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Seshadri K, Abad AND, Nagasawa KK, Yost KM, Johnson CW, Dror MJ, Tang Y. Synthetic Biology in Natural Product Biosynthesis. Chem Rev 2025; 125:3814-3931. [PMID: 40116601 DOI: 10.1021/acs.chemrev.4c00567] [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: 03/23/2025]
Abstract
Synthetic biology has played an important role in the renaissance of natural products research during the post-genomics era. The development and integration of new tools have transformed the workflow of natural product discovery and engineering, generating multidisciplinary interest in the field. In this review, we summarize recent developments in natural product biosynthesis from three different aspects. First, advances in bioinformatics, experimental, and analytical tools to identify natural products associated with predicted biosynthetic gene clusters (BGCs) will be covered. This will be followed by an extensive review on the heterologous expression of natural products in bacterial, fungal and plant organisms. The native host-independent paradigm to natural product identification, pathway characterization, and enzyme discovery is where synthetic biology has played the most prominent role. Lastly, strategies to engineer biosynthetic pathways for structural diversification and complexity generation will be discussed, including recent advances in assembly-line megasynthase engineering, precursor-directed structural modification, and combinatorial biosynthesis.
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Affiliation(s)
- Kaushik Seshadri
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, 420 Westwood Plaza, Los Angeles, California 90095, United States
| | - Abner N D Abad
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, 420 Westwood Plaza, Los Angeles, California 90095, United States
| | - Kyle K Nagasawa
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 420 Westwood Plaza, Los Angeles, California 90095, United States
| | - Karl M Yost
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 420 Westwood Plaza, Los Angeles, California 90095, United States
| | - Colin W Johnson
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 420 Westwood Plaza, Los Angeles, California 90095, United States
| | - Moriel J Dror
- Department of Bioengineering, University of California, Los Angeles, 420 Westwood Plaza, Los Angeles, California 90095, United States
| | - Yi Tang
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, 420 Westwood Plaza, Los Angeles, California 90095, United States
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 420 Westwood Plaza, Los Angeles, California 90095, United States
- Department of Bioengineering, University of California, Los Angeles, 420 Westwood Plaza, Los Angeles, California 90095, United States
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Ding Y, Perez-Ortiz G, Butulan AG, Sharif H, Barry SM. Characterization of RufT Thioesterase Domain Reveals Insights into Rufomycin Cyclization and the Biosynthetic Origin of Rufomyazine. ACS Chem Biol 2025; 20:573-580. [PMID: 40048149 PMCID: PMC11934086 DOI: 10.1021/acschembio.4c00802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2024] [Revised: 02/20/2025] [Accepted: 02/25/2025] [Indexed: 03/22/2025]
Abstract
The nonribosomal cyclic peptides (NRcPs) rufomycins, produced by Streptomyces atratus, have attracted attention as antimycobacterials. Thus, there has been interest in engineering the corresponding biosynthetic pathway to produce novel derivatives. We have thus investigated the type I thioesterase (TE) of the NRPS RufT that catalyzes rufomycin peptide macrocyclization to understand its tolerance to changes in substrate peptide sequence. In contrast to our previously reported efficient cyclization chemistry, the recombinant RufT-TE domain and RufT-PCP-TE didomain, while tolerating some substrate structural changes, both produce high levels of hydrolyzed peptide. Closer analysis led to the identification of the natural product diketopiperazine rufomyazine in assays. The data indicate, with significant implications for rufomycin production, that RufT produces both cyclic and linear peptides. We propose that rufomyazine forms non-enzymatically from the linear peptide. In addition, it provides evidence for TE domains as gatekeepers in NRPS biosynthesis.
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Affiliation(s)
- Yaoyu Ding
- Department of Chemistry, Faculty of
Natural, Mathematical and Engineering Sciences, King’s College London, Britannia House, 7 Trinity Street, London SE1 1DB, U.K.
| | - Gustavo Perez-Ortiz
- Department of Chemistry, Faculty of
Natural, Mathematical and Engineering Sciences, King’s College London, Britannia House, 7 Trinity Street, London SE1 1DB, U.K.
| | | | | | - Sarah M. Barry
- Department of Chemistry, Faculty of
Natural, Mathematical and Engineering Sciences, King’s College London, Britannia House, 7 Trinity Street, London SE1 1DB, U.K.
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Maruyama H, Yamada Y, Igarashi Y, Matsuda K, Wakimoto T. Enzymatic peptide macrocyclization via indole- N-acylation. Chem Sci 2025; 16:3872-3877. [PMID: 39911344 PMCID: PMC11792885 DOI: 10.1039/d4sc07839j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2024] [Accepted: 01/27/2025] [Indexed: 02/07/2025] Open
Abstract
Indole N-acylation is chemically challenging, due to the low nucleophilicity of the indole nitrogen. Although a few similar transformations have been proposed in the biosynthesis of indole-containing natural products, their enzymatic basis remains elusive. Here, we show that BulbE TE is an N-acylindole-forming macrocyclase involved in the biosynthesis of the non-ribosomal cyclopeptide bulbiferamide. BulbE catalyzed macrocyclization not only via the indole nitrogen, but also via a primary amine and an alcohol. The uncommon catalytic residue Cys731 in BulbE TE was indispensable for the nucleophilic attack from the indole nitrogen. While the C731S variant failed to utilize the indole nitrogen and primary alcohol as nucleophiles, it retained the ability to employ the amine nucleophile, showing a clear correlation between the catalytic residues and the nucleophile scope. A model of the acyl-enzyme complex revealed how the substrate is recognized, including interactions involving a unique second lid-like structural motif in BulbE TE. This study provides an enzymatic basis for indole N-acylation and offers important insights into the nucleophile specificity in TE-mediated macrocyclization.
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Affiliation(s)
- Hiroto Maruyama
- Faculty of Pharmaceutical Sciences, Hokkaido University Kita 12, Kita-ku Sapporo 060-0812 Japan
| | - Yuito Yamada
- Faculty of Pharmaceutical Sciences, Hokkaido University Kita 12, Kita-ku Sapporo 060-0812 Japan
| | - Yasuhiro Igarashi
- Biotechnology Research Center and Department of Biotechnology, Toyama Prefectural University 5180 Kurokawa Imizu Toyama 939-0398 Japan
| | - Kenichi Matsuda
- Faculty of Pharmaceutical Sciences, Hokkaido University Kita 12, Kita-ku Sapporo 060-0812 Japan
| | - Toshiyuki Wakimoto
- Faculty of Pharmaceutical Sciences, Hokkaido University Kita 12, Kita-ku Sapporo 060-0812 Japan
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Wang M, Li H. Structure, Function, and Biosynthesis of Siderophores Produced by Streptomyces Species. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2025; 73:4425-4439. [PMID: 39808624 DOI: 10.1021/acs.jafc.4c08231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2025]
Abstract
Since the natural supply of iron is low, microorganisms acquire iron by secreting siderophores. Streptomyces is known for its abundant secondary metabolites containing various types of siderophores, including hydroxamate, catecholate, and carboxylate. These siderophores are mainly synthesized through the nonribosomal peptide synthase (NRPS) and non-NRPS pathways and are regulated by ferric uptake regulator and diphtheria toxin regulators. Although both NRPS and non-NRPS pathways adenylate substrates, they differ significantly in the catalytic logic. Siderophores produced by Streptomyces play important roles in fields of agriculture, medicine, and environment. However, their structure, function, and synthetic mechanisms have been inadequately summarized. Therefore, this Review aimed to provide an overview of the classification, structure, biosynthesis, regulation, and applications of siderophores produced by Streptomyces. Finally, the need for a comprehensive and well-defined mechanism for synthesizing siderophores from Streptomyces was highlighted to further promote their commercialization and application in agriculture, medicine, and other areas.
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Affiliation(s)
- Mingxuan Wang
- Institute of Food Science and Engineering, School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
| | - Honglin Li
- Institute of Food Science and Engineering, School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
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François RMM, Massicard JM, Weissman KJ. The chemical ecology and physiological functions of type I polyketide natural products: the emerging picture. Nat Prod Rep 2025; 42:324-358. [PMID: 39555733 DOI: 10.1039/d4np00046c] [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: 11/19/2024]
Abstract
Covering: up to 2024.For many years, the value of complex polyketides lay in their medical properties, including their antibiotic and antifungal activities, with little consideration paid to their native functions. However, more recent evidence gathered from the study of inter-organismal interactions has revealed the influence of these metabolites upon the ecological adaptation and distribution of their hosts, as well as their modes of communication. The increasing number of sequenced genomes and associated transcriptomes has also unveiled the widespread occurrence of the underlying biosynthetic enzymes across all kingdoms of life, and the important contributions they make to physiological events specific to each organism. This review depicts the diversity of roles fulfilled by type I polyketides, particularly in light of studies carried out during the last decade, providing an initial overall picture of their diverse functions.
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Yook G, Nam J, Jo Y, Yoon H, Yang D. Metabolic engineering approaches for the biosynthesis of antibiotics. Microb Cell Fact 2025; 24:35. [PMID: 39891166 PMCID: PMC11786382 DOI: 10.1186/s12934-024-02628-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2024] [Accepted: 12/18/2024] [Indexed: 02/03/2025] Open
Abstract
BACKGROUND Antibiotics have been saving countless lives from deadly infectious diseases, which we now often take for granted. However, we are currently witnessing a significant rise in the emergence of multidrug-resistant (MDR) bacteria, making these infections increasingly difficult to treat in hospitals. MAIN TEXT The discovery and development of new antibiotic has slowed, largely due to reduced profitability, as antibiotics often lose effectiveness quickly as pathogenic bacteria evolve into MDR strains. To address this challenge, metabolic engineering has recently become crucial in developing efficient enzymes and cell factories capable of producing both existing antibiotics and a wide range of new derivatives and analogs. In this paper, we review recent tools and strategies in metabolic engineering and synthetic biology for antibiotic discovery and the efficient production of antibiotics, their derivatives, and analogs, along with representative examples. CONCLUSION These metabolic engineering and synthetic biology strategies offer promising potential to revitalize the discovery and development of new antibiotics, providing renewed hope in humanity's fight against MDR pathogenic bacteria.
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Affiliation(s)
- Geunsoo Yook
- Synthetic Biology and Enzyme Engineering Laboratory, Department of Chemical and Biological Engineering, Korea University, Seoul, 02841, Republic of Korea
| | - Jiwoo Nam
- Synthetic Biology and Enzyme Engineering Laboratory, Department of Chemical and Biological Engineering, Korea University, Seoul, 02841, Republic of Korea
| | - Yeonseo Jo
- Synthetic Biology and Enzyme Engineering Laboratory, Department of Chemical and Biological Engineering, Korea University, Seoul, 02841, Republic of Korea
| | - Hyunji Yoon
- Synthetic Biology and Enzyme Engineering Laboratory, Department of Chemical and Biological Engineering, Korea University, Seoul, 02841, Republic of Korea
| | - Dongsoo Yang
- Synthetic Biology and Enzyme Engineering Laboratory, Department of Chemical and Biological Engineering, Korea University, Seoul, 02841, Republic of Korea.
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Keatinge-Clay A, Miyazawa T. Refactoring the pikromycin synthase for the modular biosynthesis of macrolide antibiotics in E. coli. RESEARCH SQUARE 2025:rs.3.rs-5640596. [PMID: 39866879 PMCID: PMC11760250 DOI: 10.21203/rs.3.rs-5640596/v1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/28/2025]
Abstract
While engineering modular polyketide synthases (PKSs) using the recently updated module boundary has yielded libraries of triketide-pentaketides, this strategy has not yet been applied to the combinatorial biosynthesis of macrolactones or macrolide antibiotics. We developed a 2-plasmid system for the construction and expression of PKSs and employed it to obtain a refactored pikromycin synthase in E. coli that produces 85 mg of narbonolide per liter of culture. The replacement, insertion, deletion, and mutagenesis of modules enabled access to hexaketide, heptaketide, and octaketide derivatives. Supplying enzymes for desosamine biosynthesis and transfer enabled production of narbomycin, pikromycin, YC-17, methymycin, and 6 derivatives thereof. Knocking out pathways competing with desosamine biosynthesis and supplying the editing thioesterase PikAV boosted the titer of narbomycin 55-fold to 37 mgL-1. The replacement of the 3rd pikromycin module with its 5th yielded a new macrolide antibiotic and demonstrates how libraries of macrolide antibiotics can be readily accessed.
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McCullough TM, Choudhary V, Akey DL, Skiba MA, Bernard SM, Kittendorf JD, Schmidt JJ, Sherman DH, Smith JL. Substrate Trapping in Polyketide Synthase Thioesterase Domains: Structural Basis for Macrolactone Formation. ACS Catal 2024; 14:12551-12563. [PMID: 39927088 PMCID: PMC11804868 DOI: 10.1021/acscatal.4c03637] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2025]
Abstract
Emerging antibiotic resistance requires continual improvement in the arsenal of antimicrobial drugs, especially the critical macrolide antibiotics. Formation of the macrolactone scaffold of these polyketide natural products is catalyzed by a modular polyketide synthase (PKS) thioesterase (TE). The TE accepts a linear polyketide substrate from the termina PKS acyl carrier protein to generate an acyl-enzyme adduct that is resolved by attack of a substrate hydroxyl group to form the macrolactone. Our limited mechanistic understanding of TE selectivity for a substrate nucleophile and/or water has hampered development of TEs as biocatalysts that accommodate a variety of natural and non-natural substrates. To understand how TEs direct the substrate nucleophile for macrolactone formation, acyl-enzyme intermediates were trapped as stable amides by substituting the natural serine OH with an amino group. Incorporation of the unnatural amino acid, 1,3-diaminopropionic acid (DAP), was tested with five PKS TEs. DAP-modified TEs (TEDAP) from the pikromycin and erythromycin pathways were purified and tested with six full-length polyketide intermediates from three pathways. The erythromycin TE had permissive substrate selectivity, whereas the pikromycin TE was selective for its native hexaketide and heptaketide substrates. In a crystal structure of a native substrate trapped in pikromycin TEDAP, the linear heptaketide was curled in the active site with the nucleophilic hydroxyl group positioned 4 Å from the amide-enzyme linkage. The curled heptaketide displayed remarkable shape complementarity with the TE acyl cavity. The strikingly different shapes of acyl cavities in TEs of known structure, including those reported here for juvenimicin, tylosin and fluvirucin biosynthesis, provide insights to facilitate TE engineering and optimization.
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Affiliation(s)
- Tyler M. McCullough
- Life Sciences Institute, Mary Sue Coleman Hall, 210 Washtenaw Ave., University of Michigan, Ann Arbor, MI 48109-2216, United States
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109-0600, United States
| | - Vishakha Choudhary
- Life Sciences Institute, Mary Sue Coleman Hall, 210 Washtenaw Ave., University of Michigan, Ann Arbor, MI 48109-2216, United States
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109-0600, United States
| | - David L. Akey
- Life Sciences Institute, Mary Sue Coleman Hall, 210 Washtenaw Ave., University of Michigan, Ann Arbor, MI 48109-2216, United States
| | - Meredith A. Skiba
- Life Sciences Institute, Mary Sue Coleman Hall, 210 Washtenaw Ave., University of Michigan, Ann Arbor, MI 48109-2216, United States
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109-0600, United States
| | - Steffen M. Bernard
- Life Sciences Institute, Mary Sue Coleman Hall, 210 Washtenaw Ave., University of Michigan, Ann Arbor, MI 48109-2216, United States
- Program in Chemical Biology, Mary Sue Coleman Hall, 210 Washtenaw Ave., University of Michigan, Ann Arbor, MI 48109-2216, United States
| | - Jeffrey D. Kittendorf
- Life Sciences Institute, Mary Sue Coleman Hall, 210 Washtenaw Ave., University of Michigan, Ann Arbor, MI 48109-2216, United States
| | - Jennifer J. Schmidt
- Life Sciences Institute, Mary Sue Coleman Hall, 210 Washtenaw Ave., University of Michigan, Ann Arbor, MI 48109-2216, United States
| | - David H. Sherman
- Life Sciences Institute, Mary Sue Coleman Hall, 210 Washtenaw Ave., University of Michigan, Ann Arbor, MI 48109-2216, United States
- Department of Medicinal Chemistry, University of Michigan College of Pharmacy, Ann Arbor, MI 48109-1065, United States
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, United States
- Department of Microbiology & Immunology, University of Michigan Medical School, Ann Arbor, MI 48109-5632, United States
| | - Janet L. Smith
- Life Sciences Institute, Mary Sue Coleman Hall, 210 Washtenaw Ave., University of Michigan, Ann Arbor, MI 48109-2216, United States
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109-0600, United States
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9
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McCullough TM, Choudhary V, Akey DL, Skiba MA, Bernard SM, Kittendorf JD, Schmidt JJ, Sherman DH, Smith JL. Substrate Trapping in Polyketide Synthase Thioesterase Domains: Structural Basis for Macrolactone Formation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.20.599880. [PMID: 38948807 PMCID: PMC11213023 DOI: 10.1101/2024.06.20.599880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/02/2024]
Abstract
Emerging antibiotic resistance requires continual improvement in the arsenal of antimicrobial drugs, especially the critical macrolide antibiotics. Formation of the macrolactone scaffold of these polyketide natural products is catalyzed by a modular polyketide synthase (PKS) thioesterase (TE). The TE accepts a linear polyketide substrate from the termina PKS acyl carrier protein to generate an acyl-enzyme adduct that is resolved by attack of a substrate hydroxyl group to form the macrolactone. Our limited mechanistic understanding of TE selectivity for a substrate nucleophile and/or water has hampered development of TEs as biocatalysts that accommodate a variety of natural and non-natural substrates. To understand how TEs direct the substrate nucleophile for macrolactone formation, acyl-enzyme intermediates were trapped as stable amides by substituting the natural serine OH with an amino group. Incorporation of the unnatural amino acid, 1,3-diaminopropionic acid (DAP), was tested with five PKS TEs. DAP-modified TEs (TE DAP ) from the pikromycin and erythromycin pathways were purified and tested with six full-length polyketide intermediates from three pathways. The erythromycin TE had permissive substrate selectivity, whereas the pikromycin TE was selective for its native hexaketide and heptaketide substrates. In a crystal structure of a native substrate trapped in pikromycin TE DAP , the linear heptaketide was curled in the active site with the nucleophilic hydroxyl group positioned 4 Å from the amide-enzyme linkage. The curled heptaketide displayed remarkable shape complementarity with the TE acyl cavity. The strikingly different shapes of acyl cavities in TEs of known structure, including those reported here for juvenimicin, tylosin and fluvirucin biosynthesis, provide new insights to facilitate TE engineering and optimization.
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10
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Jo WS, Curtis BJ, Rehan M, Adrover-Castellano ML, Sherman DH, Healy AR. N-to- S Acyl Transfer as an Enabling Strategy in Asymmetric and Chemoenzymatic Synthesis. JACS AU 2024; 4:2058-2066. [PMID: 38818054 PMCID: PMC11134368 DOI: 10.1021/jacsau.4c00257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 05/01/2024] [Accepted: 05/02/2024] [Indexed: 06/01/2024]
Abstract
The observation of thioester-mediated acyl transfer processes in nature has inspired the development of novel protein synthesis and functionalization methodologies. The chemoselective transfer of an acyl group from S-to-N is the basis of several powerful ligation strategies. In this work, we sought to apply the reverse process, the transfer of an acyl group from N-to-S, as a method to convert stable chiral amides into more reactive thioesters. To this end, we developed a novel cysteine-derived oxazolidinone that serves as both a chiral imide auxiliary and an acyl transfer agent. This auxiliary combines the desirable features of rigid chiral imides as templates for asymmetric transformations with the synthetic applicability of thioesters. We demonstrate that the auxiliary can be applied in a range of highly selective asymmetric transformations. Subsequent intramolecular N-to-S acyl transfer of the chiral product and in situ trapping of the resulting thioester provides access to diverse carboxylic acid derivatives under mild conditions. The oxazolidinone thioester products can also be isolated and used in Pd-mediated transformations to furnish highly valuable chiral scaffolds, such as noncanonical amino acids, cyclic ketones, tetrahydropyrones, and dihydroquinolinones. Finally, we demonstrate that the oxazolidinone thioesters can also serve as a surrogate for SNAC-thioesters, enabling their seamless use as non-native substrates in biocatalytic transformations.
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Affiliation(s)
- Woonkee S Jo
- Chemistry Program, New York University Abu Dhabi (NYUAD), Saadiyat Island, Abu Dhabi 129188, United Arab Emirates (UAE)
| | - Brian J Curtis
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109, USA
| | - Mohammad Rehan
- Chemistry Program, New York University Abu Dhabi (NYUAD), Saadiyat Island, Abu Dhabi 129188, United Arab Emirates (UAE)
| | | | - David H Sherman
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109, USA
- Departments of Medicinal Chemistry, Chemistry, and Microbiology & Immunology, University of Michigan, Ann Arbor, MI 48109USA
| | - Alan R Healy
- Chemistry Program, New York University Abu Dhabi (NYUAD), Saadiyat Island, Abu Dhabi 129188, United Arab Emirates (UAE)
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11
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Paquette AR, Brazeau-Henrie JT, Boddy CN. Thioesterases as tools for chemoenzymatic synthesis of macrolactones. Chem Commun (Camb) 2024; 60:3379-3388. [PMID: 38456624 DOI: 10.1039/d4cc00401a] [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
Macrocycles are a key functional group that can impart unique properties into molecules. Their synthesis has led to the development of many outstanding chemical methodologies and yet still remains challenging. Thioesterase (TE) domains are frequently responsible for macrocyclization in natural product biosynthesis and provide unique strengths for the enzymatic synthesis of macrocycles. In this feature article, we describe our work to characterize the substrate selectivity of TEs and to use these enzymes as biocatalysts. Our efforts have shown that the linear thioester activated substrates are loaded on TEs with limited substrate selectivity to generate acyl-enzyme intermediates. We show that cyclization of the acyl-enzyme intermediates can be highly selective, with competing hydrolysis of the acyl-enzyme intermediates. The mechanisms controlling TE-mediated macrocyclization versus hydrolysis are a significant unsolved problem in TE biochemistry. The potential of TEs as biocatalysts was demonstrated by using them in the chemoenzymatic total synthesis of macrocyclic depsipeptide natural products. This article highlights the strengths and potential of TEs as biocatalysts as well as their limitations, opening exciting research opportunities including TE engineering to optimize these powerful biocatalysts.
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Affiliation(s)
- André R Paquette
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON, Canada K1N 6N5.
| | - Jordan T Brazeau-Henrie
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON, Canada K1N 6N5.
| | - Christopher N Boddy
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON, Canada K1N 6N5.
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12
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Brazeau-Henrie JT, Paquette AR, Boddy CN. In Vitro Biochemical Characterization of Excised Macrocyclizing Thioesterase Domains from Non-ribosomal Peptide Synthetases. Methods Mol Biol 2023; 2670:101-125. [PMID: 37184701 DOI: 10.1007/978-1-0716-3214-7_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Characterization of thioesterases (TEs) is an important step in understanding natural product biosynthesis. Studying non-ribosomal peptide synthetase (NRPS) TEs presents a unique set of challenges with specific cloning and expression issues as well as the challenging synthesis of the thioester peptides substrate required for characterization of the TE. In this method, we describe the cloning and expression of NRPS TEs, the synthesis of thioester peptides, and the in vitro biochemical characterization of the enzyme.
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Affiliation(s)
| | - André R Paquette
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON, Canada
| | - Christopher N Boddy
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON, Canada.
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13
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Czapinska H, Bochtler M. The Nϵ-Rule for Serine, but Not Cysteine Catalytic Triads. Angew Chem Int Ed Engl 2022; 61:e202206945. [PMID: 35983934 PMCID: PMC9825947 DOI: 10.1002/anie.202206945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Indexed: 01/11/2023]
Abstract
Catalytic triads, composed of a serine or cysteine nucleophile, a histidine, and a third triad residue (typically Asp/Glu/Asn), are common in enzyme active sites and catalyze a wide variety of chemical reactions. Two types of triads can be distinguished: We refer to them as Nδ- or Nϵ-configured, depending on whether the histidine imidazole Nδ or Nϵ atom is close to the nucleophile Oγ/Sγ. In this study, we have analyzed triad configuration. In structural triads, the more stable Nδ-configuration predominates. For catalytic triads, the configuration depends on the nucleophile. When it is a cysteine residue, both configuration types occur, depending on the family. However, when the nucleophile is a serine residue, the less stable Nϵ-configuration is almost exclusively found. We posit that the energetically less favored conformation is selected for in serine triads to facilitate the otherwise difficult proton transfer from the nucleophile to the histidine residue.
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Affiliation(s)
- Honorata Czapinska
- International Institute of Molecular and Cell BiologyTrojdena 402-109WarsawPoland
| | - Matthias Bochtler
- International Institute of Molecular and Cell BiologyTrojdena 402-109WarsawPoland,Institute of Biochemistry and Biophysics of the Polish Academy of SciencesPawinskiego 5a02-106WarsawPoland
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14
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The Nε‐Rule for Serine, but Not Cysteine Catalytic Triads. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202206945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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15
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Linking protein structural and functional change to mutation using amino acid networks. PLoS One 2022; 17:e0261829. [PMID: 35061689 PMCID: PMC8782487 DOI: 10.1371/journal.pone.0261829] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 12/11/2021] [Indexed: 11/30/2022] Open
Abstract
The function of a protein is strongly dependent on its structure. During evolution, proteins acquire new functions through mutations in the amino-acid sequence. Given the advance in deep mutational scanning, recent findings have found functional change to be position dependent, notwithstanding the chemical properties of mutant and mutated amino acids. This could indicate that structural properties of a given position are potentially responsible for the functional relevance of a mutation. Here, we looked at the relation between structure and function of positions using five proteins with experimental data of functional change available. In order to measure structural change, we modeled mutated proteins via amino-acid networks and quantified the perturbation of each mutation. We found that structural change is position dependent, and strongly related to functional change. Strong changes in protein structure correlate with functional loss, and positions with functional gain due to mutations tend to be structurally robust. Finally, we constructed a computational method to predict functionally sensitive positions to mutations using structural change that performs well on all five proteins with a mean precision of 74.7% and recall of 69.3% of all functional positions.
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16
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Zhou Y, Tao W, Qi Z, Wei J, Shi T, Kang Q, Zheng J, Zhao Y, Bai L. Structural and Mechanistic Insights into Chain Release of the Polyene PKS Thioesterase Domain. ACS Catal 2021. [DOI: 10.1021/acscatal.1c04991] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Yucong Zhou
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
- Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Wentao Tao
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
- Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Zhen Qi
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
- Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Jianhua Wei
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
- Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Ting Shi
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
- Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Qianjin Kang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
- Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Jianting Zheng
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
- Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yilei Zhao
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
- Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Linquan Bai
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
- Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University, Shanghai 200240, China
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17
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Chirality-matched catalyst-controlled macrocyclization reactions. Proc Natl Acad Sci U S A 2021; 118:2113122118. [PMID: 34599107 DOI: 10.1073/pnas.2113122118] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/28/2021] [Indexed: 11/18/2022] Open
Abstract
Macrocycles, formally defined as compounds that contain a ring with 12 or more atoms, continue to attract great interest due to their important applications in physical, pharmacological, and environmental sciences. In syntheses of macrocyclic compounds, promoting intramolecular over intermolecular reactions in the ring-closing step is often a key challenge. Furthermore, syntheses of macrocycles with stereogenic elements confer an additional challenge, while access to such macrocycles are of great interest. Herein, we report the remarkable effect peptide-based catalysts can have in promoting efficient macrocyclization reactions. We show that the chirality of the catalyst is essential for promoting favorable, matched transition-state relationships that favor macrocyclization of substrates with preexisting stereogenic elements; curiously, the chirality of the catalyst is essential for successful reactions, even though no new static (i.e., not "dynamic") stereogenic elements are created. Control experiments involving either achiral variants of the catalyst or the enantiomeric form of the catalyst fail to deliver the macrocycles in significant quantity in head-to-head comparisons. The generality of the phenomenon, demonstrated here with a number of substrates, stimulates analogies to enzymatic catalysts that produce naturally occurring macrocycles, presumably through related, catalyst-defined peripheral interactions with their acyclic substrates.
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18
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Little RF, Hertweck C. Chain release mechanisms in polyketide and non-ribosomal peptide biosynthesis. Nat Prod Rep 2021; 39:163-205. [PMID: 34622896 DOI: 10.1039/d1np00035g] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Review covering up to mid-2021The structure of polyketide and non-ribosomal peptide natural products is strongly influenced by how they are released from their biosynthetic enzymes. As such, Nature has evolved a diverse range of release mechanisms, leading to the formation of bioactive chemical scaffolds such as lactones, lactams, diketopiperazines, and tetronates. Here, we review the enzymes and mechanisms used for chain release in polyketide and non-ribosomal peptide biosynthesis, how these mechanisms affect natural product structure, and how they could be utilised to introduce structural diversity into the products of engineered biosynthetic pathways.
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Affiliation(s)
- Rory F Little
- Leibniz Institute for Natural Product Research and Infection Biology, HKI, Germany.
| | - Christian Hertweck
- Leibniz Institute for Natural Product Research and Infection Biology, HKI, Germany.
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19
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Adrover-Castellano ML, Schmidt JJ, Sherman DH. Biosynthetic Cyclization Catalysts for the Assembly of Peptide and Polyketide Natural Products. ChemCatChem 2021; 13:2095-2116. [PMID: 34335987 PMCID: PMC8320681 DOI: 10.1002/cctc.202001886] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Indexed: 12/13/2022]
Abstract
Many biologically active natural products are synthesized by nonribosomal peptide synthetases (NRPSs), polyketide synthases (PKSs) and their hybrids. These megasynthetases contain modules possessing distinct catalytic domains that allow for substrate initiation, chain extension, processing and termination. At the end of a module, a terminal domain, usually a thioesterase (TE), is responsible for catalyzing the release of the NRPS or PKS as a linear or cyclized product. In this review, we address the general cyclization mechanism of the TE domain, including oligomerization and the fungal C-C bond forming Claisen-like cyclases (CLCs). Additionally, we include examples of cyclization catalysts acting within or at the end of a module. Furthermore, condensation-like (CT) domains, terminal reductase (R) domains, reductase-like domains that catalyze Dieckmann condensation (RD), thioesterase-like Dieckmann cyclases, trans-acting TEs from the penicillin binding protein (PBP) enzyme family, product template (PT) domains and others will also be reviewed. The studies summarized here highlight the remarkable diversity of NRPS and PKS cyclization catalysts for the production of biologically relevant, complex cyclic natural products and related compounds.
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Affiliation(s)
| | - Jennifer J Schmidt
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109-2216 (USA)
| | - David H Sherman
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109-2216 (USA)
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20
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Kačar D, Cañedo LM, Rodríguez P, González EG, Galán B, Schleissner C, Leopold-Messer S, Piel J, Cuevas C, de la Calle F, García JL. Identification of trans-AT polyketide clusters in two marine bacteria reveals cryptic similarities between distinct symbiosis factors. Environ Microbiol 2021; 23:2509-2521. [PMID: 33734547 DOI: 10.1111/1462-2920.15470] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 02/26/2021] [Accepted: 03/16/2021] [Indexed: 12/23/2022]
Abstract
Glutarimide-containing polyketides are known as potent antitumoral and antimetastatic agents. The associated gene clusters have only been identified in a few Streptomyces producers and Burkholderia gladioli symbiont. The new glutarimide-family polyketides, denominated sesbanimides D, E and F along with the previously known sesbanimide A and C, were isolated from two marine alphaproteobacteria Stappia indica PHM037 and Labrenzia aggregata PHM038. Structures of the isolated compounds were elucidated based on 1D and 2D homo and heteronuclear NMR analyses and ESI-MS spectrometry. All compounds exhibited strong antitumor activity in lung, breast and colorectal cancer cell lines. Subsequent whole genome sequencing and genome mining revealed the presence of the trans-AT PKS gene cluster responsible for the sesbanimide biosynthesis, described as sbn cluster. Strikingly, the modular architecture of downstream mixed type PKS/NRPS, SbnQ, revealed high similarity to PedH in pederin and Lab13 in labrenzin gene clusters, although those clusters are responsible for the production of structurally completely different molecules. The unexpected presence of SbnQ homologues in unrelated polyketide gene clusters across phylogenetically distant bacteria, raises intriguing questions about the evolutionary relationship between glutarimide-like and pederin-like pathways, as well as the functionality of their synthetic products.
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Affiliation(s)
- Dina Kačar
- Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Librada M Cañedo
- Research and Development Department, PharmaMar S.A., Madrid, Spain
| | - Pilar Rodríguez
- Research and Development Department, PharmaMar S.A., Madrid, Spain
| | - Elena G González
- Research and Development Department, PharmaMar S.A., Madrid, Spain
| | - Beatriz Galán
- Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | | | | | | | - Carmen Cuevas
- Research and Development Department, PharmaMar S.A., Madrid, Spain
| | | | - José L García
- Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
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21
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Calzini MA, Malico AA, Mitchler MM, Williams GJ. Protein engineering for natural product biosynthesis and synthetic biology applications. Protein Eng Des Sel 2021; 34:gzab015. [PMID: 34137436 PMCID: PMC8209613 DOI: 10.1093/protein/gzab015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 05/12/2021] [Accepted: 05/17/2021] [Indexed: 11/14/2022] Open
Abstract
As protein engineering grows more salient, many strategies have emerged to alter protein structure and function, with the goal of redesigning and optimizing natural product biosynthesis. Computational tools, including machine learning and molecular dynamics simulations, have enabled the rational mutagenesis of key catalytic residues for enhanced or altered biocatalysis. Semi-rational, directed evolution and microenvironment engineering strategies have optimized catalysis for native substrates and increased enzyme promiscuity beyond the scope of traditional rational approaches. These advances are made possible using novel high-throughput screens, including designer protein-based biosensors with engineered ligand specificity. Herein, we detail the most recent of these advances, focusing on polyketides, non-ribosomal peptides and isoprenoids, including their native biosynthetic logic to provide clarity for future applications of these technologies for natural product synthetic biology.
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Affiliation(s)
- Miles A Calzini
- Department of Chemistry, NC State University, Raleigh, NC 27695-8204, USA
| | - Alexandra A Malico
- Department of Chemistry, NC State University, Raleigh, NC 27695-8204, USA
| | - Melissa M Mitchler
- Department of Chemistry, NC State University, Raleigh, NC 27695-8204, USA
| | - Gavin J Williams
- Department of Chemistry, NC State University, Raleigh, NC 27695-8204, USA
- Comparative Medicine Institute, NC State University Raleigh, Raleigh, NC 27695-8204, USA
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22
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Wang R, Tao W, Liu L, Li C, Bai L, Zhao YL, Shi T. Insights into specificity and catalytic mechanism of amphotericin B/nystatin thioesterase. Proteins 2021; 89:558-568. [PMID: 33389775 DOI: 10.1002/prot.26041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 11/22/2020] [Accepted: 12/27/2020] [Indexed: 11/12/2022]
Abstract
Polyene polyketides amphotericin B (AMB) and nystatin (NYS) are important antifungal drugs. Thioesterases (TEs), located at the last module of PKS, control the release of polyketides by cyclization or hydrolysis. Intrigued by the tiny structural difference between AMB and NYS, as well as the high sequence identity between AMB TE and NYS TE, we constructed four systems to study the structural characteristics, catalytic mechanism, and product release of AMB TE and NYS TE with combined MD simulations and quantum mechanics/molecular mechanics calculations. The results indicated that compared with AMB TE, NYS TE shows higher specificity on its natural substrate and R26 as well as D186 were proposed to a key role in substrate recognition. The energy barrier of macrocyclization in AMB-TE-Amb and AMB-TE-Nys systems were calculated to be 14.0 and 22.7 kcal/mol, while in NYS-TE-Nys and NYS-TE-Amb systems, their energy barriers were 17.5 and 25.7 kcal/mol, suggesting the cyclization with their natural substrates were more favorable than that with exchanged substrates. At last, the binding free energy obtained with the MM-PBSA.py program suggested that it was easier for natural products to leave TE enzymes after cyclization. And key residues to the departure of polyketide product from the active site were highlighted. We provided a catalytic overview of AMB TE and NYS TE including substrate recognition, catalytic mechanism and product release. These will improve the comprehension of polyene polyketide TEs and benefit for broadening the substrate flexibility of polyketide TEs.
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Affiliation(s)
- Rufan Wang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Wentao Tao
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Lei Liu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Chen Li
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Linquan Bai
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Yi-Lei Zhao
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Ting Shi
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
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23
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24
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Gao DW, Jamieson CS, Wang G, Yan Y, Zhou J, Houk KN, Tang Y. A Polyketide Cyclase That Forms Medium-Ring Lactones. J Am Chem Soc 2020; 143:80-84. [PMID: 33351624 DOI: 10.1021/jacs.0c11226] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Medium-ring lactones are synthetically challenging due to unfavorable energetics involved in cyclization. We have discovered a thioesterase enzyme DcsB, from the decarestrictine C1 (1) biosynthetic pathway, that efficiently performs medium-ring lactonizations. DcsB shows broad substrate promiscuity toward linear substrates that vary in lengths and substituents, and is a potential biocatalyst for lactonization. X-ray crystal structure and computational analyses provide insights into the molecular basis of catalysis.
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Affiliation(s)
| | | | - Gaoqian Wang
- 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, Shanghai, China
| | | | - Jiahai Zhou
- 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, Shanghai, China
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25
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Koch AA, Schmidt JJ, Lowell AN, Hansen DA, Coburn KM, Chemler JA, Sherman DH. Probing Selectivity and Creating Structural Diversity Through Hybrid Polyketide Synthases. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202004991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Aaron A. Koch
- Life Sciences Institute The University of Michigan (USA) 210 Washtenaw Avenue Ann Arbor MI 48109-2216 USA
| | - Jennifer J. Schmidt
- Life Sciences Institute The University of Michigan (USA) 210 Washtenaw Avenue Ann Arbor MI 48109-2216 USA
| | - Andrew N. Lowell
- Life Sciences Institute The University of Michigan (USA) 210 Washtenaw Avenue Ann Arbor MI 48109-2216 USA
- Current address: Department of Chemistry Virginia Tech Blacksburg VA 24061 USA
| | - Douglas A. Hansen
- Life Sciences Institute The University of Michigan (USA) 210 Washtenaw Avenue Ann Arbor MI 48109-2216 USA
| | - Katherine M. Coburn
- Life Sciences Institute The University of Michigan (USA) 210 Washtenaw Avenue Ann Arbor MI 48109-2216 USA
| | - Joseph A. Chemler
- Life Sciences Institute The University of Michigan (USA) 210 Washtenaw Avenue Ann Arbor MI 48109-2216 USA
| | - David H. Sherman
- Life Sciences Institute The University of Michigan (USA) 210 Washtenaw Avenue Ann Arbor MI 48109-2216 USA
- Departments of Medicinal Chemistry, Chemistry, Microbiology & Immunology The University of Michigan USA
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26
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Koch AA, Schmidt JJ, Lowell AN, Hansen DA, Coburn KM, Chemler JA, Sherman DH. Probing Selectivity and Creating Structural Diversity Through Hybrid Polyketide Synthases. Angew Chem Int Ed Engl 2020; 59:13575-13580. [PMID: 32357274 DOI: 10.1002/anie.202004991] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Indexed: 11/09/2022]
Abstract
Engineering polyketide synthases (PKS) to produce new metabolites requires an understanding of catalytic points of failure during substrate processing. Growing evidence indicates the thioesterase (TE) domain as a significant bottleneck within engineered PKS systems. We created a series of hybrid PKS modules bearing exchanged TE domains from heterologous pathways and challenged them with both native and non-native polyketide substrates. Reactions pairing wildtype PKS modules with non-native substrates primarily resulted in poor conversions to anticipated macrolactones. Likewise, product formation with native substrates and hybrid PKS modules bearing non-cognate TE domains was severely reduced. In contrast, non-native substrates were converted by most hybrid modules containing a substrate compatible TE, directly implicating this domain as the major catalytic gatekeeper and highlighting its value as a target for protein engineering to improve analog production in PKS pathways.
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Affiliation(s)
- Aaron A Koch
- Life Sciences Institute, The University of Michigan (USA), 210 Washtenaw Avenue, Ann Arbor, MI, 48109-2216, USA
| | - Jennifer J Schmidt
- Life Sciences Institute, The University of Michigan (USA), 210 Washtenaw Avenue, Ann Arbor, MI, 48109-2216, USA
| | - Andrew N Lowell
- Life Sciences Institute, The University of Michigan (USA), 210 Washtenaw Avenue, Ann Arbor, MI, 48109-2216, USA.,Current address: Department of Chemistry, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Douglas A Hansen
- Life Sciences Institute, The University of Michigan (USA), 210 Washtenaw Avenue, Ann Arbor, MI, 48109-2216, USA
| | - Katherine M Coburn
- Life Sciences Institute, The University of Michigan (USA), 210 Washtenaw Avenue, Ann Arbor, MI, 48109-2216, USA
| | - Joseph A Chemler
- Life Sciences Institute, The University of Michigan (USA), 210 Washtenaw Avenue, Ann Arbor, MI, 48109-2216, USA
| | - David H Sherman
- Life Sciences Institute, The University of Michigan (USA), 210 Washtenaw Avenue, Ann Arbor, MI, 48109-2216, USA.,Departments of Medicinal Chemistry, Chemistry, Microbiology & Immunology, The University of Michigan, USA
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27
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Drufva EE, Hix EG, Bailey CB. Site directed mutagenesis as a precision tool to enable synthetic biology with engineered modular polyketide synthases. Synth Syst Biotechnol 2020; 5:62-80. [PMID: 32637664 PMCID: PMC7327777 DOI: 10.1016/j.synbio.2020.04.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 04/01/2020] [Accepted: 04/06/2020] [Indexed: 12/04/2022] Open
Abstract
Modular polyketide synthases (PKSs) are a multidomain megasynthase class of biosynthetic enzymes that have great promise for the development of new compounds, from new pharmaceuticals to high value commodity and specialty chemicals. Their colinear biosynthetic logic has been viewed as a promising platform for synthetic biology for decades. Due to this colinearity, domain swapping has long been used as a strategy to introduce molecular diversity. However, domain swapping often fails because it perturbs critical protein-protein interactions within the PKS. With our increased level of structural elucidation of PKSs, using judicious targeted mutations of individual residues is a more precise way to introduce molecular diversity with less potential for global disruption of the protein architecture. Here we review examples of targeted point mutagenesis to one or a few residues harbored within the PKS that alter domain specificity or selectivity, affect protein stability and interdomain communication, and promote more complex catalytic reactivity.
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Key Words
- ACP, acyl carrier protein
- AT, acyltransferase
- DEBS, 6-deoxyerthronolide B synthase
- DH, dehydratase
- EI, enoylisomerase
- ER, enoylreductase
- KR, ketoreductase
- KS, ketosynthase
- LM, loading module
- MT, methyltransferase
- Mod, module
- PKS, polyketide synthase
- PS, pyran synthase
- Polyketide synthase
- Protein engineering
- Rational design
- SNAC, N-acetyl cysteamine
- Saturation mutagenesis
- Site directed mutagenesis
- Synthetic biology
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Affiliation(s)
- Erin E. Drufva
- Department of Chemistry, University of Tennessee-Knoxville, Knoxville, TN, 37996, USA
| | - Elijah G. Hix
- Department of Chemistry, University of Tennessee-Knoxville, Knoxville, TN, 37996, USA
| | - Constance B. Bailey
- Department of Chemistry, University of Tennessee-Knoxville, Knoxville, TN, 37996, USA
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28
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Qiao L, Fang J, Zhu P, Huang H, Dang C, Pang J, Gao W, Qiu X, Huang L, Li Y. A Novel Chemoenzymatic Approach to Produce Cilengitide Using the Thioesterase Domain from Microcystis aeruginosa Microcystin Synthetase C. Protein J 2020; 38:658-666. [PMID: 31435810 DOI: 10.1007/s10930-019-09864-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Modern organic chemistry faces many difficulties in the reliable production of cyclopeptides, such as poor yields and insufficient regio- and stereoselectivity. Thioesterase (TE) shows impressive stereospecificity, region- and chemoselectivity during the cyclization of peptide substrates. The biocatalytic properties of TE provide high value for industrial applications. Herein, a novel chemoenzymatic method to synthesize cilengitide is described based on the cyclic activity of the TE domain from microcystin synthetase C (McyC) of Microcystis aeruginosa. In addition, a single active site mutation in the McyC TE was engineered to generate a more effective macrocyclization catalyst. Compared to the chemical approach to synthesize cilengitide, this novel enzyme-catalysed methodology exhibits a higher synthetic efficiency with an approximately 3.4-fold higher yield (49.2%).
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Affiliation(s)
- Longliang Qiao
- College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, 315832, China
| | - Jian Fang
- College of Medicine, Shaoxing University, Shaoxing, 312000, China
| | - Peng Zhu
- College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, 315832, China. .,Ningbo Institute of Oceanography, Ningbo, 315832, China.
| | - Hailong Huang
- College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, 315832, China
| | - Chenyang Dang
- College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, 315832, China
| | - Jianhu Pang
- College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, 315832, China
| | - Weifang Gao
- Ningbo Institute of Oceanography, Ningbo, 315832, China
| | - Xiaoting Qiu
- College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, 315832, China
| | - Lili Huang
- Ningbo Institute of Oceanography, Ningbo, 315832, China
| | - Yanrong Li
- Ningbo Institute of Oceanography, Ningbo, 315832, China
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29
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Tainter CJ, Schley ND, Harris CM, Stec DF, Song AK, Balinski A, May JC, McLean JA, Reece KS, Harris TM. Algal Toxin Goniodomin A Binds Potassium Ion Selectively to Yield a Conformationally Altered Complex with Potential Biological Consequences. JOURNAL OF NATURAL PRODUCTS 2020; 83:1069-1081. [PMID: 32083860 PMCID: PMC9290314 DOI: 10.1021/acs.jnatprod.9b01094] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The marine toxin goniodomin A (GDA) is a polycyclic macrolide containing a spiroacetal and three cyclic ethers as part of the macrocycle backbone. GDA is produced by three species of the Alexandrium genus of dinoflagellates, blooms of which are associated with "red tides", which are widely dispersed and can cause significant harm to marine life. The toxicity of GDA has been attributed to stabilization of the filamentous form of the actin group of structural proteins, but the structural basis for its binding is not known. Japanese workers, capitalizing on the assumed rigidity of the heavily substituted macrolide ring, assigned the relative configuration and conformation by relying on NMR coupling constants and NOEs; the absolute configuration was assigned by degradation to a fragment that was compared with synthetic material. We have confirmed the absolute structure and broad features of the conformation by X-ray crystallography but have found GDA to complex with alkali metal ions in spite of two of the heterocyclic rings facing outward. Such an arrangement would have been expected to impair the ability of GDA to form a crown-ether-type multidentate complex. GDA shows preference for K+, Rb+, and Cs+ over Li+ and Na+ in determinations of relative affinities by TLC on metal-ion-impregnated silica gel plates and by electrospray mass spectrometry. NMR studies employing the K+ complex of GDA, formed from potassium tetrakis[pentafluorophenyl]borate (KBArF20), reveal a major alteration of the conformation of the macrolide ring. These observations argue against the prior assumption of rigidity of the ring. Alterations in chemical shifts, coupling constants, and NOEs indicate the involvement of most of the molecule other than ring F. Molecular mechanics simulations suggest K+ forms a heptacoordinate complex involving OA, OB, OC, OD, OE, and the C-26 and C-27 hydroxy groups. We speculate that complexation of K+ with GDA electrostatically stabilizes the complex of GDA with filamentous actin in marine animals due to the protein being negatively charged at physiological pH. GDA may also cause potassium leakage through cell membranes. This study provides insight into the structural features and chemistry of GDA that may be responsible for significant ecological damage associated with the GDA-producing algal blooms.
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Affiliation(s)
- Craig J. Tainter
- Department of Chemistry, Vanderbilt University, Nashville,
TN 37235, USA
| | - Nathan D. Schley
- Department of Chemistry, Vanderbilt University, Nashville,
TN 37235, USA
| | | | - Donald F. Stec
- Department of Chemistry, Vanderbilt University, Nashville,
TN 37235, USA
| | - Anna K. Song
- Department of Aquatic Health Sciences, Virginia Institute
of Marine Science, Gloucester Point, VA 23062, USA
| | - Andrzej Balinski
- Department of Chemistry, Vanderbilt University, Nashville,
TN 37235, USA
| | - Jody C. May
- Department of Chemistry, Vanderbilt University, Nashville,
TN 37235, USA
| | - John A. McLean
- Department of Chemistry, Vanderbilt University, Nashville,
TN 37235, USA
| | - Kimberly S. Reece
- Department of Aquatic Health Sciences, Virginia Institute
of Marine Science, Gloucester Point, VA 23062, USA
| | - Thomas M. Harris
- Department of Chemistry, Vanderbilt University, Nashville,
TN 37235, USA
- Department of Aquatic Health Sciences, Virginia Institute
of Marine Science, Gloucester Point, VA 23062, USA
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30
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Schmidt JJ, Khatri Y, Brody SI, Zhu C, Pietraszkiewicz H, Valeriote FA, Sherman DH. A Versatile Chemoenzymatic Synthesis for the Discovery of Potent Cryptophycin Analogs. ACS Chem Biol 2020; 15:524-532. [PMID: 31961651 DOI: 10.1021/acschembio.9b00998] [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
The cryptophycins are a family of macrocyclic depsipeptide natural products that display exceptionally potent antiproliferative activity against drug-resistant cancers. Unique challenges facing the synthesis and derivatization of this complex group of molecules motivated us to investigate a chemoenzymatic synthesis designed to access new analogs for biological evaluation. The cryptophycin thioesterase (CrpTE) and the cryptophycin epoxidase (CrpE) are a versatile set of enzymes that catalyze macrocyclization and epoxidation of over 20 natural cryptophycin metabolites. Thus, we envisioned a drug development strategy involving their use as standalone biocatalysts for production of unnatural derivatives. Herein, we developed a scalable synthesis of 12 new unit A-B-C-D linear chain elongation intermediates containing heterocyclic aromatic groups as alternatives to the native unit A benzyl group. N-Acetyl cysteamine activated forms of each intermediate were assessed for conversion to macrocyclic products using wild type CrpTE, which demonstrated the exceptional flexibility of this enzyme. Semipreparative scale reactions were conducted for isolation and structural characterization of new cryptophycins. Each was then evaluated as a substrate for CrpE P450 and its ability to generate the epoxidized products from these substrates that possess altered electronics at the unit A styrenyl double bond position. Finally, biological evaluation of the new cryptophycins revealed a des-β-epoxy analog with low picomolar potency, previously limited to cryptophycins bearing epoxide functionality.
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Affiliation(s)
| | | | | | | | - Halina Pietraszkiewicz
- Department of Internal Medicine, Henry Ford Cancer Institute, Henry Ford Health System, Detroit, Michigan 48202, United States
| | - Frederick A. Valeriote
- Department of Internal Medicine, Henry Ford Cancer Institute, Henry Ford Health System, Detroit, Michigan 48202, United States
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31
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Engineering enzymatic assembly lines to produce new antibiotics. Curr Opin Microbiol 2019; 51:88-96. [PMID: 31743841 PMCID: PMC6908967 DOI: 10.1016/j.mib.2019.10.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 10/17/2019] [Accepted: 10/18/2019] [Indexed: 02/07/2023]
Abstract
Many clinical antibiotics are natural products produced by thiotemplate-based assembly line biosynthetic pathways. Assembly line pathways provide an opportunity for rational bioengineering to modify complex natural product structures. New, rule-based mix and match strategies facilitate the engineering of non-ribosomal peptide assembly line synthetases. Evolutionary guided approaches highlight new avenues for polyketide synthase assembly line reprogramming.
Numerous important therapeutic agents, including widely-used antibiotics, anti-cancer drugs, immunosuppressants, agrochemicals and other valuable compounds, are produced by microorganisms. Many of these are biosynthesised by modular enzymatic assembly line polyketide synthases, non-ribosomal peptide synthetases, and hybrids thereof. To alter the backbone structure of these valuable but difficult to modify compounds, the respective enzymatic machineries can be engineered to create even more valuable molecules with improved properties and/or to bypass resistance mechanisms. In the past, many attempts to achieve assembly line pathway engineering failed or led to enzymes with compromised activity. Recently our understanding of assembly line structural biology, including an appreciation of the conformational changes that occur during the catalytic cycle, have improved hugely. This has proven to be a driving force for new approaches and several recent examples have demonstrated the production of new-to-nature molecules, including anti-infectives. We discuss the developments of the last few years and highlight selected, illuminating examples of assembly line engineering.
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Robinson SL, Christenson JK, Wackett LP. Biosynthesis and chemical diversity of β-lactone natural products. Nat Prod Rep 2019; 36:458-475. [PMID: 30191940 DOI: 10.1039/c8np00052b] [Citation(s) in RCA: 105] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Covering: up to 2018 β-Lactones are strained rings that are useful organic synthons and pharmaceutical warheads. Over 30 core scaffolds of β-lactone natural products have been described to date, many with potent bioactivity against bacteria, fungi, or human cancer cell lines. β-Lactone natural products are chemically diverse and have high clinical potential, but production of derivatized drug leads has been largely restricted to chemical synthesis partly due to gaps in biochemical knowledge about β-lactone biosynthesis. Here we review recent discoveries in enzymatic β-lactone ring closure via ATP-dependent synthetases, intramolecular cyclization from seven-membered rings, and thioesterase-mediated cyclization during release from nonribosomal peptide synthetase assembly lines. We also comprehensively cover the diversity and taxonomy of source organisms for β-lactone natural products including their isolation from bacteria, fungi, plants, insects, and marine sponges. This work identifies computational and experimental bottlenecks and highlights future directions for genome-based discovery of biosynthetic gene clusters that may produce novel compounds with β-lactone rings.
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Affiliation(s)
- Serina L Robinson
- BioTechnology Institute, University of Minnesota - Twin Cities 140 Gortner Laboratory, 1479 Gortner Avenue, Saint Paul, MN 55108, USA.
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33
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Kornfuehrer T, Eustáquio AS. Diversification of polyketide structures via synthase engineering. MEDCHEMCOMM 2019; 10:1256-1272. [PMID: 32180918 PMCID: PMC7053703 DOI: 10.1039/c9md00141g] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 05/09/2019] [Indexed: 12/16/2022]
Abstract
Polyketide natural products possess diverse biological activities including antibiotic, anticancer, and immunosuppressive. Their equally varied and complex structures arise from head-to-tail condensation of simple carboxyacyl monomers. Since the seminal discovery that biosynthesis of polyketides such as the macrolide erythromycin is catalyzed by uncharacteristically large, multifunctional enzymes, termed modular type I polyketide synthases, chemists and biologists alike have been inspired to harness the apparent modularity of the synthases to further diversify polyketide structures. Yet, initial attempts to perform "combinatorial biosynthesis" failed due to challenges associated with maintaining the structural and catalytic integrity of large, chimeric synthases. Fast forward nearly 30 years, and advancements in our understanding of polyketide synthase structure and function have allowed the field to make significant progress toward effecting desired modifications to polyketide scaffolds in addition to engineering small, chiral fragments. This review highlights selected examples of polyketide diversification via control of monomer selection, oxidation state, stereochemistry, and cyclization. We conclude with a perspective on the present and future of polyketide structure diversification and hope that the examples presented here will encourage medicinal chemists to embrace polyketide synthetic biology as a means to revitalize polyketide drug discovery.
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Affiliation(s)
- Taylor Kornfuehrer
- Department of Medicinal Chemistry and Pharmacognosy and Center for Biomolecular Sciences , College of Pharmacy , University of Illinois at Chicago , Chicago , Illinois 60607 , USA . ; Tel: +1 3124137082
| | - Alessandra S Eustáquio
- Department of Medicinal Chemistry and Pharmacognosy and Center for Biomolecular Sciences , College of Pharmacy , University of Illinois at Chicago , Chicago , Illinois 60607 , USA . ; Tel: +1 3124137082
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The structural basis of N-acyl-α-amino-β-lactone formation catalyzed by a nonribosomal peptide synthetase. Nat Commun 2019; 10:3432. [PMID: 31366889 PMCID: PMC6668435 DOI: 10.1038/s41467-019-11383-7] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 07/11/2019] [Indexed: 01/19/2023] Open
Abstract
Nonribosomal peptide synthetases produce diverse natural products using a multidomain architecture where the growing peptide, attached to an integrated carrier domain, is delivered to neighboring catalytic domains for bond formation and modification. Investigation of these systems can lead to the discovery of new structures, unusual biosynthetic transformations, and to the engineering of catalysts for generating new products. The antimicrobial β-lactone obafluorin is produced nonribosomally from dihydroxybenzoic acid and a β-hydroxy amino acid that cyclizes into the β-lactone during product release. Here we report the structure of the nonribosomal peptide synthetase ObiF1, highlighting the structure of the β-lactone-producing thioesterase domain and an interaction between the C-terminal MbtH-like domain with an upstream adenylation domain. Biochemical assays examine catalytic promiscuity, provide mechanistic insight, and demonstrate utility for generating obafluorin analogs. These results advance our understanding of the structural cycle of nonribosomal peptide synthetases and provide insights into the production of β-lactone natural products. The antimicrobial β-lactone obafluorin is produced by a Nonribosomal Peptide Synthetase (NRPS). Here the authors present the crystal structure of the obafluorin NRPS and develop a reconstitution assay that allows them to analyse product formation from obafluorin NRPS mutants and alternate substrates.
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35
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Stamm A, Biundo A, Schmidt B, Brücher J, Lundmark S, Olsén P, Fogelström L, Malmström E, Bornscheuer UT, Syrén P. A Retro-biosynthesis-Based Route to Generate Pinene-Derived Polyesters. Chembiochem 2019; 20:1664-1671. [PMID: 30793830 PMCID: PMC6618282 DOI: 10.1002/cbic.201900046] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Indexed: 12/21/2022]
Abstract
Significantly increased production of biobased polymers is a prerequisite to replace petroleum-based materials towards reaching a circular bioeconomy. However, many renewable building blocks from wood and other plant material are not directly amenable for polymerization, due to their inert backbones and/or lack of functional group compatibility with the desired polymerization type. Based on a retro-biosynthetic analysis of polyesters, a chemoenzymatic route from (-)-α-pinene towards a verbanone-based lactone, which is further used in ring-opening polymerization, is presented. Generated pinene-derived polyesters showed elevated degradation and glass transition temperatures, compared with poly(ϵ-decalactone), which lacks a ring structure in its backbone. Semirational enzyme engineering of the cyclohexanone monooxygenase from Acinetobacter calcoaceticus enabled the biosynthesis of the key lactone intermediate for the targeted polyester. As a proof of principle, one enzyme variant identified from screening in a microtiter plate was used in biocatalytic upscaling, which afforded the bicyclic lactone in 39 % conversion in shake flask scale reactions.
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Affiliation(s)
- Arne Stamm
- KTH Royal Institute of TechnologySchool of Engineering Sciences in ChemistryBiotechnology and Health, Department of Fibre and Polymer TechnologyTeknikringen 56–58100 44StockholmSweden
- KTH Royal Institute of TechnologyScience for Life LaboratorySchool of Engineering Sciences in ChemistryBiotechnology and HealthTomtebodavägen 23Box 1031171 21 SolnaStockholmSweden
| | - Antonino Biundo
- KTH Royal Institute of TechnologySchool of Engineering Sciences in ChemistryBiotechnology and Health, Department of Fibre and Polymer TechnologyTeknikringen 56–58100 44StockholmSweden
- KTH Royal Institute of TechnologyScience for Life LaboratorySchool of Engineering Sciences in ChemistryBiotechnology and HealthTomtebodavägen 23Box 1031171 21 SolnaStockholmSweden
| | - Björn Schmidt
- KTH Royal Institute of TechnologySchool of Engineering Sciences in ChemistryBiotechnology and Health, Department of Fibre and Polymer TechnologyTeknikringen 56–58100 44StockholmSweden
- KTH Royal Institute of TechnologyScience for Life LaboratorySchool of Engineering Sciences in ChemistryBiotechnology and HealthTomtebodavägen 23Box 1031171 21 SolnaStockholmSweden
| | | | - Stefan Lundmark
- Perstorp AB, InnovationPerstorp Industrial Park284 80PerstorpSweden
| | - Peter Olsén
- KTH Royal Institute of TechnologySchool of Engineering Sciences in ChemistryBiotechnology and Health, Department of Fibre and Polymer TechnologyTeknikringen 56–58100 44StockholmSweden
| | - Linda Fogelström
- KTH Royal Institute of TechnologySchool of Engineering Sciences in ChemistryBiotechnology and Health, Department of Fibre and Polymer TechnologyTeknikringen 56–58100 44StockholmSweden
- Wallenberg Wood Science CenterTeknikringen 56–58100 44StockholmSweden
| | - Eva Malmström
- KTH Royal Institute of TechnologySchool of Engineering Sciences in ChemistryBiotechnology and Health, Department of Fibre and Polymer TechnologyTeknikringen 56–58100 44StockholmSweden
- Wallenberg Wood Science CenterTeknikringen 56–58100 44StockholmSweden
| | - Uwe T. Bornscheuer
- Department of Biotechnology and Enzyme CatalysisInstitute of BiochemistryUniversität GreifswaldFelix-Hausdorff-Strasse 417487GreifswaldGermany
| | - Per‐Olof Syrén
- KTH Royal Institute of TechnologySchool of Engineering Sciences in ChemistryBiotechnology and Health, Department of Fibre and Polymer TechnologyTeknikringen 56–58100 44StockholmSweden
- KTH Royal Institute of TechnologyScience for Life LaboratorySchool of Engineering Sciences in ChemistryBiotechnology and HealthTomtebodavägen 23Box 1031171 21 SolnaStockholmSweden
- KTH Royal Institute of TechnologyScience for Life LaboratorySchool of Engineering Sciences in ChemistryBiotechnology and Health, Division of Protein TechnologyTomtebodavägen 23Box 1031171 21 SolnaStockholmSweden
- Wallenberg Wood Science CenterTeknikringen 56–58100 44StockholmSweden
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36
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“Bridge regions” regulate catalysis and protein stability of acylpeptide hydrolase. Biochem Eng J 2019. [DOI: 10.1016/j.bej.2019.01.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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37
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Heberlig GW, Brown JTC, Simard RD, Wirz M, Zhang W, Wang M, Susser LI, Horsman ME, Boddy CN. Chemoenzymatic macrocycle synthesis using resorcylic acid lactone thioesterase domains. Org Biomol Chem 2019; 16:5771-5779. [PMID: 30052255 DOI: 10.1039/c8ob01512k] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A key missing tool in the chemist's toolbox is an effective biocatalyst for macrocyclization. Macrocycles limit the conformational flexibility of small molecules, often improving their ability to bind selectively and with high affinity to a target, making them a privileged structure in drug discovery. Macrocyclic natural product biosynthesis offers an obvious starting point for biocatalyst discovery via the native macrocycle forming biosynthetic mechanism. Herein we demonstrate that the thioesterase domains (TEs) responsible for macrocyclization of resorcylic acid lactones are promising catalysts for the chemoenzymatic synthesis of 12- to 18-member ring macrolactones and macrolactams. The TE domains responsible for zearalenone and radicicol biosynthesis successfully generate resorcylate-like 12- to 18-member macrolactones and a 14-member macrolactam. In addition these enzymes can also macrolactonize a non-resorcylate containing depsipeptide, suggesting they are versatile biocatalysts. Simple saturated omega-hydroxy acyl chains are not macrocyclized, nor are the alpha-beta unsaturated derivatives, clearly outlining the scope of the substrate tolerance. These data dramatically expand our understanding of substrate tolerance of these enzymes and are consistent with our understanding of the role of TEs in iterative polyketide biosynthesis. In addition this work shows these TEs to be the most substrate tolerant polyketide macrocyclizing enzymes known, accessing resorcylate lactone and lactams as well as cyclicdepsipeptides, which are highly biologically relevant frameworks.
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Affiliation(s)
- Graham W Heberlig
- Department of Chemistry and Biomolecular Sciences, Centre for Catalysis Research and Innovation, University of Ottawa, Ottawa, ON K1N 6N5, Canada.
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38
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Fan S, Wang R, Li C, Bai L, Zhao YL, Shi T. Insight into Structural Characteristics of Protein-Substrate Interaction in Pimaricin Thioesterase. Int J Mol Sci 2019; 20:ijms20040877. [PMID: 30781619 PMCID: PMC6412417 DOI: 10.3390/ijms20040877] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 02/05/2019] [Accepted: 02/06/2019] [Indexed: 01/23/2023] Open
Abstract
As a polyene antibiotic of great pharmaceutical significance, pimaricin has been extensively studied to enhance its productivity and effectiveness. In our previous studies, pre-reaction state (PRS) has been validated as one of the significant conformational categories before macrocyclization, and is critical to mutual recognition and catalytic preparation in thioesterase (TE)-catalyzed systems. In our study, molecular dynamics (MD) simulations were conducted on pimaricin TE-polyketide complex and PRS, as well as pre-organization state (POS), a molecular conformation possessing a pivotal intra-molecular hydrogen bond, were detected. Conformational transition between POS and PRS was observed in one of the simulations, and POS was calculated to be energetically more stable than PRS by 4.58 kcal/mol. The structural characteristics of PRS and POS-based hydrogen-bonding, and hydrophobic interactions were uncovered, and additional simulations were carried out to rationalize the functions of several key residues (Q29, M210, and R186). Binding energies, obtained from MM/PBSA calculations, were further decomposed to residues, in order to reveal their roles in product release. Our study advanced a comprehensive understanding of pimaricin TE-catalyzed macrocyclization from the perspectives of conformational change, protein-polyketide recognition, and product release, and provided potential residues for rational modification of pimaricin TE.
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Affiliation(s)
- Shuobing Fan
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
| | - Rufan Wang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
| | - Chen Li
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
| | - Linquan Bai
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
| | - Yi-Lei Zhao
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
| | - Ting Shi
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
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Kalkreuter E, CroweTipton JM, Lowell AN, Sherman DH, Williams GJ. Engineering the Substrate Specificity of a Modular Polyketide Synthase for Installation of Consecutive Non-Natural Extender Units. J Am Chem Soc 2019; 141:1961-1969. [PMID: 30676722 DOI: 10.1021/jacs.8b10521] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
There is significant interest in diversifying the structures of polyketides to create new analogues of these bioactive molecules. This has traditionally been done by focusing on engineering the acyltransferase (AT) domains of polyketide synthases (PKSs) responsible for the incorporation of malonyl-CoA extender units. Non-natural extender units have been utilized by engineered PKSs previously; however, most of the work to date has been accomplished with ATs that are either naturally promiscuous and/or located in terminal modules lacking downstream bottlenecks. These limitations have prevented the engineering of ATs with low native promiscuity and the study of any potential gatekeeping effects by domains downstream of an engineered AT. In an effort to address this gap in PKS engineering knowledge, the substrate preferences of the final two modules of the pikromycin PKS were compared for several non-natural extender units and through active site mutagenesis. This led to engineering of the methylmalonyl-CoA specificity of both modules and inversion of their selectivity to prefer consecutive non-natural derivatives. Analysis of the product distributions of these bimodular reactions revealed unexpected metabolites resulting from gatekeeping by the downstream ketoreductase and ketosynthase domains. Despite these new bottlenecks, AT engineering provided the first full-length polyketide products incorporating two non-natural extender units. Together, this combination of tandem AT engineering and the identification of previously poorly characterized bottlenecks provides a platform for future advancements in the field.
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Affiliation(s)
- Edward Kalkreuter
- Department of Chemistry , NC State University , Raleigh , North Carolina 27695 , United States.,Comparative Medicine Institute , NC State University , Raleigh , North Carolina 27695 , United States
| | - Jared M CroweTipton
- Department of Chemistry , NC State University , Raleigh , North Carolina 27695 , United States
| | - Andrew N Lowell
- Life Sciences Institute, Department of Medicinal Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - David H Sherman
- Life Sciences Institute, Department of Medicinal Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States.,Department of Chemistry and Department of Microbiology & Immunology , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Gavin J Williams
- Department of Chemistry , NC State University , Raleigh , North Carolina 27695 , United States.,Comparative Medicine Institute , NC State University , Raleigh , North Carolina 27695 , United States
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40
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Liu L, Tao W, Bai L, Kim ES, Zhao YL, Shi T. Why does tautomycetin thioesterase prefer hydrolysis to macrocyclization? Theoretical study on its catalytic mechanism. Catal Sci Technol 2019. [DOI: 10.1039/c9cy01355e] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this study, we attempted to uncover the reasons why Tautomycetin thioesterase (TMC TE) prefers hydrolysis rather than macrocyclization, and reveal the molecular basis of TE-catalyzed hydrolysis and macrocyclization.
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Affiliation(s)
- Lei Liu
- State Key Laboratory of Microbial Metabolism
- Joint International Research Laboratory of Metabolic and Developmental Sciences
- School of Life Sciences and Biotechnology
- Shanghai Jiao Tong University
- Shanghai 200240
| | - Wentao Tao
- State Key Laboratory of Microbial Metabolism
- Joint International Research Laboratory of Metabolic and Developmental Sciences
- School of Life Sciences and Biotechnology
- Shanghai Jiao Tong University
- Shanghai 200240
| | - Linquan Bai
- State Key Laboratory of Microbial Metabolism
- Joint International Research Laboratory of Metabolic and Developmental Sciences
- School of Life Sciences and Biotechnology
- Shanghai Jiao Tong University
- Shanghai 200240
| | - Eung-Soo Kim
- Department of Biological Engineering
- Inha University
- Incheon
- Korea
| | - Yi-Lei Zhao
- State Key Laboratory of Microbial Metabolism
- Joint International Research Laboratory of Metabolic and Developmental Sciences
- School of Life Sciences and Biotechnology
- Shanghai Jiao Tong University
- Shanghai 200240
| | - Ting Shi
- State Key Laboratory of Microbial Metabolism
- Joint International Research Laboratory of Metabolic and Developmental Sciences
- School of Life Sciences and Biotechnology
- Shanghai Jiao Tong University
- Shanghai 200240
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41
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Kalkreuter E, Williams GJ. Engineering enzymatic assembly lines for the production of new antimicrobials. Curr Opin Microbiol 2018; 45:140-148. [PMID: 29733997 DOI: 10.1016/j.mib.2018.04.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 04/22/2018] [Indexed: 01/06/2023]
Abstract
A large portion of natural products are biosynthesized by the polyketide synthase and non-ribosomal peptide synthetase enzymatic assembly lines. Recent advancements in the study of these megasynthases has led to many new examples that demonstrate the production of non-natural natural products. The field is likely nearing the ability to design and build new biosynthetic pathways de novo. We discuss the various recent approaches taken towards this goal, focusing on the installation of new substrates, the swapping of enzymatic domains and modules, and the impact of metabolic engineering and synthetic biology. We also address the challenges remaining alongside the many successes in this area.
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Affiliation(s)
- Edward Kalkreuter
- Department of Chemistry, NC State University, Raleigh, NC 27695, United States; Comparative Medicine Institute, NC State University, Raleigh, NC 27695, United States
| | - Gavin J Williams
- Department of Chemistry, NC State University, Raleigh, NC 27695, United States; Comparative Medicine Institute, NC State University, Raleigh, NC 27695, United States.
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42
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Shi T, Liu L, Tao W, Luo S, Fan S, Wang XL, Bai L, Zhao YL. Theoretical Studies on the Catalytic Mechanism and Substrate Diversity for Macrocyclization of Pikromycin Thioesterase. ACS Catal 2018. [DOI: 10.1021/acscatal.8b01156] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Ting Shi
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China
| | - Lanxuan Liu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China
| | - Wentao Tao
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China
| | - Shenggan Luo
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China
| | - Shuobing Fan
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China
| | - Xiao-Lei Wang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China
| | - Linquan Bai
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China
| | - Yi-Lei Zhao
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China
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43
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Hill RA, Sutherland A. Hot off the press. Nat Prod Rep 2017; 34:1340-1344. [PMID: 29090285 DOI: 10.1039/c7np90044a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A personal selection of 32 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products such as tryptorubin A isolated from a Streptomyces species.
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Affiliation(s)
- Robert A Hill
- School of Chemistry, Glasgow University, Glasgow, UKG12 8QQ.
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Koch A, Hansen DA, Shende VV, Furan LR, Houk KN, Jiménez-Osés G, Sherman DH. A Single Active Site Mutation in the Pikromycin Thioesterase Generates a More Effective Macrocyclization Catalyst. J Am Chem Soc 2017; 139:13456-13465. [PMID: 28836768 PMCID: PMC5617804 DOI: 10.1021/jacs.7b06436] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Indexed: 11/28/2022]
Abstract
Macrolactonization of natural product analogs presents a significant challenge to both biosynthetic assembly and synthetic chemistry. In the preceding paper , we identified a thioesterase (TE) domain catalytic bottleneck processing unnatural substrates in the pikromycin (Pik) system, preventing the formation of epimerized macrolactones. Here, we perform molecular dynamics simulations showing the epimerized hexaketide was accommodated within the Pik TE active site; however, intrinsic conformational preferences of the substrate resulted in predominately unproductive conformations, in agreement with the observed hydrolysis. Accordingly, we engineered the stereoselective Pik TE to yield a variant (TES148C) with improved reaction kinetics and gain-of-function processing of an unnatural, epimerized hexaketide. Quantum mechanical comparison of model TES148C and TEWT reaction coordinate diagrams revealed a change in mechanism from a stepwise addition-elimination (TEWT) to a lower energy concerted acyl substitution (TES148C), accounting for the gain-of-function and improved reaction kinetics. Finally, we introduced the S148C mutation into a polyketide synthase module (PikAIII-TE) to impart increased substrate flexibility, enabling the production of diastereomeric macrolactones.
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Affiliation(s)
- Aaron
A. Koch
- Life
Sciences Institute, Cancer Biology Graduate Program, Department of Medicinal Chemistry, Program in Chemical
Biology, Department of Chemistry, and Department of Microbiology & Immunology, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Douglas A. Hansen
- Life
Sciences Institute, Cancer Biology Graduate Program, Department of Medicinal Chemistry, Program in Chemical
Biology, Department of Chemistry, and Department of Microbiology & Immunology, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Vikram V. Shende
- Life
Sciences Institute, Cancer Biology Graduate Program, Department of Medicinal Chemistry, Program in Chemical
Biology, Department of Chemistry, and Department of Microbiology & Immunology, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Lawrence R. Furan
- Life
Sciences Institute, Cancer Biology Graduate Program, Department of Medicinal Chemistry, Program in Chemical
Biology, Department of Chemistry, and Department of Microbiology & Immunology, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - K. N. Houk
- Department
of Chemistry and Biochemistry, University
of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095, United States
| | - Gonzalo Jiménez-Osés
- Departamento
de Química, Centro de Investigación en Síntesis
Química, Universidad de La Rioja, 26006 Logroño, La Rioja, Spain
| | - David H. Sherman
- Life
Sciences Institute, Cancer Biology Graduate Program, Department of Medicinal Chemistry, Program in Chemical
Biology, Department of Chemistry, and Department of Microbiology & Immunology, University of Michigan, Ann Arbor, Michigan 48109, United States
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45
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Hansen DA, Koch AA, Sherman DH. Identification of a Thioesterase Bottleneck in the Pikromycin Pathway through Full-Module Processing of Unnatural Pentaketides. J Am Chem Soc 2017; 139:13450-13455. [PMID: 28836772 DOI: 10.1021/jacs.7b06432] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Polyketide biosynthetic pathways have been engineered to generate natural product analogs for over two decades. However, manipulation of modular type I polyketide synthases (PKSs) to make unnatural metabolites commonly results in attenuated yields or entirely inactive pathways, and the mechanistic basis for compromised production is rarely elucidated since rate-limiting or inactive domain(s) remain unidentified. Accordingly, we synthesized and assayed a series of modified pikromycin (Pik) pentaketides that mimic early pathway engineering to probe the substrate tolerance of the PikAIII-TE module in vitro. Truncated pentaketides were processed with varying efficiencies to corresponding macrolactones, while pentaketides with epimerized chiral centers were poorly processed by PikAIII-TE and failed to generate 12-membered ring products. Isolation and identification of extended but prematurely offloaded shunt products suggested that the Pik thioesterase (TE) domain has limited substrate flexibility and functions as a gatekeeper in the processing of unnatural substrates. Synthesis of an analogous hexaketide with an epimerized nucleophilic hydroxyl group allowed for direct evaluation of the substrate stereoselectivity of the excised TE domain. The epimerized hexaketide failed to undergo cyclization and was exclusively hydrolyzed, confirming the TE domain as a key catalytic bottleneck. In an accompanying paper , we engineer the standalone Pik thioesterase to yield a thioesterase (TES148C) and module (PikAIII-TES148C) that display gain-of-function processing of substrates with inverted hydroxyl groups.
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Affiliation(s)
- Douglas A Hansen
- Life Sciences Institute, ‡Department of Medicinal Chemistry, §Cancer Biology Graduate Program, ⊥Department of Chemistry, and ∥Department of Microbiology & Immunology, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Aaron A Koch
- Life Sciences Institute, ‡Department of Medicinal Chemistry, §Cancer Biology Graduate Program, ⊥Department of Chemistry, and ∥Department of Microbiology & Immunology, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - David H Sherman
- Life Sciences Institute, ‡Department of Medicinal Chemistry, §Cancer Biology Graduate Program, ⊥Department of Chemistry, and ∥Department of Microbiology & Immunology, University of Michigan , Ann Arbor, Michigan 48109, United States
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