1
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Li X, Fu J, Li Y, Liu J, Gao R, Shi Y, Li Y, Sun H, Wang L, Li Y, Jiang B, Wu L, Hong B. Cytochrome P450 Monooxygenase for Catalyzing C-42 Hydroxylation of the Glycine-Derived Fragment in Hangtaimycin Biosynthesis. Org Lett 2022; 24:1388-1393. [PMID: 35138108 DOI: 10.1021/acs.orglett.2c00242] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A hybrid trans-AT PKS/NRPS gene cluster htm was identified with defined boundaries for hangtaimycin biosynthesis in Streptomyces spectabilis CPCC200148. Deoxyhangtaimycin, a new derivative of hangtaimycin, was identified from the htm11 gene knockout mutant. In vitro biochemical assays demonstrated that the cytochrome P450 monooxygenase Htm11 was responsible for the stereoselective hydroxylation of deoxyhangtaimycin to hangtaimycin. More importantly, deoxyhangtaimycin showed activity against influenza A virus at the micromolar level, highlighting its potential as an antiviral lead compound.
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Affiliation(s)
- Xingxing Li
- NHC Key Laboratory of Biotechnology of Antibiotics, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Tiantan Xili, 100050 Beijing, China
- CAMS Key Laboratory of Synthetic Biology for Drug Innovation, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Tiantan Xili, 100050 Beijing, China
| | - Jie Fu
- NHC Key Laboratory of Biotechnology of Antibiotics, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Tiantan Xili, 100050 Beijing, China
- CAMS Key Laboratory of Synthetic Biology for Drug Innovation, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Tiantan Xili, 100050 Beijing, China
| | - Yihua Li
- NHC Key Laboratory of Biotechnology of Antibiotics, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Tiantan Xili, 100050 Beijing, China
| | - Jiachang Liu
- NHC Key Laboratory of Biotechnology of Antibiotics, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Tiantan Xili, 100050 Beijing, China
- CAMS Key Laboratory of Synthetic Biology for Drug Innovation, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Tiantan Xili, 100050 Beijing, China
| | - Rongmei Gao
- NHC Key Laboratory of Biotechnology of Antibiotics, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Tiantan Xili, 100050 Beijing, China
| | - Yuanyuan Shi
- NHC Key Laboratory of Biotechnology of Antibiotics, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Tiantan Xili, 100050 Beijing, China
- CAMS Key Laboratory of Synthetic Biology for Drug Innovation, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Tiantan Xili, 100050 Beijing, China
| | - Yihong Li
- NHC Key Laboratory of Biotechnology of Antibiotics, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Tiantan Xili, 100050 Beijing, China
- CAMS Key Laboratory of Synthetic Biology for Drug Innovation, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Tiantan Xili, 100050 Beijing, China
| | - Hongmin Sun
- NHC Key Laboratory of Biotechnology of Antibiotics, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Tiantan Xili, 100050 Beijing, China
- CAMS Key Laboratory of Synthetic Biology for Drug Innovation, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Tiantan Xili, 100050 Beijing, China
| | - Lifei Wang
- NHC Key Laboratory of Biotechnology of Antibiotics, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Tiantan Xili, 100050 Beijing, China
- CAMS Key Laboratory of Synthetic Biology for Drug Innovation, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Tiantan Xili, 100050 Beijing, China
| | - Yuhuan Li
- NHC Key Laboratory of Biotechnology of Antibiotics, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Tiantan Xili, 100050 Beijing, China
| | - Bingya Jiang
- NHC Key Laboratory of Biotechnology of Antibiotics, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Tiantan Xili, 100050 Beijing, China
- CAMS Key Laboratory of Synthetic Biology for Drug Innovation, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Tiantan Xili, 100050 Beijing, China
| | - Linzhuan Wu
- NHC Key Laboratory of Biotechnology of Antibiotics, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Tiantan Xili, 100050 Beijing, China
- CAMS Key Laboratory of Synthetic Biology for Drug Innovation, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Tiantan Xili, 100050 Beijing, China
| | - Bin Hong
- NHC Key Laboratory of Biotechnology of Antibiotics, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Tiantan Xili, 100050 Beijing, China
- CAMS Key Laboratory of Synthetic Biology for Drug Innovation, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Tiantan Xili, 100050 Beijing, China
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2
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The Discovery of Actinospene, a New Polyene Macrolide with Broad Activity against Plant Fungal Pathogens and Pathogenic Yeasts. Molecules 2021; 26:molecules26227020. [PMID: 34834113 PMCID: PMC8621364 DOI: 10.3390/molecules26227020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 11/17/2021] [Accepted: 11/17/2021] [Indexed: 02/07/2023] Open
Abstract
Phytopathogenic fungi infect crops, presenting a worldwide threat to agriculture. Polyene macrolides are one of the most effective antifungal agents applied in human therapy and crop protection. In this study, we found a cryptic polyene biosynthetic gene cluster in Actinokineospora spheciospongiae by genome mining. Then, this gene cluster was activated via varying fermentation conditions, leading to the discovery of new polyene actinospene (1), which was subsequently isolated and its structure determined through spectroscopic techniques including UV, HR-MS, and NMR. The absolute configuration was confirmed by comparing the calculated and experimental electronic circular dichroism (ECD) spectra. Unlike known polyene macrolides, actinospene (1) demonstrated more versatile post-assembling decorations including two epoxide groups and an unusual isobutenyl side chain. In bioassays, actinospene (1) showed a broad spectrum of antifungal activity against several plant fungal pathogens as well as pathogenic yeasts with minimum inhibitory concentrations ranging between 2 and 10 μg/mL.
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3
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Walker PD, Weir ANM, Willis CL, Crump MP. Polyketide β-branching: diversity, mechanism and selectivity. Nat Prod Rep 2021; 38:723-756. [PMID: 33057534 DOI: 10.1039/d0np00045k] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Covering: 2008 to August 2020 Polyketides are a family of natural products constructed from simple building blocks to generate a diverse range of often complex chemical structures with biological activities of both pharmaceutical and agrochemical importance. Their biosynthesis is controlled by polyketide synthases (PKSs) which catalyse the condensation of thioesters to assemble a functionalised linear carbon chain. Alkyl-branches may be installed at the nucleophilic α- or electrophilic β-carbon of the growing chain. Polyketide β-branching is a fascinating biosynthetic modification that allows for the conversion of a β-ketone into a β-alkyl group or functionalised side-chain. The overall transformation is catalysed by a multi-protein 3-hydroxy-3-methylglutaryl synthase (HMGS) cassette and is reminiscent of the mevalonate pathway in terpene biosynthesis. The first step most commonly involves the aldol addition of acetate to the electrophilic carbon of the β-ketothioester catalysed by a 3-hydroxy-3-methylglutaryl synthase (HMGS). Subsequent dehydration and decarboxylation selectively generates either α,β- or β,γ-unsaturated β-alkyl branches which may be further modified. This review covers 2008 to August 2020 and summarises the diversity of β-branch incorporation and the mechanistic details of each catalytic step. This is extended to discussion of polyketides containing multiple β-branches and the selectivity exerted by the PKS to ensure β-branching fidelity. Finally, the application of HMGS in data mining, additional β-branching mechanisms and current knowledge of the role of β-branches in this important class of biologically active natural products is discussed.
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Affiliation(s)
- P D Walker
- Institute of Metabolism and Systems Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - A N M Weir
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
| | - C L Willis
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
| | - M P Crump
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
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4
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Becerril A, Pérez-Victoria I, Ye S, Braña AF, Martín J, Reyes F, Salas JA, Méndez C. Discovery of Cryptic Largimycins in Streptomyces Reveals Novel Biosynthetic Avenues Enriching the Structural Diversity of the Leinamycin Family. ACS Chem Biol 2020; 15:1541-1553. [PMID: 32310633 DOI: 10.1021/acschembio.0c00160] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Largimycins are hybrid nonribosomal peptide-polyketides that constitute a new group of metabolites in the leinamycin family of natural products displaying unique structural features such as containing an oxazole instead of a thiazole ring or being oxime ester macrocycles, unprecedented in nature, rather than macrolactams. Their discovery in Streptomyces argillaceus and Streptomyces canus has relied on the activation of two homologous silent gene clusters by overexpressing a transcriptional activator and cultivating in specific media. The proposed biosynthesis of largimycins includes the key action of the oxidoreductase LrgO, responsible for the formation of the oxime group involved in macrocyclization, and two putative cryptic biosynthetic steps consisting of chlorination of l-Thr by the NRPS loading module and incorporation of an olefinic exomethylene group by LrgJ PKS. The discovery of largimycins uncovers novel biosynthetic avenues employed in nature to enrich the structural diversity of leinamycins and provides tools for combinatorial biosynthesis.
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Affiliation(s)
- Adriana Becerril
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), Universidad de Oviedo, Oviedo, Spain
- Instituto de Investigación Sanitaria de Asturias (ISPA), Oviedo, Spain
| | - Ignacio Pérez-Victoria
- Fundación MEDINA, Centro de Excelencia en Investigación de Medicamentos Innovadores en Andalucía, Armilla, Granada, Spain
| | - Suhui Ye
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), Universidad de Oviedo, Oviedo, Spain
- Instituto de Investigación Sanitaria de Asturias (ISPA), Oviedo, Spain
| | - Alfredo F. Braña
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), Universidad de Oviedo, Oviedo, Spain
- Instituto de Investigación Sanitaria de Asturias (ISPA), Oviedo, Spain
| | - Jesús Martín
- Fundación MEDINA, Centro de Excelencia en Investigación de Medicamentos Innovadores en Andalucía, Armilla, Granada, Spain
| | - Fernando Reyes
- Fundación MEDINA, Centro de Excelencia en Investigación de Medicamentos Innovadores en Andalucía, Armilla, Granada, Spain
| | - José A. Salas
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), Universidad de Oviedo, Oviedo, Spain
- Instituto de Investigación Sanitaria de Asturias (ISPA), Oviedo, Spain
| | - Carmen Méndez
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), Universidad de Oviedo, Oviedo, Spain
- Instituto de Investigación Sanitaria de Asturias (ISPA), Oviedo, Spain
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5
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Wan X, Yao G, Liu Y, Chen J, Jiang H. Research Progress in the Biosynthetic Mechanisms of Marine Polyether Toxins. Mar Drugs 2019; 17:E594. [PMID: 31652489 PMCID: PMC6835853 DOI: 10.3390/md17100594] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 10/17/2019] [Accepted: 10/18/2019] [Indexed: 12/28/2022] Open
Abstract
Marine polyether toxins, mainly produced by marine dinoflagellates, are novel, complex, and diverse natural products with extensive toxicological and pharmacological effects. Owing to their harmful effects during outbreaks of marine red tides, as well as their potential value for the development of new drugs, marine polyether toxins have been extensively studied, in terms of toxicology, pharmacology, detection, and analysis, structural identification, as well as their biosynthetic mechanisms. Although the biosynthetic mechanisms of marine polyether toxins are still unclear, certain progress has been made. In this review, research progress and current knowledge on the biosynthetic mechanisms of polyether toxins are summarized, including the mechanisms of carbon skeleton deletion, pendant alkylation, and polyether ring formation, along with providing a summary of mined biosynthesis-related genes. Finally, future research directions and applications of marine polyether toxins are discussed.
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Affiliation(s)
- Xiukun Wan
- State Key Laboratory of NBC Protection for Civilian, Beijing 102205, China.
| | - Ge Yao
- State Key Laboratory of NBC Protection for Civilian, Beijing 102205, China.
| | - Yanli Liu
- State Key Laboratory of NBC Protection for Civilian, Beijing 102205, China.
| | - Jisheng Chen
- State Key Laboratory of NBC Protection for Civilian, Beijing 102205, China.
| | - Hui Jiang
- State Key Laboratory of NBC Protection for Civilian, Beijing 102205, China.
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6
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Kosol S, Jenner M, Lewandowski JR, Challis GL. Protein-protein interactions in trans-AT polyketide synthases. Nat Prod Rep 2019; 35:1097-1109. [PMID: 30280735 DOI: 10.1039/c8np00066b] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Covering: up to 2018 The construction of polyketide natural products by type I modular polyketide synthases (PKSs) requires the coordinated action of several protein subunits to ensure biosynthetic fidelity. This is particularly the case for trans-AT PKSs, which in contrast to most cis-AT PKSs, contain split modules and employ several trans-acting catalytic domains. This article summarises recent advances in understanding the protein-protein interactions underpinning subunit assembly and intra-subunit communication in such systems and highlights potential avenues and approaches for future research.
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Affiliation(s)
- Simone Kosol
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK.
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7
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Helfrich EJN, Piel J. Biosynthesis of polyketides by trans-AT polyketide synthases. Nat Prod Rep 2016; 33:231-316. [DOI: 10.1039/c5np00125k] [Citation(s) in RCA: 230] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
This review discusses the biosynthesis of natural products that are generated bytrans-AT polyketide synthases, a family of catalytically versatile enzymes that represents one of the major group of proteins involved in the production of bioactive polyketides.
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Affiliation(s)
- Eric J. N. Helfrich
- Institute of Microbiology
- Eidgenössische Technische Hochschule (ETH) Zurich
- 8093 Zurich
- Switzerland
| | - Jörn Piel
- Institute of Microbiology
- Eidgenössische Technische Hochschule (ETH) Zurich
- 8093 Zurich
- Switzerland
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8
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Abstract
Polyketides are a structurally and functionally diverse family of bioactive natural products that have found widespread application as pharmaceuticals, agrochemicals, and veterinary medicines. In bacteria complex polyketides are biosynthesized by giant multifunctional megaenzymes, termed modular polyketide synthases (PKSs), which construct their products in a highly coordinated assembly line-like fashion from a pool of simple precursor substrates. Not only is the multifaceted enzymology of PKSs a fascinating target for study, but it also presents considerable opportunities for the reengineering of these systems affording access to functionally optimized unnatural natural products. Here we provide an introductory primer to modular polyketide synthase structure and function, and highlight recent advances in the characterization and exploitation of these systems.
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Affiliation(s)
- Marisa Till
- School of Biochemistry, University of Bristol, Medical Sciences Building, University Walk, Bristol, BS8 1TD, UK
- BrisSynBio Synthetic Biology Research Centre, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol, BS8 1TQ, UK
| | - Paul R Race
- School of Biochemistry, University of Bristol, Medical Sciences Building, University Walk, Bristol, BS8 1TD, UK
- BrisSynBio Synthetic Biology Research Centre, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol, BS8 1TQ, UK
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9
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Van Wagoner RM, Satake M, Wright JLC. Polyketide biosynthesis in dinoflagellates: what makes it different? Nat Prod Rep 2014; 31:1101-37. [DOI: 10.1039/c4np00016a] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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10
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Abstract
Covering: up to the end of 2013. Myxobacteria produce a vast range of structurally diverse natural products with prominent biological activities. Here, we provide a detailed description and judge the potential of all antibiotically active myxobacterial compounds as lead structures, pointing out their particularities and, if known, their mode of action. Thus, the review provides an overview of the potential of specific compounds, suitable for future investigations and possible clinical applications.
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Affiliation(s)
- Till F Schäberle
- Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany.
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11
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Walsh CT, Wencewicz TA. Prospects for new antibiotics: a molecule-centered perspective. J Antibiot (Tokyo) 2013; 67:7-22. [DOI: 10.1038/ja.2013.49] [Citation(s) in RCA: 272] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 04/22/2013] [Accepted: 05/01/2013] [Indexed: 12/12/2022]
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12
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Lohman JR, Bingman CA, Phillips GN, Shen B. Structure of the bifunctional acyltransferase/decarboxylase LnmK from the leinamycin biosynthetic pathway revealing novel activity for a double-hot-dog fold. Biochemistry 2013; 52:902-11. [PMID: 23320975 PMCID: PMC3567400 DOI: 10.1021/bi301652y] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The β-branched C3 unit in leinamycin biosynthesis is installed by a set of four proteins, LnmFKLM. In vitro biochemical investigation confirmed that LnmK is a bifunctional acyltransferase/decarboxylase (AT/DC) that catalyzes first self-acylation using methylmalonyl-CoA as a substrate and subsequently transacylation of the methylmalonyl group to the phosphopantetheinyl group of the LnmL acyl carrier protein [Liu, T., Huang, Y., and Shen, B. (2009) J. Am. Chem. Soc. 131, 6900-6901]. LnmK shows no sequence homology to proteins of known function, representing a new family of AT/DC enzymes. Here we report the X-ray structure of LnmK. LnmK is homodimer with each of the monomers adopting a double-hot-dog fold. Cocrystallization of LnmK with methylmalonyl-CoA revealed an active site tunnel terminated by residues from the dimer interface. In contrast to canonical AT and ketosynthase enzymes that employ Ser or Cys as an active site residue, none of these residues are found in the vicinity of the LnmK active site. Instead, three tyrosines were identified, one of which, Tyr62, was established, by site-directed mutagenesis, to be the most likely active site residue for the AT activity of LnmK. LnmK represents the first AT enzyme that employs a Tyr as an active site residue and the first member of the family of double-hot-dog fold enzymes that displays an AT activity known to date. The LnmK structure sets the stage for probing of the DC activity of LnmK through site-directed mutagenesis. These findings highlight natural product biosynthetic machinery as a rich source of novel enzyme activities, mechanisms, and structures.
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Affiliation(s)
- Jeremy R. Lohman
- Department of Chemistry The Scripps Research institute, Jupiter, Florida 33485
| | - Craig A. Bingman
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - George N. Phillips
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
,Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77251
| | - Ben Shen
- Department of Chemistry The Scripps Research institute, Jupiter, Florida 33485
,Department of Molecular Therapeutics The Scripps Research institute, Jupiter, Florida 33485
,Department of Natural Products Library Initiative at The Scripps Research Institute, The Scripps Research institute, Jupiter, Florida 33485
,To whom correspondence should be addressed: The Scripps Research Institute, 130 Scripps Way, #3A1, Jupiter, FL 33458; Tel: (561) 228-2456; Fax: (561) 228-2472;
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13
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Myxobacterium-produced antibiotic TA (myxovirescin) inhibits type II signal peptidase. Antimicrob Agents Chemother 2012; 56:2014-21. [PMID: 22232277 DOI: 10.1128/aac.06148-11] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Antibiotic TA is a macrocyclic secondary metabolite produced by myxobacteria that has broad-spectrum bactericidal activity. The structure of TA is unique, and its molecular target is unknown. Here, we sought to elucidate TA's mode of action (MOA) through two parallel genetic approaches. First, chromosomal Escherichia coli TA-resistant mutants were isolated. One mutant that showed specific resistance toward TA was mapped and resulted from an IS4 insertion in the lpp gene, which encodes an abundant outer membrane (Braun's) lipoprotein. In a second approach, the comprehensive E. coli ASKA plasmid library was screened for overexpressing clones that conferred TA(r). This effort resulted in the isolation of the lspA gene, which encodes the type II signal peptidase that cleaves signal sequences from prolipoproteins. In whole cells, TA was shown to inhibit Lpp prolipoprotein processing, similar to the known LspA inhibitor globomycin. Based on genetic evidence and prior globomycin studies, a block in Lpp expression or prevention of Lpp covalent cell wall attachment confers TA(r) by alleviating a toxic buildup of mislocalized pro-Lpp. Taken together, these data argue that LspA is the molecular target of TA. Strikingly, the giant ta biosynthetic gene cluster encodes two lspA paralogs that we hypothesize play a role in producer strain resistance.
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14
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Buchholz TJ, Rath CM, Lopanik NB, Gardner NP, Håkansson K, Sherman DH. Polyketide β-branching in bryostatin biosynthesis: identification of surrogate acetyl-ACP donors for BryR, an HMG-ACP synthase. ACTA ACUST UNITED AC 2011; 17:1092-100. [PMID: 21035732 DOI: 10.1016/j.chembiol.2010.08.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Revised: 08/10/2010] [Accepted: 08/17/2010] [Indexed: 10/18/2022]
Abstract
In vitro analysis of natural product biosynthetic gene products isolated from unculturable symbiotic bacteria is necessary to probe the functionalities of these enzymes. Herein, we report the biochemical characterization of BryR, the 3-hydroxy-3-methylglutaryl (HMG)-CoA synthase (HMGS) homolog implicated in β-branching at C13 and C21 of the core ring system from the bryostatin metabolic pathway (Bry). We confirmed the activity of BryR using two complementary methods, radio-SDS PAGE, and Fourier transform ion cyclotron resonance-mass spectrometry (FTICR-MS). The activity of BryR depended on pairing of the native acetoacetyl-BryM3 acceptor acyl carrier protein (ACP) with an appropriate donor acetyl-ACP from a heterologous HMGS cassette. Additionally, the ability of BryR to discriminate between various ACPs was assessed using a surface plasmon resonance (SPR)-based protein-protein binding assay. Our data suggest that specificity for a protein-bound acyl group is a distinguishing feature between HMGS homologs found in PKS or PKS/NRPS biosynthetic pathways and those of primary metabolism. These findings reveal an important example of molecular recognition between protein components that are essential for biosynthetic fidelity in natural product assembly and modification.
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Affiliation(s)
- Tonia J Buchholz
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
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15
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Irschik H, Kopp M, Weissman KJ, Buntin K, Piel J, Müller R. Analysis of the sorangicin gene cluster reinforces the utility of a combined phylogenetic/retrobiosynthetic analysis for deciphering natural product assembly by trans-AT PKS. Chembiochem 2011; 11:1840-9. [PMID: 20715267 DOI: 10.1002/cbic.201000313] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Herbert Irschik
- Microbial Drugs, Helmholtz Center for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
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16
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Huang Y, Huang SX, Ju J, Tang G, Liu T, Shen B. Characterization of the lnmKLM genes unveiling key intermediates for β-alkylation in leinamycin biosynthesis. Org Lett 2010; 13:498-501. [PMID: 21192727 DOI: 10.1021/ol102838y] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Leinamycin (LNM, 1) biosynthesis is proposed to involve β-alkylation of the polyketide intermediate, catalyzed by LnmKLM. Inactivation of lnmK, lnmL, or lnmM afforded mutant strains that accumulated LNM K-1 (2), K-2 (3), K-3 (4), and isomers LNM K-1' (5), K-2' (6), and K-3' (7) whose polyketide origin was established by feeding experiments with sodium [1-(13)C]acetate. These findings confirm the indispensability of LnmKLM in 1 biosynthesis and suggest that β-alkylation proceeds on the growing polyketide intermediate while bound to the LNM polyketide synthase.
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Affiliation(s)
- Yong Huang
- Division of Pharmaceutical Sciences, University of Wisconsin, Madison, Wisconsin 53705-2222, USA
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17
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Erol Ö, Schäberle TF, Schmitz A, Rachid S, Gurgui C, El Omari M, Lohr F, Kehraus S, Piel J, Müller R, König GM. Biosynthesis of the Myxobacterial Antibiotic Corallopyronin A. Chembiochem 2010; 11:1253-65. [DOI: 10.1002/cbic.201000085] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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18
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Abstract
This review discusses the biosynthesis of natural products that are generated by trans-AT polyketide synthases, a family of catalytically versatile enzymes that have recently been recognized as one of the major group of proteins involved in the production of bioactive polyketides. 436 references are cited.
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Affiliation(s)
- Jörn Piel
- Kekulé Institute of Organic Chemistry and Biochemistry, University of Bonn, Bonn, Germany.
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Hochmuth T, Piel J. Polyketide synthases of bacterial symbionts in sponges--evolution-based applications in natural products research. PHYTOCHEMISTRY 2009; 70:1841-1849. [PMID: 19443000 DOI: 10.1016/j.phytochem.2009.04.010] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Revised: 04/09/2009] [Accepted: 04/15/2009] [Indexed: 05/27/2023]
Abstract
Marine sponges are an unusually rich source of bioactive natural products with clinical potential. They also often harbor rich communities of symbiotic bacteria that have often been suspected as the true producers of sponge-derived compounds. To date, these bacteria can in most cases not be cultivated, but culture-independent methods, such as isolating and analyzing biosynthetic gene clusters using metagenomic strategies, have recently provided first insights into their chemical potential. This review summarizes recent work of our laboratory on the study of polyketide synthases (PKSs). These studies revealed two evolutionarily distinct, unusual PKS types that are commonly found in sponge metagenomes and were shown to be of bacterial origin. One, the sup PKS, dominates sponge metagenomic DNA libraries, occurs widespread in bacteriosponges and is to date exclusively known from such animals. Data suggest that it is a type of synthase that generates methyl-branched fatty acids, which are commonly present in sponges. The other PKS type, termed trans-acyltransferase (AT) PKS, is responsible for the biosynthesis of complex, bioactive polyketides, such as the onnamides, and also occurs in free-living bacteria. The diversity of PKS genes present in a single sponge metagenome can be enormous. However, the phylogenetic approaches outlined in this review can provide valuable insights into the PKS function and structures of polyketides and can assist in the targeted isolation of gene clusters.
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Affiliation(s)
- Thomas Hochmuth
- Kekulé Institute of Organic Chemistry and Biochemistry, University of Bonn, Bonn, Germany
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Liu T, Huang Y, Shen B. Bifunctional acyltransferase/decarboxylase LnmK as the missing link for beta-alkylation in polyketide biosynthesis. J Am Chem Soc 2009; 131:6900-1. [PMID: 19405532 DOI: 10.1021/ja9012134] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Beta-alkylations contribute to the vast structural diversity displayed by polyketide natural products. A unified pathway has been proposed for introduction of both beta-methyl and beta-ethyl branches catalyzed by hydroxymethylglutaryl-CoA synthase homologues that utilize acetyl- or propionyl-S-acyl carrier protein (ACP) as a substrate. While the origin of acetyl-S-ACP has been established, that of propionyl-S-ACP remains unknown. Here we report the characterization of LnmK from the leinamycin biosynthetic machinery as a bifunctional acyltransferase/decarboxylase (AT/DC) that derives propionyl-S-ACP from methylmalonyl-CoA, accounting for the missing link of the beta-ethyl or propionyl branch in polyketide biosynthesis. LnmK represents an emerging family of novel AT/DC enzymes and could be exploited by combinatorial biosynthesis methods to engineer novel polyketides, especially those with beta-alkyl branches.
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Affiliation(s)
- Tao Liu
- Division of Pharmaceutical Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53705-2222, USA
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Kusebauch B, Busch B, Scherlach K, Roth M, Hertweck C. Polyketide-Chain Branching by an Enzymatic Michael Addition. Angew Chem Int Ed Engl 2009; 48:5001-4. [DOI: 10.1002/anie.200900277] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Kusebauch B, Busch B, Scherlach K, Roth M, Hertweck C. Polyketide-Chain Branching by an Enzymatic Michael Addition. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200900277] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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25
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A brief tour of myxobacterial secondary metabolism. Bioorg Med Chem 2009; 17:2121-36. [DOI: 10.1016/j.bmc.2008.11.025] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2008] [Revised: 11/07/2008] [Accepted: 11/11/2008] [Indexed: 12/16/2022]
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Wenzel SC, Müller R. The impact of genomics on the exploitation of the myxobacterial secondary metabolome. Nat Prod Rep 2009; 26:1385-407. [DOI: 10.1039/b817073h] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Riesenfeld CS, Murray AE, Baker BJ. Characterization of the microbial community and polyketide biosynthetic potential in the palmerolide-producing tunicate Synoicum adareanum. JOURNAL OF NATURAL PRODUCTS 2008; 71:1812-1818. [PMID: 18950228 DOI: 10.1021/np800287n] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Palmerolide A (1) is a macrolide isolated from the Antarctic tunicate Synoicum adareanum that is of interest due to its potential as an antimelanoma drug. Biosynthesis is predicted to occur via a hybrid PKS-NRPS pathway within S. adareanum, but the identity of the palmerolide-producing organism (host or putative host-associated microorganism) has not been established. Microscopic observation revealed a dense microbial community inside the tunicate, and evidence from 16S rRNA gene DGGE profiles and clone library sequences suggests that the bacterial community has moderate phylogenetic complexity. The alpha and gamma classes of Proteobacteria account for ∼75% of the cloned 16S rRNA genes, and the majority of these sequences are affiliated with the genera Pseudovibrio and Microbulbifer. DNA sequences encoding type I PKS ketosynthase (KS) domains were detected by PCR. The S. adareanum KS sequences, which affiliate with the trans-AT clade, are similar to portions of PKS proteins that lack integrated acyltransferase domains in pathways for generating bioactive polyketide compounds, including bryostatin, leinamycin, and pederin.
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Menche D, Arikan F, Perlova O, Horstmann N, Ahlbrecht W, Wenzel SC, Jansen R, Irschik H, Müller R. Stereochemical Determination and Complex Biosynthetic Assembly of Etnangien, a Highly Potent RNA Polymerase Inhibitor from the Myxobacterium Sorangium cellulosum. J Am Chem Soc 2008; 130:14234-43. [DOI: 10.1021/ja804194c] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Dirk Menche
- University of Heidelberg, Department of Organic Chemistry, INF 270, D-69120 Heidelberg, Germany, Helmholtz Centre for Infection Research (HZI), Medicinal Chemistry, Inhoffenstrasse 7, D-38124 Braunschweig, Germany, Helmholtz Centre for Infection Research (HZI), Microbial Drugs and Saarland University, Pharmaceutical Biotechnology, P.O. Box 151150, D-66041 Saarbrücken, Germany
| | - Fatih Arikan
- University of Heidelberg, Department of Organic Chemistry, INF 270, D-69120 Heidelberg, Germany, Helmholtz Centre for Infection Research (HZI), Medicinal Chemistry, Inhoffenstrasse 7, D-38124 Braunschweig, Germany, Helmholtz Centre for Infection Research (HZI), Microbial Drugs and Saarland University, Pharmaceutical Biotechnology, P.O. Box 151150, D-66041 Saarbrücken, Germany
| | - Olena Perlova
- University of Heidelberg, Department of Organic Chemistry, INF 270, D-69120 Heidelberg, Germany, Helmholtz Centre for Infection Research (HZI), Medicinal Chemistry, Inhoffenstrasse 7, D-38124 Braunschweig, Germany, Helmholtz Centre for Infection Research (HZI), Microbial Drugs and Saarland University, Pharmaceutical Biotechnology, P.O. Box 151150, D-66041 Saarbrücken, Germany
| | - Nicole Horstmann
- University of Heidelberg, Department of Organic Chemistry, INF 270, D-69120 Heidelberg, Germany, Helmholtz Centre for Infection Research (HZI), Medicinal Chemistry, Inhoffenstrasse 7, D-38124 Braunschweig, Germany, Helmholtz Centre for Infection Research (HZI), Microbial Drugs and Saarland University, Pharmaceutical Biotechnology, P.O. Box 151150, D-66041 Saarbrücken, Germany
| | - Wiebke Ahlbrecht
- University of Heidelberg, Department of Organic Chemistry, INF 270, D-69120 Heidelberg, Germany, Helmholtz Centre for Infection Research (HZI), Medicinal Chemistry, Inhoffenstrasse 7, D-38124 Braunschweig, Germany, Helmholtz Centre for Infection Research (HZI), Microbial Drugs and Saarland University, Pharmaceutical Biotechnology, P.O. Box 151150, D-66041 Saarbrücken, Germany
| | - Silke C. Wenzel
- University of Heidelberg, Department of Organic Chemistry, INF 270, D-69120 Heidelberg, Germany, Helmholtz Centre for Infection Research (HZI), Medicinal Chemistry, Inhoffenstrasse 7, D-38124 Braunschweig, Germany, Helmholtz Centre for Infection Research (HZI), Microbial Drugs and Saarland University, Pharmaceutical Biotechnology, P.O. Box 151150, D-66041 Saarbrücken, Germany
| | - Rolf Jansen
- University of Heidelberg, Department of Organic Chemistry, INF 270, D-69120 Heidelberg, Germany, Helmholtz Centre for Infection Research (HZI), Medicinal Chemistry, Inhoffenstrasse 7, D-38124 Braunschweig, Germany, Helmholtz Centre for Infection Research (HZI), Microbial Drugs and Saarland University, Pharmaceutical Biotechnology, P.O. Box 151150, D-66041 Saarbrücken, Germany
| | - Herbert Irschik
- University of Heidelberg, Department of Organic Chemistry, INF 270, D-69120 Heidelberg, Germany, Helmholtz Centre for Infection Research (HZI), Medicinal Chemistry, Inhoffenstrasse 7, D-38124 Braunschweig, Germany, Helmholtz Centre for Infection Research (HZI), Microbial Drugs and Saarland University, Pharmaceutical Biotechnology, P.O. Box 151150, D-66041 Saarbrücken, Germany
| | - Rolf Müller
- University of Heidelberg, Department of Organic Chemistry, INF 270, D-69120 Heidelberg, Germany, Helmholtz Centre for Infection Research (HZI), Medicinal Chemistry, Inhoffenstrasse 7, D-38124 Braunschweig, Germany, Helmholtz Centre for Infection Research (HZI), Microbial Drugs and Saarland University, Pharmaceutical Biotechnology, P.O. Box 151150, D-66041 Saarbrücken, Germany
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Weissman KJ, Müller R. Protein–Protein Interactions in Multienzyme Megasynthetases. Chembiochem 2008; 9:826-48. [DOI: 10.1002/cbic.200700751] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Calderone CT, Iwig DF, Dorrestein PC, Kelleher NL, Walsh CT. Incorporation of nonmethyl branches by isoprenoid-like logic: multiple beta-alkylation events in the biosynthesis of myxovirescin A1. ACTA ACUST UNITED AC 2007; 14:835-46. [PMID: 17656320 PMCID: PMC2084360 DOI: 10.1016/j.chembiol.2007.06.008] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Revised: 06/19/2007] [Accepted: 06/22/2007] [Indexed: 10/23/2022]
Abstract
Several polyketide secondary metabolites are predicted to undergo isoprenoid-like beta-alkylations during biosynthesis. One such secondary metabolite is myxovirescin A1, produced by Myxococcus xanthus. Myxovirescin is of special interest in that it appears to undergo two distinct beta-alkylations. Additionally, the myxovirescin biosynthetic gene cluster lacks tandem thiolation domains required in the synthesis of other beta-branched secondary metabolites. To probe the origins of the beta-branches in myxovirescin, we heterologously overexpressed the proteins predicted to be responsible for myxovirescin beta-alkylation and reconstituted their activities in vitro on model substrates. Our results confirm that myxovirescin undergoes two isoprenoid-like beta-alkylations during its biosynthesis, including an unprecedented beta-ethylation. The study of its biosynthesis should shed light on the scope and requirements for isoprenoid-like biosynthetic logic in a polyketide context.
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Geders TW, Gu L, Mowers JC, Liu H, Gerwick WH, Håkansson K, Sherman DH, Smith JL. Crystal Structure of the ECH2 Catalytic Domain of CurF from Lyngbya majuscula. J Biol Chem 2007; 282:35954-63. [DOI: 10.1074/jbc.m703921200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Moldenhauer J, Chen XH, Borriss R, Piel J. Biosynthesis of the Antibiotic Bacillaene, the Product of a Giant Polyketide Synthase Complex of thetrans-AT Family. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200703386] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Moldenhauer J, Chen XH, Borriss R, Piel J. Biosynthesis of the Antibiotic Bacillaene, the Product of a Giant Polyketide Synthase Complex of thetrans-AT Family. Angew Chem Int Ed Engl 2007; 46:8195-7. [PMID: 17886826 DOI: 10.1002/anie.200703386] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Jana Moldenhauer
- Kekulé Institute of Organic Chemistry and Biochemistry, University of Bonn, Gerhard-Domagk-Strasse 1, 53121 Bonn, Germany
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Fürstner A, Bonnekessel M, Blank JT, Radkowski K, Seidel G, Lacombe F, Gabor B, Mynott R. Total Synthesis of Myxovirescin A1. Chemistry 2007; 13:8762-83. [PMID: 17768720 DOI: 10.1002/chem.200700926] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A convergent total synthesis of the antibiotic macrolide myxovirescin A1 (1) is described that is largely based on reagent- and catalyst-controlled transformations. This includes a highly regioselective Negishi reaction of dibromo-alkene 48 with an alkynylzinc reagent, and a palladium catalyzed alkyl-Suzuki coupling of the resulting enyne derivative 12 with the 9-BBN-adduct derived from alkene 61. The latter was obtained via an asymmetric hydrogenation of the chlorinated beta-ketoester 49 and an anti-selective oxyallylation of the functionalized aldehyde 53 as the key steps. The preparation of the bis-borylated allyl-donor 57 used in the oxyallylation step, however, required careful optimization and led to important insights into the nature of the classical hydroborating agent "di(isopinocampheyl)borane (Ipc2BH)". It was unambiguously shown by X-ray crystallography that in the solid state this compound is dimeric, but it is prone to undergo an essentially quantitative mono-deborylation when dissolved in CH2Cl2 or benzene; its composition in ethereal solvents is even more complex as evident from 11B NMR data. Product 71 derived from 12 and 61 was elaborated into the enyne-yne derivative 75, which served as the substrate for an exquisitely selective ring closing alkyne metathesis reaction (RCAM) catalyzed by the molybdenum tris-amido complex 20 activated in situ with CH2Cl2. The resulting cyclic enyne 76 was subjected to a ruthenium catalyzed trans-hydrosilylation/proto-desilylation tandem. Although [Cp*Ru(MeCN)3]PF6 had previously been recommended as catalyst of choice for trans-hydrosilylation reactions of internal alkynes, this complex failed to afford the desired product, whereas its sterically less hindered congener [CpRu(MeCN)3]PF6 permitted the reaction to be performed in appreciable yield, but at the expense of a lower stereoselectivity. AgF-mediated proto-desilylation of the isomeric silanes 79 and 80 followed by cleavage of the remaining acetal protecting groups afforded myxovirescin A1 and its hitherto unknown 14Z-isomer 81, respectively.
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Affiliation(s)
- Alois Fürstner
- Max-Planck-Institut für Kohlenforschung, 45470 Mülheim/Ruhr, Germany.
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Simunovic V, Müller R. Mutational Analysis of the Myxovirescin Biosynthetic Gene Cluster Reveals Novel Insights into the Functional Elaboration of Polyketide Backbones. Chembiochem 2007; 8:1273-80. [PMID: 17583882 DOI: 10.1002/cbic.200700153] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
It has been proposed that two acyl carrier proteins (ACPs)-TaB and TaE--and two 3-hydroxy-3-methylglutaryl synthases (HMGSs)--TaC and TaF--could constitute two functional ACP-HMGS pairs (TaB/TaC and TaE/TaF) responsible for the incorporation of acetate and propionate units into the myxovirescin A scaffold, leading to the formation of beta-methyl and beta-ethyl groups, respectively. It has been suggested that three more proteins--TaX and TaY, which are members of the superfamily of enoyl-CoA hydratases (ECHs), and a variant ketosynthase (KS) TaK--are shared between two ACP-HMGS pairs, to give the complete set of enzymes required to perform the beta-alkylations. The beta-methyl branch is presumably further hydroxylated (by TaH) and methylated to produce the methoxymethyl group observed in myxovirescin A. To substantiate this hypothesis, a series of gene-deletion mutants were created, and the effects of these mutations on myxovirescin production were examined. As predicted, DeltataB and DeltataE ACP mutants revealed similar phenotypes to their associated HMGS mutants DeltataC and DeltataF, respectively, thus providing direct evidence for the role of TaE/TaF in the formation of the beta-ethyl branch and implying a role for TaB/TaC in the formation of the beta-methyl group. Production of myxovirescin A was dramatically reduced in a DeltataK mutant and abolished in both the DeltataX and the DeltataY mutant backgrounds. Analysis of a DeltataH mutant confirmed the role of the cytochrome P450 TaH in hydroxylation of the beta-methyl group. Taken together, these experiments support a model in which the discrete ACPs TaB and TaE are compatible only with their associated HMGSs TaC and TaF, respectively, and function in a substrate-specific manner. Both TaB and TaC are essential for myxovirescin production, and the TaB/TaC pair can rescue antibiotic production in the absence of either TaE or TaF. Finally, the reduced level of myxovirescin production in the DeltataE mutant, relative to the DeltataF strain, suggests an additional function of the TaE ACP.
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Affiliation(s)
- Vesna Simunovic
- Pharmaceutical Biotechnology, Saarland University, P.O. Box 151150, 66041 Saarbrücken, Germany
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Mahmud T. Isotope tracer investigations of natural products biosynthesis: the discovery of novel metabolic pathways. J Labelled Comp Radiopharm 2007. [DOI: 10.1002/jlcr.1391] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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