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Daniel-Ivad P, Ryan KS. New reactions by pyridoxal phosphate-dependent enzymes. Curr Opin Chem Biol 2024; 81:102472. [PMID: 38815536 DOI: 10.1016/j.cbpa.2024.102472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Revised: 05/02/2024] [Accepted: 05/08/2024] [Indexed: 06/01/2024]
Abstract
Pyridoxal phosphate (PLP) is a cofactor that is widely employed in enzymology. This pyridine-containing cofactor can be used for reactions ranging from transaminations to oxidations. The catalytic versatility can be understood by considering the chemical features of this cofactor. In recent years, exciting new reactions involving PLP have been discovered in natural products biosynthesis, upending our understanding of what this cofactor is capable of. Here we review some of the most exciting PLP-dependent reactions from the last five years.
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Affiliation(s)
- Phillip Daniel-Ivad
- Department of Chemistry, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Katherine S Ryan
- Department of Chemistry, The University of British Columbia, Vancouver, British Columbia, Canada.
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2
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Zmich A, Perkins LJ, Bingman C, Acheson JF, Buller AR. Multiplexed Assessment of Promiscuous Non-Canonical Amino Acid Synthase Activity in a Pyridoxal Phosphate-Dependent Protein Family. ACS Catal 2023; 13:11644-11655. [PMID: 37720819 PMCID: PMC10501158 DOI: 10.1021/acscatal.3c02498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/19/2023]
Abstract
Pyridoxal phosphate (PLP)-dependent enzymes afford access to a variety of non-canonical amino acids (ncAAs), which are premier buildings blocks for the construction of complex bioactive molecules. The vinylglycine ketimine (VGK) subfamily of PLP-dependent enzymes plays a critical role in sulfur metabolism and is home to a growing set of secondary metabolic enzymes that synthesize γ-substituted ncAAs. Identification of VGK enzymes for biocatalysis faces a distinct challenge because the subfamily contains both desirable synthases as well as lyases that break down ncAAs. Some enzymes have both activities, which may contribute to pervasive mis-annotation. To navigate this complex functional landscape, we used a substrate multiplexed screening approach to rapidly measure the substrate promiscuity of 40 homologs in the VGK subfamily. We found that enzymes involved in transsulfuration are less likely to have promiscuous activities and often possess undesirable lyase activity. Enzymes from direct sulfuration and secondary metabolism generally had a high degree of substrate promiscuity. From this cohort, we identified an exemplary γ-synthase from Caldicellulosiruptor hydrothermalis (CahyGS). This enzyme is thermostable and has high expression (~400 mg protein per L culture), enabling preparative scale synthesis of thioether containing ncAAs. When assayed with l-allylglycine, CahyGS catalyzes a stereoselective γ-addition reaction to afford access to a unique set of γ-methyl branched ncAAs. We determined high-resolution crystal structures of this enzyme that define an open-close transition associated with ligand binding and set the stage for future engineering within this enzyme subfamily.
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Affiliation(s)
- Anna Zmich
- Department of Biochemistry, University of Wisconsin−Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Lydia J. Perkins
- Department of Chemistry, University of Wisconsin−Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Craig Bingman
- Department of Biochemistry, University of Wisconsin−Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Justin F Acheson
- Department of Biochemistry, University of Wisconsin−Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Andrew R. Buller
- Department of Biochemistry, University of Wisconsin−Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
- Department of Chemistry, University of Wisconsin−Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
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3
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Stout CN, Wasfy NM, Chen F, Renata H. Charting the Evolution of Chemoenzymatic Strategies in the Syntheses of Complex Natural Products. J Am Chem Soc 2023; 145:18161-18181. [PMID: 37553092 PMCID: PMC11107883 DOI: 10.1021/jacs.3c03422] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2023]
Abstract
Bolstered by recent advances in bioinformatics, genetics, and enzyme engineering, the field of chemoenzymatic synthesis has enjoyed a rapid increase in popularity and utility. This Perspective explores the integration of enzymes into multistep chemical syntheses, highlighting the unique potential of biocatalytic transformations to streamline the synthesis of complex natural products. In particular, we identify four primary conceptual approaches to chemoenzymatic synthesis and illustrate each with a number of landmark case studies. Future opportunities and challenges are also discussed.
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Affiliation(s)
- Carter N. Stout
- Skaggs Doctoral Program in the Chemical and Biological Sciences, Scripps Research, La Jolla, CA 92037, USA
| | - Nour M. Wasfy
- Department of Chemistry, BioScience Research Collaborative, Rice University, Houston, Texas, 77005, United States
| | - Fang Chen
- Department of Chemistry, BioScience Research Collaborative, Rice University, Houston, Texas, 77005, United States
| | - Hans Renata
- Department of Chemistry, BioScience Research Collaborative, Rice University, Houston, Texas, 77005, United States
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4
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Yee DA, Niwa K, Perlatti B, Chen M, Li Y, Tang Y. Genome mining for unknown-unknown natural products. Nat Chem Biol 2023; 19:633-640. [PMID: 36702957 PMCID: PMC10159913 DOI: 10.1038/s41589-022-01246-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 12/20/2022] [Indexed: 01/27/2023]
Abstract
Genome mining of biosynthetic pathways with no identifiable core enzymes can lead to discovery of the so-called unknown (biosynthetic route)-unknown (molecular structure) natural products. Here we focused on a conserved fungal biosynthetic pathway that lacks a canonical core enzyme and used heterologous expression to identify the associated natural product, a highly modified cyclo-arginine-tyrosine dipeptide. Biochemical characterization of the pathway led to identification of a new arginine-containing cyclodipeptide synthase (RCDPS), which was previously annotated as a hypothetical protein and has no sequence homology to non-ribosomal peptide synthetase or bacterial cyclodipeptide synthase. RCDPS homologs are widely encoded in fungal genomes; other members of this family can synthesize diverse cyclo-arginine-Xaa dipeptides, and characterization of a cyclo-arginine-tryptophan RCDPS showed that the enzyme is aminoacyl-tRNA dependent. Further characterization of the biosynthetic pathway led to discovery of new compounds whose structures would not have been predicted without knowledge of RCDPS function.
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Affiliation(s)
- Danielle A Yee
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, CA, USA
- Hexagon Bio, Menlo Park, CA, USA
| | - Kanji Niwa
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, CA, USA
| | - Bruno Perlatti
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, USA
- Hexagon Bio, Menlo Park, CA, USA
| | - Mengbin Chen
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, CA, USA
- Department of Process Research and Development, Merck & Co., Inc., Rahway, NJ, USA
| | - Yuqing Li
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, CA, USA
| | - Yi Tang
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, CA, USA.
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, USA.
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5
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Lawrinowitz S, Wurlitzer JM, Weiss D, Arndt HD, Kothe E, Gressler M, Hoffmeister D. Blue Light-Dependent Pre-mRNA Splicing Controls Pigment Biosynthesis in the Mushroom Terana caerulea. Microbiol Spectr 2022; 10:e0106522. [PMID: 36094086 PMCID: PMC9603100 DOI: 10.1128/spectrum.01065-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 08/18/2022] [Indexed: 12/30/2022] Open
Abstract
Light induces the production of ink-blue pentacyclic natural products, the corticin pigments, in the cobalt crust mushroom Terana caerulea. Here, we describe the genetic locus for corticin biosynthesis and provide evidence for a light-dependent dual transcriptional/cotranscriptional regulatory mechanism. Light selectively induces the expression of the corA gene encoding the gateway enzyme, the first described mushroom polyporic acid synthetase CorA, while other biosynthetic genes for modifying enzymes necessary to complete corticin assembly are induced only at lower levels. The strongest corA induction was observed following exposure to blue and UV light. A second layer of regulation is provided by the light-dependent splicing of the three introns in the pre-mRNA of corA. Our results provide insight into the fundamental organization of how mushrooms regulate natural product biosynthesis. IMPORTANCE The regulation of natural product biosyntheses in mushrooms in response to environmental cues is poorly understood. We addressed this knowledge gap and chose the cobalt crust mushroom Terana caerulea as our model. Our work discovered a dual-level regulatory mechanism that connects light as an abiotic stimulus with a physiological response, i.e., the production of dark-blue pigments. Exposure to blue light elicits strongly increased transcription of the gene encoding the gateway enzyme, the polyporic acid synthetase CorA, that catalyzes the formation of the pigment core structure. Additionally, light is a prerequisite for the full splicing of corA pre-mRNA and, thus, its proper maturation. Dual transcriptional/cotranscriptional light-dependent control of fungal natural product biosynthesis has previously been unknown. As it allows the tight control of a key metabolic step, it may be a much more prevalent mechanism among these organisms.
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Affiliation(s)
- Stefanie Lawrinowitz
- Friedrich-Schiller-Universität Jena, Institute of Pharmacy, Jena, Germany
- Pharmaceutical Microbiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute, Jena, Germany
| | - Jacob M. Wurlitzer
- Friedrich-Schiller-Universität Jena, Institute of Pharmacy, Jena, Germany
- Pharmaceutical Microbiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute, Jena, Germany
| | - Dieter Weiss
- Friedrich-Schiller-Universität Jena, Institute for Organic Chemistry and Macromolecular Chemistry, Jena, Germany
| | - Hans-Dieter Arndt
- Friedrich-Schiller-Universität Jena, Institute for Organic Chemistry and Macromolecular Chemistry, Jena, Germany
| | - Erika Kothe
- Friedrich-Schiller-Universität Jena, Institute for Microbiology, Jena, Germany
| | - Markus Gressler
- Friedrich-Schiller-Universität Jena, Institute of Pharmacy, Jena, Germany
- Pharmaceutical Microbiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute, Jena, Germany
| | - Dirk Hoffmeister
- Friedrich-Schiller-Universität Jena, Institute of Pharmacy, Jena, Germany
- Pharmaceutical Microbiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute, Jena, Germany
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6
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Panth N, Wenger ES, Krebs C, Bollinger JM, Grossman RB. Synthesis of 6,6- and 7,7-difluoro-1-acetamidopyrrolizidines and their oxidation catalyzed by the nonheme Fe oxygenase LolO. Chembiochem 2022; 23:e202200081. [PMID: 35482316 DOI: 10.1002/cbic.202200081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Revised: 03/26/2022] [Indexed: 11/11/2022]
Abstract
LolO, a 2-oxoglutarate-dependent nonheme Fe oxygenase, catalyzes both the hydroxylation and cycloetherification of 1- exo -acetamidopyrrolizidine (AcAP), a pathway intermediate in the biosynthesis of the loline alkaloids. We have prepared fluorinated AcAP analogs to aid in continued mechanistic investigation of the unusual LolO-catalyzed cycloetherification step. LolO was able to first hydroxylate and then cycloetherify 6,6-difluoro-AcAP (prepared from N , O -protected 4-oxoproline), forming a difluorinated analog of N -acetylnorloline (NANL) and providing evidence for a cycloetherification mechanism involving a C(7) radical as opposed to a C(7) carbocation. By contrast, LolO was able to hydroxylate 7,7-difluoro-AcAP (prepared from 3-oxoproline) but failed to cycloetherify it, forming (1 R , 2 R , 8 S )-7,7-difluoro-2-hydroxy-AcAP as the sole product. Because it completely blocks the cycloetherification step, 7,7-difluoro-AcAP has the potential to become an important tool for accumulating and characterizing the LolO intermediate responsible for catalyzing cycloetherification of 2-hydroxy-AcAP.
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Affiliation(s)
- Nabin Panth
- University of Kentucky, Chemistry, UNITED STATES
| | | | - Carsten Krebs
- The Pennsylvania State University, Chemistry; Biochemistry and Molecular Biology, UNITED STATES
| | - J Martin Bollinger
- The Pennsylvania State University, Chemistry; Biochemistry and Molecular Biology, UNITED STATES
| | - Robert B Grossman
- University of Kentucky, Chemistry, Chemistry-Physics Building, 40506-0055, Lexington, UNITED STATES
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7
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Hauth F, Buck H, Stanoppi M, Hartig JS. Canavanine utilization via homoserine and hydroxyguanidine by a PLP-dependent γ-lyase in Pseudomonadaceae and Rhizobiales. RSC Chem Biol 2022; 3:1240-1250. [PMID: 36320885 PMCID: PMC9533460 DOI: 10.1039/d2cb00128d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 08/18/2022] [Indexed: 12/02/2022] Open
Abstract
Canavanine, the δ-oxa-analogue of arginine, is produced as one of the main nitrogen storage compounds in legume seeds and has repellent properties. Its toxicity originates from incorporation into proteins as well as arginase-mediated hydrolysis to canaline that forms stable oximes with carbonyls. So far no pathway or enzyme has been identified acting specifically on canavanine. Here we report the characterization of a novel PLP-dependent enzyme, canavanine-γ-lyase, that catalyzes the elimination of hydroxyguanidine from canavanine to subsequently yield homoserine. Homoserine-dehydrogenase, aspartate–semialdehyde–dehydrogenase and ammonium–aspartate–lyase activities are also induced for facilitating canavanine utilization. We demonstrate that this novel pathway is found in certain Pseudomonas species and the Rhizobiales symbionts of legumes. The findings broaden the diverse reactions that the versatile class of PLP-dependent enzymes is able to catalyze. Since canavanine utilization is found prominently in root-associated bacteria, it could have important implications for the establishment and maintenance of the legume rhizosphere. A novel degradation pathway enables rhizosphere-associated bacteria to utilize canavanine.![]()
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Affiliation(s)
- Franziskus Hauth
- Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
- Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Hiltrun Buck
- Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Marco Stanoppi
- Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Jörg S. Hartig
- Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
- Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
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8
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Chen M, Liu CT, Tang Y. Discovery and Biocatalytic Application of a PLP-Dependent Amino Acid γ-Substitution Enzyme That Catalyzes C-C Bond Formation. J Am Chem Soc 2020; 142:10506-10515. [PMID: 32434326 DOI: 10.1021/jacs.0c03535] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Pyridoxal phosphate (PLP)-dependent enzymes can catalyze transformations of l-amino acids at α, β, and γ positions. These enzymes are frequently involved in the biosynthesis of nonproteinogenic amino acids as building blocks of natural products and are attractive biocatalysts. Here, we report the discovery of a two-step enzymatic synthesis of (2S,6S)-6-methyl pipecolate 1, from the biosynthetic pathway of citrinadin. The key enzyme CndF is PLP-dependent and catalyzes the synthesis of (S)-2-amino-6-oxoheptanoate 3 that is in equilibrium with the cyclic Schiff base. The second enzyme CndE is a stereoselective imine reductase that gives 1. Biochemical characterization of CndF showed this enzyme performs γ-elimination of O-acetyl-l-homoserine to generate the vinylglycine ketimine, which is subjected to nucleophilic attack by acetoacetate to form the new Cγ-Cδ bond in 3 and complete the γ-substitution reaction. CndF displays promiscuity toward different β-keto carboxylate and esters. With use of an Aspergillus strain expressing CndF and CndE, feeding various alkyl-β-keto esters led to the biosynthesis of 6-substituted l-pipecolates. The discovery of CndF expands the repertoire of reactions that can be catalyzed by PLP-dependent enzymes.
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Affiliation(s)
- Mengbin Chen
- Department of Chemical and Biomolecular Engineering, University of California Los Angeles, Los Angeles, California 90095, United States
| | - Chun-Ting Liu
- Department of Chemical and Biomolecular Engineering, University of California Los Angeles, Los Angeles, California 90095, United States.,Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Yi Tang
- Department of Chemical and Biomolecular Engineering, University of California Los Angeles, Los Angeles, California 90095, United States.,Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California 90095, United States
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9
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Cui Z, Overbay J, Wang X, Liu X, Zhang Y, Bhardwaj M, Lemke A, Wiegmann D, Niro G, Thorson JS, Ducho C, Van Lanen SG. Pyridoxal-5'-phosphate-dependent alkyl transfer in nucleoside antibiotic biosynthesis. Nat Chem Biol 2020; 16:904-911. [PMID: 32483377 PMCID: PMC7377962 DOI: 10.1038/s41589-020-0548-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 04/10/2020] [Indexed: 11/09/2022]
Abstract
Several nucleoside antibiotics are structurally characterized by a 5′′-amino-5′′-deoxyribose (ADR) appended via a glycosidic bond to a high-carbon sugar nucleoside, (5′S,6′S)-5′-C-glycyluridine (GlyU). GlyU is further modified with an N-alkylamine linker, the biosynthetic origins of which have yet to be established. By using a combination of feeding experiments with isotopically labeled precursors and characterization of recombinant proteins from multiple pathways, the biosynthetic mechanism for N-alkylamine installation for ADR-GlyU-containing nucleoside antibiotics has been uncovered. The data reveal S-adenosyl-l-methionine (AdoMet) as the direct precursor of the N-alkylamine, but unlike conventional AdoMet- or decarboxylated AdoMet-dependent alkyltransferases, the reaction is catalyzed by a pyridoxal-5′-phophosate (PLP)-dependent aminobutyryltransferase (ABTase) using a stepwise γ-replacement mechanism that couples γ-elimination of AdoMet with aza-γ-addition onto the disaccharide alkyl acceptor. In addition to utilizing a conceptually different strategy for AdoMet-dependent alkylation, the newly discovered ABTases require a phosphorylated disaccharide alkyl acceptor, revealing a cryptic intermediate in the biosynthetic pathway.
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Affiliation(s)
- Zheng Cui
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA
| | - Jonathan Overbay
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA
| | - Xiachang Wang
- Center for Pharmaceutical Research and Innovation, College of Pharmacy, University of Kentucky, Lexington, KY, USA.,Jiangsu Key Laboratory for Functional Substance of Chinese Medicine, School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, People's Republic of China
| | - Xiaodong Liu
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA
| | - Yinan Zhang
- Center for Pharmaceutical Research and Innovation, College of Pharmacy, University of Kentucky, Lexington, KY, USA.,Jiangsu Key Laboratory for Functional Substance of Chinese Medicine, School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, People's Republic of China
| | - Minakshi Bhardwaj
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA
| | - Anke Lemke
- Department of Pharmacy, Pharmaceutical and Medicinal Chemistry, Saarland University, Saarbrücken, Germany
| | - Daniel Wiegmann
- Department of Pharmacy, Pharmaceutical and Medicinal Chemistry, Saarland University, Saarbrücken, Germany
| | - Giuliana Niro
- Department of Pharmacy, Pharmaceutical and Medicinal Chemistry, Saarland University, Saarbrücken, Germany
| | - Jon S Thorson
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA.,Center for Pharmaceutical Research and Innovation, College of Pharmacy, University of Kentucky, Lexington, KY, USA
| | - Christian Ducho
- Department of Pharmacy, Pharmaceutical and Medicinal Chemistry, Saarland University, Saarbrücken, Germany
| | - Steven G Van Lanen
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA.
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10
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Jovanovic M, Petkovic M, Jovanovic P, Simic M, Tasic G, Eric S, Savic V. Proline Derived Bicyclic Derivatives through Metal Catalysed Cyclisations of Allenes: Synthesis of Longamide B, Stylisine D and their Derivatives. European J Org Chem 2019. [DOI: 10.1002/ejoc.201901554] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Milos Jovanovic
- Faculty of Pharmacy; Department of Organic Chemistry; University of Belgrade; Vojvode Stepe 450 11221 Belgrade Serbia
| | - Milos Petkovic
- Faculty of Pharmacy; Department of Organic Chemistry; University of Belgrade; Vojvode Stepe 450 11221 Belgrade Serbia
| | - Predrag Jovanovic
- Faculty of Pharmacy; Department of Organic Chemistry; University of Belgrade; Vojvode Stepe 450 11221 Belgrade Serbia
| | - Milena Simic
- Faculty of Pharmacy; Department of Organic Chemistry; University of Belgrade; Vojvode Stepe 450 11221 Belgrade Serbia
| | - Gordana Tasic
- Faculty of Pharmacy; Department of Organic Chemistry; University of Belgrade; Vojvode Stepe 450 11221 Belgrade Serbia
| | - Slavica Eric
- Faculty of Pharmacy; Department of Pharmaceutical Chemistry; University of Belgrade; Vojvode Stepe 450 11221 Belgrade Serbia
| | - Vladimir Savic
- Faculty of Pharmacy; Department of Organic Chemistry; University of Belgrade; Vojvode Stepe 450 11221 Belgrade Serbia
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11
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Infection Rates and Alkaloid Patterns of Different Grass Species with Systemic Epichloë Endophytes. Appl Environ Microbiol 2019; 85:AEM.00465-19. [PMID: 31227553 DOI: 10.1128/aem.00465-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 06/14/2019] [Indexed: 01/05/2023] Open
Abstract
Symbiotic Epichloë species are fungal endophytes of cool-season grasses that can produce alkaloids with toxicity to vertebrates and/or invertebrates. Monitoring infections and presence of alkaloids in grasses infected with Epichloë species can provide an estimate of possible intoxication risks for livestock. We sampled 3,046 individuals of 13 different grass species in three regions on 150 study sites in Germany. We determined infection rates and used PCR to identify Epichloë species diversity based on the presence of different alkaloid biosynthesis genes, then confirmed the possible chemotypes with high-performance liquid chromatography (HPLC)/ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and gas chromatography-mass spectrometry (GC-MS) measurements. Infections of Epichloë spp. were found in Festuca pratensis Huds. (81%), Festuca ovina L. aggregate (agg.) (73%), Lolium perenne L. (15%), Festuca rubra L. (15%) and Dactylis glomerata L. (8%). The other eight grass species did not appear to be infected. For the majority of Epichloë-infected L. perenne samples (98%), the alkaloids lolitrem B and peramine were present, but ergovaline was not detected, which was consistent with the genetic evaluation, as dmaW, the gene encoding the first step of the ergot alkaloid biosynthesis pathway, was absent. Epichloë uncinata in F. pratensis produced anti-insect loline compounds. The Epichloë spp. observed in the F. ovina agg. samples showed the greatest level of diversity, and different intermediates of the indole-diterpene pathway could be detected. Epichloë infection rates alone are insufficient to estimate intoxication risks for livestock, as other factors, like the ability of the endophyte to produce the alkaloids, also need to be assessed.IMPORTANCE Severe problems of livestock intoxication from Epichloë-infected forage grasses have been reported from New Zealand, Australia, and the United States, but much less frequently from Europe, and particularly not from Germany. Nevertheless, it is important to monitor infection rates and alkaloids of grasses with Epichloë fungi to estimate possible intoxication risks. Most studies focus on agricultural grass species like Lolium perenne and Festuca arundinacea, but other cool-season grass species can also be infected. We show that in Germany, infection rates and alkaloids differ between grass species and that some of the alkaloids can be toxic to livestock. Changes in grassland management due to changing climate, especially with a shift toward grasslands dominated with Epichloë-infected species such as Lolium perenne, may result in greater numbers of intoxicated livestock in the near future. We therefore suggest regular monitoring of grass species for infections and alkaloids and call for maintaining heterogenous grasslands for livestock.
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12
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Du YL, Ryan KS. Pyridoxal phosphate-dependent reactions in the biosynthesis of natural products. Nat Prod Rep 2019; 36:430-457. [DOI: 10.1039/c8np00049b] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
We review reactions catalyzed by pyridoxal phosphate-dependent enzymes, highlighting enzymes reported in the recent natural product biosynthetic literature.
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Affiliation(s)
- Yi-Ling Du
- Institute of Pharmaceutical Biotechnology
- Zhejiang University School of Medicine
- Hangzhou
- China
| | - Katherine S. Ryan
- Department of Chemistry
- University of British Columbia
- Vancouver
- Canada
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13
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Yi M, Hendricks WQ, Kaste J, Charlton ND, Nagabhyru P, Panaccione DG, Young CA. Molecular identification and characterization of endophytes from uncultivated barley. Mycologia 2018; 110:453-472. [PMID: 29923795 DOI: 10.1080/00275514.2018.1464818] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Epichloë species (Clavicipitaceae, Ascomycota) are endophytic symbionts of many cool-season grasses. Many interactions between Epichloë and their host grasses contribute to plant growth promotion, protection from many pathogens and insect pests, and tolerance to drought stress. Resistance to insect herbivores by endophytes associated with Hordeum species has been previously shown to vary depending on the endophyte-grass-insect combination. We explored the genetic and chemotypic diversity of endophytes present in wild Hordeum species. We analyzed seeds of Hordeum bogdanii, H. brevisubulatum, and H. comosum obtained from the US Department of Agriculture's (USDA) National Plant Germplasm System (NPGS), of which some have been reported as endophyte-infected. Using polymerase chain reaction (PCR) with primers specific to Epichloë species, we were able to identify endophytes in seeds from 17 of the 56 Plant Introduction (PI) lines, of which only 9 lines yielded viable seed. Phylogenetic analyses of housekeeping, alkaloid biosynthesis, and mating type genes suggest that the endophytes of the infected PI lines separate into five taxa: Epichloë bromicola, Epichloë tembladerae, and three unnamed interspecific hybrid species. One PI line contained an endophyte that is considered a new taxonomic group, Epichloë sp. HboTG-3 (H. bogdanii Taxonomic Group 3). Phylogenetic analyses of the interspecific hybrid endophytes from H. bogdanii and H. brevisubulatum indicate that these taxa all have an E. bromicola allele but the second allele varies. We verified in planta alkaloid production from the five genotypes yielding viable seed. Morphological characteristics of the isolates from the viable Hordeum species were analyzed for their features in culture and in planta. In the latter, we observed epiphyllous growth and in some cases sporulation on leaves of infected plants.
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Affiliation(s)
- Mihwa Yi
- a Noble Research Institute, LLC , Ardmore , Oklahoma 73401
| | | | - Joshua Kaste
- a Noble Research Institute, LLC , Ardmore , Oklahoma 73401
| | | | - Padmaja Nagabhyru
- b Department of Plant Pathology , University of Kentucky , Lexington , Kentucky 40546
| | - Daniel G Panaccione
- c Division of Plant and Soil Sciences , West Virginia University , Morgantown , West Virginia 26506
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Pan J, Bhardwaj M, Zhang B, Chang WC, Schardl CL, Krebs C, Grossman RB, Bollinger JM. Installation of the Ether Bridge of Lolines by the Iron- and 2-Oxoglutarate-Dependent Oxygenase, LolO: Regio- and Stereochemistry of Sequential Hydroxylation and Oxacyclization Reactions. Biochemistry 2018. [PMID: 29537853 PMCID: PMC5895980 DOI: 10.1021/acs.biochem.8b00157] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
The core of the loline
family of insecticidal alkaloids is the
bicyclic pyrrolizidine unit with an additional strained ether bridge
between carbons 2 and 7. Previously reported genetic and in
vivo biochemical analyses showed that the presumptive iron-
and 2-oxoglutarate-dependent (Fe/2OG) oxygenase, LolO, is required
for installation of the ether bridge upon the pathway intermediate,
1-exo-acetamidopyrrolizidine (AcAP). Here we show
that LolO is, in fact, solely responsible for this biosynthetic four-electron
oxidation. In sequential 2OG- and O2-consuming steps, LolO
removes hydrogens from C2 and C7 of AcAP to form both carbon–oxygen
bonds in N-acetylnorloline (NANL), the precursor
to all other lolines. When supplied with substoichiometric 2OG, LolO
only hydroxylates AcAP. At higher 2OG:AcAP ratios, the enzyme further
processes the alcohol to the tricyclic NANL. Characterization of the
alcohol intermediate by mass spectrometry and nuclear magnetic resonance
spectroscopy shows that it is 2-endo-hydroxy-1-exo-acetamidopyrrolizidine (2-endo-OH-AcAP).
Kinetic and spectroscopic analyses of reactions with site-specifically
deuteriated AcAP substrates confirm that the C2–H bond is cleaved
first and that the responsible intermediate is, as expected, an FeIV–oxo (ferryl) complex. Analyses of the loline products
from cultures fed with stereospecifically deuteriated AcAP precursors,
proline and aspartic acid, establish that LolO removes the endo hydrogens
from C2 and C7 and forms both new C–O bonds with retention
of configuration. These findings delineate the pathway to an important
class of natural insecticides and lay the foundation for mechanistic
dissection of the chemically challenging oxacyclization reaction.
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Affiliation(s)
- Juan Pan
- Department of Chemistry and Department of Biochemistry and Molecular Biology , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | | | - Bo Zhang
- Department of Chemistry and Department of Biochemistry and Molecular Biology , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Wei-Chen Chang
- Department of Chemistry and Department of Biochemistry and Molecular Biology , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | | | - Carsten Krebs
- Department of Chemistry and Department of Biochemistry and Molecular Biology , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | | | - J Martin Bollinger
- Department of Chemistry and Department of Biochemistry and Molecular Biology , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
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Pan J, Bhardwaj M, Nagabhyru P, Grossman RB, Schardl CL. Enzymes from fungal and plant origin required for chemical diversification of insecticidal loline alkaloids in grass-Epichloë symbiota. PLoS One 2014; 9:e115590. [PMID: 25531527 PMCID: PMC4274035 DOI: 10.1371/journal.pone.0115590] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2014] [Accepted: 11/29/2014] [Indexed: 11/19/2022] Open
Abstract
The lolines are a class of bioprotective alkaloids that are produced by Epichloë species, fungal endophytes of grasses. These alkaloids are saturated 1-aminopyrrolizidines with a C2 to C7 ether bridge, and are structurally differentiated by the various modifications of the 1-amino group: -NH2 (norloline), -NHCH3 (loline), -N(CH3)2 (N-methylloline), -N(CH3)Ac (N-acetylloline), -NHAc (N-acetylnorloline), and -N(CH3)CHO (N-formylloline). Other than the LolP cytochrome P450, which is required for conversion of N-methylloline to N-formylloline, the enzymatic steps for loline diversification have not yet been established. Through isotopic labeling, we determined that N-acetylnorloline is the first fully cyclized loline alkaloid, implying that deacetylation, methylation, and acetylation steps are all involved in loline alkaloid diversification. Two genes of the loline alkaloid biosynthesis (LOL) gene cluster, lolN and lolM, were predicted to encode an N-acetamidase (deacetylase) and a methyltransferase, respectively. A knockout strain lacking both lolN and lolM stopped the biosynthesis at N-acetylnorloline, and complementation with the two wild-type genes restored production of N-formylloline and N-acetylloline. These results indicated that lolN and lolM are required in the steps from N-acetylnorloline to other lolines. The function of LolM as an N-methyltransferase was confirmed by its heterologous expression in yeast resulting in conversion of norloline to loline, and of loline to N-methylloline. One of the more abundant lolines, N-acetylloline, was observed in some but not all plants with symbiotic Epichloë siegelii, and when provided with exogenous loline, asymbiotic meadow fescue (Lolium pratense) plants produced N-acetylloline, suggesting that a plant acetyltransferase catalyzes N-acetylloline formation. We conclude that although most loline alkaloid biosynthesis reactions are catalyzed by fungal enzymes, both fungal and plant enzymes are responsible for the chemical diversification steps in symbio.
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Affiliation(s)
- Juan Pan
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky, United States of America
| | - Minakshi Bhardwaj
- Department of Chemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Padmaja Nagabhyru
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky, United States of America
| | - Robert B. Grossman
- Department of Chemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Christopher L. Schardl
- Department of Chemistry, University of Kentucky, Lexington, Kentucky, United States of America
- * E-mail:
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Charlton ND, Craven KD, Afkhami ME, Hall BA, Ghimire SR, Young CA. Interspecific hybridization and bioactive alkaloid variation increases diversity in endophytic Epichloë species of Bromus laevipes. FEMS Microbiol Ecol 2014; 90:276-89. [PMID: 25065688 DOI: 10.1111/1574-6941.12393] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 05/27/2014] [Accepted: 07/18/2014] [Indexed: 11/29/2022] Open
Abstract
Studying geographic variation of microbial mutualists, especially variation in traits related to benefits they provide their host, is critical for understanding how these associations impact key ecological processes. In this study, we investigate the phylogenetic population structure of Epichloë species within Bromus laevipes, a native cool-season bunchgrass found predominantly in California. Phylogenetic classification supported inference of three distinct Epichloë taxa, of which one was nonhybrid and two were interspecific hybrids. Inheritance of mating-type idiomorphs revealed that at least one of the hybrid species arose from independent hybridization events. We further investigated the geographic variation of endophyte-encoded alkaloid genes, which is often associated with key benefits of natural enemy protection for the host. Marker diversity at the ergot alkaloid, loline, indole-diterpene, and peramine loci revealed four alkaloid genotypes across the three identified Epichloë species. Predicted chemotypes were tested using endophyte-infected plant material that represented each endophyte genotype, and 11 of the 13 predicted alkaloids were confirmed. This multifaceted approach combining phylogenetic, genotypic, and chemotypic analyses allowed us to reconstruct the diverse evolutionary histories of Epichloë species present within B. laevipes and highlight the complex and dynamic processes underlying these grass-endophyte symbioses.
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Affiliation(s)
- Nikki D Charlton
- Forage Improvement Division, The Samuel Roberts Noble Foundation, Ardmore, OK, USA
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Pan J, Bhardwaj M, Faulkner JR, Nagabhyru P, Charlton ND, Higashi RM, Miller AF, Young CA, Grossman RB, Schardl CL. Ether bridge formation in loline alkaloid biosynthesis. PHYTOCHEMISTRY 2014; 98:60-8. [PMID: 24374065 PMCID: PMC3929955 DOI: 10.1016/j.phytochem.2013.11.015] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 11/01/2013] [Accepted: 11/21/2013] [Indexed: 05/18/2023]
Abstract
Lolines are potent insecticidal agents produced by endophytic fungi of cool-season grasses. These alkaloids are composed of a pyrrolizidine ring system and an uncommon ether bridge linking carbons 2 and 7. Previous results indicated that 1-aminopyrrolizidine was a pathway intermediate. We used RNA interference to knock down expression of lolO, resulting in the accumulation of an alkaloid identified as exo-1-acetamidopyrrolizidine based on high-resolution MS and NMR. Genomes of endophytes differing in alkaloid profiles were sequenced, revealing that those with mutated lolO accumulated exo-1-acetamidopyrrolizidine but no lolines. Heterologous expression of wild-type lolO complemented a lolO mutant, resulting in the production of N-acetylnorloline. These results indicated that the non-heme iron oxygenase, LolO, is required for ether bridge formation, probably through oxidation of exo-1-acetamidopyrrolizidine.
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Affiliation(s)
- Juan Pan
- Department of Plant Pathology, 201F Plant Sciences Building, 1405 Veterans Drive, University of Kentucky, Lexington, KY 40546-0312, USA
| | - Minakshi Bhardwaj
- Department of Chemistry, 339 Chemistry-Physics Building, 505 Rose Street, University of Kentucky, Lexington, KY 40506-0055, USA
| | - Jerome R Faulkner
- Department of Plant Pathology, 201F Plant Sciences Building, 1405 Veterans Drive, University of Kentucky, Lexington, KY 40546-0312, USA
| | - Padmaja Nagabhyru
- Department of Plant Pathology, 201F Plant Sciences Building, 1405 Veterans Drive, University of Kentucky, Lexington, KY 40546-0312, USA
| | - Nikki D Charlton
- The Samuel Roberts Noble Foundation, Forage Improvement Division, 2510 Sam Noble Parkway, Ardmore, OK 73401-2124, USA
| | - Richard M Higashi
- Graduate Center for Toxicology, 521 Biopharmacy Building, 1000 South Limestone, University of Kentucky, Lexington, KY 40536-0293, USA
| | - Anne-Frances Miller
- Department of Chemistry, 339 Chemistry-Physics Building, 505 Rose Street, University of Kentucky, Lexington, KY 40506-0055, USA
| | - Carolyn A Young
- The Samuel Roberts Noble Foundation, Forage Improvement Division, 2510 Sam Noble Parkway, Ardmore, OK 73401-2124, USA
| | - Robert B Grossman
- Department of Chemistry, 339 Chemistry-Physics Building, 505 Rose Street, University of Kentucky, Lexington, KY 40506-0055, USA
| | - Christopher L Schardl
- Department of Plant Pathology, 201F Plant Sciences Building, 1405 Veterans Drive, University of Kentucky, Lexington, KY 40546-0312, USA.
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Schardl CL, Young CA, Pan J, Florea S, Takach JE, Panaccione DG, Farman ML, Webb JS, Jaromczyk J, Charlton ND, Nagabhyru P, Chen L, Shi C, Leuchtmann A. Currencies of mutualisms: sources of alkaloid genes in vertically transmitted epichloae. Toxins (Basel) 2013; 5:1064-88. [PMID: 23744053 PMCID: PMC3717770 DOI: 10.3390/toxins5061064] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Revised: 05/17/2013] [Accepted: 05/29/2013] [Indexed: 11/17/2022] Open
Abstract
The epichloae (Epichloë and Neotyphodium species), a monophyletic group of fungi in the family Clavicipitaceae, are systemic symbionts of cool-season grasses (Poaceae subfamily Poöideae). Most epichloae are vertically transmitted in seeds (endophytes), and most produce alkaloids that attack nervous systems of potential herbivores. These protective metabolites include ergot alkaloids and indole-diterpenes (tremorgens), which are active in vertebrate systems, and lolines and peramine, which are more specific against invertebrates. Several Epichloë species have been described which are sexual and capable of horizontal transmission, and most are vertically transmissible also. Asexual epichloae are mainly or exclusively vertically transmitted, and many are interspecific hybrids with genomic contributions from two or three ancestral Epichloë species. Here we employ genome-scale analyses to investigate the origins of biosynthesis gene clusters for ergot alkaloids (EAS), indole-diterpenes (IDT), and lolines (LOL) in 12 hybrid species. In each hybrid, the alkaloid-gene and housekeeping-gene relationships were congruent. Interestingly, hybrids frequently had alkaloid clusters that were rare in their sexual ancestors. Also, in those hybrids that had multiple EAS, IDT or LOL clusters, one cluster lacked some genes, usually for late pathway steps. Possible implications of these findings for the alkaloid profiles and endophyte ecology are discussed.
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Affiliation(s)
- Christopher L. Schardl
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA; E-Mails: (J.P.); (S.F.); (M.L.F.); (P.N.); (L.C.); (C.S.)
| | - Carolyn A. Young
- Forage Improvement Division, The Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA; E-Mails: (C.A.Y.); (J.E.T.); (N.D.C.)
| | - Juan Pan
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA; E-Mails: (J.P.); (S.F.); (M.L.F.); (P.N.); (L.C.); (C.S.)
| | - Simona Florea
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA; E-Mails: (J.P.); (S.F.); (M.L.F.); (P.N.); (L.C.); (C.S.)
| | - Johanna E. Takach
- Forage Improvement Division, The Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA; E-Mails: (C.A.Y.); (J.E.T.); (N.D.C.)
| | - Daniel G. Panaccione
- Division of Plant and Soil Sciences, West Virginia University, Morgantown, WV 26506, USA; E-Mail:
| | - Mark L. Farman
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA; E-Mails: (J.P.); (S.F.); (M.L.F.); (P.N.); (L.C.); (C.S.)
| | - Jennifer S. Webb
- Advanced Genetic Technologies Center, University of Kentucky, Lexington, KY 40546, USA; E-Mails: (J.S.W.); (J.J.)
| | - Jolanta Jaromczyk
- Advanced Genetic Technologies Center, University of Kentucky, Lexington, KY 40546, USA; E-Mails: (J.S.W.); (J.J.)
| | - Nikki D. Charlton
- Forage Improvement Division, The Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA; E-Mails: (C.A.Y.); (J.E.T.); (N.D.C.)
| | - Padmaja Nagabhyru
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA; E-Mails: (J.P.); (S.F.); (M.L.F.); (P.N.); (L.C.); (C.S.)
| | - Li Chen
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA; E-Mails: (J.P.); (S.F.); (M.L.F.); (P.N.); (L.C.); (C.S.)
- School of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China
| | - Chong Shi
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA; E-Mails: (J.P.); (S.F.); (M.L.F.); (P.N.); (L.C.); (C.S.)
- School of Grassland & Environmental Science, Xinjiang Agricultural University, Urumqi 830052, China
| | - Adrian Leuchtmann
- Institute of Integrative Biology, ETH Zürich, Zürich CH-8092, Switzerland; E-Mail:
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Schardl CL, Young CA, Hesse U, Amyotte SG, Andreeva K, Calie PJ, Fleetwood DJ, Haws DC, Moore N, Oeser B, Panaccione DG, Schweri KK, Voisey CR, Farman ML, Jaromczyk JW, Roe BA, O'Sullivan DM, Scott B, Tudzynski P, An Z, Arnaoudova EG, Bullock CT, Charlton ND, Chen L, Cox M, Dinkins RD, Florea S, Glenn AE, Gordon A, Güldener U, Harris DR, Hollin W, Jaromczyk J, Johnson RD, Khan AK, Leistner E, Leuchtmann A, Li C, Liu J, Liu J, Liu M, Mace W, Machado C, Nagabhyru P, Pan J, Schmid J, Sugawara K, Steiner U, Takach JE, Tanaka E, Webb JS, Wilson EV, Wiseman JL, Yoshida R, Zeng Z. Plant-symbiotic fungi as chemical engineers: multi-genome analysis of the clavicipitaceae reveals dynamics of alkaloid loci. PLoS Genet 2013; 9:e1003323. [PMID: 23468653 PMCID: PMC3585121 DOI: 10.1371/journal.pgen.1003323] [Citation(s) in RCA: 271] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Accepted: 12/31/2012] [Indexed: 01/01/2023] Open
Abstract
The fungal family Clavicipitaceae includes plant symbionts and parasites that produce several psychoactive and bioprotective alkaloids. The family includes grass symbionts in the epichloae clade (Epichloë and Neotyphodium species), which are extraordinarily diverse both in their host interactions and in their alkaloid profiles. Epichloae produce alkaloids of four distinct classes, all of which deter insects, and some-including the infamous ergot alkaloids-have potent effects on mammals. The exceptional chemotypic diversity of the epichloae may relate to their broad range of host interactions, whereby some are pathogenic and contagious, others are mutualistic and vertically transmitted (seed-borne), and still others vary in pathogenic or mutualistic behavior. We profiled the alkaloids and sequenced the genomes of 10 epichloae, three ergot fungi (Claviceps species), a morning-glory symbiont (Periglandula ipomoeae), and a bamboo pathogen (Aciculosporium take), and compared the gene clusters for four classes of alkaloids. Results indicated a strong tendency for alkaloid loci to have conserved cores that specify the skeleton structures and peripheral genes that determine chemical variations that are known to affect their pharmacological specificities. Generally, gene locations in cluster peripheries positioned them near to transposon-derived, AT-rich repeat blocks, which were probably involved in gene losses, duplications, and neofunctionalizations. The alkaloid loci in the epichloae had unusual structures riddled with large, complex, and dynamic repeat blocks. This feature was not reflective of overall differences in repeat contents in the genomes, nor was it characteristic of most other specialized metabolism loci. The organization and dynamics of alkaloid loci and abundant repeat blocks in the epichloae suggested that these fungi are under selection for alkaloid diversification. We suggest that such selection is related to the variable life histories of the epichloae, their protective roles as symbionts, and their associations with the highly speciose and ecologically diverse cool-season grasses.
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Schardl CL, Young CA, Faulkner JR, Florea S, Pan J. Chemotypic diversity of epichloae, fungal symbionts of grasses. FUNGAL ECOL 2012. [DOI: 10.1016/j.funeco.2011.04.005] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Domínguez de María P, van Gemert RW, Straathof AJJ, Hanefeld U. Biosynthesis of ethers: unusual or common natural events? Nat Prod Rep 2010; 27:370-92. [PMID: 20179877 DOI: 10.1039/b809416k] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ether bonds are found in a wide variety of natural products--mainly secondary metabolites--including lipids, oxiranes, terpenoids, flavonoids, polyketides, and carbohydrate derivatives, to name some representative examples. To furnish such a biodiversity of structures, a large number of different enzymes are involved in several different biosynthetic pathways. Depending on the compound and on the (micro) environment in which the reaction is performed, ethers are produced by very different (enzymatic) reactions, thus providing an impressive display of how Nature has combined evolution and thermodynamics to be able to produce a vast number of compounds. In addition, many of these compounds possess different biological activities of pharmacological interest. Moreover, some of these ethers (i.e., epoxides) have high chemical reactivity, and can be useful starting materials for further synthetic processes. This review aims to provide an overview of the different strategies that are found in Nature for the formation of these "bioethers". Both fundamental and practical insights of the biosynthetic processes will be discussed.
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Zhang DX, Stromberg AJ, Spiering MJ, Schardl CL. Coregulated expression of loline alkaloid-biosynthesis genes in Neotyphodium uncinatum cultures. Fungal Genet Biol 2009; 46:517-30. [DOI: 10.1016/j.fgb.2009.03.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2008] [Revised: 03/08/2009] [Accepted: 03/30/2009] [Indexed: 11/30/2022]
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Zhang DX, Nagabhyru P, Schardl CL. Regulation of a chemical defense against herbivory produced by symbiotic fungi in grass plants. PLANT PHYSIOLOGY 2009; 150:1072-82. [PMID: 19403726 PMCID: PMC2689992 DOI: 10.1104/pp.109.138222] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2009] [Accepted: 04/20/2009] [Indexed: 05/18/2023]
Abstract
Neotyphodium uncinatum and Neotyphodium siegelii are fungal symbionts (endophytes) of meadow fescue (MF; Lolium pratense), which they protect from insects by producing loline alkaloids. High levels of lolines are produced following insect damage or mock herbivory (clipping). Although loline alkaloid levels were greatly elevated in regrowth after clipping, loline-alkaloid biosynthesis (LOL) gene expression in regrowth and basal tissues was similar to unclipped controls. The dramatic increase of lolines in regrowth reflected the much higher concentrations in young (center) versus older (outer) leaf blades, so LOL gene expression was compared in these tissues. In MF-N. siegelii, LOL gene expression was similar in younger and older leaf blades, whereas expression of N. uncinatum LOL genes and some associated biosynthesis genes was higher in younger than older leaf blades. Because lolines are derived from amino acids that are mobilized to new growth, we tested the amino acid levels in center and outer leaf blades. Younger leaf blades of aposymbiotic plants (no endophyte present) had significantly higher levels of asparagine and sometimes glutamine compared to older leaf blades. The amino acid levels were much lower in MF-N. siegelii and MF-N. uncinatum compared to aposymbiotic plants and MF with Epichloë festucae (a closely related symbiont), which lacked lolines. We conclude that loline alkaloid production in young tissue depleted these amino acid pools and was apparently regulated by availability of the amino acid substrates. As a result, lolines maximally protect young host tissues in a fashion similar to endogenous plant metabolites that conform to optimal defense theory.
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Affiliation(s)
- Dong-Xiu Zhang
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky 40146-0312, USA
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Spiering MJ, Faulkner JR, Zhang DX, Machado C, Grossman RB, Schardl CL. Role of the LolP cytochrome P450 monooxygenase in loline alkaloid biosynthesis. Fungal Genet Biol 2008; 45:1307-14. [DOI: 10.1016/j.fgb.2008.07.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2008] [Revised: 06/28/2008] [Accepted: 07/01/2008] [Indexed: 11/25/2022]
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Koulman A, Seeliger C, Edwards PJB, Fraser K, Simpson W, Johnson L, Cao M, Rasmussen S, Lane GA. E/Z-Thesinine-O-4'-alpha-rhamnoside, pyrrolizidine conjugates produced by grasses (Poaceae). PHYTOCHEMISTRY 2008; 69:1927-32. [PMID: 18466931 DOI: 10.1016/j.phytochem.2008.03.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2007] [Revised: 03/17/2008] [Accepted: 03/20/2008] [Indexed: 05/13/2023]
Abstract
Based on direct infusion mass spectrometry we identified a novel alkaloid as a major component of perennial ryegrass (Lolium perenne). Initial mass spectral data suggested it to be a pyrrolizidine conjugate. As this class of alkaloids has not been described before from grasses, we isolated it to elucidate its structure. The isolated alkaloid proved to be a mixture of two stereoisomers. The structures of the two compounds as determined by 1D and 2D NMR spectroscopy, were E-thesinine-O-4'-alpha-rhamnoside (1) and Z-thesinine-O-4'-alpha-rhamnoside (2). These identifications were supported by the characterisation by GC-MS and optical rotation of (+)-isoretronecanol as the necine base released on alkaline hydrolysis of these alkaloids. 1 and 2 together with the aglycone and a hexoside were also detected in tall fescue (Festuca arundinacea). This is the first report of pyrrolizidine alkaloids produced by grasses (Poaceae).
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Affiliation(s)
- Albert Koulman
- AgResearch Grasslands Research Centre, Tennent Drive, Private Bag 11008, Palmerston North, New Zealand
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Schardl CL, Grossman RB, Nagabhyru P, Faulkner JR, Mallik UP. Loline alkaloids: Currencies of mutualism. PHYTOCHEMISTRY 2007; 68:980-96. [PMID: 17346759 DOI: 10.1016/j.phytochem.2007.01.010] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2006] [Revised: 01/06/2007] [Accepted: 01/19/2007] [Indexed: 05/14/2023]
Abstract
Several species of Lolium and other cool-season grasses (Poaceae subfamily Pooideae) tend to harbor symbiotic, seed-transmitted, fungi that enhance their fitness by various means. These fungal endophytes--species of Neotyphodium or Epichloë (Clavicipitaceae)--are known for production of antiherbivore metabolites such as the bioprotective loline alkaloids. Lolines are saturated pyrrolizidines with an exo-1-amine and an ether bridge between C-2 and C-7. The ether bridge is an unusual feature for a biogenic compound in that it links two bridgehead carbon atoms. Much of the loline-biosynthetic pathway has been elucidated by administering isotopically labeled precursors to fungal cultures and by comparisons of loline biosynthesis genes to known gene families. The first step appears to be an unusual gamma-substitution reaction involving an enzyme related to O-acetylhomoserine (thiol) lyase, but which uses the secondary amine of L-proline rather than a sulfhydryl group as the nucleophile. The strained ether bridge is added after formation of the pyrrolizidine rings. Lolines with dimethylated or acylated 1-amines have insect antifeedant and insecticidal activities comparable to nicotine, but little or no toxicity to mammals. Considering the surprising abundance of lolines in some grass-endophyte symbiota, possible additional effects on plant stress tolerance and physiology are worth future consideration. In this review, we discuss the history of loline discovery, methods of analysis, biological activities and distribution in nature, as well as progress on the genetics and biochemistry of their biosynthesis, and on the chemical synthesis of these alkaloids.
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Affiliation(s)
- Christopher L Schardl
- Department of Plant Pathology, 201F Plant Science Building, 1405 Veterans Drive, University of Kentucky, Lexington, KY 40546-0312, USA
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Sullivan TJ, Rodstrom J, Vandop J, Librizzi J, Graham C, Schardl CL, Bultman TL. Symbiont-mediated changes in Lolium arundinaceum inducible defenses: evidence from changes in gene expression and leaf composition. THE NEW PHYTOLOGIST 2007; 176:673-679. [PMID: 17822401 DOI: 10.1111/j.1469-8137.2007.02201.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Plants have multiple strategies to deal with herbivory, ranging from chemical or physical defenses to tolerating damage and allocating resources for regrowth. Grasses usually tolerate herbivory, but for some cool-season grasses, their strategy may depend upon their interactions with intracellular symbionts. Neotyphodium endophytes are common symbionts in pooid grasses, and, for some host species, they provide chemical defenses against both vertebrate and invertebrate herbivores. Here, it was tested whether defenses provided by Neotyphodium coenophialum in Lolium arundinaceum (tall fescue) are inducible by both mechanical damage and herbivory from an invertebrate herbivore, Spodoptera frugiperda (fall armyworm), via a bioassay and by quantifying mRNA expression for lolC, a gene required for loline biosysnthesis. Both mechanical and herbivore damage had a negative effect on the reproduction of a subsequent herbivore, Rhopalosiphum padi (bird cherry-oat aphid), and herbivore damage caused an up-regulation of lolC. Uninfected grass hosts also had significantly higher foliar N% and lower C:N ratio compared with infected hosts, suggesting greater allocation to growth rather than defense. For L. arundinaceum, N. coenophialum appears to switch its host's defensive strategy from tolerance via compensation to resistance.
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Affiliation(s)
| | - John Rodstrom
- Department of Biology, Hope College, Holland, MI 49423, USA
| | - Joshua Vandop
- Department of Biology, Hope College, Holland, MI 49423, USA
| | - James Librizzi
- Department of Biology, Hope College, Holland, MI 49423, USA
| | - Candace Graham
- Department of Biology, Hope College, Holland, MI 49423, USA
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