1
|
Kim A, Ngamnithiporn A, Du E, Stoltz BM. Recent Advances in the Total Synthesis of the Tetrahydroisoquinoline Alkaloids (2002-2020). Chem Rev 2023; 123:9447-9496. [PMID: 37429001 PMCID: PMC10416225 DOI: 10.1021/acs.chemrev.3c00054] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Indexed: 07/12/2023]
Abstract
The tetrahydroisoquinoline (THIQ) natural products constitute one of the largest families of alkaloids and exhibit a wide range of structural diversity and biological activity. Ranging from simple THIQ natural products to complex trisTHIQ alkaloids such as the ecteinascidins, the chemical syntheses of these alkaloids and their analogs have been thoroughly investigated due to their intricate structural features and functionalities, as well as their high therapeutic potential. This review describes the general structure and biosynthesis of each family of THIQ alkaloids as well as recent advancements of the total synthesis of these natural products from 2002 to 2020. Recent chemical syntheses that have emerged harnessing novel, creative synthetic design, and modern chemical methodology will be highlighted. This review will hopefully serve as a guide for the unique strategies and tools used in the total synthesis of THIQ alkaloids, as well as address the longstanding challenges in their chemical and biosynthesis.
Collapse
Affiliation(s)
- Alexia
N. Kim
- The
Warren and Katharine Schlinger Laboratory for Chemistry and Chemical
Engineering, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Aurapat Ngamnithiporn
- Laboratory
of Medicinal Chemistry, Chulabhorn Research
Institute, 54 Kamphaeng
Phet 6 Road, Bangkok 10210, Thailand
| | - Emily Du
- The
Warren and Katharine Schlinger Laboratory for Chemistry and Chemical
Engineering, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Brian M. Stoltz
- The
Warren and Katharine Schlinger Laboratory for Chemistry and Chemical
Engineering, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| |
Collapse
|
2
|
Potent Antibiotic Lemonomycin: A Glimpse of Its Discovery, Origin, and Chemical Synthesis. Molecules 2022; 27:molecules27134324. [PMID: 35807568 PMCID: PMC9268379 DOI: 10.3390/molecules27134324] [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] [Received: 06/11/2022] [Revised: 07/01/2022] [Accepted: 07/01/2022] [Indexed: 02/05/2023] Open
Abstract
Lemonomycin (1) was first isolated from the fermentation broth of Streptomyces candidus in 1964. The complete chemical structure was not elucidated until 2000 with extensive spectroscopic analysis. Lemonomycin is currently known as the only glycosylated tetrahydroisoquinoline antibiotic. Its potent antibacterial activity against Staphylococcus aureus and Bacillus subtilis and complex architecture make it an ideal target for total synthesis. In this short review, we summarize the research status of lemonomycin for biological activity, biosynthesis, and chemical synthesis. The unique deoxy aminosugar-lemonose was proposed to play a crucial role in biological activity, as shown in other antibiotics, such as arimetamycin A, nocathiacin I, glycothiohexide α, and thiazamycins. Given the self-resistance of the original bacterial host, the integration of biosynthesis and chemical synthesis to pursue efficient synthesis and further derivatization is in high demand for the development of novel antibiotics to combat antibiotic-resistant infections.
Collapse
|
3
|
Morshed MT, Lacey E, Vuong D, Lacey AE, Lean SS, Moggach SA, Karuso P, Chooi YH, Booth TJ, Piggott AM. Chlorinated metabolites from Streptomyces sp. highlight the role of biosynthetic mosaics and superclusters in the evolution of chemical diversity. Org Biomol Chem 2021; 19:6147-6159. [PMID: 34180937 DOI: 10.1039/d1ob00600b] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
LCMS-guided screening of a library of biosynthetically talented bacteria and fungi identified Streptomyces sp. MST- as a prolific producer of chlorinated metabolites. We isolated and characterised six new and nine reported compounds from MST-, belonging to three discrete classes - the depsipeptide svetamycins, the indolocarbazole borregomycins and the aromatic polyketide anthrabenzoxocinones. Following genome sequencing of MST-, we describe, for the first time, the svetamycin biosynthetic gene cluster (sve), its mosaic structure and its relationship to several distantly related gene clusters. Our analysis of the sve cluster suggested that the reported stereostructures of the svetamycins may be incorrect. This was confirmed by single-crystal X-ray diffraction analysis, allowing us to formally revise the absolute configurations of svetamycins A-G. We also show that the borregomycins and anthrabenzoxocinones are encoded by a single supercluster (bab) implicating superclusters as potential nucleation points for the evolution of biosynthetic gene clusters. These clusters highlight how individual enzymes and functional subclusters can be co-opted during the formation of biosynthetic gene clusters, providing a rare insight into the poorly understood mechanisms underpinning the evolution of chemical diversity.
Collapse
Affiliation(s)
- Mahmud T Morshed
- Department of Molecular Sciences, Macquarie University, NSW 2109, Australia.
| | - Ernest Lacey
- Department of Molecular Sciences, Macquarie University, NSW 2109, Australia. and Microbial Screening Technologies, Smithfield, NSW 2164, Australia
| | - Daniel Vuong
- Microbial Screening Technologies, Smithfield, NSW 2164, Australia
| | - Alastair E Lacey
- Microbial Screening Technologies, Smithfield, NSW 2164, Australia
| | - Soo Sum Lean
- School of Molecular Sciences, University of Western Australia, Perth, WA 6009, Australia.
| | - Stephen A Moggach
- School of Molecular Sciences, University of Western Australia, Perth, WA 6009, Australia.
| | - Peter Karuso
- Department of Molecular Sciences, Macquarie University, NSW 2109, Australia.
| | - Yit-Heng Chooi
- School of Molecular Sciences, University of Western Australia, Perth, WA 6009, Australia.
| | - Thomas J Booth
- School of Molecular Sciences, University of Western Australia, Perth, WA 6009, Australia.
| | - Andrew M Piggott
- Department of Molecular Sciences, Macquarie University, NSW 2109, Australia.
| |
Collapse
|
4
|
Singh P. Synthetic Approaches Towards the Synthesis of C-1 Azole Substituted Tetrahydroisoquinolines. CURR ORG CHEM 2021. [DOI: 10.2174/1385272824999201228140959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
C-1 substituted tetrahydroisoquinolines have emerged as important scaffolds in
pharmaceutical and medical research. Although various methods for α-substitution on tetrahydroisoquinolines
have been discovered, the introduction of the azole group at C-1 position
remains a challenge. Recently, direct C-H activation methods and multicomponent reactions
have been employed towards the synthesis of azole containing tetrahydroisoquinolines. A
summary of such synthetic strategies is presented here as these promising methods can help
in developing more efficient synthetic routes. This minireview covers the available synthetic
methods and their mechanistic pathways for the preparation of C-1 azole substituted tetrahydroisoquinolines.
Collapse
Affiliation(s)
- Pushpinder Singh
- Department of Chemistry, DAV University, Jalandhar, Punjab, 144012, India
| |
Collapse
|
5
|
Ali HS, Henchman RH, Warwicker J, de Visser SP. How Do Electrostatic Perturbations of the Protein Affect the Bifurcation Pathways of Substrate Hydroxylation versus Desaturation in the Nonheme Iron-Dependent Viomycin Biosynthesis Enzyme? J Phys Chem A 2021; 125:1720-1737. [DOI: 10.1021/acs.jpca.1c00141] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Hafiz Saqib Ali
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Richard H. Henchman
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Jim Warwicker
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K
- School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Sam P. de Visser
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K
- Department of Chemical Engineering and Analytical Science, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| |
Collapse
|
6
|
Copeland RA, Davis KM, Shoda TKC, Blaesi EJ, Boal AK, Krebs C, Bollinger JM. An Iron(IV)-Oxo Intermediate Initiating l-Arginine Oxidation but Not Ethylene Production by the 2-Oxoglutarate-Dependent Oxygenase, Ethylene-Forming Enzyme. J Am Chem Soc 2021; 143:2293-2303. [PMID: 33522811 DOI: 10.1021/jacs.0c10923] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Ethylene-forming enzyme (EFE) is an ambifunctional iron(II)- and 2-oxoglutarate-dependent (Fe/2OG) oxygenase. In its major (EF) reaction, it converts carbons 1, 2, and 5 of 2OG to CO2 and carbons 3 and 4 to ethylene, a four-electron oxidation drastically different from the simpler decarboxylation of 2OG to succinate mediated by all other Fe/2OG enzymes. EFE also catalyzes a minor reaction, in which the normal decarboxylation is coupled to oxidation of l-arginine (a required activator for the EF pathway), resulting in its conversion to l-glutamate semialdehyde and guanidine. Here we show that, consistent with precedent, the l-Arg-oxidation (RO) pathway proceeds via an iron(IV)-oxo (ferryl) intermediate. Use of 5,5-[2H2]-l-Arg slows decay of the ferryl complex by >16-fold, implying that RO is initiated by hydrogen-atom transfer (HAT) from C5. That this large substrate deuterium kinetic isotope effect has no impact on the EF:RO partition ratio implies that the same ferryl intermediate cannot be on the EF pathway; the pathways must diverge earlier. Consistent with this conclusion, the variant enzyme bearing the Asp191Glu ligand substitution accumulates ∼4 times as much of the ferryl complex as the wild-type enzyme and exhibits a ∼40-fold diminished EF:RO partition ratio. The selective detriment of this nearly conservative substitution to the EF pathway implies that it has unusually stringent stereoelectronic requirements. An active-site, like-charge guanidinium pair, which involves the l-Arg substrate/activator and is unique to EFE among four crystallographically characterized l-Arg-modifying Fe/2OG oxygenases, may serve to selectively stabilize the transition state leading to the unique EF branch.
Collapse
|
7
|
p-Aminophenylalanine Involved in the Biosynthesis of Antitumor Dnacin B1 for Quinone Moiety Formation. Molecules 2020; 25:molecules25184186. [PMID: 32932689 PMCID: PMC7570522 DOI: 10.3390/molecules25184186] [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: 08/25/2020] [Revised: 09/08/2020] [Accepted: 09/10/2020] [Indexed: 12/04/2022] Open
Abstract
Actinosynnema species produce diverse natural products with important biological activities, which represent an important resource of antibiotic discovery. Advances in genome sequencing and bioinformatics tools have accelerated the exploration of the biosynthetic gene clusters (BGCs) encoding natural products. Herein, the completed BGCs of dnacin B1 were first discovered in two Actinosynnema pretiosum subsp. auranticum strains DSM 44131T (hereafter abbreviated as strain DSM 44131T) and X47 by comparative genome mining strategy. The BGC for dnacin B1 contains 41 ORFs and spans a 66.9 kb DNA region in strain DSM 44131T. Its involvement in dnacin B1 biosynthesis was identified through the deletion of a 9.7 kb region. Based on the functional gene analysis, we proposed the biosynthetic pathway for dnacin B1. Moreover, p-amino-phenylalanine (PAPA) unit was found to be the dnacin B1 precursor for the quinone moiety formation, and this was confirmed by heterologous expression of dinV, dinE and dinF in Escherichia coli. Furthermore, nine potential PAPA aminotransferases (APAT) from the genome of strain DSM 44131T were explored and expressed. Biochemical evaluation of their amino group transformation ability was carried out with p-amino-phenylpyruvic acid (PAPP) or PAPA as the substrate for the final product formation. Two of those, APAT4 and APAT9, displayed intriguing aminotransferase ability for the formation of PAPA. The proposed dnacin B1 biosynthetic machinery and PAPA biosynthetic investigations not only enriched the knowledge of tetrahydroisoquinoline (THIQ) biosynthesis, but also provided PAPA building blocks to generate their structurally unique homologues.
Collapse
|
8
|
Calcaterra A, Mangiardi L, Delle Monache G, Quaglio D, Balducci S, Berardozzi S, Iazzetti A, Franzini R, Botta B, Ghirga F. The Pictet-Spengler Reaction Updates Its Habits. Molecules 2020; 25:E414. [PMID: 31963860 PMCID: PMC7024544 DOI: 10.3390/molecules25020414] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 01/05/2020] [Accepted: 01/09/2020] [Indexed: 12/31/2022] Open
Abstract
The Pictet-Spengler reaction (P-S) is one of the most direct, efficient, and variable synthetic method for the construction of privileged pharmacophores such as tetrahydro-isoquinolines (THIQs), tetrahydro-β-carbolines (THBCs), and polyheterocyclic frameworks. In the lustro (five-year period) following its centenary birthday, the P-S reaction did not exit the stage but it came up again on limelight with new features. This review focuses on the interesting results achieved in this period (2011-2015), analyzing the versatility of this reaction. Classic P-S was reported in the total synthesis of complex alkaloids, in combination with chiral catalysts as well as for the generation of libraries of compounds in medicinal chemistry. The P-S has been used also in tandem reactions, with the sequences including ring closing metathesis, isomerization, Michael addition, and Gold- or Brønsted acid-catalyzed N-acyliminium cyclization. Moreover, the combination of P-S reaction with Ugi multicomponent reaction has been exploited for the construction of highly complex polycyclic architectures in few steps and high yields. The P-S reaction has also been successfully employed in solid-phase synthesis, affording products with different structures, including peptidomimetics, synthetic heterocycles, and natural compounds. Finally, the enzymatic version of P-S has been reported for biosynthesis, biotransformations, and bioconjugations.
Collapse
Affiliation(s)
- Andrea Calcaterra
- Department of Chemistry and Technology of Drugs, “Department of Excellence 2018−2022”, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy; (L.M.); (G.D.M.); (D.Q.); (S.B.); (A.I.); (R.F.); (B.B.)
| | - Laura Mangiardi
- Department of Chemistry and Technology of Drugs, “Department of Excellence 2018−2022”, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy; (L.M.); (G.D.M.); (D.Q.); (S.B.); (A.I.); (R.F.); (B.B.)
- Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, Viale Regina Elena 291, 00161 Rome, Italy;
| | - Giuliano Delle Monache
- Department of Chemistry and Technology of Drugs, “Department of Excellence 2018−2022”, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy; (L.M.); (G.D.M.); (D.Q.); (S.B.); (A.I.); (R.F.); (B.B.)
| | - Deborah Quaglio
- Department of Chemistry and Technology of Drugs, “Department of Excellence 2018−2022”, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy; (L.M.); (G.D.M.); (D.Q.); (S.B.); (A.I.); (R.F.); (B.B.)
| | - Silvia Balducci
- Department of Chemistry and Technology of Drugs, “Department of Excellence 2018−2022”, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy; (L.M.); (G.D.M.); (D.Q.); (S.B.); (A.I.); (R.F.); (B.B.)
| | - Simone Berardozzi
- Department of Chemistry and Applied Biosciences, ETH-Zürich, Vladimir-Prelog Weg 4, 8093 Zürich, Switzerland
| | - Antonia Iazzetti
- Department of Chemistry and Technology of Drugs, “Department of Excellence 2018−2022”, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy; (L.M.); (G.D.M.); (D.Q.); (S.B.); (A.I.); (R.F.); (B.B.)
| | - Roberta Franzini
- Department of Chemistry and Technology of Drugs, “Department of Excellence 2018−2022”, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy; (L.M.); (G.D.M.); (D.Q.); (S.B.); (A.I.); (R.F.); (B.B.)
| | - Bruno Botta
- Department of Chemistry and Technology of Drugs, “Department of Excellence 2018−2022”, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy; (L.M.); (G.D.M.); (D.Q.); (S.B.); (A.I.); (R.F.); (B.B.)
| | - Francesca Ghirga
- Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, Viale Regina Elena 291, 00161 Rome, Italy;
| |
Collapse
|
9
|
Tanifuji R, Minami A, Oguri H, Oikawa H. Total synthesis of alkaloids using both chemical and biochemical methods. Nat Prod Rep 2020; 37:1098-1121. [DOI: 10.1039/c9np00073a] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A chemoenzymatic approach to synthesize structurally complex natural alkaloids (tetrahydroisoquinoline antibiotics, indole diterpenes, and monoterpene indole alkaloids) has been reviewed.
Collapse
Affiliation(s)
- Ryo Tanifuji
- Department of Applied Chemistry
- Graduate School of Engineering
- Tokyo University of Agriculture and Technology
- Koganei
- Japan
| | - Atsushi Minami
- Division of Chemistry
- Graduate School of Science
- Hokkaido University
- Sapporo
- Japan
| | - Hiroki Oguri
- Department of Applied Chemistry
- Graduate School of Engineering
- Tokyo University of Agriculture and Technology
- Koganei
- Japan
| | - Hideaki Oikawa
- Division of Chemistry
- Graduate School of Science
- Hokkaido University
- Sapporo
- Japan
| |
Collapse
|
10
|
Abstract
Natural nonproteinogenic amino acids vastly outnumber the well-known 22 proteinogenic amino acids. Such amino acids are generated in specialized metabolic pathways. In these pathways, diverse biosynthetic transformations, ranging from isomerizations to the stereospecific functionalization of C-H bonds, are employed to generate structural diversity. The resulting nonproteinogenic amino acids can be integrated into more complex natural products. Here we review recently discovered biosynthetic routes to freestanding nonproteinogenic α-amino acids, with an emphasis on work reported between 2013 and mid-2019.
Collapse
Affiliation(s)
- Jason B Hedges
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Katherine S Ryan
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| |
Collapse
|
11
|
Guo J, Higgins MA, Daniel-Ivad P, Ryan KS. An Asymmetric Reductase That Intercepts Acyclic Imino Acids Produced in Situ by a Partner Oxidase. J Am Chem Soc 2019; 141:12258-12267. [PMID: 31298853 DOI: 10.1021/jacs.9b03307] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Acyclic imines are unstable in aqueous conditions. For this reason, known imine reductases, which enable the synthesis of chiral amines, mainly intercept stable cyclic imines. Here we report the detailed biochemical and structural characterization of Bsp5, an imino acid reductase from the d-2-hydroxyacid dehydrogenase family that reduces acyclic imino acids produced in situ by a partner oxidase. We determine a 1.6 Å resolution structure of Bsp5 in complex with d-arginine and coenzyme NADPH. Combined with mutagenesis work, our study reveals the minimal structural constraints for its biosynthetic activity. Furthermore, we demonstrate that Bsp5 can intercept more complex products from an alternate oxidase partner, suggesting that this oxidase-imino acid reductase pair could be evolved for biocatalytic conversion of l-amino acids to d-amino acids.
Collapse
Affiliation(s)
- Jin Guo
- Department of Chemistry , University of British Columbia , Vancouver , British Columbia V6T 1Z4 , Canada
| | - Melanie A Higgins
- Department of Chemistry , University of British Columbia , Vancouver , British Columbia V6T 1Z4 , Canada
| | - Phillip Daniel-Ivad
- Department of Chemistry , University of British Columbia , Vancouver , British Columbia V6T 1Z4 , Canada
| | - Katherine S Ryan
- Department of Chemistry , University of British Columbia , Vancouver , British Columbia V6T 1Z4 , Canada
| |
Collapse
|
12
|
Gil-Negrete JM, Pérez Sestelo J, Sarandeses LA. Transition-Metal-Free Oxidative Cross-Coupling of Triorganoindium Reagents with Tetrahydroisoquinolines. J Org Chem 2019; 84:9778-9785. [DOI: 10.1021/acs.joc.9b00928] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- José M. Gil-Negrete
- Centro de Investigaciones Científicas Avanzadas (CICA) and Departamento de Química, Universidade da Coruña, E-15071 A Coruña, Spain
| | - José Pérez Sestelo
- Centro de Investigaciones Científicas Avanzadas (CICA) and Departamento de Química, Universidade da Coruña, E-15071 A Coruña, Spain
| | - Luis A. Sarandeses
- Centro de Investigaciones Científicas Avanzadas (CICA) and Departamento de Química, Universidade da Coruña, E-15071 A Coruña, Spain
| |
Collapse
|
13
|
Auerbach D, Yan F, Zhang Y, Müller R. Characterization of an Unusual Glycerate Esterification Process in Vioprolide Biosynthesis. ACS Chem Biol 2018; 13:3123-3130. [PMID: 30286293 DOI: 10.1021/acschembio.8b00826] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Bacteria produce a large number of secondary metabolites with extraordinary chemical structures and bioactivities. Vioprolides are promising anticancer and antifungal lead compounds produced by the myxobacterium Cystobacter violaceus Cb vi35, which are initially synthesized as acylated precursors (previoprolides) by nonribosomal peptide synthetases (NRPS). Here, we describe and characterize an unprecedented glycerate esterification process in the biosynthesis of vioprolides. In vitro biochemical investigations revealed that the fatty acyl chain of previoprolides is adenylated by the starting fatty acyl-AMP ligase (FAAL) domain, while the glycerate moiety is incorporated by the FkbH domain. An unusual ester-bond forming condensation domain is shown responsible for the acylation of glycerate. LC-MS analysis and bioactivity assays suggest that the acylation serves for directed membrane transport rather than representing a prodrug mechanism.
Collapse
Affiliation(s)
- David Auerbach
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research and Department of Pharmacy, Saarland University, Saarland University Campus, Building E8.1, 66123 Saarbrücken, Germany
| | - Fu Yan
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research and Department of Pharmacy, Saarland University, Saarland University Campus, Building E8.1, 66123 Saarbrücken, Germany
| | - Youming Zhang
- Shandong University-Helmholtz Joint Institute of Biotechnology, State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Qingdao, People’s Republic of China
| | - Rolf Müller
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research and Department of Pharmacy, Saarland University, Saarland University Campus, Building E8.1, 66123 Saarbrücken, Germany
| |
Collapse
|
14
|
Dunham NP, Mitchell AJ, Del Río Pantoja JM, Krebs C, Bollinger JM, Boal AK. α-Amine Desaturation of d-Arginine by the Iron(II)- and 2-(Oxo)glutarate-Dependent l-Arginine 3-Hydroxylase, VioC. Biochemistry 2018; 57:6479-6488. [PMID: 30403469 DOI: 10.1021/acs.biochem.8b00901] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
When challenged with substrate analogues, iron(II)- and 2-(oxo)glutarate-dependent (Fe/2OG) oxygenases can promote transformations different from those they enact upon their native substrates. We show here that the Fe/2OG enzyme, VioC, which is natively an l-arginine 3-hydroxylase, catalyzes an efficient oxidative deamination of its substrate enantiomer, d-Arg. The reactant complex with d-Arg retains all interactions between enzyme and substrate functional groups, but the required structural adjustments and opposite configuration of C2 position this carbon more optimally than C3 to donate hydrogen (H•) to the ferryl intermediate. The simplest possible mechanism, C2 hydroxylation followed by elimination of ammonia, is inconsistent with the demonstrated solvent origin of the ketone oxygen in the product. Rather, the reaction proceeds via a hydrolytically labile C2-iminium intermediate, demonstrated by its reductive trapping in solution with NaB2H4 to produce racemic [2H]Arg. Of two alternative pathways to the iminium species, C2 hydroxylation followed by dehydration versus direct desaturation, the latter possibility appears to be more likely, because the former mechanism would be expected to result in detectable incorporation of 18O from 18O2. The direct desaturation of a C-N bond implied by this analysis is analogous to that recently posited for the reaction of the l-Arg 4,5-desaturase, NapI, thus lending credence to the prior mechanistic proposal. Such a pathway could also potentially be operant in a subset of reactions catalyzed by Fe/2OG N-demethylases, which have instead been purported to enact C-N bond cleavage by methyl hydroxylation and elimination of formaldehyde.
Collapse
|
15
|
Extracellularly oxidative activation and inactivation of matured prodrug for cryptic self-resistance in naphthyridinomycin biosynthesis. Proc Natl Acad Sci U S A 2018; 115:11232-11237. [PMID: 30327344 DOI: 10.1073/pnas.1800502115] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Understanding how antibiotic-producing bacteria deal with highly reactive chemicals will ultimately guide therapeutic strategies to combat the increasing clinical resistance crisis. Here, we uncovered a distinctive self-defense strategy featured by a secreted oxidoreductase NapU to perform extracellularly oxidative activation and conditionally overoxidative inactivation of a matured prodrug in naphthyridinomycin (NDM) biosynthesis from Streptomyces lusitanus NRRL 8034. It was suggested that formation of NDM first involves a nonribosomal peptide synthetase assembly line to generate a prodrug. After exclusion and prodrug maturation, we identified a pharmacophore-inactivated intermediate, which required reactivation by NapU via oxidative C-H bond functionalization extracellularly to afford NDM. Beyond that, NapU could further oxidatively inactivate the NDM pharmacophore to avoid self-cytotoxicity if they coexist longer than necessary. This discovery represents an amalgamation of sophisticatedly temporal and spatial shielding mode conferring self-resistance in antibiotic biosynthesis from Gram-positive bacteria.
Collapse
|
16
|
Tanifuji R, Koketsu K, Takakura M, Asano R, Minami A, Oikawa H, Oguri H. Chemo-enzymatic Total Syntheses of Jorunnamycin A, Saframycin A, and N-Fmoc Saframycin Y3. J Am Chem Soc 2018; 140:10705-10709. [DOI: 10.1021/jacs.8b07161] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Ryo Tanifuji
- Department of Applied Chemistry, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan
| | - Kento Koketsu
- Division of Chemistry, Graduate School of Science, Hokkaido University, North 10 West 8, Sapporo 060-0810, Japan
| | - Michiko Takakura
- Division of Chemistry, Graduate School of Science, Hokkaido University, North 10 West 8, Sapporo 060-0810, Japan
| | - Ryutaro Asano
- Department of Biotechnology and Life Science, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan
| | - Atsushi Minami
- Division of Chemistry, Graduate School of Science, Hokkaido University, North 10 West 8, Sapporo 060-0810, Japan
| | - Hideaki Oikawa
- Division of Chemistry, Graduate School of Science, Hokkaido University, North 10 West 8, Sapporo 060-0810, Japan
| | - Hiroki Oguri
- Department of Applied Chemistry, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan
| |
Collapse
|
17
|
Dunham NP, Chang WC, Mitchell AJ, Martinie RJ, Zhang B, Bergman JA, Rajakovich LJ, Wang B, Silakov A, Krebs C, Boal AK, Bollinger JM. Two Distinct Mechanisms for C-C Desaturation by Iron(II)- and 2-(Oxo)glutarate-Dependent Oxygenases: Importance of α-Heteroatom Assistance. J Am Chem Soc 2018; 140:7116-7126. [PMID: 29708749 PMCID: PMC5999578 DOI: 10.1021/jacs.8b01933] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hydroxylation of aliphatic carbons by nonheme Fe(IV)-oxo (ferryl) complexes proceeds by hydrogen-atom (H•) transfer (HAT) to the ferryl and subsequent coupling between the carbon radical and Fe(III)-coordinated oxygen (termed rebound). Enzymes that use H•-abstracting ferryl complexes for other transformations must either suppress rebound or further process hydroxylated intermediates. For olefin-installing C-C desaturations, it has been proposed that a second HAT to the Fe(III)-OH complex from the carbon α to the radical preempts rebound. Deuterium (2H) at the second site should slow this step, potentially making rebound competitive. Desaturations mediated by two related l-arginine-modifying iron(II)- and 2-(oxo)glutarate-dependent (Fe/2OG) oxygenases behave oppositely in this key test, implicating different mechanisms. NapI, the l-Arg 4,5-desaturase from the naphthyridinomycin biosynthetic pathway, abstracts H• first from C5 but hydroxylates this site (leading to guanidine release) to the same modest extent whether C4 harbors 1H or 2H. By contrast, an unexpected 3,4-desaturation of l-homoarginine (l-hArg) by VioC, the l-Arg 3-hydroxylase from the viomycin biosynthetic pathway, is markedly disfavored relative to C4 hydroxylation when C3 (the second hydrogen donor) harbors 2H. Anchimeric assistance by N6 permits removal of the C4-H as a proton in the NapI reaction, but, with no such assistance possible in the VioC desaturation, a second HAT step (from C3) is required. The close proximity (≤3.5 Å) of both l-hArg carbons to the oxygen ligand in an X-ray crystal structure of VioC harboring a vanadium-based ferryl mimic supports and rationalizes the sequential-HAT mechanism. The results suggest that, although the sequential-HAT mechanism is feasible, its geometric requirements may make competing hydroxylation unavoidable, thus explaining the presence of α-heteroatoms in nearly all native substrates for Fe/2OG desaturases.
Collapse
Affiliation(s)
- Noah P. Dunham
- Department of Biochemistry and Molecular Biology, The Pennsylvania
State University, University Park, PA 16802
| | - Wei-chen Chang
- Department of Chemistry, The Pennsylvania State University,
University Park, PA 16802
| | - Andrew J. Mitchell
- Department of Biochemistry and Molecular Biology, The Pennsylvania
State University, University Park, PA 16802
| | - Ryan J. Martinie
- Department of Chemistry, The Pennsylvania State University,
University Park, PA 16802
| | - Bo Zhang
- Department of Chemistry, The Pennsylvania State University,
University Park, PA 16802
| | - Jonathan A. Bergman
- Department of Biochemistry and Molecular Biology, The Pennsylvania
State University, University Park, PA 16802
| | - Lauren J. Rajakovich
- Department of Biochemistry and Molecular Biology, The Pennsylvania
State University, University Park, PA 16802
| | - Bo Wang
- Department of Chemistry, The Pennsylvania State University,
University Park, PA 16802
| | - Alexey Silakov
- Department of Chemistry, The Pennsylvania State University,
University Park, PA 16802
| | - Carsten Krebs
- Department of Biochemistry and Molecular Biology, The Pennsylvania
State University, University Park, PA 16802
- Department of Chemistry, The Pennsylvania State University,
University Park, PA 16802
| | - Amie K. Boal
- Department of Biochemistry and Molecular Biology, The Pennsylvania
State University, University Park, PA 16802
- Department of Chemistry, The Pennsylvania State University,
University Park, PA 16802
| | - J. Martin Bollinger
- Department of Biochemistry and Molecular Biology, The Pennsylvania
State University, University Park, PA 16802
- Department of Chemistry, The Pennsylvania State University,
University Park, PA 16802
| |
Collapse
|
18
|
A Six‐Oxidase Cascade for Tandem C−H Bond Activation Revealed by Reconstitution of Bicyclomycin Biosynthesis. Angew Chem Int Ed Engl 2018; 57:719-723. [DOI: 10.1002/anie.201710529] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Indexed: 11/07/2022]
|
19
|
Meng S, Han W, Zhao J, Jian X, Pan H, Tang G. A Six‐Oxidase Cascade for Tandem C−H Bond Activation Revealed by Reconstitution of Bicyclomycin Biosynthesis. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201710529] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Song Meng
- State Key Laboratory of Bio-organic and Natural Products ChemistryShanghai Institute of Organic ChemistryUniversity of Chinese Academy of SciencesChinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
| | - Wei Han
- State Key Laboratory of Bio-organic and Natural Products ChemistryShanghai Institute of Organic ChemistryUniversity of Chinese Academy of SciencesChinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
| | - Juan Zhao
- State Key Laboratory of Bio-organic and Natural Products ChemistryShanghai Institute of Organic ChemistryUniversity of Chinese Academy of SciencesChinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
| | - Xiao‐Hong Jian
- State Key Laboratory of Bio-organic and Natural Products ChemistryShanghai Institute of Organic ChemistryUniversity of Chinese Academy of SciencesChinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
| | - Hai‐Xue Pan
- State Key Laboratory of Bio-organic and Natural Products ChemistryShanghai Institute of Organic ChemistryUniversity of Chinese Academy of SciencesChinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
| | - Gong‐Li Tang
- State Key Laboratory of Bio-organic and Natural Products ChemistryShanghai Institute of Organic ChemistryUniversity of Chinese Academy of SciencesChinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
| |
Collapse
|
20
|
Martinez S, Hausinger RP. Biochemical and Spectroscopic Characterization of the Non-Heme Fe(II)- and 2-Oxoglutarate-Dependent Ethylene-Forming Enzyme from Pseudomonas syringae pv. phaseolicola PK2. Biochemistry 2016; 55:5989-5999. [PMID: 27749027 DOI: 10.1021/acs.biochem.6b00890] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The ethylene-forming enzyme (EFE) from Pseudomonas syringae pv. phaseolicola PK2 is a member of the mononuclear non-heme Fe(II)- and 2-oxoglutarate (2OG)-dependent oxygenase superfamily. This enzyme is reported to simultaneously catalyze the conversion of 2OG into ethylene and three CO2 molecules and the Cδ hydroxylation of l-arginine (l-Arg) while oxidatively decarboxylating 2OG to form succinate and carbon dioxide. A new plasmid construct for expression in recombinant Escherichia coli cells allowed for the purification of large amounts of EFE with activity greater than that previously recorded. A variety of assays were used to quantify and confirm the identity of the proposed products, including the first experimental demonstration of l-Δ1-pyrroline-5-carboxylate and guanidine derived from 5-hydroxyarginine. Selected l-Arg derivatives could induce ethylene formation without undergoing hydroxylation, demonstrating that ethylene production and l-Arg hydroxylation activities are not linked. Similarly, EFE utilizes the alternative α-keto acid 2-oxoadipate as a cosubstrate (forming glutaric acid) during the hydroxylation of l-Arg, with this reaction unlinked from ethylene formation. Kinetic constants were determined for both ethylene formation and l-Arg hydroxylation reactions. Anaerobic UV-visible difference spectra were used to monitor the binding of Fe(II) and substrates to the enzyme. On the basis of our results and what is generally known about EFE and Fe(II)- and 2OG-dependent oxygenases, an updated model for the reaction mechanism is presented.
Collapse
Affiliation(s)
- Salette Martinez
- Department of Microbiology and Molecular Genetics and ‡Department of Biochemistry and Molecular Biology, Michigan State University , East Lansing, Michigan 48824, United States
| | - Robert P Hausinger
- Department of Microbiology and Molecular Genetics and ‡Department of Biochemistry and Molecular Biology, Michigan State University , East Lansing, Michigan 48824, United States
| |
Collapse
|
21
|
Saha S, Rokita SE. An Activator of an Adenylation Domain Revealed by Activity but Not Sequence Homology. Chembiochem 2016; 17:1818-1823. [PMID: 27447757 DOI: 10.1002/cbic.201600291] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Indexed: 11/10/2022]
Abstract
Nonribosomal peptide synthetases (NRPSs), which are responsible for synthesizing many medicinally important natural products, frequently use adenylation domain activators (ADAs) to promote substrate loading. Although ADAs are usually MbtH-like proteins (MLPs), a new type of ADA appears to promote an NRPS-dependent incorporation of a dihydropyrrole unit into sibiromycin. The adenylation and thiolation didomain of the NRPS SibD catalyzes the adenylation of a limited number of amino acids including l-Tyr, the precursor in dihydropyrrole biosynthesis, as determined by a standard radioactivity exchange assay. LC-MS/MS analysis confirmed loading of l-Tyr onto the thiolation domain. SibB, a small protein with no prior functional assignment or sequence homology to MLPs, was found to promote the exchange activity. MLPs from bacteria expressing homologous biosynthetic pathways were unable to replace this function of SibB. The discovery of this new type of ADA demonstrates the importance of searching beyond the conventional MLP standard for proteins affecting NRPS activity.
Collapse
Affiliation(s)
- Shalini Saha
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, 20742, USA.
| | - Steven E Rokita
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles St, Baltimore, MD, 21218, USA.
| |
Collapse
|
22
|
Wu LF, Meng S, Tang GL. Ferrous iron and α-ketoglutarate-dependent dioxygenases in the biosynthesis of microbial natural products. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2016; 1864:453-70. [DOI: 10.1016/j.bbapap.2016.01.012] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 01/22/2016] [Accepted: 01/29/2016] [Indexed: 01/29/2023]
|
23
|
Tanifuji R, Oguri H, Koketsu K, Yoshinaga Y, Minami A, Oikawa H. Catalytic asymmetric synthesis of the common amino acid component in the biosynthesis of tetrahydroisoquinoline alkaloids. Tetrahedron Lett 2016. [DOI: 10.1016/j.tetlet.2015.12.110] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
|
24
|
Du YL, Singh R, Alkhalaf LM, Kuatsjah E, He HY, Eltis LD, Ryan KS. A pyridoxal phosphate–dependent enzyme that oxidizes an unactivated carbon-carbon bond. Nat Chem Biol 2016; 12:194-9. [DOI: 10.1038/nchembio.2009] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 12/02/2015] [Indexed: 11/09/2022]
|
25
|
Schofield MM, Jain S, Porat D, Dick GJ, Sherman DH. Identification and analysis of the bacterial endosymbiont specialized for production of the chemotherapeutic natural product ET-743. Environ Microbiol 2015; 17:3964-75. [PMID: 26013440 PMCID: PMC4618771 DOI: 10.1111/1462-2920.12908] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 05/15/2015] [Accepted: 05/16/2015] [Indexed: 11/26/2022]
Abstract
Ecteinascidin 743 (ET-743, Yondelis) is a clinically approved chemotherapeutic natural product isolated from the Caribbean mangrove tunicate Ecteinascidia turbinata. Researchers have long suspected that a microorganism may be the true producer of the anticancer drug, but its genome has remained elusive due to our inability to culture the bacterium in the laboratory using standard techniques. Here, we sequenced and assembled the complete genome of the ET-743 producer, Candidatus Endoecteinascidia frumentensis, directly from metagenomic DNA isolated from the tunicate. Analysis of the ∼ 631 kb microbial genome revealed strong evidence of an endosymbiotic lifestyle and extreme genome reduction. Phylogenetic analysis suggested that the producer of the anti-cancer drug is taxonomically distinct from other sequenced microorganisms and could represent a new family of Gammaproteobacteria. The complete genome has also greatly expanded our understanding of ET-743 production and revealed new biosynthetic genes dispersed across more than 173 kb of the small genome. The gene cluster's architecture and its preservation demonstrate that the drug is likely essential to the interactions of the microorganism with its mangrove tunicate host. Taken together, these studies elucidate the lifestyle of a unique, and pharmaceutically important microorganism and highlight the wide diversity of bacteria capable of making potent natural products.
Collapse
Affiliation(s)
- Michael M. Schofield
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, USA
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Sunit Jain
- Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, USA
| | - Daphne Porat
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Gregory J. Dick
- Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, USA
- Center for Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, USA
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
| | - David H. Sherman
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, USA
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
- Departments of Medicinal Chemistry and Chemistry, University of Michigan, Ann Arbor, USA
| |
Collapse
|
26
|
In vitro reconstitution of indolmycin biosynthesis reveals the molecular basis of oxazolinone assembly. Proc Natl Acad Sci U S A 2015; 112:2717-22. [PMID: 25730866 DOI: 10.1073/pnas.1419964112] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The bacterial tryptophanyl-tRNA synthetase inhibitor indolmycin features a unique oxazolinone heterocycle whose biogenetic origins have remained obscure for over 50 years. Here we identify and characterize the indolmycin biosynthetic pathway, using systematic in vivo gene inactivation, in vitro biochemical assays, and total enzymatic synthesis. Our work reveals that a phenylacetate-CoA ligase-like enzyme Ind3 catalyzes an unusual ATP-dependent condensation of indolmycenic acid and dehydroarginine, driving oxazolinone ring assembly. We find that Ind6, which also has chaperone-like properties, acts as a gatekeeper to direct the outcome of this reaction. With Ind6 present, the normal pathway ensues. Without Ind6, the pathway derails to an unusual shunt product. Our work reveals the complete pathway for indolmycin formation and sets the stage for using genetic and chemoenzymatic methods to generate indolmycin derivatives as potential therapeutic agents.
Collapse
|