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Kubiak X, Polsinelli I, Chavas LMG, Fyfe CD, Guillot A, Fradale L, Brewee C, Grimaldi S, Gerbaud G, Thureau A, Legrand P, Berteau O, Benjdia A. Structural and mechanistic basis for RiPP epimerization by a radical SAM enzyme. Nat Chem Biol 2024; 20:382-391. [PMID: 38158457 DOI: 10.1038/s41589-023-01493-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 10/30/2023] [Indexed: 01/03/2024]
Abstract
D-Amino acid residues, found in countless peptides and natural products including ribosomally synthesized and post-translationally modified peptides (RiPPs), are critical for the bioactivity of several antibiotics and toxins. Recently, radical S-adenosyl-L-methionine (SAM) enzymes have emerged as the only biocatalysts capable of installing direct and irreversible epimerization in RiPPs. However, the mechanism underpinning this biochemical process is ill-understood and the structural basis for this post-translational modification remains unknown. Here we report an atomic-resolution crystal structure of a RiPP-modifying radical SAM enzyme in complex with its substrate properly positioned in the active site. Crystallographic snapshots, size-exclusion chromatography-small-angle x-ray scattering, electron paramagnetic resonance spectroscopy and biochemical analyses reveal how epimerizations are installed in RiPPs and support an unprecedented enzyme mechanism for peptide epimerization. Collectively, our study brings unique perspectives on how radical SAM enzymes interact with RiPPs and catalyze post-translational modifications in natural products.
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Affiliation(s)
- Xavier Kubiak
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, ChemSyBio, Jouy-en-Josas, France
| | - Ivan Polsinelli
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, ChemSyBio, Jouy-en-Josas, France
| | | | - Cameron D Fyfe
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, ChemSyBio, Jouy-en-Josas, France
| | - Alain Guillot
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, ChemSyBio, Jouy-en-Josas, France
| | - Laura Fradale
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, ChemSyBio, Jouy-en-Josas, France
| | - Clémence Brewee
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, ChemSyBio, Jouy-en-Josas, France
| | | | | | - Aurélien Thureau
- Synchrotron SOLEIL, HelioBio Group, L'Orme des Merisiers, Saint-Aubin, France
| | - Pierre Legrand
- Synchrotron SOLEIL, HelioBio Group, L'Orme des Merisiers, Saint-Aubin, France
| | - Olivier Berteau
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, ChemSyBio, Jouy-en-Josas, France.
| | - Alhosna Benjdia
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, ChemSyBio, Jouy-en-Josas, France.
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2
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Walls WG, Vagstad A, Delridge T, Piel J, Broderick WE, Broderick JB. Direct Detection of the α-Carbon Radical Intermediate Formed by OspD: Mechanistic Insights into Radical S-Adenosyl-l-methionine Peptide Epimerization. J Am Chem Soc 2024; 146:5550-5559. [PMID: 38364824 PMCID: PMC11302384 DOI: 10.1021/jacs.3c13829] [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: 02/18/2024]
Abstract
OspD is a radical S-adenosyl-l-methionine (SAM) peptide epimerase that converts an isoleucine (Ile) and valine (Val) of the OspA substrate to d-amino acids during biosynthesis of the ribosomally synthesized and post-translationally modified peptide (RiPP) natural product landornamide A. OspD is proposed to carry out this reaction via α-carbon (Cα) H-atom abstraction to form a peptidyl Cα radical that is stereospecifically quenched by hydrogen atom transfer (HAT) from a conserved cysteine (Cys). Here we use site-directed mutagenesis, freeze-quench trapping, isotopic labeling, and electron paramagnetic resonance (EPR) spectroscopy to provide new insights into the OspD catalytic mechanism including the direct observation of the substrate peptide Cα radical intermediate. The putative quenching Cys334 was changed to serine to generate an OspD C334S variant impaired in HAT quenching. The reaction of reduced OspD C334S with SAM and OspA freeze-quenched at 15 s exhibits a doublet EPR signal characteristic of a Cα radical coupled to a single β-H. Using isotopologues of OspA deuterated at either Ile or Val, or both Ile and Val, reveals that the initial Cα radical intermediate forms exclusively on the Ile of OspA. Time-dependent freeze quench coupled with EPR spectroscopy provided evidence for loss of the Ile Cα radical concomitant with gain of a Val Cα radical, directly demonstrating the N-to-C directionality of epimerization by OspD. These results provide direct evidence for the aforementioned OspD-catalyzed peptide epimerization mechanism via a central Cα radical intermediate during RiPP maturation of OspA, a mechanism that may extend to other proteusin peptide epimerases.
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Affiliation(s)
- William G. Walls
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT 59717, United States
| | - Anna Vagstad
- Institute of Microbiology, Eidgenössische Technische Hochschule (ETH) Zürich, Vladimir-Prelog-Weg 4, Zürich 8093, Switzerland
| | - Tyler Delridge
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT 59717, United States
| | - Jörn Piel
- Institute of Microbiology, Eidgenössische Technische Hochschule (ETH) Zürich, Vladimir-Prelog-Weg 4, Zürich 8093, Switzerland
| | - William E. Broderick
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT 59717, United States
| | - Joan B. Broderick
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT 59717, United States
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3
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Johnson BA, Clark KA, Bushin LB, Spolar CN, Seyedsayamdost MR. Expanding the Landscape of Noncanonical Amino Acids in RiPP Biosynthesis. J Am Chem Soc 2024; 146:3805-3815. [PMID: 38316431 DOI: 10.1021/jacs.3c10824] [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: 02/07/2024]
Abstract
Advancements in DNA sequencing technologies and bioinformatics have enabled the discovery of new metabolic reactions from overlooked microbial species and metagenomic sequences. Using a bioinformatic co-occurrence strategy, we previously generated a network of ∼600 uncharacterized quorum-sensing-regulated biosynthetic gene clusters that code for ribosomally synthesized and post-translationally modified peptide (RiPP) natural products and are tailored by radical S-adenosylmethionine (RaS) enzymes in streptococci. The most complex of these is the GRC subfamily, named after a conserved motif in the precursor peptide and found exclusively in Streptococcus pneumoniae, the causative agent of bacterial pneumonia. In this study, using both in vivo and in vitro approaches, we have elucidated the modifications installed by the grc biosynthetic enzymes, including a ThiF-like adenylyltransferase/cyclase that generates a C-terminal Glu-to-Cys thiolactone macrocycle, and two RaS enzymes, which selectively epimerize the β-carbon of threonine and desaturate histidine to generate the first instances of l-allo-Thr and didehydrohistidine in RiPP biosynthesis. RaS-RiPPs that have been discovered thus far have stood out for their exotic macrocycles. The product of the grc cluster breaks this trend by generating two noncanonical residues rather than an unusual macrocycle in the peptide substrate. These modifications expand the landscape of nonproteinogenic amino acids in RiPP natural product biosynthesis and motivate downstream biocatalytic applications of the corresponding enzymes.
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Affiliation(s)
- Brooke A Johnson
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Kenzie A Clark
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Leah B Bushin
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Calvin N Spolar
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Mohammad R Seyedsayamdost
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, United States
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4
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Hazra S, Begley TP. Alkylcysteine Sulfoxide C-S Monooxygenase Uses a Flavin-Dependent Pummerer Rearrangement. J Am Chem Soc 2023; 145:11933-11938. [PMID: 37229602 PMCID: PMC10863075 DOI: 10.1021/jacs.3c03545] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Indexed: 05/27/2023]
Abstract
Flavoenzymes are highly versatile and participate in the catalysis of a wide range of reactions, including key reactions in the metabolism of sulfur-containing compounds. S-Alkyl cysteine is formed primarily by the degradation of S-alkyl glutathione generated during electrophile detoxification. A recently discovered S-alkyl cysteine salvage pathway uses two flavoenzymes (CmoO and CmoJ) to dealkylate this metabolite in soil bacteria. CmoO catalyzes a stereospecific sulfoxidation, and CmoJ catalyzes the cleavage of one of the sulfoxide C-S bonds in a new reaction of unknown mechanism. In this paper, we investigate the mechanism of CmoJ. We provide experimental evidence that eliminates carbanion and radical intermediates and conclude that the reaction proceeds via an unprecedented enzyme-mediated modified Pummerer rearrangement. The elucidation of the mechanism of CmoJ adds a new motif to the flavoenzymology of sulfur-containing natural products and demonstrates a new strategy for the enzyme-catalyzed cleavage of C-S bonds.
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Affiliation(s)
- Sohan Hazra
- 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
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Zhang X, Wang Z, Li Z, Shaik S, Wang B. [4Fe–4S]-Mediated Proton-Coupled Electron Transfer Enables the Efficient Degradation of Chloroalkenes by Reductive Dehalogenases. ACS Catal 2023. [DOI: 10.1021/acscatal.2c06306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Xuan Zhang
- State Key Laboratory Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, P. R. China
| | - Zikuan Wang
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany
| | - Zhen Li
- State Key Laboratory Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, P. R. China
| | - Sason Shaik
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Binju Wang
- State Key Laboratory Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, P. R. China
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6
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Li X, Yu F, Wang F, Wang S, Han R, Cheng Y, Zhao M, Sun J, Xue Z. Point mutation of V252 in neomycin C epimerase enlarges substrate-binding pocket and improves neomycin B accumulation in Streptomyces fradiae. BIORESOUR BIOPROCESS 2022; 9:123. [PMID: 38647873 PMCID: PMC10991966 DOI: 10.1186/s40643-022-00613-4] [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: 09/20/2022] [Accepted: 11/19/2022] [Indexed: 12/09/2022] Open
Abstract
Neomycin, an aminoglycoside antibiotic with broad-spectrum antibacterial resistance, is widely used in pharmaceutical and agricultural fields. However, separation and purification of neomycin B as an active substance from Streptomyces fradiae are complicated. Although NeoN can catalyze conversion of neomycin C to neomycin B, the underlying catalytic mechanism is still unclear. In this study, the genomic information of high-yielding mutant S. fradiae SF-2 was elucidated using whole-genome sequencing. Subsequently, the mechanism of NeoN in catalyzing conversion of neomycin C to neomycin B was resolved based on NeoN-SAM-neomycin C ternary complex. Mutant NeoNV252A showed improved NeoN activity, and the recombinant strain SF-2-NeoNV252A accumulated 16,766.6 U/mL neomycin B, with a decrease in neomycin C ratio from 16.1% to 6.28%, when compared with the parental strain SF-2. In summary, this study analyzed the catalytic mechanism of NeoN, providing significant reference for rational design of NeoN to improve neomycin B production and weaken the proportion of neomycin C.
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Affiliation(s)
- Xiangfei Li
- Engineering Laboratory for Industrial Microbiology Molecular Beeding of Anhui Province, College of Biologic and Food Engineering, Anhui Polytechnic University, 8 Middle Beijing Road, Wuhu, 241000, China
| | - Fei Yu
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Fang Wang
- Engineering Laboratory for Industrial Microbiology Molecular Beeding of Anhui Province, College of Biologic and Food Engineering, Anhui Polytechnic University, 8 Middle Beijing Road, Wuhu, 241000, China
| | - Sang Wang
- Engineering Laboratory for Industrial Microbiology Molecular Beeding of Anhui Province, College of Biologic and Food Engineering, Anhui Polytechnic University, 8 Middle Beijing Road, Wuhu, 241000, China
| | - Rumeng Han
- Engineering Laboratory for Industrial Microbiology Molecular Beeding of Anhui Province, College of Biologic and Food Engineering, Anhui Polytechnic University, 8 Middle Beijing Road, Wuhu, 241000, China
| | - Yihan Cheng
- Engineering Laboratory for Industrial Microbiology Molecular Beeding of Anhui Province, College of Biologic and Food Engineering, Anhui Polytechnic University, 8 Middle Beijing Road, Wuhu, 241000, China
| | - Ming Zhao
- Engineering Laboratory for Industrial Microbiology Molecular Beeding of Anhui Province, College of Biologic and Food Engineering, Anhui Polytechnic University, 8 Middle Beijing Road, Wuhu, 241000, China
| | - Junfeng Sun
- Engineering Laboratory for Industrial Microbiology Molecular Beeding of Anhui Province, College of Biologic and Food Engineering, Anhui Polytechnic University, 8 Middle Beijing Road, Wuhu, 241000, China
| | - Zhenglian Xue
- Engineering Laboratory for Industrial Microbiology Molecular Beeding of Anhui Province, College of Biologic and Food Engineering, Anhui Polytechnic University, 8 Middle Beijing Road, Wuhu, 241000, China.
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7
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Chen Z, Sato S, Geng Y, Zhang J, Liu HW. Identification of the Early Steps in Herbicidin Biosynthesis Reveals an Atypical Mechanism of C-Glycosylation. J Am Chem Soc 2022; 144:15653-15661. [PMID: 35981300 DOI: 10.1021/jacs.2c05728] [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
Herbicidins are adenosine-derived nucleoside antibiotics with an unusual tricyclic core structure. Deletion of the genes responsible for formation of the tricyclic skeleton in Streptomyces sp. L-9-10 reveals the in vivo importance of Her4, Her5, and Her6 in the early stages of herbicidin biosynthesis. In vitro characterization of Her4 and Her5 demonstrates their involvement in an initial, two-stage C-C coupling reaction that results in net C5'-glycosylation of ADP/ATP by UDP/TDP-glucuronic acid. Biochemical analyses and intermediate trapping experiments imply a noncanonical mechanism of C-glycosylation reminiscent of NAD-dependent S-adenosylhomocysteine (SAH)-hydrolase catalysis. Structural characterization of the isolated metabolites suggests possible reactions catalyzed by Her6 and Her7. An overall herbicidin biosynthetic pathway is proposed based on these observations.
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Affiliation(s)
- Zhang Chen
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Shusuke Sato
- Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Yujie Geng
- Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Jiawei Zhang
- 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 and Medicinal Chemistry, College of Pharmacy, The University of Texas at Austin, Austin, Texas 78712, United States
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8
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Zhang J, Hou X, Chen Z, Ko Y, Ruszczycky MW, Chen Y, Zhou J, Liu HW. Dioxane Bridge Formation during the Biosynthesis of Spectinomycin Involves a Twitch Radical S-Adenosyl Methionine Dehydrogenase That May Have Evolved from an Epimerase. J Am Chem Soc 2022; 144:9910-9919. [PMID: 35622017 PMCID: PMC9204835 DOI: 10.1021/jacs.2c02676] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Spectinomycin is a dioxane-bridged, tricyclic aminoglycoside produced by Streptomyces spectabilis ATCC 27741. While the spe biosynthetic gene cluster for spectinomycin has been reported, the chemistry underlying construction of the dioxane ring is unknown. The twitch radical SAM enzyme SpeY from the spe cluster is shown here to catalyze dehydrogenation of the C2' alcohol of (2'R,3'S)-tetrahydrospectinomycin to yield (3'S)-dihydrospectinomycin as a likely biosynthetic intermediate. This reaction is radical-mediated and initiated via H atom abstraction from C2' of the substrate by the 5'-deoxyadenosyl radical equivalent generated upon reductive cleavage of SAM. Crystallographic analysis of the ternary Michaelis complex places serine-183 adjacent to C2' of the bound substrate opposite C5' of SAM. Mutation of this residue to cysteine converts SpeY to the corresponding C2' epimerase mirroring the opposite phenomenon observed in the homologous twitch radical SAM epimerase HygY from the hygromycin B biosynthetic pathway. Phylogenetic analysis suggests a relatively recent evolutionary branching of putative twitch radical SAM epimerases bearing homologous cysteine residues to generate the SpeY clade of enzymes.
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Affiliation(s)
- Jiawei Zhang
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Xueli Hou
- Shaanxi Key Laboratory of Natural Products & Chemical Biology, College of Chemistry & Pharmacy, Northwest A&F University, Yangling 712100, Shaanxi, China
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
| | - Zhang Chen
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Yeonjin Ko
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Mark W Ruszczycky
- Division of Chemical Biology & Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712, United States
| | - Yutian Chen
- Division of Chemical Biology & Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712, United States
| | - Jiahai Zhou
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
- CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - 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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9
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Li H, Zhao J, Ding W, Zhang Q. Glucuronyl C4 dehydrogenation by the radical SAM enzyme BlsE involved in blasticidin S biosynthesis. Chem Commun (Camb) 2022; 58:3561-3564. [PMID: 35199117 DOI: 10.1039/d1cc07132g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Here we report functional investigation of the radical S-adenosylmethionine enzyme BlsE by using cytosylglucuronamide (CGM), which is the amide analog of cytosylglucuronic acid (CGA), an intermediate involved in blasticidin S biosynthesis. We showed that, instead of decarboxylation of CGA reported previously, BlsE catalyzes C4'-dehydrogenation of CGM, and the resulting ketone is acted on by an aminotransferase BlsH to install the C4'-amino group, which uses L-Asp as the amino donor.
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Affiliation(s)
- He Li
- Department of Chemistry, Fudan University, Shanghai, 200433, China.
| | - Junfeng Zhao
- State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Wei Ding
- State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Qi Zhang
- Department of Chemistry, Fudan University, Shanghai, 200433, China.
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