1
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Cheek LE, Zhu W. Structural features and substrate engagement in peptide-modifying radical SAM enzymes. Arch Biochem Biophys 2024; 756:110012. [PMID: 38663796 DOI: 10.1016/j.abb.2024.110012] [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: 01/18/2024] [Revised: 04/16/2024] [Accepted: 04/17/2024] [Indexed: 05/04/2024]
Abstract
In recent years, the biological significance of ribosomally synthesized, post-translationally modified peptides (RiPPs) and the intriguing chemistry catalyzed by their tailoring enzymes has garnered significant attention. A subgroup of bacterial radical S-adenosylmethionine (rSAM) enzymes can activate C-H bonds in peptides, which leads to the production of a diverse range of RiPPs. The remarkable ability of these enzymes to facilitate various chemical processes, to generate and harbor high-energy radical species, and to accommodate large substrates with a high degree of flexibility is truly intriguing. The wide substrate scope and diversity of the chemistry performed by rSAM enzymes raise one question: how does the protein environment facilitate these distinct chemical conversions while sharing a similar structural fold? In this review, we discuss recent advances in the field of RiPP-rSAM enzymes, with a particular emphasis on domain architectures and substrate engagements identified by biophysical and structural characterizations. We provide readers with a comparative analysis of six examples of RiPP-rSAM enzymes with experimentally characterized structures. Linking the structural elements and the nature of rSAM-catalyzed RiPP production will provide insight into the functional engineering of enzyme activity to harness their catalytic power in broader applications.
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Affiliation(s)
- Lilly E Cheek
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, 32306, USA
| | - Wen Zhu
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, 32306, USA.
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2
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Chen JY, van der Donk WA. Multinuclear non-heme iron dependent oxidative enzymes (MNIOs) involved in unusual peptide modifications. Curr Opin Chem Biol 2024; 80:102467. [PMID: 38772214 DOI: 10.1016/j.cbpa.2024.102467] [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: 03/04/2024] [Revised: 04/28/2024] [Accepted: 04/29/2024] [Indexed: 05/23/2024]
Abstract
Multinuclear non-heme iron dependent oxidative enzymes (MNIOs), formerly known as domain of unknown function 692 (DUF692), are involved in the post-translational modification of peptides during the biosynthesis of peptide-based natural products. These enzymes catalyze highly unusual and diverse chemical modifications. Several class-defining features of this large family (>14 000 members) are beginning to emerge. Structurally, the enzymes are characterized by a TIM-barrel fold and a set of conserved residues for a di- or tri-iron binding site. They use molecular oxygen to modify peptide substrates, often in a four-electron oxidation taking place at a cysteine residue. This review summarizes the current understanding of MNIOs. Four modifications are discussed in detail: oxazolone-thioamide formation, β-carbon excision, hydantoin-macrocycle formation, and 5-thiooxazole formation. Briefly discussed are two other reactions that do not take place on Cys residues.
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Affiliation(s)
- Jeff Y Chen
- Department of Chemistry, The Carl R. Woese Institute for Genomic Biology, The Howard Hughes Medical Institute at the University of Illinois at Urbana-Champaign, 1206 W Gregory Drive, Urbana, IL 61801, USA
| | - Wilfred A van der Donk
- Department of Chemistry, The Carl R. Woese Institute for Genomic Biology, The Howard Hughes Medical Institute at the University of Illinois at Urbana-Champaign, 1206 W Gregory Drive, Urbana, IL 61801, USA.
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3
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Abad AND, Seshadri K, Ohashi M, Delgadillo DA, de Moraes LS, Nagasawa KK, Liu M, Johnson S, Nelson HM, Tang Y. Discovery and Characterization of Pyridoxal 5'-Phosphate-Dependent Cycloleucine Synthases. J Am Chem Soc 2024; 146:14672-14684. [PMID: 38743881 PMCID: PMC11390345 DOI: 10.1021/jacs.4c02142] [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: 05/16/2024]
Abstract
Pyridoxal 5'-phosphate (PLP)-dependent enzymes are the most versatile biocatalysts for synthesizing nonproteinogenic amino acids. α,α-Disubstituted quaternary amino acids, such as 1-aminocyclopentane-1-carboxylic acid (cycloleucine), are useful building blocks for pharmaceuticals. In this study, starting with the biosynthesis of fusarilin A, we discovered a family of PLP-dependent enzymes that can facilitate tandem carbon-carbon forming steps to catalyze an overall [3 + 2]-annulation. In the first step, the cycloleucine synthases use SAM as the latent electrophile and an in situ-generated enamine as the nucleophile for γ-substitution. Whereas previously characterized γ-replacement enzymes protonate the resulting α-carbon and release the acyclic amino acid, cycloleucine synthases can catalyze an additional, intramolecular aldol or Mannich reaction with the nucleophilic α-carbon to form the substituted cyclopentane. Overall, the net [3 + 2]-annulation reaction can lead to 2-hydroxy or 2-aminocycloleucine products. These studies further expand the biocatalytic scope of PLP-dependent enzymes.
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Affiliation(s)
- Abner N D Abad
- Departments of Chemical and Biomolecular Engineering, University of California, Los Angeles, California 90095, United States
| | - Kaushik Seshadri
- Departments of Chemical and Biomolecular Engineering, University of California, Los Angeles, California 90095, United States
| | - Masao Ohashi
- Departments of Chemical and Biomolecular Engineering, University of California, Los Angeles, California 90095, United States
| | - David A Delgadillo
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Lygia S de Moraes
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Kyle K Nagasawa
- Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Mengting Liu
- Departments of Chemical and Biomolecular Engineering, University of California, Los Angeles, California 90095, United States
| | - Samuel Johnson
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Hosea M Nelson
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Yi Tang
- Departments of Chemical and Biomolecular Engineering, University of California, Los Angeles, California 90095, United States
- Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
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4
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Nguyen DT, Zhu L, Gray DL, Woods TJ, Padhi C, Flatt KM, Mitchell DA, van der Donk WA. Biosynthesis of Macrocyclic Peptides with C-Terminal β-Amino-α-keto Acid Groups by Three Different Metalloenzymes. ACS CENTRAL SCIENCE 2024; 10:1022-1032. [PMID: 38799663 PMCID: PMC11117315 DOI: 10.1021/acscentsci.4c00088] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 03/29/2024] [Accepted: 03/29/2024] [Indexed: 05/29/2024]
Abstract
Advances in genome sequencing and bioinformatics methods have identified a myriad of biosynthetic gene clusters (BGCs) encoding uncharacterized molecules. By mining genomes for BGCs containing a prevalent peptide-binding domain used for the biosynthesis of ribosomally synthesized and post-translationally modified peptides (RiPPs), we uncovered a new compound class involving modifications installed by a cytochrome P450, a multinuclear iron-dependent non-heme oxidative enzyme (MNIO, formerly DUF692), a cobalamin- and radical S-adenosyl-l-methionine-dependent enzyme (B12-rSAM), and a methyltransferase. All enzymes were functionally expressed in Burkholderia sp. FERM BP-3421. Structural characterization demonstrated that the P450 enzyme catalyzed the formation of a biaryl C-C cross-link between two Tyr residues with the B12-rSAM generating β-methyltyrosine. The MNIO transformed a C-terminal Asp residue into aminopyruvic acid, while the methyltransferase acted on the β-carbon of this α-keto acid. Exciton-coupled circular dichroism spectroscopy and microcrystal electron diffraction (MicroED) were used to elucidate the stereochemical configuration of the atropisomer formed upon biaryl cross-linking. To the best of our knowledge, the MNIO featured in this pathway is the first to modify a residue other than Cys. This study underscores the utility of genome mining to isolate new macrocyclic RiPPs biosynthesized via previously undiscovered enzyme chemistry.
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Affiliation(s)
- Dinh T. Nguyen
- Department
of Chemistry, Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Lingyang Zhu
- School
of Chemical Sciences NMR Laboratory, University
of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Danielle L. Gray
- School
of Chemical Sciences George L. Clark X-Ray Facility and 3M Materials
Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Toby J. Woods
- School
of Chemical Sciences George L. Clark X-Ray Facility and 3M Materials
Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Chandrashekhar Padhi
- Department
of Chemistry, Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Kristen M. Flatt
- Materials
Research Laboratory, University of Illinois
at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Douglas A. Mitchell
- Department
of Chemistry, Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Wilfred A. van der Donk
- Department
of Chemistry, Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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5
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Phan CS, Chang L, Nguyen TQN, Suarez AFL, Ho XH, Chen H, Koh IYF, Morinaka BI. Substrate Promiscuity of the Triceptide Maturase XncB Leads to Incorporation of Various Amino Acids and Detection of Oxygenated Products. ACS Chem Biol 2024; 19:855-860. [PMID: 38452396 DOI: 10.1021/acschembio.3c00782] [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: 03/09/2024]
Abstract
Triceptides are cyclophane-containing ribosomally synthesized and post-translationally modified peptides. The characteristic cross-links are formed between an aromatic ring to Cβ on three-residue Ω1X2X3 motifs (Ω1 = aromatic). Here, we explored the promiscuity of the XYE family triceptide maturase, XncB from Xenorhabdus nematophila DSM 3370. Single amino acid variants were coexpressed with XncB in vivo in Escherichia coli, and we show that a variety of amino acids can be incorporated into the Phe-Gly-Asn cyclophane. Aromatic amino acids at the X3 position were accepted by the enzyme but yielded hydroxylated, rather than the typical cyclophane, products. These studies show that oxygen can be inserted but diverges in the final product formed relative to daropeptide maturases. Finally, truncations of the leader peptide showed that it is necessary for complete modification by XncB.
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Affiliation(s)
- Chin-Soon Phan
- Department of Pharmacy, National University of Singapore, Singapore 117544, Singapore
| | - Litao Chang
- Department of Pharmacy, National University of Singapore, Singapore 117544, Singapore
| | - Thi Quynh Ngoc Nguyen
- Department of Pharmacy, National University of Singapore, Singapore 117544, Singapore
| | | | - Xuen Huei Ho
- Department of Pharmacy, National University of Singapore, Singapore 117544, Singapore
| | - Huiyi Chen
- Department of Pharmacy, National University of Singapore, Singapore 117544, Singapore
| | - Ivan Yu Fan Koh
- Department of Pharmacy, National University of Singapore, Singapore 117544, Singapore
| | - Brandon I Morinaka
- Department of Pharmacy, National University of Singapore, Singapore 117544, Singapore
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6
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Colombatti Olivieri MA, Fresia P, Graña M, Cuerda MX, Nagel A, Alvarado Pinedo F, Romano MI, Caimi K, Berná L, Santangelo MP. Genomic comparison of two strains of Mycobacterium avium subsp. paratuberculosis with contrasting pathogenic phenotype. Tuberculosis (Edinb) 2023; 138:102299. [PMID: 36587510 DOI: 10.1016/j.tube.2022.102299] [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: 09/30/2022] [Revised: 11/28/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022]
Abstract
In a previous study, we evaluated the degree of virulence of Mycobacterium avium subsp. paratuberculosis (Map) strains isolated from cattle in Argentina in a murine model. This assay allowed us to differentiate between high-virulent MapARG1347 and low-virulent MapARG1543 strains. To corroborate whether the differences in virulence could be attributed to genetic differences between the strains, we performed Whole Genome Sequencing and compared the genomes and gene content between them and determined the differences related to the reference strain MapK10. We found 233 SNPs/INDELS in one or both strains relative to Map K10. The two strains share most of the variations, but we found 15 mutations present in only one of the strains. Considering NS-SNP/INDELS that produced a severe effect in the coding sequence, we focus the analysis on four predicted proteins, putatively related to virulence. Survival of MapARG1347 strain in bMDM was higher than MapARG1543 and was more resistant to acidic pH and H2O2 stresses than MapK10. The genomic differences between the two strains found in genes MAP1203 (a putative peptidoglycan hydrolase), MAP0403 (a putative serine protease) MAP1003c (a member of the PE-PPE family) and MAP4152 (a putative mycofactocin binding protein) could contribute to explain the contrasting phenotype previously observed in mice models.
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Affiliation(s)
- M A Colombatti Olivieri
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), INTA-CONICET, Dr. Nicolás Repetto y De Los Reseros S/Nº B1686IGC, Hurlingham, Buenos Aires, Argentina.
| | - P Fresia
- Unidad Mixta Pasteur+INIA, Institut Pasteur de Montevideo, Mataojo 2020, CP11400, Montevideo, Uruguay.
| | - M Graña
- Unidad de Bioinformática, Institut Pasteur de Montevideo, Mataojo 2020, CP11400, Montevideo, Uruguay.
| | - M X Cuerda
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), INTA-CONICET, Dr. Nicolás Repetto y De Los Reseros S/Nº B1686IGC, Hurlingham, Buenos Aires, Argentina.
| | - A Nagel
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), INTA-CONICET, Dr. Nicolás Repetto y De Los Reseros S/Nº B1686IGC, Hurlingham, Buenos Aires, Argentina.
| | - F Alvarado Pinedo
- Centro de Diagnóstico e Investigaciones Veterinarias (CEDIVE), Facultad de Ciencias Veterinarias - Universidad de La Plata (UNLP), Chascomus, Buenos Aires, Argentina.
| | - M I Romano
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), INTA-CONICET, Dr. Nicolás Repetto y De Los Reseros S/Nº B1686IGC, Hurlingham, Buenos Aires, Argentina.
| | - K Caimi
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), INTA-CONICET, Dr. Nicolás Repetto y De Los Reseros S/Nº B1686IGC, Hurlingham, Buenos Aires, Argentina.
| | - L Berná
- Unidad de Biología Molecular, Institut Pasteur de Montevideo, Mataojo 2020, CP 11400, Montevideo, Uruguay.
| | - M P Santangelo
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), INTA-CONICET, Dr. Nicolás Repetto y De Los Reseros S/Nº B1686IGC, Hurlingham, Buenos Aires, Argentina.
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7
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Phan CS, Morinaka BI. A Prevalent Group of Actinobacterial Radical SAM/SPASM Maturases Involved in Triceptide Biosynthesis. ACS Chem Biol 2022; 17:3284-3289. [PMID: 36454686 DOI: 10.1021/acschembio.2c00621] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Triceptides are ribosomally synthesized and post-translationally modified peptides characterized by three-residue cyclophanes. The cyclophanes are installed by radical SAM/SPASM maturases referred to as 3-residue cyclophane forming enzymes (3-CyFEs) which catalyze C(sp2)-Cβ(sp3) bond formation on three residue motifs at the C-terminus of precursor peptides. Here, we bioinformatically map uncharacterized rSAM/SPASM enzymes, referred to as Actinobacterial multiple cyclophane maturases. The enzyme FwwB from Actinospira robinae was selected for in vivo functional studies in Escherichia coli, and was found to catalyze formation of multiple Phe- and Trp-derived 3-residue cyclophanes. FwwB was shown to accept a series of engineered substrates but showed specificity for the native 3-residue motif.
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Affiliation(s)
- Chin-Soon Phan
- Department of Pharmacy, National University of Singapore, Singapore 117544, Singapore
| | - Brandon I Morinaka
- Department of Pharmacy, National University of Singapore, Singapore 117544, Singapore
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8
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Ellerhorst M, Barth SA, Graça AP, Al-Jammal WK, Peña-Ortiz L, Vilotijevic I, Lackner G. S-Adenosylmethionine (SAM)-Dependent Methyltransferase MftM is Responsible for Methylation of the Redox Cofactor Mycofactocin. ACS Chem Biol 2022; 17:3207-3217. [PMID: 36288793 PMCID: PMC9679996 DOI: 10.1021/acschembio.2c00659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Mycobacteria produce several unusual cofactors that contribute to their metabolic versatility and capability to survive in different environments. Mycofactocin (MFT) is a redox cofactor involved in ethanol metabolism. The redox-active core moiety of mycofactocin is derived from the short precursor peptide MftA, which is modified by several maturases. Recently, it has been shown that the core moiety is decorated by a β-1,4-glucan chain. Remarkably, the second glucose moiety of the oligosaccharide chain was found to be 2-O-methylated in Mycolicibacterium smegmatis. The biosynthetic gene responsible for this methylation, however, remained elusive, and no methyltransferase gene was part of the MFT biosynthetic gene cluster. Here, we applied reverse genetics to identify the gene product of MSMEG_6237 (mftM) as the SAM-dependent methyltransferase was responsible for methylation of the cofactor in M. smegmatis. According to metabolic analysis and comparative genomics, the occurrence of methylated MFT species was correlated with the presence of mftM homologues in the genomes of mycofactocin producers. This study revealed that the pathogen Mycobacterium tuberculosis does not methylate mycofactocins. Interestingly, mftM homologues co-occur with both mycofactocin biosynthesis genes as well as the putative mycofactocin-dependent alcohol dehydrogenase Mdo. We further showed that mftM knock-out mutants of M. smegmatis suffer from a prolonged lag phase when grown on ethanol as a carbon source. In addition, in vitro digestion of the glucose chain by cellulase suggested a protective function of glucan methylation. These results close an important knowledge gap and provide a basis for future studies into the physiological functions of this unusual cofactor modification.
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Affiliation(s)
- Mark Ellerhorst
- Junior
Research Group Synthetic Microbiology, Leibniz
Institute for Natural Product Research and Infection Biology—Hans
Knöll Institute, Beutenbergstr. 11a, 07745 Jena, Germany
| | - Stefanie A. Barth
- Friedrich-Loeffler-Institut—Federal
Research Institute for Animal Health (FLI), Institute of Molecular
Pathogenesis, Naumburger
Str. 96a, 07743 Jena, Germany
| | - Ana Patrícia Graça
- Junior
Research Group Synthetic Microbiology, Leibniz
Institute for Natural Product Research and Infection Biology—Hans
Knöll Institute, Beutenbergstr. 11a, 07745 Jena, Germany
| | - Walid K. Al-Jammal
- Institute
of Organic Chemistry and Macromolecular Chemistry, Friedrich Schiller University Jena, Humboldtstraße 10, 07743 Jena, Germany
| | - Luis Peña-Ortiz
- Junior
Research Group Synthetic Microbiology, Leibniz
Institute for Natural Product Research and Infection Biology—Hans
Knöll Institute, Beutenbergstr. 11a, 07745 Jena, Germany
| | - Ivan Vilotijevic
- Institute
of Organic Chemistry and Macromolecular Chemistry, Friedrich Schiller University Jena, Humboldtstraße 10, 07743 Jena, Germany
| | - Gerald Lackner
- Junior
Research Group Synthetic Microbiology, Leibniz
Institute for Natural Product Research and Infection Biology—Hans
Knöll Institute, Beutenbergstr. 11a, 07745 Jena, Germany,
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9
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Clark KA, Bushin LB, Seyedsayamdost MR. RaS-RiPPs in Streptococci and the Human Microbiome. ACS BIO & MED CHEM AU 2022; 2:328-339. [PMID: 35996476 PMCID: PMC9389541 DOI: 10.1021/acsbiomedchemau.2c00004] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
![]()
Radical S-adenosylmethionine (RaS) enzymes have
quickly advanced to one of the most abundant and versatile enzyme
superfamilies known. Their chemistry is predicated upon reductive
homolytic cleavage of a carbon–sulfur bond in cofactor S-adenosylmethionine forming an oxidizing carbon-based radical,
which can initiate myriad radical transformations. An emerging role
for RaS enzymes is their involvement in the biosynthesis of ribosomally
synthesized and post-translationally modified peptides (RiPPs), a
natural product family that has become known as RaS-RiPPs. These metabolites
are especially prevalent in human and mammalian microbiomes because
the complex chemistry of RaS enzymes gives rise to correspondingly
complex natural products with minimal cellular energy and genomic
fingerprint, a feature that is advantageous in microbes with small,
host-adapted genomes in competitive environments. Herein, we review
the discovery and characterization of RaS-RiPPs from the human microbiome
with a focus on streptococcal bacteria. We discuss the varied chemical
modifications that RaS enzymes introduce onto their peptide substrates
and the diverse natural products that they give rise to. The majority
of RaS-RiPPs remain to be discovered, providing an intriguing avenue
for future investigations at the intersection of metalloenzymology,
chemical ecology, and the human microbiome.
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Affiliation(s)
- 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
| | - 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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10
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Fu B, Nazemi A, Levin BJ, Yang Z, Kulik HJ, Balskus EP. Mechanistic Studies of a Skatole-Forming Glycyl Radical Enzyme Suggest Reaction Initiation via Hydrogen Atom Transfer. J Am Chem Soc 2022; 144:11110-11119. [PMID: 35704859 PMCID: PMC9248008 DOI: 10.1021/jacs.1c13580] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Gut microbial decarboxylation
of amino acid-derived arylacetates
is a chemically challenging enzymatic transformation which generates
small molecules that impact host physiology. The glycyl radical enzyme
(GRE) indoleacetate decarboxylase from Olsenella uli (Ou IAD) performs the non-oxidative radical decarboxylation
of indole-3-acetate (I3A) to yield skatole, a disease-associated metabolite
produced in the guts of swine and ruminants. Despite the importance
of IAD, our understanding of its mechanism is limited. Here, we characterize
the mechanism of Ou IAD, evaluating previously proposed
hypotheses of: (1) a Kolbe-type decarboxylation reaction involving
an initial 1-e– oxidation of the carboxylate of
I3A or (2) a hydrogen atom abstraction from the α-carbon of
I3A to generate an initial carbon-centered radical. Site-directed
mutagenesis, kinetic isotope effect experiments, analysis of reactions
performed in D2O, and computational modeling are consistent
with a mechanism involving initial hydrogen atom transfer. This finding
expands the types of radical mechanisms employed by GRE decarboxylases
and non-oxidative decarboxylases, more broadly. Elucidating the mechanism
of IAD decarboxylation enhances our understanding of radical enzymes
and may inform downstream efforts to modulate this disease-associated
metabolism.
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Affiliation(s)
- Beverly Fu
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Azadeh Nazemi
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Benjamin J Levin
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Zhongyue Yang
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Heather J Kulik
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Emily P Balskus
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States.,Howard Hughes Medical Institute, Harvard University, Cambridge, Massachusetts 02138, United States
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11
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Lee YH, Hou X, Chen R, Feng J, Liu X, Ruszczycky MW, Gao JM, Wang B, Zhou J, Liu HW. Radical S-Adenosyl Methionine Enzyme BlsE Catalyzes a Radical-Mediated 1,2-Diol Dehydration during the Biosynthesis of Blasticidin S. J Am Chem Soc 2022; 144:4478-4486. [PMID: 35238201 DOI: 10.1021/jacs.1c12010] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The biosynthesis of blasticidin S has drawn attention due to the participation of the radical S-adenosyl methionine (SAM) enzyme BlsE. The original assignment of BlsE as a radical-mediated, redox-neutral decarboxylase is unusual because this reaction appears to serve no biosynthetic purpose and would need to be reversed by a subsequent carboxylation step. Furthermore, with the exception of BlsE, all other radical SAM decarboxylases reported to date are oxidative in nature. Careful analysis of the BlsE reaction, however, demonstrates that BlsE is not a decarboxylase but instead a lyase that catalyzes the dehydration of cytosylglucuronic acid (CGA) to form cytosyl-4'-keto-3'-deoxy-d-glucuronic acid, which can rapidly decarboxylate nonenzymatically in vitro. Analysis of substrate isotopologs, fluorinated analogues, as well as computational models based on X-ray crystal structures of the BlsE·SAM (2.09 Å) and BlsE·SAM·CGA (2.62 Å) complexes suggests that BlsE catalysis likely proceeds via direct elimination of water from the CGA C4' α-hydroxyalkyl radical as opposed to 1,2-migration of the C3'-hydroxyl prior to dehydration. Biosynthetic and mechanistic implications of the revised assignment of BlsE are discussed.
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Affiliation(s)
- Yu-Hsuan Lee
- 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
| | - Ridao Chen
- Division of Chemical Biology & Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712, United States.,State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
| | - Jianqiang Feng
- State Key Laboratory of 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, China
| | - Xiao Liu
- Division of Chemical Biology & Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712, United States.,School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 100029, China
| | - Mark W Ruszczycky
- Division of Chemical Biology & Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712, United States
| | - Jin-Ming Gao
- Shaanxi Key Laboratory of Natural Products & Chemical Biology, College of Chemistry & Pharmacy, Northwest A&F University, Yangling 712100, Shaanxi China
| | - Binju Wang
- State Key Laboratory of 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, China
| | - 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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12
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Mendauletova A, Kostenko A, Lien Y, Latham J. How a Subfamily of Radical S-Adenosylmethionine Enzymes Became a Mainstay of Ribosomally Synthesized and Post-translationally Modified Peptide Discovery. ACS BIO & MED CHEM AU 2022; 2:53-59. [PMID: 37102180 PMCID: PMC10114670 DOI: 10.1021/acsbiomedchemau.1c00045] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
Radical S-adenosylmethionine (rSAM) enzymes are a large and diverse superfamily of enzymes, some of which are known to participate in the biosynthesis of ribosomally synthesized and post-translationally modified peptides (RiPPs). Specifically, a subfamily of rSAM proteins with an elongated C-terminus known as a SPASM domain have become a fixation in the discovery of new RiPP natural products. Arguably, a structural study, a bioinformatic study, and a functional study built the foundation of the research for rSAM-SPASM-protein-modified RiPPs. In this Review, we focus on these three studies and how they initiated what has become an increasingly productive field. In addition, we discuss the current state of RiPPs that depends on rSAM-SPASM proteins and provide guidelines to consider in future research. Lastly, we discuss how genome mining tools have become a powerful means to identify and predict new RiPP natural products. Despite the state of our current knowledge, we do not completely understand the relationship of rSAM-SPASM chemistry, substrate recognition, and the structure-function relationship as it pertains to RiPP biosynthesis, and as such, there remain many interesting findings waiting to be discovered in the future.
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Affiliation(s)
- Aigera Mendauletova
- Department
of Chemistry and Biochemistry, University
of Denver, Denver, Colorado 80210, United States
| | - Anastasiia Kostenko
- Department
of Chemistry and Biochemistry, University
of Denver, Denver, Colorado 80210, United States
| | - Yi Lien
- Department
of Chemistry and Biochemistry, University
of Denver, Denver, Colorado 80210, United States
| | - John Latham
- Department
of Chemistry and Biochemistry, University
of Denver, Denver, Colorado 80210, United States
- ; Tel.: +1 303 871 2533; Fax: +1 303 871 2254
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13
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Zhi N, Zhu H, Qiao J, Dong M. Recent progress in radical SAM enzymes: New reactions and mechanisms. CHINESE SCIENCE BULLETIN-CHINESE 2021. [DOI: 10.1360/tb-2021-1067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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14
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Mendauletova A, Latham JA. Biosynthesis of the redox cofactor mycofactocin is controlled by the transcriptional regulator MftR and induced by long-chain acyl-CoA species. J Biol Chem 2021; 298:101474. [PMID: 34896395 PMCID: PMC8728441 DOI: 10.1016/j.jbc.2021.101474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 11/30/2021] [Accepted: 12/01/2021] [Indexed: 11/11/2022] Open
Abstract
Mycofactocin (MFT) is a ribosomally synthesized and post-translationally-modified redox cofactor found in pathogenic mycobacteria. While MFT biosynthetic proteins have been extensively characterized, the physiological conditions under which MFT biosynthesis is required are not well understood. To gain insights into the mechanisms of regulation of MFT expression in Mycobacterium smegmatis mc2155, we investigated the DNA-binding and ligand-binding activities of the putative TetR-like transcription regulator, MftR. In this study, we demonstrated that MftR binds to the mft promoter region. We used DNase I footprinting to identify the 27 bp palindromic operator located 5′ to mftA and found it to be highly conserved in Mycobacterium tuberculosis, Mycobacterium bovis, Mycobacterium ulcerans, and Mycobacterium marinum. To determine under which conditions the mft biosynthetic gene cluster (BGC) is induced, we screened for effectors of MftR. As a result, we found that MftR binds to long-chain acyl-CoAs with low micromolar affinities. To demonstrate that oleoyl-CoA induces the mft BGC in vivo, we re-engineered a fluorescent protein reporter system to express an MftA–mCherry fusion protein. Using this mCherry fluorescent readout, we show that the mft BGC is upregulated in M. smegmatis mc2155 when oleic acid is supplemented to the media. These results suggest that MftR controls expression of the mft BGC and that MFT production is induced by long-chain acyl-CoAs. Since MFT-dependent dehydrogenases are known to colocalize with acyl carrier protein/CoA-modifying enzymes, these results suggest that MFT might be critical for fatty acid metabolism or cell wall reorganization.
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Affiliation(s)
- Aigera Mendauletova
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado, USA
| | - John A Latham
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado, USA.
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15
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Besandre RA, Chen Z, Davis I, Zhang J, Ruszczycky MW, Liu A, Liu HW. HygY Is a Twitch Radical SAM Epimerase with Latent Dehydrogenase Activity Revealed upon Mutation of a Single Cysteine Residue. J Am Chem Soc 2021; 143:15152-15158. [PMID: 34491039 DOI: 10.1021/jacs.1c05727] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
HygY is a SPASM/twitch radical SAM enzyme hypothesized to catalyze the C2'-epimerization of galacamine during the biosynthesis of hygromycin B. This activity is confirmed via biochemical and structural analysis of the derivatized reaction products using chemically synthesized deuterated substrate, high-resolution mass spectrometry and 1H NMR. Electron paramagnetic resonance spectroscopy of the reduced enzyme is consistent with ligation of two [Fe4S4] clusters characteristic of the twitch radical SAM subgroup. HygY catalyzed epimerization proceeds with incorporation of a single solvent Hydron into the talamine product facilitated by the catalytic cysteine-183 residue. Mutation of this cysteine to alanine converts HygY from a C2'-epimerase to an C2'-dehydrogenase with comparable activity. The SPASM/twitch radical SAM enzymes often serve as anaerobic oxidases making the redox-neutral epimerases in this class rather interesting. The discovery of latent dehydrogenase activity in a twitch epimerase may therefore offer new insights into the mechanistic features that distinguish oxidative versus redox-neutral SPASM/twitch enzymes and lead to the evolution of new enzyme activities.
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Affiliation(s)
- Ronald A Besandre
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712, United States
| | - Zhang Chen
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712, United States
| | - Ian Davis
- Department of Chemistry, University of Texas at San Antonio, San Antonio, TX 78249, United States
| | - Jiawei Zhang
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712, United States
| | - Mark Walter Ruszczycky
- Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, TX 78712, United States
| | - Aimin Liu
- Department of Chemistry, University of Texas at San Antonio, San Antonio, TX 78249, United States
| | - Hung-Wen Liu
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712, United States.,Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, TX 78712, United States
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16
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Balo AR, Tao L, Britt RD. Characterizing SPASM/twitch Domain-Containing Radical SAM Enzymes by EPR Spectroscopy. APPLIED MAGNETIC RESONANCE 2021; 53:809-820. [PMID: 35509369 PMCID: PMC9012708 DOI: 10.1007/s00723-021-01406-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 07/28/2021] [Accepted: 07/30/2021] [Indexed: 06/14/2023]
Abstract
Owing to their importance, diversity and abundance of generated paramagnetic species, radical S-adenosylmethionine (rSAM) enzymes have become popular targets for electron paramagnetic resonance (EPR) spectroscopic studies. In contrast to prototypic single-domain and thus single-[4Fe-4S]-containing rSAM enzymes, there is a large subfamily of rSAM enzymes with multiple domains and one or two additional iron-sulfur cluster(s) called the SPASM/twitch domain-containing rSAM enzymes. EPR spectroscopy is a powerful tool that allows for the observation of the iron-sulfur clusters as well as potentially trappable paramagnetic reaction intermediates. Here, we review continuous-wave and pulse EPR spectroscopic studies of SPASM/twitch domain-containing rSAM enzymes. Among these enzymes, we will review in greater depth four well-studied enzymes, BtrN, MoaA, PqqE, and SuiB. Towards establishing a functional consensus of the additional architecture in these enzymes, we describe the commonalities between these enzymes as observed by EPR spectroscopy.
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Affiliation(s)
- Aidin R. Balo
- Department of Chemistry, University of California, Davis, CA 95616 USA
| | - Lizhi Tao
- Department of Chemistry, University of California, Davis, CA 95616 USA
| | - R. David Britt
- Department of Chemistry, University of California, Davis, CA 95616 USA
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17
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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: 399] [Impact Index Per Article: 133.0] [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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18
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Peña-Ortiz L, Schlembach I, Lackner G, Regestein L. Impact of Oxygen Supply and Scale Up on Mycobacterium smegmatis Cultivation and Mycofactocin Formation. Front Bioeng Biotechnol 2020; 8:593781. [PMID: 33344432 PMCID: PMC7744413 DOI: 10.3389/fbioe.2020.593781] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 11/16/2020] [Indexed: 11/13/2022] Open
Abstract
Mycofactocin (MFT) is a recently discovered glycosylated redox cofactor, which has been associated with the detoxification of antibiotics in pathogenic mycobacteria, and, therefore, of potential medical interest. The MFT biosynthetic gene cluster is commonly found in mycobacteria, including Mycobacterium tuberculosis, the causative agent of tuberculosis. Since the MFT molecule is highly interesting for basic research and could even serve as a potential drug target, large-scale production of the molecule is highly desired. However, conventional shake flask cultivations failed to produce enough MFT for further biochemical characterization like kinetic studies and structure elucidation, and a more comprehensive study of cultivation parameters is urgently needed. Being a redox cofactor, it can be hypothesized that the oxygen transfer rate (OTR) is a critical parameter for MFT formation. Using the non-pathogenic strain Mycobacterium smegmatis mc2 155, shake flask experiments with online measurement of the oxygen uptake and the carbon dioxide formation, were conducted under different levels of oxygen supply. Using liquid chromatography and high-resolution mass spectrometry, a 4-8 times increase of MFT production was identified under oxygen-limited conditions, in both complex and mineral medium. Moreover, the level of oxygen supply modulates not only the overall MFT formation but also the length of the glycosidic chain. Finally, all results were scaled up into a 7 L stirred tank reactor to elucidate the kinetics of MFT formation. Ultimately, this study enables the production of high amounts of these redox cofactors, to perform further investigations into the role and importance of MFTs.
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Affiliation(s)
- Luis Peña-Ortiz
- Junior Research Group Synthetic Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena, Germany
| | - Ivan Schlembach
- Bio Pilot Plant, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena, Germany
- Faculty of Biological Sciences, Friedrich-Schiller-University, Jena, Germany
| | - Gerald Lackner
- Junior Research Group Synthetic Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena, Germany
| | - Lars Regestein
- Bio Pilot Plant, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena, Germany
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19
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Nguyen TQN, Tooh YW, Sugiyama R, Nguyen TPD, Purushothaman M, Leow LC, Hanif K, Yong RHS, Agatha I, Winnerdy FR, Gugger M, Phan AT, Morinaka BI. Post-translational formation of strained cyclophanes in bacteria. Nat Chem 2020; 12:1042-1053. [DOI: 10.1038/s41557-020-0519-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 07/04/2020] [Indexed: 11/09/2022]
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20
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Lu J, Wang B, Shaik S, Lai W. QM/MM Calculations Reveal the Important Role of α-Heteroatom Substituents in Controlling Selectivity of Mononuclear Nonheme HppE-Catalyzed Reactions. ACS Catal 2020. [DOI: 10.1021/acscatal.0c01803] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Jiarui Lu
- Department of Chemistry, Renmin University of China, Beijing 100872, China
| | - Binju Wang
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 360015, P. R. China
| | - Sason Shaik
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - Wenzhen Lai
- Department of Chemistry, Renmin University of China, Beijing 100872, China
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21
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Zhu W, Walker LM, Tao L, Iavarone AT, Wei X, Britt RD, Elliott SJ, Klinman JP. Structural Properties and Catalytic Implications of the SPASM Domain Iron-Sulfur Clusters in Methylorubrum extorquens PqqE. J Am Chem Soc 2020; 142:12620-12634. [PMID: 32643933 DOI: 10.1021/jacs.0c02044] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Understanding the relationship between the metallocofactor and its protein environment is the key to uncovering the mechanism of metalloenzymes. PqqE, a radical S-adenosylmethionine enzyme in pyrroloquinoline quinone (PQQ) biosynthesis, contains three iron-sulfur cluster binding sites. Two auxiliary iron-sulfur cluster binding sites, designated as AuxI and AuxII, use distinctive ligands compared to other proteins in the family while their functions remain unclear. Here, we investigate the electronic properties of these iron-sulfur clusters and compare the catalytic efficiency of wild-type (WT) Methylorubrum extorquens AM1 PqqE to a range of mutated constructs. Using native mass spectrometry, protein film electrochemistry, and electron paramagnetic resonance spectroscopy, we confirm the previously proposed incorporation of a mixture of [2Fe-2S] and [4Fe-4S] clusters at the AuxI site and are able to assign redox potentials to each of the three iron-sulfur clusters. Significantly, a conservative mutation at AuxI, C268H, shown to selectively incorporate a [4Fe-4S] cluster, catalyzes an enhancement of uncoupled S-adenosylmethionine cleavage relative to WT, together with the elimination of detectable peptide cross-linked product. While a [4Fe-4S] cluster can be tolerated at the AuxI site, the aggregate findings suggest a functional [2Fe-2S] configuration within the AuxI site. PqqE variants with nondestructive ligand replacements at AuxII also show that the reduction potential at this site can be manipulated by changing the electronegativity of the unique aspartate ligand. A number of novel mechanistic features are proposed based on the kinetic and spectroscopic data. Additionally, bioinformatic analyses suggest that the unique ligand environment of PqqE may be relevant to its role in PQQ biosynthesis within an oxygen-dependent biosynthetic pathway.
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Affiliation(s)
- Wen Zhu
- California Institute for Quantitative Biosciences, University of California-Berkeley, Berkeley, California 94720, United States
| | - Lindsey M Walker
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
| | - Lizhi Tao
- Department of Chemistry, University of California-Davis, Davis, California 95616, United States
| | - Anthony T Iavarone
- California Institute for Quantitative Biosciences, University of California-Berkeley, Berkeley, California 94720, United States
| | - Xuetong Wei
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, California 94720, United States
| | - R David Britt
- Department of Chemistry, University of California-Davis, Davis, California 95616, United States
| | - Sean J Elliott
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
| | - Judith P Klinman
- California Institute for Quantitative Biosciences, University of California-Berkeley, Berkeley, California 94720, United States.,Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, California 94720, United States.,Department of Chemistry, University of California-Berkeley, Berkeley, California 94720, United States
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22
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Peña-Ortiz L, Graça AP, Guo H, Braga D, Köllner TG, Regestein L, Beemelmanns C, Lackner G. Structure elucidation of the redox cofactor mycofactocin reveals oligo-glycosylation by MftF. Chem Sci 2020; 11:5182-5190. [PMID: 33014324 PMCID: PMC7491314 DOI: 10.1039/d0sc01172j] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 04/18/2020] [Indexed: 01/13/2023] Open
Abstract
Mycofactocin (MFT) is a redox cofactor belonging to the family of ribosomally synthesized and post-translationally modified peptides (RiPPs) and is involved in alcohol metabolism of mycobacteria including Mycobacterium tuberculosis. A preliminary biosynthetic model had been established by bioinformatics and in vitro studies, while the structure of natural MFT and key biosynthetic steps remained elusive. Here, we report the discovery of glycosylated MFT by 13C-labeling metabolomics and establish a model of its biosynthesis in Mycolicibacterium smegmatis. Extensive structure elucidation including NMR revealed that MFT is decorated with up to nine β-1,4-linked glucose residues including 2-O-methylglucose. Dissection of biosynthetic genes demonstrated that the oligoglycosylation is catalyzed by the glycosyltransferase MftF. Furthermore, we confirm the redox cofactor function of glycosylated MFTs by activity-based metabolic profiling using the carveol dehydrogenase LimC and show that the MFT pool expands during cultivation on ethanol. Our results will guide future studies into the biochemical functions and physiological roles of MFT in bacteria.
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Affiliation(s)
- Luis Peña-Ortiz
- Junior Research Group Synthetic Microbiology , Leibniz Institute for Natural Product Research and Infection Biology (HKI) , Beutenbergstr. 11a , 07745 Jena , Germany . .,Friedrich Schiller University , Beutenbergstr. 11a , 07745 Jena , Germany
| | - Ana Patrícia Graça
- Junior Research Group Synthetic Microbiology , Leibniz Institute for Natural Product Research and Infection Biology (HKI) , Beutenbergstr. 11a , 07745 Jena , Germany . .,Friedrich Schiller University , Beutenbergstr. 11a , 07745 Jena , Germany
| | - Huijuan Guo
- Junior Research Group Chemical Biology of Microbe-Host Interactions , Leibniz Institute for Natural Product Research and Infection Biology (HKI) , Beutenbergstr. 11a , 07745 Jena , Germany
| | - Daniel Braga
- Junior Research Group Synthetic Microbiology , Leibniz Institute for Natural Product Research and Infection Biology (HKI) , Beutenbergstr. 11a , 07745 Jena , Germany . .,Friedrich Schiller University , Beutenbergstr. 11a , 07745 Jena , Germany
| | - Tobias G Köllner
- Department of Biochemistry , Max Planck Institute for Chemical Ecology , Hans-Knöll-Str. 8 , 07745 Jena , Germany
| | - Lars Regestein
- Bio Pilot Plant , Leibniz Institute for Natural Product Research and Infection Biology (HKI) , Beutenbergstr. 11a , 07745 Jena , Germany
| | - Christine Beemelmanns
- Junior Research Group Chemical Biology of Microbe-Host Interactions , Leibniz Institute for Natural Product Research and Infection Biology (HKI) , Beutenbergstr. 11a , 07745 Jena , Germany
| | - Gerald Lackner
- Junior Research Group Synthetic Microbiology , Leibniz Institute for Natural Product Research and Infection Biology (HKI) , Beutenbergstr. 11a , 07745 Jena , Germany . .,Friedrich Schiller University , Beutenbergstr. 11a , 07745 Jena , Germany
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23
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Li H, Liu Y. Mechanistic Investigation of Isonitrile Formation Catalyzed by the Nonheme Iron/α-KG-Dependent Decarboxylase (ScoE). ACS Catal 2020. [DOI: 10.1021/acscatal.9b05411] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Hong Li
- Key Lab of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan, Shandong 250100, China
| | - Yongjun Liu
- Key Lab of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan, Shandong 250100, China
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24
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Jin WB, Wu S, Xu YF, Yuan H, Tang GL. Recent advances in HemN-like radical S-adenosyl-l-methionine enzyme-catalyzed reactions. Nat Prod Rep 2020; 37:17-28. [DOI: 10.1039/c9np00032a] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
HemN-like radical S-adenosyl-l-methionine (SAM) enzymes have been recently disclosed to catalyze diverse chemically challenging reactions from primary to secondary metabolic pathways.
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Affiliation(s)
- Wen-Bing Jin
- State Key Laboratory of Bio-organic and Natural Products Chemistry
- Center for Excellence in Molecular Synthesis
- Shanghai Institute of Organic Chemistry
- University of Chinese Academy of Sciences
- Chinese Academy of Sciences
| | - Sheng Wu
- State Key Laboratory of Bio-organic and Natural Products Chemistry
- Center for Excellence in Molecular Synthesis
- Shanghai Institute of Organic Chemistry
- University of Chinese Academy of Sciences
- Chinese Academy of Sciences
| | - Yi-Fan Xu
- State Key Laboratory of Bio-organic and Natural Products Chemistry
- Center for Excellence in Molecular Synthesis
- Shanghai Institute of Organic Chemistry
- University of Chinese Academy of Sciences
- Chinese Academy of Sciences
| | - Hua Yuan
- State Key Laboratory of Bio-organic and Natural Products Chemistry
- Center for Excellence in Molecular Synthesis
- Shanghai Institute of Organic Chemistry
- University of Chinese Academy of Sciences
- Chinese Academy of Sciences
| | - Gong-Li Tang
- State Key Laboratory of Bio-organic and Natural Products Chemistry
- Center for Excellence in Molecular Synthesis
- Shanghai Institute of Organic Chemistry
- University of Chinese Academy of Sciences
- Chinese Academy of Sciences
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25
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Tao L, Zhu W, Klinman JP, Britt RD. Electron Paramagnetic Resonance Spectroscopic Identification of the Fe-S Clusters in the SPASM Domain-Containing Radical SAM Enzyme PqqE. Biochemistry 2019; 58:5173-5187. [PMID: 31769977 DOI: 10.1021/acs.biochem.9b00960] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Pyrroloquinoline quinone (PQQ) is an important redox active quinocofactor produced by a wide variety of bacteria. A key step in PQQ biosynthesis is a carbon-carbon cross-link reaction between glutamate and tyrosine side chains within the ribosomally synthesized peptide substrate PqqA. This reaction is catalyzed by the radical SAM enzyme PqqE. Previous X-ray crystallographic and spectroscopic studies suggested that PqqE, like the other members of the SPASM domain family, contains two auxiliary Fe-S clusters (AuxI and AuxII) in addition to the radical SAM [4Fe-4S] cluster. However, a clear assignment of the electron paramagnetic resonance (EPR) signal of each Fe-S cluster was hindered by the isolation of a His6-tagged PqqE variant with an altered AuxI cluster. In this work, we are able to isolate soluble PqqE variants by using a less disruptive strep-tactin chromatographic approach. We have unambiguously identified the EPR signatures for four forms of Fe-S clusters present in PqqE through the use of multifrequency EPR spectroscopy: the RS [4Fe-4S] cluster, the AuxII [4Fe-4S] cluster, and two different clusters ([4Fe-4S] and [2Fe-2S]) bound in the AuxI site. The RS [4Fe-4S] cluster, the AuxII [4Fe-4S] cluster, and the [2Fe-2S] cluster form in the AuxI site can all be reduced by sodium dithionite, with g tensors of their reduced form determined as [2.040, 1.927, 1.897], [2.059, 1.940, 1.903], and [2.004, 1.958, 1.904], respectively. The AuxI [4Fe-4S] cluster that is determined on the basis of its relaxation profile can be reduced only by using low-potential reductants such as Ti(III) citrate or Eu(II)-DTPA to give rise to a g1 = 2.104 signal. Identification of the EPR signature for each cluster paves the way for further investigations of SPASM domain radical SAM enzymes.
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Affiliation(s)
- Lizhi Tao
- Department of Chemistry , University of California , Davis , California 95616 , United States
| | - Wen Zhu
- Department of Chemistry, Department of Molecular and Cell Biology, and California Institute for Quantitative Biosciences , University of California , Berkeley , California 94720 , United States
| | - Judith P Klinman
- Department of Chemistry, Department of Molecular and Cell Biology, and California Institute for Quantitative Biosciences , University of California , Berkeley , California 94720 , United States
| | - R David Britt
- Department of Chemistry , University of California , Davis , California 95616 , United States
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26
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Suess CJ, Martins FL, Croft AK, Jäger CM. Radical Stabilization Energies for Enzyme Engineering: Tackling the Substrate Scope of the Radical Enzyme QueE. J Chem Inf Model 2019; 59:5111-5125. [PMID: 31730347 DOI: 10.1021/acs.jcim.9b00017] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Experimental assessment of catalytic reaction mechanisms and profiles of radical enzymes can be severely challenging due to the reactive nature of the intermediates and sensitivity of cofactors such as iron-sulfur clusters. Here, we present an enzyme-directed computational methodology for the assessment of thermodynamic reaction profiles and screening for radical stabilization energies (RSEs) for the assessment of catalytic turnovers in radical enzymes. We have applied this new screening method to the radical S-adenosylmethione enzyme 7-carboxy-7-deazaguanine synthase (QueE), following a detailed molecular dynamics (MD) analysis that clarifies the role of both specific enzyme residues and bound Mg2+, Ca2+, or Na+. The MD simulations provided the basis for a statistical approach to sample different conformational outcomes. RSE calculation at the M06-2X/6-31+G* level of theory provided the most computationally cost-effective assessment of enzyme-based energies, facilitated by an initial triage using semiempirical methods. The impact of intermolecular interactions on RSE was clearly established, and application to the assessment of potential alternative substrates (focusing on radical clock type rearrangements) proposes a selection of carbon-substituted analogues that would react to afford cyclopropylcarbinyl radical intermediates as candidates for catalytic turnover by QueE.
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Affiliation(s)
- Christian J Suess
- Department of Chemical and Environmental Engineering , The University of Nottingham , University Park, Nottingham NG7 2RD , United Kingdom
| | - Floriane L Martins
- Department of Chemical and Environmental Engineering , The University of Nottingham , University Park, Nottingham NG7 2RD , United Kingdom
| | - Anna K Croft
- Department of Chemical and Environmental Engineering , The University of Nottingham , University Park, Nottingham NG7 2RD , United Kingdom
| | - Christof M Jäger
- Department of Chemical and Environmental Engineering , The University of Nottingham , University Park, Nottingham NG7 2RD , United Kingdom
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27
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Ayikpoe RS, Latham JA. MftD Catalyzes the Formation of a Biologically Active Redox Center in the Biosynthesis of the Ribosomally Synthesized and Post-translationally Modified Redox Cofactor Mycofactocin. J Am Chem Soc 2019; 141:13582-13591. [PMID: 31381312 DOI: 10.1021/jacs.9b06102] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Mycofactocin (MFT) is a putative ribosomally synthesized and post-translationally modified (RiPP) redox cofactor. The biosynthesis of MFT is encoded by the gene cluster mftABCDEF. While processing of the precursor peptide by MftB, MftC, and MftE has been shown to result in the formation of the small molecule 3-amino-5-[(p-hydroxyphenyl)methyl]-4,4-dimethyl-2-pyrrolidinone (AHDP), no activity has been shown for the putative dehydrogenase MftD and the putative glycosyltransferase MftF. In addition, evidence demonstrating that MFT is a redox cofactor has only been limited to the requirement of mft genes for ethanol assimilation in Mycobacterium smegmatis mc2155. Here, we demonstrate that MftD catalyzes the oxidative deamination of AHDP, forming an α-keto moiety on the resulting molecule, which we call pre-mycofactocin (PMFT). We characterize PMFT by 1D and 2D NMR spectroscopy techniques and by high-resolution mass spectrometry data to solve its structure. We further characterized PMFT by cyclic voltammetry and found its midpoint potential to be ∼255 mV. Lastly, we demonstrate that PMFT is a biologically active redox cofactor that oxidizes NADH bound by M. smegmatis carveol dehydrogenase (MsCDH) and can be used by MsCDH in the oxidation of carveol. These data demonstrate for the first time that PMFT functions as a biologically active redox mediator and provides the most direct evidence to date that MFT is a RiPP-derived redox cofactor.
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Affiliation(s)
- Richard S Ayikpoe
- Department of Chemistry and Biochemistry , University of Denver , Denver , Colorado 80210 , United States
| | - John A Latham
- Department of Chemistry and Biochemistry , University of Denver , Denver , Colorado 80210 , United States
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28
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Abstract
Bacterial natural products display astounding structural diversity, which, in turn, endows them with a remarkable range of biological activities that are of significant value to modern society. Such structural features are generated by biosynthetic enzymes that construct core scaffolds or perform peripheral modifications, and can thus define natural product families, introduce pharmacophores and permit metabolic diversification. Modern genomics approaches have greatly enhanced our ability to access and characterize natural product pathways via sequence-similarity-based bioinformatics discovery strategies. However, many biosynthetic enzymes catalyse exceptional, unprecedented transformations that continue to defy functional prediction and remain hidden from us in bacterial (meta)genomic sequence data. In this Review, we highlight exciting examples of unusual enzymology that have been uncovered recently in the context of natural product biosynthesis. These suggest that much of the natural product diversity, including entire substance classes, awaits discovery. New approaches to lift the veil on the cryptic chemistries of the natural product universe are also discussed.
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29
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Abstract
Mycofactocin (MFT) belongs to the class of ribosomally synthesized and posttranslationally modified peptides conserved in many Actinobacteria Mycobacterium tuberculosis assimilates cholesterol during chronic infection, and its in vitro growth in the presence of cholesterol requires most of the MFT biosynthesis genes (mftA, mftB, mftC, mftD, mftE, and mftF), although the reasons for this requirement remain unclear. To identify the function of MFT, we characterized MFT biosynthesis mutants constructed in Mycobacterium smegmatis, M. marinum, and M. tuberculosis We found that the growth deficit of mft deletion mutants in medium containing cholesterol-a phenotypic basis for gene essentiality prediction-depends on ethanol, a solvent used to solubilize cholesterol. Furthermore, functionality of MFT was strictly required for growth of free-living mycobacteria in ethanol and other primary alcohols. Among other genes encoding predicted MFT-associated dehydrogenases, MSMEG_6242 was indispensable for M. smegmatis ethanol assimilation, suggesting that it is a candidate catalytic interactor with MFT. Despite being a poor growth substrate, ethanol treatment resulted in a reductive cellular state with NADH accumulation in M. tuberculosis During ethanol treatment, mftC mutant expressed the transcriptional signatures that are characteristic of respirational dysfunction and a redox-imbalanced cellular state. Counterintuitively, there were no differences in cellular bioenergetics and redox parameters in mftC mutant cells treated with ethanol. Therefore, further understanding of the function of MFT in ethanol metabolism is required to identify the cause of growth retardation of MFT mutants in cholesterol. Nevertheless, our results establish the physiological role of MFT and also provide new insights into the specific functions of MFT homologs in other actinobacterial systems.IMPORTANCE Tuberculosis is caused by Mycobacterium tuberculosis, and the increasing emergence of multidrug-resistant strains renders current treatment options ineffective. Although new antimycobacterial drugs are urgently required, their successful development often relies on complete understanding of the metabolic pathways-e.g., cholesterol assimilation-that are critical for persistence and for pathogenesis of M. tuberculosis In this regard, mycofactocin (MFT) function appears to be important because its biosynthesis genes are predicted to be essential for M. tuberculosis in vitro growth in cholesterol. In determining the metabolic basis of this genetic requirement, our results unexpectedly revealed the essential function of MFT in ethanol metabolism. The metabolic dysfunction thereof was found to affect the mycobacterial growth in cholesterol which is solubilized by ethanol. This knowledge is fundamental in recognizing the bona fide function of MFT, which likely resembles the pyrroloquinoline quinone-dependent ethanol oxidation in acetic acid bacteria exploited for industrial production of vinegar.
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30
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Occurrence, function, and biosynthesis of mycofactocin. Appl Microbiol Biotechnol 2019; 103:2903-2912. [PMID: 30778644 DOI: 10.1007/s00253-019-09684-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 02/04/2019] [Accepted: 02/05/2019] [Indexed: 10/27/2022]
Abstract
Mycofactocin is a member of the rapidly growing class of ribosomally synthesized and post-translationally modified peptide (RiPP) natural products. Although the mycofactocin biosynthetic pathway is widely distributed among Mycobacterial species, the structure, function, and biosynthesis of the pathway product remain unknown. This mini-review will discuss the current state of knowledge regarding the mycofactocin biosynthetic pathway. In particular, we focus on the architecture and distribution of the mycofactocin biosynthetic cluster, mftABCDEF, among the Actinobacteria phylum. We discuss the potential molecular and physiological role of mycofactocin. We review known biosynthetic steps involving MftA, MftB, MftC, and MftE and relate them to pyrroloquinoline quinone biosynthesis. Lastly, we propose the function of the remaining putative biosynthetic enzymes, MftD and MftF.
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31
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Ayikpoe R, Ngendahimana T, Langton M, Bonitatibus S, Walker LM, Eaton SS, Eaton GR, Pandelia ME, Elliott SJ, Latham JA. Spectroscopic and Electrochemical Characterization of the Mycofactocin Biosynthetic Protein, MftC, Provides Insight into Its Redox Flipping Mechanism. Biochemistry 2019; 58:940-950. [PMID: 30628436 DOI: 10.1021/acs.biochem.8b01082] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mycofactocin is a putative redox cofactor and is classified as a ribosomally synthesized and post-translationally modified peptide (RiPP). Some RiPP natural products, including mycofactocin, rely on a radical S-adenosylmethionine (RS, SAM) protein to modify the precursor peptide. Mycofactocin maturase, MftC, is a unique RS protein that catalyzes the oxidative decarboxylation and C-C bond formation on the precursor peptide MftA. However, the number, chemical nature, and catalytic roles for the MftC [Fe-S] clusters remain unknown. Here, we report that MftC binds a RS [4Fe-4S] cluster and two auxiliary [4Fe-4S] clusters that are required for MftA modification. Furthermore, electron paramagnetic resonance spectra of MftC suggest that SAM and MftA affect the environments of the RS and Aux I cluster, whereas the Aux II cluster is unaffected by the substrates. Lastly, reduction potential assignments of individual [4Fe-4S] clusters by protein film voltammetry show that their potentials are within 100 mV of each other.
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Affiliation(s)
- Richard Ayikpoe
- Department of Chemistry and Biochemistry , University of Denver , Denver , Colorado 80208 , United States
| | - Thacien Ngendahimana
- Department of Chemistry and Biochemistry , University of Denver , Denver , Colorado 80208 , United States
| | - Michelle Langton
- Department of Biochemistry , Brandeis University , Waltham , Massachusetts 02453 , United States
| | - Sheila Bonitatibus
- Department of Chemistry , Boston University , Boston , Massachusetts 02215 , United States
| | - Lindsey M Walker
- Department of Chemistry , Boston University , Boston , Massachusetts 02215 , United States
| | - Sandra S Eaton
- Department of Chemistry and Biochemistry , University of Denver , Denver , Colorado 80208 , United States
| | - Gareth R Eaton
- Department of Chemistry and Biochemistry , University of Denver , Denver , Colorado 80208 , United States
| | - Maria-Eirini Pandelia
- Department of Biochemistry , Brandeis University , Waltham , Massachusetts 02453 , United States
| | - Sean J Elliott
- Department of Chemistry , Boston University , Boston , Massachusetts 02215 , United States
| | - John A Latham
- Department of Chemistry and Biochemistry , University of Denver , Denver , Colorado 80208 , United States
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32
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Yu CP, Tang Y, Cha L, Milikisiyants S, Smirnova TI, Smirnov AI, Guo Y, Chang WC. Elucidating the Reaction Pathway of Decarboxylation-Assisted Olefination Catalyzed by a Mononuclear Non-Heme Iron Enzyme. J Am Chem Soc 2018; 140:15190-15193. [PMID: 30376630 DOI: 10.1021/jacs.8b10077] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Installation of olefins into molecules is a key transformation in organic synthesis. The recently discovered decarboxylation-assisted olefination in the biosynthesis of rhabduscin by a mononuclear non-heme iron enzyme ( P.IsnB) represents a novel approach in olefin construction. This method is commonly employed in natural product biosynthesis. Herein, we demonstrate that a ferryl intermediate is used for C-H activation at the benzylic position of the substrate. We further establish that P.IsnB reactivity can be switched from olefination to hydroxylation using electron-withdrawing groups appended on the phenyl moiety of the analogues. These experimental observations imply that a pathway involving an initial C-H activation followed by a benzylic carbocation species or by electron transfer coupled β-scission is likely utilized to complete C═C bond formation.
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Affiliation(s)
- Cheng-Ping Yu
- Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695 , United States
| | - Yijie Tang
- Department of Chemistry , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States
| | - Lide Cha
- Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695 , United States
| | - Sergey Milikisiyants
- Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695 , United States
| | - Tatyana I Smirnova
- Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695 , United States
| | - Alex I Smirnov
- Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695 , United States
| | - 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
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33
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Biocatalytic hydrogen atom transfer: an invigorating approach to free-radical reactions. Curr Opin Chem Biol 2018; 49:16-24. [PMID: 30269010 DOI: 10.1016/j.cbpa.2018.09.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 09/02/2018] [Indexed: 10/28/2022]
Abstract
Initiating and terminating free-radical reactionis via hydrogen atom transfer (HAT) is an attractive means of avoiding substrate prefunctionalization. Small molecule catalysts and reagents, however, struggle to execute this fundamental step with useful levels of diastereoselectivity and enantioselectivity. In contrast, nature often carries out HAT with exquisite levels of selectivity for even electronically unactivated carbon-hydrogen bonds. By understanding how enzymes exploit and control this fundamental step, new strategies can be developed to address several long-standing challenges in free-radical reactions. This review will cover recent discoveries in biocatalysis that exploit a HAT mechanism to either initiate or terminate novel one-electron reactions.
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34
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Ayikpoe R, Salazar J, Majestic B, Latham JA. Mycofactocin Biosynthesis Proceeds through 3-Amino-5-[( p-hydroxyphenyl)methyl]-4,4-dimethyl-2-pyrrolidinone (AHDP); Direct Observation of MftE Specificity toward MftA. Biochemistry 2018; 57:5379-5383. [PMID: 30183269 DOI: 10.1021/acs.biochem.8b00816] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The structure of the ribosomally synthesized and post-translationally modified peptide product mycofactocin is unknown. Recently, the first step in mycofactocin biosynthesis was shown to be catalyzed by MftC in two S-adenosylmethionine-dependent steps. In the first step, MftC catalyzes the oxidative decarboxylation of the MftA peptide to produce the styrene-containing intermediate MftA**, followed by a subsequent C-C bond formation to yield the lactam-containing MftA*. Here, we demonstrate the subsequent biosynthetic step catalyzed by MftE is specific for MftA*. The hydrolysis of MftA* leads to the formation of MftA(1-28) and 3-amino-5-[( p-hydroxyphenyl)methyl]-4,4-dimethyl-2-pyrrolidinone (AHDP). The hydrolysis reaction is Fe2+-dependent, and addition of the metal to the reaction mixture leads to a kobs of ∼0.2 min-1. Lastly, we validate the structure of AHDP by 1H, 13C, and COSY nuclear magnetic resonance techniques as well as mass spectrometry.
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Affiliation(s)
- Richard Ayikpoe
- Department of Chemistry and Biochemistry , University of Denver , Denver , Colorado 80208 , United States
| | - Joe Salazar
- Department of Chemistry and Biochemistry , University of Denver , Denver , Colorado 80208 , United States
| | - Brian Majestic
- Department of Chemistry and Biochemistry , University of Denver , Denver , Colorado 80208 , United States
| | - John A Latham
- Department of Chemistry and Biochemistry , University of Denver , Denver , Colorado 80208 , United States
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35
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Kincannon WM, Bruender NA, Bandarian V. A Radical Clock Probe Uncouples H Atom Abstraction from Thioether Cross-Link Formation by the Radical S-Adenosyl-l-methionine Enzyme SkfB. Biochemistry 2018; 57:4816-4823. [PMID: 29965747 PMCID: PMC6094349 DOI: 10.1021/acs.biochem.8b00537] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Sporulation
killing factor (SKF) is a ribosomally synthesized and
post-translationally modified peptide (RiPP) produced by Bacillus. SKF contains a thioether cross-link between the α-carbon
at position 40 and the thiol of Cys32, introduced by a member of the
radical S-adenosyl-l-methionine (SAM) superfamily,
SkfB. Radical SAM enzymes employ a 4Fe–4S cluster to bind and
reductively cleave SAM to generate a 5′-deoxyadenosyl radical.
SkfB utilizes this radical intermediate to abstract the α-H
atom at Met40 to initiate cross-linking. In addition to the cluster
that binds SAM, SkfB also has an auxiliary cluster, the function of
which is not known. We demonstrate that a substrate analogue with
a cyclopropylglycine (CPG) moiety replacing the wild-type Met40 side
chain forgoes thioether cross-linking for an alternative radical ring
opening of the CPG side chain. The ring opening reaction also takes
place with a catalytically inactive SkfB variant in which the auxiliary
Fe–S cluster is absent. Therefore, the CPG-containing peptide
uncouples H atom abstraction from thioether bond formation, limiting
the role of the auxiliary cluster to promoting thioether cross-link
formation. CPG proves to be a valuable tool for uncoupling H atom
abstraction from peptide modification in RiPP maturases and demonstrates
potential to leverage RS enzyme reactivity to create noncanonical
amino acids.
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Affiliation(s)
- William M Kincannon
- Department of Chemistry , University of Utah , 315 South 1400 East , Salt Lake City , Utah 84112 , United States
| | - Nathan A Bruender
- Department of Chemistry , University of Utah , 315 South 1400 East , Salt Lake City , Utah 84112 , United States
| | - Vahe Bandarian
- Department of Chemistry , University of Utah , 315 South 1400 East , Salt Lake City , Utah 84112 , United States
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36
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Guengerich FP, Yoshimoto FK. Formation and Cleavage of C-C Bonds by Enzymatic Oxidation-Reduction Reactions. Chem Rev 2018; 118:6573-6655. [PMID: 29932643 DOI: 10.1021/acs.chemrev.8b00031] [Citation(s) in RCA: 154] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Many oxidation-reduction (redox) enzymes, particularly oxygenases, have roles in reactions that make and break C-C bonds. The list includes cytochrome P450 and other heme-based monooxygenases, heme-based dioxygenases, nonheme iron mono- and dioxygenases, flavoproteins, radical S-adenosylmethionine enzymes, copper enzymes, and peroxidases. Reactions involve steroids, intermediary metabolism, secondary natural products, drugs, and industrial and agricultural chemicals. Many C-C bonds are formed via either (i) coupling of diradicals or (ii) generation of unstable products that rearrange. C-C cleavage reactions involve several themes: (i) rearrangement of unstable oxidized products produced by the enzymes, (ii) oxidation and collapse of radicals or cations via rearrangement, (iii) oxygenation to yield products that are readily hydrolyzed by other enzymes, and (iv) activation of O2 in systems in which the binding of a substrate facilitates O2 activation. Many of the enzymes involve metals, but of these, iron is clearly predominant.
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Affiliation(s)
- F Peter Guengerich
- Department of Biochemistry , Vanderbilt University School of Medicine , Nashville , Tennessee 37232-0146 , United States.,Department of Chemistry , University of Texas-San Antonio , San Antonio , Texas 78249-0698 , United States
| | - Francis K Yoshimoto
- Department of Biochemistry , Vanderbilt University School of Medicine , Nashville , Tennessee 37232-0146 , United States.,Department of Chemistry , University of Texas-San Antonio , San Antonio , Texas 78249-0698 , United States
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37
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Huang JL, Tang Y, Yu CP, Sanyal D, Jia X, Liu X, Guo Y, Chang WC. Mechanistic Investigation of Oxidative Decarboxylation Catalyzed by Two Iron(II)- and 2-Oxoglutarate-Dependent Enzymes. Biochemistry 2018; 57:1838-1841. [PMID: 29485871 DOI: 10.1021/acs.biochem.8b00115] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Two non-heme iron enzymes, IsnB and AmbI3, catalyze a novel decarboxylation-assisted olefination to produce indole vinyl isonitrile, an important building block for many natural products. Compared to other reactions catalyzed by this enzyme family, decarboxylation-assisted olefination represents an attractive biosynthetic route and a mechanistically unexplored pathway in constructing a C═C bond. Using mechanistic probes, transient state kinetics, reactive intermediate trapping, spectroscopic characterizations, and product analysis, we propose that both IsnB and AmbI3 initiate stereoselective olefination via a benzylic C-H bond activation by an Fe(IV)-oxo intermediate, and the reaction likely proceeds through a radical- or carbocation-induced decarboxylation to complete C═C bond installation.
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Affiliation(s)
- Jhih-Liang Huang
- Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695 , United States
| | - Yijie Tang
- Department of Chemistry , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States
| | - Cheng-Ping Yu
- Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695 , United States
| | - Dev Sanyal
- Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695 , United States
| | - Xinglin Jia
- Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695 , United States
| | - Xinyu Liu
- Department of Chemistry , University of Pittsburgh , Pittsburgh , Pennsylvania 15260 , United States
| | - 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
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38
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Guengerich FP. Introduction to Metals in Biology 2018: Copper homeostasis and utilization in redox enzymes. J Biol Chem 2018; 293:4603-4605. [PMID: 29425098 DOI: 10.1074/jbc.tm118.002255] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
This 11th Thematic Metals in Biology Thematic Series deals with copper, a transition metal with a prominent role in biochemistry. Copper is a very versatile element, and both deficiencies and excesses can be problematic. The five Minireviews in this series deal with several aspects of copper homeostasis in microorganisms and mammals and the role of this metal in two enzymes, copper-only superoxide dismutase and cytochrome c oxidase.
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Affiliation(s)
- F Peter Guengerich
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146.
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39
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Benjdia A, Balty C, Berteau O. Radical SAM Enzymes in the Biosynthesis of Ribosomally Synthesized and Post-translationally Modified Peptides (RiPPs). Front Chem 2017; 5:87. [PMID: 29167789 PMCID: PMC5682303 DOI: 10.3389/fchem.2017.00087] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 10/11/2017] [Indexed: 11/13/2022] Open
Abstract
Ribosomally-synthesized and post-translationally modified peptides (RiPPs) are a large and diverse family of natural products. They possess interesting biological properties such as antibiotic or anticancer activities, making them attractive for therapeutic applications. In contrast to polyketides and non-ribosomal peptides, RiPPs derive from ribosomal peptides and are post-translationally modified by diverse enzyme families. Among them, the emerging superfamily of radical SAM enzymes has been shown to play a major role. These enzymes catalyze the formation of a wide range of post-translational modifications some of them having no counterparts in living systems or synthetic chemistry. The investigation of radical SAM enzymes has not only illuminated unprecedented strategies used by living systems to tailor peptides into complex natural products but has also allowed to uncover novel RiPP families. In this review, we summarize the current knowledge on radical SAM enzymes catalyzing RiPP post-translational modifications and discuss their mechanisms and growing importance notably in the context of the human microbiota.
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Affiliation(s)
- Alhosna Benjdia
- Micalis Institute, ChemSyBio, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Clémence Balty
- Micalis Institute, ChemSyBio, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Olivier Berteau
- Micalis Institute, ChemSyBio, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
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40
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Mahanta N, Hudson GA, Mitchell DA. Radical S-Adenosylmethionine Enzymes Involved in RiPP Biosynthesis. Biochemistry 2017; 56:5229-5244. [PMID: 28895719 DOI: 10.1021/acs.biochem.7b00771] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Ribosomally synthesized and post-translationally modified peptides (RiPPs) display a diverse range of structures and continue to expand as a natural product class. Accordingly, RiPPs exhibit a wide array of bioactivities, acting as broad and narrow spectrum growth suppressors, antidiabetics, and antinociception and anticancer agents. Because of these properties, and the complex repertoire of post-translational modifications (PTMs) that give rise to these molecules, RiPP biosynthesis has been intensely studied. RiPP biosynthesis often involves enzymes that perform unique chemistry with intriguing reaction mechanisms, which attract chemists and biochemists alike to study and re-engineer these pathways. One particular type of RiPP biosynthetic enzyme is the so-called radical S-adenosylmethionine (rSAM) enzyme, which utilizes radical-based chemistry to install several distinct PTMs. Here, we describe the rSAM enzymes characterized over the past decade that catalyze six reaction types from several RiPP biosynthetic pathways. We present the current state of mechanistic understanding and conclude with possible directions for future characterization of this enzyme family.
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Affiliation(s)
- Nilkamal Mahanta
- Department of Chemistry, University of Illinois at Urbana-Champaign , 600 South Mathews Avenue, Urbana, Illinois 61801, United States.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign , 1206 West Gregory Drive, Urbana, Illinois 61801, United States
| | - Graham A Hudson
- Department of Chemistry, University of Illinois at Urbana-Champaign , 600 South Mathews Avenue, Urbana, Illinois 61801, United States
| | - Douglas A Mitchell
- Department of Chemistry, University of Illinois at Urbana-Champaign , 600 South Mathews Avenue, Urbana, Illinois 61801, United States.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign , 1206 West Gregory Drive, Urbana, Illinois 61801, United States
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41
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Latham JA, Barr I, Klinman JP. At the confluence of ribosomally synthesized peptide modification and radical S-adenosylmethionine (SAM) enzymology. J Biol Chem 2017; 292:16397-16405. [PMID: 28830931 DOI: 10.1074/jbc.r117.797399] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Radical S-adenosylmethionine (RS) enzymology has emerged as a major biochemical strategy for the homolytic cleavage of unactivated C-H bonds. At the same time, the post-translational modification of ribosomally synthesized peptides is a rapidly expanding area of investigation. We discuss the functional cross-section of these two disciplines, highlighting the recently uncovered importance of protein-protein interactions, especially between the peptide substrate and its chaperone, which functions either as a stand-alone protein or as an N-terminal fusion to the respective RS enzyme. The need for further work on this class of enzymes is emphasized, given the poorly understood roles performed by multiple, auxiliary iron-sulfur clusters and the paucity of protein X-ray structural data.
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Affiliation(s)
- John A Latham
- From the Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208 and
| | - Ian Barr
- the California Institute of Quantitative Biosciences, University of California at Berkeley, Berkeley, California 94720
| | - Judith P Klinman
- the California Institute of Quantitative Biosciences, University of California at Berkeley, Berkeley, California 94720 .,the Departments of Chemistry and.,Molecular and Cell Biology and
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42
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Khaliullin B, Ayikpoe R, Tuttle M, Latham JA. Mechanistic elucidation of the mycofactocin-biosynthetic radical S-adenosylmethionine protein, MftC. J Biol Chem 2017. [PMID: 28634235 DOI: 10.1074/jbc.m117.795682] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Ribosomally synthesized and posttranslationally modified peptide (RiPP) pathways produce a diverse array of natural products. A subset of these pathways depends on radical S-adenosylmethionine proteins to modify the RiPP-produced peptide. Mycofactocin biosynthesis is one example of an S-adenosylmethionine protein-dependent RiPP pathway. Recently, it has been shown that MftC catalyzes the oxidative decarboxylation of the C-terminal tyrosine (Tyr-30) on the mycofactocin precursor peptide MftA; however, this product has not been verified by techniques other than MS. Herein, we provide a more detailed study of MftC catalysis and report a revised mechanism for MftC chemistry. We show that MftC catalyzes the formation of two isomeric products. Using a combination of MS, isotope labeling, and 1H and 13C NMR techniques, we established that the major product, MftA*, is a tyramine-valine-cross-linked peptide formed by MftC through two S-adenosylmethionine-dependent turnovers. In addition, we show that the hydroxyl group on MftA Tyr-30 is required for MftC catalysis. Furthermore, we show that a substitution in the penultimate MftA Val-29 position causes the accumulation of an MftA** minor product. The 1H NMR spectrum indicates that this minor product contains an αβ-unsaturated bond that likely arises from an aborted intermediate of MftA* synthesis. The finding that MftA* is the major product formed during MftC catalysis could have implications for the further elucidation of mycofactocin biosynthesis.
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Affiliation(s)
- Bulat Khaliullin
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208
| | - Richard Ayikpoe
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208
| | - Mason Tuttle
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208
| | - John A Latham
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208.
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43
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Evans RL, Latham JA, Xia Y, Klinman JP, Wilmot CM. Nuclear Magnetic Resonance Structure and Binding Studies of PqqD, a Chaperone Required in the Biosynthesis of the Bacterial Dehydrogenase Cofactor Pyrroloquinoline Quinone. Biochemistry 2017; 56:2735-2746. [PMID: 28481092 DOI: 10.1021/acs.biochem.7b00247] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Biosynthesis of the ribosomally synthesized and post-translationally modified peptide (RiPP), pyrroloquinoline quinone (PQQ), is initiated when the precursor peptide, PqqA, is recognized and bound by the RiPP precursor peptide recognition element (RRE), PqqD, for presentation to the first enzyme in the pathway, PqqE. Unlike other RiPP-producing, postribosomal peptide synthesis (PRPS) pathways in which the RRE is a component domain of the first enzyme, PqqD is predominantly a separate scaffolding protein that forms a ternary complex with the precursor peptide and first tailoring enzyme. As PqqD is a stable, independent RRE, this makes the PQQ pathway an ideal PRPS model system for probing RRE interactions using nuclear magnetic resonance (NMR). Herein, we present both the solution NMR structure of Methylobacterium extorquens PqqD and results of 1H-15N HSQC binding experiments that identify the PqqD residues involved in binding the precursor peptide, PqqA, and the enzyme, PqqE. The reported structural model for an independent RRE, along with the mapped binding surfaces, will inform future efforts both to understand and to manipulate PRPS pathways.
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Affiliation(s)
- Robert L Evans
- Department of Biochemistry, Molecular Biology, and Biophysics and Biotechnology Institute, University of Minnesota, Twin Cities , St. Paul, Minnesota 55108, United States
| | - John A Latham
- Department of Chemistry and Department of Molecular and Cell Biology, University of California, Berkeley , Berkeley, California 94720, United States
| | - Youlin Xia
- Minnesota NMR Center, University of Minnesota, Twin Cities , Minneapolis, Minnesota 55455, United States
| | - Judith P Klinman
- Department of Chemistry and Department of Molecular and Cell Biology, University of California, Berkeley , Berkeley, California 94720, United States
| | - Carrie M Wilmot
- Department of Biochemistry, Molecular Biology, and Biophysics and Biotechnology Institute, University of Minnesota, Twin Cities , St. Paul, Minnesota 55108, United States
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44
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Benjdia A, Decamps L, Guillot A, Kubiak X, Ruffié P, Sandström C, Berteau O. Insights into the catalysis of a lysine-tryptophan bond in bacterial peptides by a SPASM domain radical S-adenosylmethionine (SAM) peptide cyclase. J Biol Chem 2017; 292:10835-10844. [PMID: 28476884 PMCID: PMC5491770 DOI: 10.1074/jbc.m117.783464] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 04/26/2017] [Indexed: 11/06/2022] Open
Abstract
Radical S-adenosylmethionine (SAM) enzymes are emerging as a major superfamily of biological catalysts involved in the biosynthesis of the broad family of bioactive peptides called ribosomally synthesized and post-translationally modified peptides (RiPPs). These enzymes have been shown to catalyze unconventional reactions, such as methyl transfer to electrophilic carbon atoms, sulfur to Cα atom thioether bonds, or carbon-carbon bond formation. Recently, a novel radical SAM enzyme catalyzing the formation of a lysine-tryptophan bond has been identified in Streptococcus thermophilus, and a reaction mechanism has been proposed. By combining site-directed mutagenesis, biochemical assays, and spectroscopic analyses, we show here that this enzyme, belonging to the emerging family of SPASM domain radical SAM enzymes, likely contains three [4Fe-4S] clusters. Notably, our data support that the seven conserved cysteine residues, present within the SPASM domain, are critical for enzyme activity. In addition, we uncovered the minimum substrate requirements and demonstrate that KW cyclic peptides are more widespread than anticipated, notably in pathogenic bacteria. Finally, we show a strict specificity of the enzyme for lysine and tryptophan residues and the dependence of an eight-amino acid leader peptide for activity. Altogether, our study suggests novel mechanistic links among SPASM domain radical SAM enzymes and supports the involvement of non-cysteinyl ligands in the coordination of auxiliary clusters.
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Affiliation(s)
- Alhosna Benjdia
- From the Micalis Institute, ChemSyBio, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France and
| | - Laure Decamps
- From the Micalis Institute, ChemSyBio, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France and
| | - Alain Guillot
- From the Micalis Institute, ChemSyBio, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France and
| | - Xavier Kubiak
- From the Micalis Institute, ChemSyBio, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France and
| | - Pauline Ruffié
- From the Micalis Institute, ChemSyBio, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France and
| | - Corine Sandström
- the Department of Molecular Sciences, Uppsala BioCenter, Swedish University of Agricultural Sciences, P. O. Box 7015, Uppsala 750-07, Sweden
| | - Olivier Berteau
- From the Micalis Institute, ChemSyBio, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France and
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45
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Haft DH, Pierce PG, Mayclin SJ, Sullivan A, Gardberg AS, Abendroth J, Begley DW, Phan IQ, Staker BL, Myler PJ, Marathias VM, Lorimer DD, Edwards TE. Mycofactocin-associated mycobacterial dehydrogenases with non-exchangeable NAD cofactors. Sci Rep 2017; 7:41074. [PMID: 28120876 PMCID: PMC5264612 DOI: 10.1038/srep41074] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 12/12/2016] [Indexed: 01/08/2023] Open
Abstract
During human infection, Mycobacterium tuberculosis (Mtb) survives the normally bacteriocidal phagosome of macrophages. Mtb and related species may be able to combat this harsh acidic environment which contains reactive oxygen species due to the mycobacterial genomes encoding a large number of dehydrogenases. Typically, dehydrogenase cofactor binding sites are open to solvent, which allows NAD/NADH exchange to support multiple turnover. Interestingly, mycobacterial short chain dehydrogenases/reductases (SDRs) within family TIGR03971 contain an insertion at the NAD binding site. Here we present crystal structures of 9 mycobacterial SDRs in which the insertion buries the NAD cofactor except for a small portion of the nicotinamide ring. Line broadening and STD-NMR experiments did not show NAD or NADH exchange on the NMR timescale. STD-NMR demonstrated binding of the potential substrate carveol, the potential product carvone, the inhibitor tricyclazol, and an external redox partner 2,6-dichloroindophenol (DCIP). Therefore, these SDRs appear to contain a non-exchangeable NAD cofactor and may rely on an external redox partner, rather than cofactor exchange, for multiple turnover. Incidentally, these genes always appear in conjunction with the mftA gene, which encodes the short peptide MftA, and with other genes proposed to convert MftA into the external redox partner mycofactocin.
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Affiliation(s)
- Daniel H Haft
- National Institutes of Health (NIH), Bethesda, MD 20892, USA
| | - Phillip G Pierce
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA 98109, USA.,Beryllium Discovery Corp., 7869 NE Day Road West, Bainbridge Island, WA 98110, USA
| | - Stephen J Mayclin
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA 98109, USA.,Beryllium Discovery Corp., 7869 NE Day Road West, Bainbridge Island, WA 98110, USA
| | - Amy Sullivan
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA 98109, USA.,Beryllium Discovery Corp., 7869 NE Day Road West, Bainbridge Island, WA 98110, USA
| | - Anna S Gardberg
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA 98109, USA.,Beryllium Discovery Corp., 7869 NE Day Road West, Bainbridge Island, WA 98110, USA
| | - Jan Abendroth
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA 98109, USA.,Beryllium Discovery Corp., 7869 NE Day Road West, Bainbridge Island, WA 98110, USA
| | - Darren W Begley
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA 98109, USA.,Beryllium Discovery Corp., 7869 NE Day Road West, Bainbridge Island, WA 98110, USA
| | - Isabelle Q Phan
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA 98109, USA.,Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute), 307 Westlake Avenue North, Seattle WA 98109, USA
| | - Bart L Staker
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA 98109, USA.,Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute), 307 Westlake Avenue North, Seattle WA 98109, USA
| | - Peter J Myler
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA 98109, USA.,Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute), 307 Westlake Avenue North, Seattle WA 98109, USA.,University of Washington, Department of Medical Education and Biomedical Informatics &Department of Global Health, Seattle WA 98195, USA
| | - Vasilios M Marathias
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA 98109, USA.,Beryllium Discovery Corp., 7869 NE Day Road West, Bainbridge Island, WA 98110, USA
| | - Donald D Lorimer
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA 98109, USA.,Beryllium Discovery Corp., 7869 NE Day Road West, Bainbridge Island, WA 98110, USA
| | - Thomas E Edwards
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA 98109, USA.,Beryllium Discovery Corp., 7869 NE Day Road West, Bainbridge Island, WA 98110, USA
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46
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Bruender NA, Bandarian V. The Creatininase Homolog MftE from Mycobacterium smegmatis Catalyzes a Peptide Cleavage Reaction in the Biosynthesis of a Novel Ribosomally Synthesized Post-translationally Modified Peptide (RiPP). J Biol Chem 2017; 292:4371-4381. [PMID: 28077628 DOI: 10.1074/jbc.m116.762062] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 01/03/2017] [Indexed: 11/06/2022] Open
Abstract
Most ribosomally synthesized and post-translationally modified peptide (RiPP) natural products are processed by tailoring enzymes to create complex natural products that are still recognizably peptide-based. However, some tailoring enzymes dismantle the peptide en route to synthesis of small molecules. A small molecule natural product of as yet unknown structure, mycofactocin, is thought to be synthesized in this way via the mft gene cluster found in many strains of mycobacteria. This cluster harbors at least six genes, which appear to be conserved across species. We have previously shown that one enzyme from this cluster, MftC, catalyzes the oxidative decarboxylation of the C-terminal Tyr of the substrate peptide MftA in a reaction that requires the MftB protein. Herein we show that mftE encodes a creatininase homolog that catalyzes cleavage of the oxidatively decarboxylated MftA peptide to liberate its final two residues, including the C-terminal decarboxylated Tyr (VY*). Unlike MftC, which requires MftB for function, MftE catalyzes the cleavage reaction in the absence of MftB. The identification of this novel metabolite, VY*, supports the notion that the mft cluster is involved in generating a small molecule from the MftA peptide. The ability to produce VY* from MftA by in vitro reconstitution of the activities of MftB, MftC, and MftE sets the stage for identification of the novel metabolite that results from the proteins encoded by the mft cluster.
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Affiliation(s)
- Nathan A Bruender
- From the Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
| | - Vahe Bandarian
- From the Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
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47
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Abstract
Read the original article at doi: 10.1002/1873-3468.12249.
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48
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Khaliullin B, Aggarwal P, Bubas M, Eaton GR, Eaton SS, Latham JA. Mycofactocin biosynthesis: modification of the peptide MftA by the radical S-adenosylmethionine protein MftC. FEBS Lett 2016; 590:2538-48. [DOI: 10.1002/1873-3468.12249] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 06/01/2016] [Accepted: 06/05/2016] [Indexed: 02/04/2023]
Affiliation(s)
- Bulat Khaliullin
- Department of Chemistry and Biochemistry; University of Denver; CO USA
| | - Priyanka Aggarwal
- Department of Chemistry and Biochemistry; University of Denver; CO USA
| | - Michael Bubas
- Department of Chemistry and Biochemistry; University of Denver; CO USA
| | - Gareth R. Eaton
- Department of Chemistry and Biochemistry; University of Denver; CO USA
| | - Sandra S. Eaton
- Department of Chemistry and Biochemistry; University of Denver; CO USA
| | - John A. Latham
- Department of Chemistry and Biochemistry; University of Denver; CO USA
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