1
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Wang S, Wu K, Tang YJ, Deng H. Dehydroamino acid residues in bioactive natural products. Nat Prod Rep 2024; 41:273-297. [PMID: 37942836 PMCID: PMC10880069 DOI: 10.1039/d3np00041a] [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: 09/08/2023] [Indexed: 11/10/2023]
Abstract
Covering: 2000 to up to 2023α,β-Dehydroamino acids (dhAAs) are unsaturated nonproteinogenic amino acids found in a wide array of naturally occurring peptidyl metabolites, predominantly those from bacteria. Other organisms, such as fungi, higher plants and marine invertebrates, have also been found to produce dhAA-containing peptides. The α,β-unsaturation in dhAAs has profound effects on the properties of these molecules. They display significant synthetic flexibility, readily undergoing reactions such as Michael additions, transition-metal-catalysed cross-couplings, and cycloadditions. These residues in peptides/proteins also exhibit great potential in bioorthogonal applications using click chemistry. Peptides containing contiguous dhAA residues have been extensively investigated in the field of foldamers, self-assembling supermolecules that mimic biomacromolecules such as proteins to fold into well-defined conformations. dhAA residues in these peptidyl materials tend to form a 2.05-helix. As a result, stretches of dhAA residues arrange in an extended conformation. In particular, peptidyl foldamers containing β-enamino acid units display interesting conformational, electronic, and supramolecular aggregation properties that can be modulated by light-dependent E-Z isomerization. Among approximately 40 dhAAs found in the natural product inventory, dehydroalanine (Dha) and dehydrobutyrine (Dhb) are the most abundant. Dha is the simplest dehydro-α-amino acid, or α-dhAA, without any geometrical isomers, while its re-arranged isomer, 3-aminoacrylic acid (Aaa or ΔβAla), is the simplest dehydro-β-amino acid, or β-enamino acid, and displays E/Z isomerism. Dhb is the simplest α-dhAA that exhibits E/Z isomerism. The Z-isomer of Dhb (Z-Dhb) is sterically favourable and is present in the majority of naturally occurring peptides containing Dhb residues. Dha and Z-Dhb motifs are commonly found in ribosomally synthesized and post-translationally modified peptides (RiPPs). In the last decade, the formation of Dha and Dhb motifs in RiPPs has been extensively investigated, which will be briefly discussed in this review. The formation of other dhAA residues in natural products (NPs) is, however, less understood. In this review, we will discuss recent advances in the biosynthesis of peptidyl NPs containing unusual dhAA residues and cryptic dhAA residues. The proposed biosynthetic pathways of these natural products will also be discussed.
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Affiliation(s)
- Shan Wang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China.
| | - Kewen Wu
- Department of Chemistry, University of Aberdeen, Aberdeen AB24 3UE, UK.
| | - Ya-Jie Tang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China.
| | - Hai Deng
- Department of Chemistry, University of Aberdeen, Aberdeen AB24 3UE, UK.
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2
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Patel KD, MacDonald MR, Ahmed SF, Singh J, Gulick AM. Structural advances toward understanding the catalytic activity and conformational dynamics of modular nonribosomal peptide synthetases. Nat Prod Rep 2023; 40:1550-1582. [PMID: 37114973 PMCID: PMC10510592 DOI: 10.1039/d3np00003f] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Indexed: 04/29/2023]
Abstract
Covering: up to fall 2022.Nonribosomal peptide synthetases (NRPSs) are a family of modular, multidomain enzymes that catalyze the biosynthesis of important peptide natural products, including antibiotics, siderophores, and molecules with other biological activity. The NRPS architecture involves an assembly line strategy that tethers amino acid building blocks and the growing peptides to integrated carrier protein domains that migrate between different catalytic domains for peptide bond formation and other chemical modifications. Examination of the structures of individual domains and larger multidomain proteins has identified conserved conformational states within a single module that are adopted by NRPS modules to carry out a coordinated biosynthetic strategy that is shared by diverse systems. In contrast, interactions between modules are much more dynamic and do not yet suggest conserved conformational states between modules. Here we describe the structures of NRPS protein domains and modules and discuss the implications for future natural product discovery.
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Affiliation(s)
- Ketan D Patel
- University at Buffalo, Department of Structural Biology, Jacobs School of Medicine and Biomedical Sciences, 55 Main St. Buffalo, NY 14203, USA.
| | - Monica R MacDonald
- University at Buffalo, Department of Structural Biology, Jacobs School of Medicine and Biomedical Sciences, 55 Main St. Buffalo, NY 14203, USA.
| | - Syed Fardin Ahmed
- University at Buffalo, Department of Structural Biology, Jacobs School of Medicine and Biomedical Sciences, 55 Main St. Buffalo, NY 14203, USA.
| | - Jitendra Singh
- University at Buffalo, Department of Structural Biology, Jacobs School of Medicine and Biomedical Sciences, 55 Main St. Buffalo, NY 14203, USA.
| | - Andrew M Gulick
- University at Buffalo, Department of Structural Biology, Jacobs School of Medicine and Biomedical Sciences, 55 Main St. Buffalo, NY 14203, USA.
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3
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Patel KD, Ahmed SF, MacDonald MR, Gulick AM. Structural Studies of Modular Nonribosomal Peptide Synthetases. Methods Mol Biol 2023; 2670:17-46. [PMID: 37184698 DOI: 10.1007/978-1-0716-3214-7_2] [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
The non-ribosomal peptide synthetases (NRPSs) are a family of modular enzymes involved in the production of peptide natural products. Not restricted by the constraints of ribosomal peptide and protein production, the NRPSs are able to incorporate unusual amino acids and other suitable building blocks into the final product. The NRPSs operate with an assembly line strategy in which peptide intermediates are covalently tethered to a peptidyl carrier protein and transported to different catalytic domains for the multiple steps in the biosynthesis. Often the carrier and catalytic domains are joined into a single large multidomain protein. This chapter serves to introduce the NRPS enzymes, using the nocardicin NRPS system as an example that highlights many common features to NRPS biochemistry. We then describe recent advances in the structural biology of NRPSs focusing on large multidomain structures that have been determined.
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Affiliation(s)
- Ketan D Patel
- Department of Structural Biology, University at Buffalo, SUNY, Buffalo, NY, USA
| | - Syed Fardin Ahmed
- Department of Structural Biology, University at Buffalo, SUNY, Buffalo, NY, USA
| | - Monica R MacDonald
- Department of Structural Biology, University at Buffalo, SUNY, Buffalo, NY, USA
| | - Andrew M Gulick
- Department of Structural Biology, University at Buffalo, SUNY, Buffalo, NY, USA.
- Department of Structural Biology, Jacobs School of Medicine & Biomedical Sciences, Buffalo, NY, USA.
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4
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Chen B, Kuai C, Xu J, Wu X. Manganese(III)‐Promoted Double Carbonylation of Anilines Toward α‐Ketoamides Synthesis. Adv Synth Catal 2021. [DOI: 10.1002/adsc.202101233] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Bo Chen
- Dalian National Laboratory for Clean Energy Dalian Institute of Chemical Physics Chinese Academy of Sciences 116023 Dalian Liaoning People's Republic of China
| | - Chang‐Sheng Kuai
- Dalian National Laboratory for Clean Energy Dalian Institute of Chemical Physics Chinese Academy of Sciences 116023 Dalian Liaoning People's Republic of China
| | - Jian‐Xing Xu
- Dalian National Laboratory for Clean Energy Dalian Institute of Chemical Physics Chinese Academy of Sciences 116023 Dalian Liaoning People's Republic of China
| | - Xiao‐Feng Wu
- Dalian National Laboratory for Clean Energy Dalian Institute of Chemical Physics Chinese Academy of Sciences 116023 Dalian Liaoning People's Republic of China
- Leibniz-Institut für Katalyse e.V. 18059 Rostock Germany
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5
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Dekimpe S, Masschelein J. Beyond peptide bond formation: the versatile role of condensation domains in natural product biosynthesis. Nat Prod Rep 2021; 38:1910-1937. [DOI: 10.1039/d0np00098a] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Condensation domains perform highly diverse functions during natural product biosynthesis and are capable of generating remarkable chemical diversity.
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Affiliation(s)
- Sofie Dekimpe
- Laboratory for Biomolecular Discovery & Engineering
- Department of Biology
- KU Leuven
- Leuven
- Belgium
| | - Joleen Masschelein
- Laboratory for Biomolecular Discovery & Engineering
- Department of Biology
- KU Leuven
- Leuven
- Belgium
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6
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Zhang JJ, Moore BS. Site-Directed Mutagenesis of Large Biosynthetic Gene Clusters via Oligonucleotide Recombineering and CRISPR/Cas9 Targeting. ACS Synth Biol 2020; 9:1917-1922. [PMID: 32584552 DOI: 10.1021/acssynbio.0c00265] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Genetic engineering of natural product biosynthetic gene clusters represents an attractive approach to access new and complex bioactive small molecules. However, due to the large number and size of some genes involved in specialized metabolism, notably those encoding modular polyketide synthase and nonribosomal peptide synthetase megaproteins, it remains difficult to introduce precise genetic mutations to probe domain activity or alter chemical product formation. Here, we report the development and validation of a robust method combining oligonucleotide recombineering and CRISPR/Cas9 targeting for rapid site-directed mutagenesis of cloned pathways, which can be directly transferred to a heterologous host for expression. We rapidly generated 12 point mutations and identified several important determinants of successful mutagenesis, including the protospacer/PAM sequence and presence of regions of local homology. Our approach may be broadly applicable for researchers interested in probing natural product biosynthesis or performing pathway engineering.
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Affiliation(s)
- Jia Jia Zhang
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, California 92037, United States
| | - Bradley S. Moore
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, California 92037, United States
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California at San Diego, La Jolla, California 92037, United States
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7
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El-Shorbagi AN, Chaudhary S. Monobactams: A Unique Natural Scaffold of Four-Membered Ring Skeleton, Recent Development to Clinically Overcome Infections by Multidrug- Resistant Microbes. LETT DRUG DES DISCOV 2019. [DOI: 10.2174/1570180816666190516113202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Background:
Monobactam antibiotics have been testified to demonstrate significant antibacterial
activity especially the treatment of infections by superbug microbes. Recently, research has
been focused on the structural modifications, and new generation of this privileged natural scaffold.
Objective:
Efforts have been made to discover the structure-antibacterial relationship of monbactams
in order to avoid the aimless work involving the ongoing generated analogues. This review aims to
summarize the current knowledge and development of monobactams as a broad-spectrum antibacterial
scaffolds. The recent structural modifications that expand the activity, especially in the infections
by resistant-strains, combinational therapies and dosing, as well as the possibility of crosshypersensitivity/
reactivity/tolerability with penicillins and cephalosporins will also be summarized
and inferred. Different approaches will be covered with emphasis on chemical methods and Structure-
Activity Relationship (SAR), in addition to the proposed mechanisms of action. Clinical investigation
of monobactams tackling various aspects will not be missed in this review.
Conclusion:
The conclusion includes the novels approaches, that could be followed to design new
research projects and reduce the pitfalls in the future development of monobactams.
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Affiliation(s)
- Abdel Nasser El-Shorbagi
- Department of Medicinal Chemistry, College of Pharmacy, University of Sharjah, Sharjah 27272, United Arab Emirates
| | - Sachin Chaudhary
- Department of Medicinal Chemistry, College of Pharmacy, University of Sharjah, Sharjah 27272, United Arab Emirates
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8
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Pass-back chain extension expands multimodular assembly line biosynthesis. Nat Chem Biol 2019; 16:42-49. [PMID: 31636431 PMCID: PMC6917876 DOI: 10.1038/s41589-019-0385-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 09/06/2019] [Indexed: 11/26/2022]
Abstract
Modular nonribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) enzymatic assembly lines are large and dynamic protein machines that generally effect a linear sequence of catalytic cycles. Here we report the heterologous reconstitution and comprehensive characterization of two hybrid NRPS-PKS assembly lines that defy many standard rules of assembly line biosynthesis to generate a large combinatorial library of cyclic lipodepsipeptide protease inhibitors called thalassospiramides. We generate a series of precise domain-inactivating mutations in thalassospiramide assembly lines and present evidence for an unprecedented biosynthetic model that invokes inter-module substrate activation and tailoring, module skipping, and pass-back chain extension, whereby the ability to pass the growing chain back to a preceding module is flexible and substrate-driven. Expanding bidirectional inter-module domain interactions could represent a viable mechanism for generating chemical diversity without increasing the size of biosynthetic assembly lines and challenges our understanding of the potential elasticity of multi-modular megaenzymes.
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9
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Dhakal D, Rayamajhi V, Mishra R, Sohng JK. Bioactive molecules from Nocardia: diversity, bioactivities and biosynthesis. ACTA ACUST UNITED AC 2019; 46:385-407. [DOI: 10.1007/s10295-018-02120-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 12/19/2018] [Indexed: 02/06/2023]
Abstract
Abstract
Nocardia spp. are catalase positive, aerobic, and non-motile Gram-positive filamentous bacteria. Many Nocarida spp. have been reported as unusual causes of diverse clinical diseases in both humans and animals. Therefore, they have been studied for a long time, primarily focusing on strain characterization, taxonomic classification of new isolates, and host pathophysiology. Currently, there are emerging interests in isolating bioactive molecules from diverse actinobacteria including Nocardia spp. and studying their biosynthetic mechanisms. In addition, these species possess significant metabolic capacity, which has been utilized for generating diverse functionalized bioactive molecules by whole cell biotransformation. This review summarizes the structural diversity and biological activities of compounds biosynthesized or biotransformed by Nocardia spp. Furthermore, the recent advances on biosynthetic mechanisms and genetic engineering approaches for enhanced production or structural/functional modification are presented.
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Affiliation(s)
- Dipesh Dhakal
- 0000 0004 0533 4202 grid.412859.3 Department of Life Science and Biochemical Engineering SunMoon University 70 Sunmoon-ro 221, Tangjeong-myeon 31460 Asan-si Chungnam Republic of Korea
| | - Vijay Rayamajhi
- 0000 0004 0533 4202 grid.412859.3 Department of Life Science and Biochemical Engineering SunMoon University 70 Sunmoon-ro 221, Tangjeong-myeon 31460 Asan-si Chungnam Republic of Korea
| | - Ravindra Mishra
- 0000 0004 0533 4202 grid.412859.3 Department of Life Science and Biochemical Engineering SunMoon University 70 Sunmoon-ro 221, Tangjeong-myeon 31460 Asan-si Chungnam Republic of Korea
| | - Jae Kyung Sohng
- 0000 0004 0533 4202 grid.412859.3 Department of Life Science and Biochemical Engineering SunMoon University 70 Sunmoon-ro 221, Tangjeong-myeon 31460 Asan-si Chungnam Republic of Korea
- 0000 0004 0533 4202 grid.412859.3 Department of BT-Convergent Pharmaceutical Engineering SunMoon University 70 Sunmoon-ro 221, Tangjeong-myeon 31460 Asan-si Chungnam Republic of Korea
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10
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Long DH, Townsend CA. Mechanism of Integrated β-Lactam Formation by a Nonribosomal Peptide Synthetase during Antibiotic Synthesis. Biochemistry 2018; 57:3353-3358. [PMID: 29701951 DOI: 10.1021/acs.biochem.8b00411] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Modular nonribosomal peptide synthetases (NRPSs) are large, multidomain engines of bioactive natural product biosynthesis that function as molecular "assembly lines" in which monomer units are selectively bound, modified, and linked in a specific order and number dictated by their mega-enzyme templates. Recently, a condensation domain in an NRPS was discovered to carry out the synthesis of an integrated β-lactam ring from a substrate seryl residue during antibiotic biosynthesis. We report here a series of experiments supporting a mechanism that involves C-N bond formation by stepwise elimination/addition reactions followed by canonical NRPS-catalyzed amide bond synthesis to achieve β-lactam formation. Partitioning of reactive intermediates formed during the multistep catalytic cycle provided insight into the ability of the NRPS to overcome the reversibility of corresponding reactions in solution and enforce directionality during synthesis.
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Affiliation(s)
- Darcie H Long
- Department of Chemistry , Johns Hopkins University , Baltimore , Maryland 21218 , United States
| | - Craig A Townsend
- Department of Chemistry , Johns Hopkins University , Baltimore , Maryland 21218 , United States
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11
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Waldman AJ, Ng TL, Wang P, Balskus EP. Heteroatom-Heteroatom Bond Formation in Natural Product Biosynthesis. Chem Rev 2017; 117:5784-5863. [PMID: 28375000 PMCID: PMC5534343 DOI: 10.1021/acs.chemrev.6b00621] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Natural products that contain functional groups with heteroatom-heteroatom linkages (X-X, where X = N, O, S, and P) are a small yet intriguing group of metabolites. The reactivity and diversity of these structural motifs has captured the interest of synthetic and biological chemists alike. Functional groups containing X-X bonds are found in all major classes of natural products and often impart significant biological activity. This review presents our current understanding of the biosynthetic logic and enzymatic chemistry involved in the construction of X-X bond containing functional groups within natural products. Elucidating and characterizing biosynthetic pathways that generate X-X bonds could both provide tools for biocatalysis and synthetic biology, as well as guide efforts to uncover new natural products containing these structural features.
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Affiliation(s)
- Abraham J. Waldman
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
| | - Tai L. Ng
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
| | - Peng Wang
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
| | - Emily P. Balskus
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
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12
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Townsend CA. Convergent biosynthetic pathways to β-lactam antibiotics. Curr Opin Chem Biol 2016; 35:97-108. [PMID: 27693891 DOI: 10.1016/j.cbpa.2016.09.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 09/14/2016] [Accepted: 09/15/2016] [Indexed: 02/05/2023]
Abstract
Five naturally-occurring families of β-lactams have inspired a class of drugs that constitute >60% of the antimicrobials used in human medicine. Their biosynthetic pathways reveal highly individualized synthetic strategies that yet converge on a common azetidinone ring assembled in structural contexts that confer selective binding and inhibition of d,d-transpeptidases that play essential roles in bacterial cell wall (peptidoglycan) biosynthesis. These enzymes belong to a single 'clan' of evolutionarily distinct serine hydrolases whose active site geometry and mechanism of action is specifically matched by these antibiotics for inactivation that is kinetically competitive with their native function. Unusual enzyme-mediated reactions and catalytic multitasking in these pathways are discussed with particular attention to the diverse ways the β-lactam itself is generated, and more broadly how the intrinsic reactivity of this core structural element is modulated in natural systems through the introduction of ring strain and electronic effects.
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Affiliation(s)
- Craig A Townsend
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA.
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13
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Pang B, Wang M, Liu W. Cyclization of polyketides and non-ribosomal peptides on and off their assembly lines. Nat Prod Rep 2016; 33:162-73. [PMID: 26604034 DOI: 10.1039/c5np00095e] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Modular polyketide synthases (PKSs) and non-ribosomal peptide synthetases (NRPSs) are multifunctional megaenzymes that serve as templates to program the assembly of short carboxylic acids and amino acids in a primarily co-linear manner. The variation, combination, permutation and evolution of their functional units (e.g., modules, domains and proteins) along with their association with external enzymes have resulted in the generation of numerous versions of templates, the roles of which have not been fully recognized in the structural diversification of polyketides, non-ribosomal peptides and their hybrids present in nature. In this Highlight, we focus on the assembly-line enzymology and associated chemistry by providing examples of some newly characterized cyclization reactions that occur on and off the assembly lines during and after chain elongation for the purpose of elucidating the template effects of PKSs and NRPSs. A fundamental understanding of the underlying biosynthetic logic would facilitate the elucidation of chemical information contained within the PKS or NRPS templates and benefit the development of strategies for genome mining, biosynthesis-inspired chemical synthesis and combinatorial biosynthesis.
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Affiliation(s)
- Bo Pang
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China.
| | - Min Wang
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China.
| | - Wen Liu
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China. and Huzhou Center of Bio-Synthetic Innovation, 1366 Hongfeng Road, Huzhou 313000, China
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14
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Gaudelli NM, Long DH, Townsend CA. β-Lactam formation by a non-ribosomal peptide synthetase during antibiotic biosynthesis. Nature 2015; 520:383-7. [PMID: 25624104 PMCID: PMC4401618 DOI: 10.1038/nature14100] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Accepted: 11/19/2014] [Indexed: 01/23/2023]
Abstract
Non-ribosomal peptide synthetases (NRPSs) are giant enzymes comprised of modules that house repeated sets of functional domains, which select, activate and couple amino acids drawn from a pool of nearly 500 potential building blocks.1 The structurally and stereochemically diverse peptides generated in this manner underlie the biosynthesis of a large sector of natural products. Many of their derived metabolites are bioactive such as the antibiotics vancomycin, bacitracin, daptomycin and the β-lactam-containing penicillins, cephalosporins and nocardicins. Although penicillins and cephalosporins are synthesised from a classically derived NRPS tripeptide (from ACVS, δ-(L-α-aminoadipyl)–L-cysteinyl–D-valine synthetase)2, we now report an unprecedented NRPS activity to both assemble a serine-containing peptide and mediate its cyclisation to the critical β-lactam ring of the nocardicin family of antibiotics. A histidine-rich condensation (C) domain, which typically carries out peptide bond formation during product assembly, was found to also synthesise the embedded 4-membered ring. Here, a mechanism is proposed and supporting experiments are described, which is distinct from the pathways that have evolved to the three other β-lactam antibiotic families: penicillin/cephalosporins, clavams and carbapenems. These findings raise the possibility that β-lactam rings can be regio- and stereospecifically integrated into engineered peptides for application as, for example, targeted protease inactivators.3,4
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Affiliation(s)
- Nicole M Gaudelli
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Darcie H Long
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Craig A Townsend
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA
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15
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Gaudelli NM, Townsend CA. Epimerization and substrate gating by a TE domain in β-lactam antibiotic biosynthesis. Nat Chem Biol 2014; 10:251-8. [PMID: 24531841 PMCID: PMC3961552 DOI: 10.1038/nchembio.1456] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Accepted: 12/30/2013] [Indexed: 12/01/2022]
Abstract
Nonribosomal peptide synthetases (NRPSs) are versatile engines of bioactive natural product biosynthesis that function according to the multiple carrier thiotemplate mechanism. C-terminal thioesterase (TE) domains of these giant modular proteins typically catalyze product release by hydrolysis or macrocylization. We now report an unprecedented, dual-function TE involved in nocardicin A biosynthesis, the paradigm monocyclic β-lactam antibiotic. Contrary to expectation, a stereodefined series of potential peptide substrates for the nocardicin TE domain failed to undergo hydrolysis. The stringent discrimination against peptide intermediates was dramatically overcome by prior monocyclic β-lactam formation at an L-seryl site. Kinetic data are interpreted such that the TE domain acts as a gatekeeper to hold the assembling peptide on an upstream domain until β-lactam formation takes place and then rapidly catalyzes epimerization, not previously observed as a TE catalytic function, and thioesterase cleavage to discharge a fully fledged pentapeptide β-lactam harboring nocardicin G, the universal precursor of the nocardicins.
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Affiliation(s)
- Nicole M Gaudelli
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland, USA
| | - Craig A Townsend
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland, USA
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16
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Core assembly mechanism of quinocarcin/SF-1739: bimodular complex nonribosomal peptide synthetases for sequential mannich-type reactions. ACTA ACUST UNITED AC 2013; 20:1523-35. [PMID: 24269153 DOI: 10.1016/j.chembiol.2013.10.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 10/05/2013] [Accepted: 10/12/2013] [Indexed: 11/20/2022]
Abstract
Quinocarcin and SF-1739, potent antitumor antibiotics, share a common tetracyclic tetrahydroisoquinoline (THIQ)-pyrrolidine core scaffold. Herein, we describe the identification of their biosynthetic gene clusters and biochemical analysis of Qcn18/Cya18 generating the previously unidentified extender unit dehydroarginine, which is a component of the pyrrolidine ring. ATP-inorganic pyrophosphate exchange experiments with five nonribosomal peptide synthetases (NRPSs) enabled us to identify their substrates. On the basis of these data, we propose that a biosynthetic pathway comprising a three-component NRPS/MbtH family protein complex, Qcn16/17/19, plays a key role in the construction of tetracyclic THIQ-pyrrolidine core scaffold involving sequential Pictet-Spengler and intramolecular Mannich reactions. Furthermore, data derived from gene inactivation experiments led us to propose late-modification steps of quinocarcin.
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17
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Luo Q, Hiessl S, Steinbüchel A. Functional diversity of Nocardia in metabolism. Environ Microbiol 2013; 16:29-48. [PMID: 23981049 DOI: 10.1111/1462-2920.12221] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 07/12/2013] [Accepted: 07/19/2013] [Indexed: 11/29/2022]
Abstract
Bacteria affiliated in the genus Nocardia are aerobic and Gram-positive actinomycetes that are widely found in aquatic and terrestrial habitats. As occasional pathogens, several of them cause infection diseases called 'nocardiosis' affecting lungs, central nervous system, cutaneous tissues and others. In addition, members of the genus Nocardia exhibit an enormous metabolic versatility. On one side, many secondary metabolites have been isolated from members of this genus that exhibit various biological activities such as antimicrobial, antitumor, antioxidative and immunosuppressive activities. On the other side, many species are capable of degrading or converting aliphatic and aromatic toxic hydrocarbons, natural or synthetic polymers, and other widespread environmental pollutants. Because of these valuable properties and the application potential, Nocardia species have attracted much interest in academia and industry in recent years. A solid basis of genetic tools including a set of shuttle vectors and an efficient electroporation method for further genetic and metabolic engineering studies has been established to conduct efficient research. Associated with the increasing data of nocardial genome sequences, the functional diversity of Nocardia will be much faster and better understood.
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Affiliation(s)
- Quan Luo
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Corrensstraße 3, 48149, Münster, Germany
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Gaudelli NM, Townsend CA. Stereocontrolled syntheses of peptide thioesters containing modified seryl residues as probes of antibiotic biosynthesis. J Org Chem 2013; 78:6412-26. [PMID: 23758494 PMCID: PMC3898789 DOI: 10.1021/jo4007893] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Methods have been developed to synthesize tri- and pentapeptide thioesters containing one or more p-(hydroxyphenyl)glycine (pHPG) residues and L-serine, some where the latter is O-phosphorylated, O-acetylated, or exists as a β-lactam. Selection of orthogonal protection strategies and development of conditions to achieve seryl O-phosphorylation without β-elimination and to maintain stereochemical control, especially simultaneously at exceptionally base-labile pHPG α-carbons, are described. Intramolecular closure of a seryl peptide to a β-lactam-containing peptide and the syntheses of corresponding thioester analogues are also reported. Modification of classical Mitsunobu conditions is described in the synthesis of the β-lactam-containing products, and in a broadly useful observation, it was found that simple exclusion of light from the P(OEt)3-mediated Mitsunobu ring closure afforded yields of >95%, presumably owing to reduced photodegradation of the azodicarboxylate used. These sensitive potential substrates and products will be used in mechanistic studies of the two nonribosomal peptide synthetases NocA and NocB that lie at the heart of nocardicin biosynthesis, a family of monocyclic β-lactam antibiotics.
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Affiliation(s)
| | - Craig A. Townsend
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218
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Origins of the β-lactam rings in natural products. J Antibiot (Tokyo) 2013; 66:401-10. [DOI: 10.1038/ja.2013.24] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 02/26/2013] [Accepted: 03/05/2013] [Indexed: 11/08/2022]
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Davidsen JM, Bartley DM, Townsend CA. Non-ribosomal propeptide precursor in nocardicin A biosynthesis predicted from adenylation domain specificity dependent on the MbtH family protein NocI. J Am Chem Soc 2013; 135:1749-59. [PMID: 23330869 DOI: 10.1021/ja307710d] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Nocardicin A is a monocyclic β-lactam isolated from the actinomycete Nocardia uniformis that shows moderate antibiotic activity against a broad spectrum of gram-negative bacteria. The monobactams are of renewed interest due to emerging gram-negative strains resistant to clinically available penicillins and cephalosporins. Like isopenicillin N, nocardicin A has a tripeptide core of non-ribosomal origin. Paradoxically, the nocardicin A gene cluster encodes two non-ribosomal peptide synthetases (NRPSs), NocA and NocB, predicted to encode five modules pointing to a pentapeptide precursor in nocardicin A biosynthesis, unless module skipping or other nonlinear reactions are occurring. Previous radiochemical incorporation experiments and bioinformatic analyses predict the incorporation of p-hydroxy-L-phenylglycine (L-pHPG) into positions 1, 3, and 5 and L-serine into position 4. No prediction could be made for position 2. Multidomain constructs of each module were heterologous expressed in Escherichia coli for determination of the adenylation domain (A-domain) substrate specificity using the ATP/PPi exchange assay. Three of the five A-domains, from modules 1, 2, and 4, required the addition of stoichiometric amounts of MbtH family protein NocI to detect exchange activity. On the basis of these analyses, the predicted product of the NocA and NocB NRPSs is L-pHPG-L-Arg-D-pHPG-L-Ser-L-pHPG, a pentapeptide. Despite being flanked by non-proteinogenic amino acids, proteolysis of this pentapeptide by trypsin yields two fragments from cleavage at the C terminus of the L-Arg residue. Thus, a proteolytic step is likely involved in the biosynthesis of nocardicin A, a rare but precedented editing event in the formation of non-ribosomal natural products that is supported by the identification of trypsin-encoding genes in N. uniformis.
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Affiliation(s)
- Jeanne M Davidsen
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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Hamed RB, Gomez-Castellanos JR, Henry L, Ducho C, McDonough MA, Schofield CJ. The enzymes of β-lactam biosynthesis. Nat Prod Rep 2013; 30:21-107. [DOI: 10.1039/c2np20065a] [Citation(s) in RCA: 146] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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