 141:5788-5797. [PMID: 30865439 DOI: 10.1021/jacs.8b13157] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Nosiheptide is a ribosomally synthesized and post-translationally modified thiopeptide natural product that possesses antibacterial, anticancer, and immunosuppressive properties. It contains a bicyclic structure composed of a large macrocycle and a unique side-ring system containing a 3,4-dimethylindolic acid bridge connected to the side chains of Glu6 and Cys8 of the core peptide via ester and thioester linkages, respectively. In addition to the structural peptide, encoded by the nosM gene, the biosynthesis of the side-ring structure requires the actions of NosI, -J, -K, -L, and -N. NosN is annotated as a class C radical S-adenosylmethionine (SAM) methylase, but its true function is to transfer a C1 unit from SAM to C4 of 3-methyl-2-indolic acid (MIA) with concomitant formation of a bond between the carboxylate of Glu6 of the core peptide and the nascent C1 unit. However, exactly when NosN performs its function during the biosynthesis of nosiheptide is unknown. Herein, we report the syntheses and use of three peptide mimics as potential substrates designed to address the timing of NosN's function. Our results show that NosN clearly closes the side ring before NosO forms the pyridine ring and most likely before NosD/E catalyzes formation of the dehydrated amino acids, although the possibility of a more random process (i.e., NosN acting after NosD/E) cannot be ruled out. Using a substrate mimic containing a rigid structure, we also identify and characterize two reaction-based adducts containing SAM fused to C4 of MIA. The two SAM adducts are derived from a consensus radical-containing species proposed to be the key intermediate-or a derivative of the key intermediate-in our proposed catalytic mechanism of NosN.
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16
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Ji X, Mo T, Liu W, Ding W, Deng Z, Zhang Q. Revisiting the Mechanism of the Anaerobic Coproporphyrinogen III Oxidase HemN. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201814708] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Xinjian Ji
- Department of ChemistryFudan University Shanghai 200433 China
| | - Tianlu Mo
- Department of ChemistryFudan University Shanghai 200433 China
| | - Wan‐Qiu Liu
- Department of ChemistryFudan University Shanghai 200433 China
| | - Wei Ding
- State Key Laboratory of Microbial MetabolismSchool of Life Sciences & BiotechnologyShanghai Jiao Tong University Shanghai 200240 China
| | - Zixin Deng
- State Key Laboratory of Microbial MetabolismSchool of Life Sciences & BiotechnologyShanghai Jiao Tong University Shanghai 200240 China
| | - Qi Zhang
- Department of ChemistryFudan University Shanghai 200433 China
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17
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Amara P, Mouesca JM, Bella M, Martin L, Saragaglia C, Gambarelli S, Nicolet Y. Radical S-Adenosyl-l-methionine Tryptophan Lyase (NosL): How the Protein Controls the Carboxyl Radical •CO 2- Migration. J Am Chem Soc 2018; 140:16661-16668. [PMID: 30418774 DOI: 10.1021/jacs.8b09142] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The radical S-adenosyl-l-methionine tryptophan lyase uses radical-based chemistry to convert l-tryptophan into 3-methyl-2-indolic acid, a fragment in the biosynthesis of the thiopeptide antibiotic nosiheptide. This complex reaction involves several successive steps corresponding to (i) the activation by a specific hydrogen-atom abstraction, (ii) an unprecedented •CO2- radical migration, (iii) a cyanide fragment release, and (iv) the termination of the radical-based reaction. In vitro study of this reaction is made more difficult because the enzyme produces a significant amount of a shunt product instead of the natural product. Here, using a combination of X-ray crystallography, electron paramagnetic resonance spectroscopy, and quantum and hybrid quantum mechanical/molecular mechanical calculations, we have deciphered the fine mechanism of the key •CO2- radical migration, highlighting how the preorganized active site of the protein tightly controls this reaction.
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Affiliation(s)
- Patricia Amara
- Univ. Grenoble Alpes, CEA, CNRS, IBS , Metalloproteins Unit , F-38000 Grenoble , France
| | | | - Maxime Bella
- Univ. Grenoble Alpes, CEA, CNRS, IBS , Metalloproteins Unit , F-38000 Grenoble , France
| | - Lydie Martin
- Univ. Grenoble Alpes, CEA, CNRS, IBS , Metalloproteins Unit , F-38000 Grenoble , France
| | - Claire Saragaglia
- Univ. Grenoble Alpes, CEA, CNRS, IBS , Metalloproteins Unit , F-38000 Grenoble , France
| | - Serge Gambarelli
- Univ. Grenoble Alpes, CNRS, CEA , INAC-SyMMES , 38000 Grenoble , France
| | - Yvain Nicolet
- Univ. Grenoble Alpes, CEA, CNRS, IBS , Metalloproteins Unit , F-38000 Grenoble , France
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Mandalapu D, Ji X, Zhang Q. Reductive Cleavage of Sulfoxide and Sulfone by Two Radical S-Adenosyl-l-methionine Enzymes. Biochemistry 2018; 58:36-39. [DOI: 10.1021/acs.biochem.8b00844] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
| | - Xinjian Ji
- Department of Chemistry, Fudan University, Shanghai 200433, China
| | - Qi Zhang
- Department of Chemistry, Fudan University, Shanghai 200433, China
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19
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Gagnon DM, Stich TA, Mehta AP, Abdelwahed SH, Begley TP, Britt RD. An Aminoimidazole Radical Intermediate in the Anaerobic Biosynthesis of the 5,6-Dimethylbenzimidazole Ligand to Vitamin B12. J Am Chem Soc 2018; 140:12798-12807. [PMID: 30208703 DOI: 10.1021/jacs.8b05686] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Organisms that perform the de novo biosynthesis of cobalamin (vitamin B12) do so via unique pathways depending on the presence of oxygen in the environment. The anaerobic biosynthesis pathway of 5,6-dimethylbenzimidazole, the so-called "lower ligand" to the cobalt center, has been recently identified. This process begins with the conversion of 5-aminoimidazole ribotide (AIR) to 5-hydroxybenzimidazole (HBI) by the radical S-adenosyl-l-methionine (SAM) enzyme BzaF, also known as HBI synthase. In this work we report the characterization of a radical intermediate in the reaction of BzaF using electron paramagnetic resonance spectroscopy. Using various isotopologues of AIR, we extracted hyperfine parameters for a number of nuclei, allowing us to propose plausible chemical compositions and structures for this intermediate. Specifically, we find that an aminoimidazole radical is formed in close proximity to a fragment of the ribose ring. These findings induce the revision of past proposed mechanisms and illustrate the ability of radical SAM enzymes to tightly control the radical chemistry that they engender.
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Affiliation(s)
- Derek M Gagnon
- Department of Chemistry , University of California , Davis , California 95616 , United States
| | - Troy A Stich
- Department of Chemistry , University of California , Davis , California 95616 , United States
| | - Angad P Mehta
- Department of Chemistry , Texas A&M University , College Station , Texas 77843 , United States
| | - Sameh H Abdelwahed
- Department of Chemistry , Texas A&M University , College Station , Texas 77843 , United States
| | - Tadhg P Begley
- Department of Chemistry , Texas A&M University , College Station , Texas 77843 , United States
| | - R David Britt
- Department of Chemistry , University of California , Davis , California 95616 , United States
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Iterative Methylations Resulting in the Biosynthesis of the t-Butyl Group Catalyzed by a B 12-Dependent Radical SAM Enzyme in Cystobactamid Biosynthesis. Methods Enzymol 2018; 606:199-216. [PMID: 30097093 DOI: 10.1016/bs.mie.2018.05.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
B12-dependent radical SAM enzymes that can perform methylations on sp3 carbon centers are important for functional diversity and regulation of biological activity in several nonribosomal peptides. Detailed studies on these enzymes are hindered by the complexity of the substrates and low levels of expression of active enzymes. CysS can catalyze iterative methylations of a methoxybenzene moiety during the biosynthesis of the cystobactamids. Here, we describe the overexpression, purification, substrate identification, and mechanism of this enzyme.
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21
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Abstract
The Natural Product Reports themed issue on ‘Metalloenzymes in natural product biosynthetic pathways’ is introduced by the Guest Editors, Katherine Ryan and Catherine Drennan.
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Affiliation(s)
- Katherine S Ryan
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC, CanadaV6T 1Z1.
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22
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Aminofutalosine Synthase (MqnE): A New Catalytic Motif in Radical SAM Enzymology. Methods Enzymol 2018; 606:179-198. [DOI: 10.1016/bs.mie.2018.05.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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23
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Bhandari DM, Fedoseyenko D, Begley TP. Mechanistic Studies on the Radical SAM Enzyme Tryptophan Lyase (NosL). Methods Enzymol 2018; 606:155-178. [DOI: 10.1016/bs.mie.2018.06.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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