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Du M, Wang T, Li C, Chen T. Discovery and Characterization of Epichloë Fungal Endophytes from Elymus spp. in Northwest China. Microorganisms 2024; 12:1497. [PMID: 39065265 PMCID: PMC11278780 DOI: 10.3390/microorganisms12071497] [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] [Received: 06/17/2024] [Revised: 07/09/2024] [Accepted: 07/20/2024] [Indexed: 07/28/2024] Open
Abstract
Epichloë fungal endophytes hold promise in sustainable agriculture by fortifying cool-season grasses such as Elymus spp. against various stresses. Elymus spp. are widely distributed in Northwest China with a high incidence of endophyte infections. In this study, we identified 20 Epichloë endophytic fungal strains carried by five Elymus spp. from five areas of Northwest China and systematically characterized their morphology, molecular phylogeny, mating type, and alkaloid diversity for the first time. The morphological characterization underscores strain diversity, with variable colony textures and growth rates. A phylogenetic analysis confirms all strains are E. bromicola, emphasizing their taxonomic status. Alkaloid-encoding gene profiling delineates distinct alkaloid synthesis capabilities among the strains, which are crucial for host adaptability and resistance. A mating-type analysis reveals uniformity (mtAC) across the Epichloë strains, simplifying breeding strategies. Notably, the Epichloë strains exhibit diverse alkaloid synthesis gene profiles, impacting host interactions. This research emphasizes the ecological significance of Epichloë endophytes in Elymus spp. ecosystems, offering insights into their genetic diversity and potential applications in sustainable agriculture.
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Affiliation(s)
- Mingxiang Du
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, Gansu Tech Innovation Centre of Western China Grassland Industry, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730000, China; (M.D.); (T.W.); (C.L.)
| | - Tian Wang
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, Gansu Tech Innovation Centre of Western China Grassland Industry, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730000, China; (M.D.); (T.W.); (C.L.)
| | - Chunjie Li
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, Gansu Tech Innovation Centre of Western China Grassland Industry, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730000, China; (M.D.); (T.W.); (C.L.)
- Grassland Research Center of National Forestry and Grassland Administration, Chinese Academy of Forestry, Beijing 100091, China
| | - Taixiang Chen
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, Gansu Tech Innovation Centre of Western China Grassland Industry, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730000, China; (M.D.); (T.W.); (C.L.)
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2
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Jayawickreme K, Świstak D, Ozimek E, Reszczyńska E, Rysiak A, Makuch-Kocka A, Hanaka A. Pyrrolizidine Alkaloids-Pros and Cons for Pharmaceutical and Medical Applications. Int J Mol Sci 2023; 24:16972. [PMID: 38069294 PMCID: PMC10706944 DOI: 10.3390/ijms242316972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 11/20/2023] [Accepted: 11/27/2023] [Indexed: 12/18/2023] Open
Abstract
Heterocyclic organic compounds named pyrrolizidine alkaloids (PAs) belong to a group of alkaloids and are synthesized by either plants or microorganisms. Therefore, they are naturally occurring secondary metabolites. They are found in species applied in the pharmaceutical and food industries, thus a thorough knowledge of their pharmacological properties and toxicology to humans is of great importance for their further safe employment. This review is original because it synthesizes knowledge of plant and microbial PAs, which is unusual in the scientific literature. We have focused on the Boraginaceae family, which is unique due to the exceptional richness and diversity of its PAs in plant species. We have also presented the microbial sources of PAs, both from fungi and bacteria. The structure and metabolism of PAs have been discussed. Our main aim was to summarize the effects of PAs on humans, including both negative, toxic ones, mainly concerning hepatotoxicity and carcinogenicity, as well as potentially positive ones for pharmacological and medical applications. We have collected the results of studies on the anticancer activity of PAs from plant and microbial sources (mainly Streptomyces strains) and on the antimicrobial activity of PAs on different strains of microorganisms (bacteria and fungi). Finally, we have suggested potential applications and future perspectives.
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Affiliation(s)
- Kavindi Jayawickreme
- Student Scientific Club of Phytochemists, Institute of Biological Sciences, Faculty of Biology and Biotechnology, Maria Curie-Skłodowska University, Akademicka St. 19, 20-033 Lublin, Poland
| | - Dawid Świstak
- Student Scientific Club of Phytochemists, Institute of Biological Sciences, Faculty of Biology and Biotechnology, Maria Curie-Skłodowska University, Akademicka St. 19, 20-033 Lublin, Poland
| | - Ewa Ozimek
- Department of Industrial and Environmental Microbiology, Institute of Biological Sciences, Faculty of Biology and Biotechnology, Maria Curie-Skłodowska University, Akademicka St. 19, 20-033 Lublin, Poland
| | - Emilia Reszczyńska
- Department of Biochemistry and Molecular Biology, Medical University of Lublin, Chodźki St. 1, 20-093 Lublin, Poland
- Department of Plant Physiology and Biophysics, Institute of Biological Sciences, Faculty of Biology and Biotechnology, Maria Curie-Skłodowska University, Akademicka St. 19, 20-033 Lublin, Poland
| | - Anna Rysiak
- Department of Botany, Mycology, and Ecology, Institute of Biological Sciences, Faculty of Biology and Biotechnology, Maria Curie-Skłodowska University, Akademicka St. 19, 20-033 Lublin, Poland
| | - Anna Makuch-Kocka
- Department of Pharmacology, Medical University of Lublin, Radziwiłłowska St. 11, 20-080 Lublin, Poland
| | - Agnieszka Hanaka
- Department of Plant Physiology and Biophysics, Institute of Biological Sciences, Faculty of Biology and Biotechnology, Maria Curie-Skłodowska University, Akademicka St. 19, 20-033 Lublin, Poland
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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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Fuchs B, Saikkonen K, Damerau A, Yang B, Helander M. Herbicide residues in soil decrease microbe-mediated plant protection. PLANT BIOLOGY (STUTTGART, GERMANY) 2023; 25:571-578. [PMID: 36920172 DOI: 10.1111/plb.13517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Accepted: 03/10/2023] [Indexed: 05/17/2023]
Abstract
The residues of glyphosate are found to remain in soils longer than previously reported, affecting rhizosphere microbes. This may adversely affect crop and other non-target plants because the plant's resilience and resistance largely rely on plant-associated microbes. Ubiquitous glyphosate residues in soil and how they impact mutualistic microbes inhabiting the aboveground plant parts are largely unexplored. We studied the effects of herbicide residues in soil on Epichloë sp., which are common endophytic symbionts inhabiting aerial parts of cool-season grasses. In this symbiosis, the obligate symbiont subsists entirely on its host plant, and in exchange, it provides alkaloids conferring resistance to herbivores for the host grass that invests little in its own chemical defence. We first show decreased growth of Epichloë endophytes in vitro when directly exposed to two concentrations of glyphosate or glyphosate-based herbicides. Second, we provide evidence for a reduction of Epichloë-derived, insect-toxic loline alkaloids in endophyte-symbiotic meadow fescue (F. pratensis) plants growing in soil with a glyphosate history. Plants were grown for 2 years in an open field site, and natural herbivore infestation was correlated with the glyphosate-mediated reduction of loline alkaloid concentrations. Our findings indicate that herbicides residing in soil not only affect rhizosphere microbiota but also aerial plant endophyte functionality, which emphasizes the destructive effects of glyphosate on plant symbiotic microbes, here with cascading effects on plant-pest insect interactions.
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Affiliation(s)
- B Fuchs
- Biodiversity Unit, University of Turku, Turku, Finland
| | - K Saikkonen
- Biodiversity Unit, University of Turku, Turku, Finland
| | - A Damerau
- Food Chemistry and Food Development, Department of Life Technologies, University of Turku, Turku, Finland
| | - B Yang
- Food Chemistry and Food Development, Department of Life Technologies, University of Turku, Turku, Finland
| | - M Helander
- Department of Biology, University of Turku, Turku, Finland
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5
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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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6
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Tassano E, Moore C, Dussauge S, Vargas A, Snajdrova R. Discovery of New Fe(II)/α-Ketoglutarate-Dependent Dioxygenases for Oxidation of l-Proline. Org Process Res Dev 2022. [DOI: 10.1021/acs.oprd.1c00405] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Erika Tassano
- Global Discovery Chemistry, Novartis Institute for Biomedical Research, 4056 Basel, Switzerland
| | - Charles Moore
- Global Discovery Chemistry, Novartis Institute for Biomedical Research, 4056 Basel, Switzerland
| | - Solene Dussauge
- Global Discovery Chemistry, Novartis Institute for Biomedical Research, 4056 Basel, Switzerland
| | - Alexandra Vargas
- Global Discovery Chemistry, Novartis Institute for Biomedical Research, 4056 Basel, Switzerland
| | - Radka Snajdrova
- Global Discovery Chemistry, Novartis Institute for Biomedical Research, 4056 Basel, Switzerland
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7
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Kluza A, Wojdyla Z, Mrugala B, Kurpiewska K, Porebski PJ, Niedzialkowska E, Minor W, Weiss MS, Borowski T. Regioselectivity of hyoscyamine 6β-hydroxylase-catalysed hydroxylation as revealed by high-resolution structural information and QM/MM calculations. Dalton Trans 2020; 49:4454-4469. [PMID: 32182320 DOI: 10.1039/d0dt00302f] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Hyoscyamine 6β-hydroxylase (H6H) is a bifunctional non-heme 2-oxoglutarate/Fe2+-dependent dioxygenase that catalyzes the two final steps in the biosynthesis of scopolamine. Based on high resolution crystal structures of H6H from Datura metel, detailed information on substrate binding was obtained that provided insights into the onset of the enzymatic process. In particular, the role of two prominent residues was revealed - Glu-116 that interacts with the tertiary amine located on the hyoscyamine tropane moiety and Tyr-326 that forms CH-π hydrogen bonds with the hyoscyamine phenyl ring. The structures were used as the basis for QM/MM calculations that provided an explanation for the regioselectivity of the hydroxylation reaction on the hyoscyamine tropane moiety (C6 vs. C7) and quantified contributions of active site residues to respective barrier heights.
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Affiliation(s)
- Anna Kluza
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland.
| | - Zuzanna Wojdyla
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland.
| | - Beata Mrugala
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland.
| | - Katarzyna Kurpiewska
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland. and Department of Crystal Chemistry and Crystal Physics, Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, PL-30387 Krakow, Poland
| | - Przemyslaw J Porebski
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland. and Department of Molecular Physiology and Biological Physics, University of Virginia, 1340 Jefferson Park Avenue Pinn Hall, Charlottesville, VA 22908, USA
| | - Ewa Niedzialkowska
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland. and Department of Molecular Physiology and Biological Physics, University of Virginia, 1340 Jefferson Park Avenue Pinn Hall, Charlottesville, VA 22908, USA
| | - Wladek Minor
- Department of Molecular Physiology and Biological Physics, University of Virginia, 1340 Jefferson Park Avenue Pinn Hall, Charlottesville, VA 22908, USA
| | - Manfred S Weiss
- Macromolecular Crystallography, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, D-12489, Berlin, Germany
| | - Tomasz Borowski
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland.
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8
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Green KA, Berry D, Feussner K, Eaton CJ, Ram A, Mesarich CH, Solomon P, Feussner I, Scott B. Lolium perenne apoplast metabolomics for identification of novel metabolites produced by the symbiotic fungus Epichloë festucae. THE NEW PHYTOLOGIST 2020; 227:559-571. [PMID: 32155669 PMCID: PMC7317419 DOI: 10.1111/nph.16528] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Accepted: 02/28/2020] [Indexed: 05/05/2023]
Abstract
Epichloë festucae is an endophytic fungus that forms a symbiotic association with Lolium perenne. Here we analysed how the metabolome of the ryegrass apoplast changed upon infection of this host with sexual and asexual isolates of E. festucae. A metabolite fingerprinting approach was used to analyse the metabolite composition of apoplastic wash fluid from uninfected and infected L. perenne. Metabolites enriched or depleted in one or both of these treatments were identified using a set of interactive tools. A genetic approach in combination with tandem MS was used to identify a novel product of a secondary metabolite gene cluster. Metabolites likely to be present in the apoplast were identified using MarVis in combination with the BioCyc and KEGG databases, and an in-house Epichloë metabolite database. We were able to identify the known endophyte-specific metabolites, peramine and epichloëcyclins, as well as a large number of unknown markers. To determine whether these methods can be applied to the identification of novel Epichloë-derived metabolites, we deleted a gene encoding a NRPS (lgsA) that is highly expressed in planta. Comparative MS analysis of apoplastic wash fluid from wild-type- vs mutant-infected plants identified a novel Leu/Ile glycoside metabolite present in the former.
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Affiliation(s)
- Kimberly A. Green
- School of Fundamental SciencesMassey UniversityPalmerston North4442New Zealand
- Bioprotection Research CentreMassey UniversityPalmerston North4442New Zealand
| | - Daniel Berry
- School of Fundamental SciencesMassey UniversityPalmerston North4442New Zealand
- Bioprotection Research CentreMassey UniversityPalmerston North4442New Zealand
| | - Kirstin Feussner
- Department of Plant BiochemistryAlbrecht von Haller Institute for Plant SciencesUniversity of GoettingenD‐37077GoettingenGermany
- Service Unit for Metabolomics and LipidomicsGoettingen Center for Molecular Biosciences (GZMB)University of GoettingenD‐37077GoettingenGermany
| | - Carla J. Eaton
- School of Fundamental SciencesMassey UniversityPalmerston North4442New Zealand
- Bioprotection Research CentreMassey UniversityPalmerston North4442New Zealand
| | - Arvina Ram
- School of Fundamental SciencesMassey UniversityPalmerston North4442New Zealand
| | - Carl H. Mesarich
- Bioprotection Research CentreMassey UniversityPalmerston North4442New Zealand
- School of Agriculture and EnvironmentMassey UniversityPalmerston North4442New Zealand
| | - Peter Solomon
- Research School of BiologyAustralian National UniversityCanberraACT0200Australia
| | - Ivo Feussner
- Department of Plant BiochemistryAlbrecht von Haller Institute for Plant SciencesUniversity of GoettingenD‐37077GoettingenGermany
- Service Unit for Metabolomics and LipidomicsGoettingen Center for Molecular Biosciences (GZMB)University of GoettingenD‐37077GoettingenGermany
- Department of Plant BiochemistryGoettingen Center for Molecular Biosciences (GZMB)University of GoettingenD‐37077GoettingenGermany
| | - Barry Scott
- School of Fundamental SciencesMassey UniversityPalmerston North4442New Zealand
- Bioprotection Research CentreMassey UniversityPalmerston North4442New Zealand
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9
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Bharadwaj R, Jagadeesan H, Kumar SR, Ramalingam S. Molecular mechanisms in grass-Epichloë interactions: towards endophyte driven farming to improve plant fitness and immunity. World J Microbiol Biotechnol 2020; 36:92. [PMID: 32562008 DOI: 10.1007/s11274-020-02868-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Accepted: 06/10/2020] [Indexed: 11/26/2022]
Abstract
All plants harbor many microbial species including bacteria and fungi in their tissues. The interactions between the plant and these microbes could be symbiotic, mutualistic, parasitic or commensalistic. Mutualistic microorganisms are endophytic in nature and are known to play a role in plant growth, development and fitness. Endophytes display complex diversity depending upon the agro-climatic conditions and this diversity could be exploited for crop improvement and sustainable agriculture. Plant-endophyte partnerships are highly specific, several genetic and molecular cascades play a key role in colonization of endophytes in host plants leading to rapid changes in host and endophyte metabolism. This results in the accumulation of secondary metabolites, which play an important role in plant defense against biotic and abiotic stress conditions. Alkaloids are one of the important class of metabolites produced by Epichloë genus and other related classes of endophytes and confer protection against insect and mammalian herbivory. In this context, this review discusses the evolutionary aspects of the Epichloë genus along with key molecular mechanisms determining the lifestyle of Epichloë endophytes in host system. Novel hypothesis is proposed to outline the initial cellular signaling events during colonization of Epichloë in cool season grasses. Complex clustering of alkaloid biosynthetic genes and molecular mechanisms involved in the production of alkaloids have been elaborated in detail. The natural defense and advantages of the endophyte derived metabolites have also been extensively discussed. Finally, this review highlights the importance of endophyte-arbitrated plant immunity to develop novel approaches for eco-friendly agriculture.
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Affiliation(s)
- R Bharadwaj
- Plant Genetic Engineering Laboratory, Department of Biotechnology, Bharathiar University, Coimbatore, Tamil Nadu, 641046, India
| | - H Jagadeesan
- Department of Biotechnology, PSG College of Technology, Coimbatore, Tamil Nadu, India
| | - S R Kumar
- Plant Genetic Engineering Laboratory, Department of Biotechnology, Bharathiar University, Coimbatore, Tamil Nadu, 641046, India
| | - S Ramalingam
- Plant Genetic Engineering Laboratory, Department of Biotechnology, Bharathiar University, Coimbatore, Tamil Nadu, 641046, India.
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10
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Li J, Liao HJ, Tang Y, Huang JL, Cha L, Lin TS, Lee JL, Kurnikov IV, Kurnikova MG, Chang WC, Chan NL, Guo Y. Epoxidation Catalyzed by the Nonheme Iron(II)- and 2-Oxoglutarate-Dependent Oxygenase, AsqJ: Mechanistic Elucidation of Oxygen Atom Transfer by a Ferryl Intermediate. J Am Chem Soc 2020; 142:6268-6284. [PMID: 32131594 PMCID: PMC7343540 DOI: 10.1021/jacs.0c00484] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Mechanisms of enzymatic epoxidation via oxygen atom transfer (OAT) to an olefin moiety is mainly derived from the studies on thiolate-heme containing epoxidases, such as cytochrome P450 epoxidases. The molecular basis of epoxidation catalyzed by nonheme-iron enzymes is much less explored. Herein, we present a detailed study on epoxidation catalyzed by the nonheme iron(II)- and 2-oxoglutarate-dependent (Fe/2OG) oxygenase, AsqJ. The native substrate and analogues with different para substituents ranging from electron-donating groups (e.g., methoxy) to electron-withdrawing groups (e.g., trifluoromethyl) were used to probe the mechanism. The results derived from transient-state enzyme kinetics, Mössbauer spectroscopy, reaction product analysis, X-ray crystallography, density functional theory calculations, and molecular dynamic simulations collectively revealed the following mechanistic insights: (1) The rapid O2 addition to the AsqJ Fe(II) center occurs with the iron-bound 2OG adopting an online-binding mode in which the C1 carboxylate group of 2OG is trans to the proximal histidine (His134) of the 2-His-1-carboxylate facial triad, instead of assuming the offline-binding mode with the C1 carboxylate group trans to the distal histidine (His211); (2) The decay rate constant of the ferryl intermediate is not strongly affected by the nature of the para substituents of the substrate during the OAT step, a reactivity behavior that is drastically different from nonheme Fe(IV)-oxo synthetic model complexes; (3) The OAT step most likely proceeds through a stepwise process with the initial formation of a C(benzylic)-O bond to generate an Fe-alkoxide species, which is observed in the AsqJ crystal structure. The subsequent C3-O bond formation completes the epoxide installation.
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Affiliation(s)
- Jikun Li
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Hsuan-Jen Liao
- Institute of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Yijie Tang
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Jhih-Liang Huang
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Lide Cha
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Te-Sheng Lin
- Institute of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Justin L. Lee
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Igor V. Kurnikov
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Maria G. Kurnikova
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Wei-chen Chang
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Nei-Li Chan
- Institute of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Yisong Guo
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
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11
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Pidot SJ, Rizzacasa MA. The Nargenicin Family of Oxa-Bridged Macrolide Antibiotics. Chemistry 2020; 26:2780-2792. [PMID: 31667915 DOI: 10.1002/chem.201904053] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Indexed: 11/06/2022]
Abstract
The nargenicin family of antibiotic macrolides comprise a group of bacterial natural products with a rare ether bridged cis-decalin moiety and a narrow spectrum of activity. Most family members were identified almost four decades ago and were placed on the shelf due to the numbers of broad-spectrum compounds available at the time. However, in light of rising rates of antimicrobial resistance, there has been a renewed interest in the use of narrow-spectrum antimicrobials. Here, we review the history of this family of compounds, including synthetic approaches, and highlight the recently uncovered genetic basis for nargenicin production. Given the renewed pharmaceutical interest in these compounds, we also investigate structure-activity relationships among these molecules, with a view to the future development of members of this unusual antibiotic family.
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Affiliation(s)
- Sacha J Pidot
- Department of Microbiology and Immunology at the Doherty Institute, University of Melbourne, 3000, Melbourne, VIC, Australia
| | - Mark A Rizzacasa
- School of Chemistry, The Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, 3000, Melbourne, VIC, Australia
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12
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Bhardwaj M, Ai Q, Parkin SR, Grossman RB. An unusually short inter-molecular N-H⋯N hydrogen bond in crystals of the hemi-hydro-chloride salt of 1- exo-acetamido-pyrrolizidine. Acta Crystallogr E Crystallogr Commun 2020; 76:77-81. [PMID: 31921456 PMCID: PMC6944077 DOI: 10.1107/s2056989019016517] [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: 12/04/2019] [Accepted: 12/07/2019] [Indexed: 11/16/2022]
Abstract
The title compound [systematic name: (1R*, 8S)-2-acetamidoocta-hydro-pyrrol-izin-4-ium chloride-N-[(1R, 8S)-hexa-hydro-1H-pyrrolizin-2-yl)acetamide (1/1)], 2(C9H16N2O)·HCl or C9H17N2O+·Cl-·C9H16N2O, arose as an unexpected product when 1-exo-acetamido-pyrrolizidine (AcAP; C9H16N2O) was dissolved in CHCl3. Within the AcAP pyrrolizidine group, the unsubstituted five-membered ring is disordered over two orientations in a 0.897 (5):0.103 (5) ratio. Two AcAP mol-ecules related by a crystallographic twofold axis link to H+ and Cl- ions lying on the rotation axis, thereby forming N-H⋯N and N-H⋯Cl⋯H-N hydrogen bonds. The first of these has an unusually short N⋯N separation of 2.616 (2) Å: refinement of different models against the present data set could not distinguish between a symmetrical hydrogen bond (H atom lying on the twofold axis and equidistant from the N atoms) or static or dynamic disorder models (i.e. N-H⋯N + N⋯H-N). Computational studies suggest that the disorder model is slightly more stable, but the energy difference is very small.
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Affiliation(s)
| | - Qianxiang Ai
- University of Kentucky, Lexington, Kentucky, 40506-0055, USA
| | - Sean R. Parkin
- University of Kentucky, Lexington, Kentucky, 40506-0055, USA
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Pan J, Wenger ES, Matthews ML, Pollock CJ, Bhardwaj M, Kim AJ, Allen BD, Grossman RB, Krebs C, Bollinger JM. Evidence for Modulation of Oxygen Rebound Rate in Control of Outcome by Iron(II)- and 2-Oxoglutarate-Dependent Oxygenases. J Am Chem Soc 2019; 141:15153-15165. [PMID: 31475820 DOI: 10.1021/jacs.9b06689] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Iron(II)- and 2-oxoglutarate-dependent (Fe/2OG) oxygenases generate iron(IV)-oxo (ferryl) intermediates that can abstract hydrogen from aliphatic carbons (R-H). Hydroxylation proceeds by coupling of the resultant substrate radical (R•) and oxygen of the Fe(III)-OH complex ("oxygen rebound"). Nonhydroxylation outcomes result from different fates of the Fe(III)-OH/R• state; for example, halogenation results from R• coupling to a halogen ligand cis to the hydroxide. We previously suggested that halogenases control substrate-cofactor disposition to disfavor oxygen rebound and permit halogen coupling to prevail. Here, we explored the general implication that, when a ferryl intermediate can ambiguously target two substrate carbons for different outcomes, rebound to the site capable of the alternative outcome should be slower than to the adjacent, solely hydroxylated site. We evaluated this prediction for (i) the halogenase SyrB2, which exclusively hydroxylates C5 of norvaline appended to its carrier protein but can either chlorinate or hydroxylate C4 and (ii) two bifunctional enzymes that normally hydroxylate one carbon before coupling that oxygen to a second carbon (producing an oxacycle) but can, upon encountering deuterium at the first site, hydroxylate the second site instead. In all three cases, substrate hydroxylation incorporates a greater fraction of solvent-derived oxygen at the site that can also undergo the alternative outcome than at the other site, most likely reflecting an increased exchange of the initially O2-derived oxygen ligand in the longer-lived Fe(III)-OH/R• states. Suppression of rebound may thus be generally important for nonhydroxylation outcomes by these enzymes.
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Affiliation(s)
| | | | | | | | - Minakshi Bhardwaj
- Department of Chemistry , University of Kentucky , Lexington , Kentucky 40546-0312 , United States
| | | | | | - Robert B Grossman
- Department of Chemistry , University of Kentucky , Lexington , Kentucky 40546-0312 , United States
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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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Pidot SJ, Herisse M, Sharkey L, Atkin L, Porter JL, Seemann T, Howden BP, Rizzacasa MA, Stinear TP. Biosynthesis and Ether‐Bridge Formation in Nargenicin Macrolides. Angew Chem Int Ed Engl 2019; 58:3996-4001. [DOI: 10.1002/anie.201900290] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Indexed: 01/09/2023]
Affiliation(s)
- Sacha J. Pidot
- Department of Microbiology and Immunology at the Doherty InstituteUniversity of Melbourne Melbourne VIC 3000 Australia
| | - Marion Herisse
- Department of Microbiology and Immunology at the Doherty InstituteUniversity of Melbourne Melbourne VIC 3000 Australia
| | - Liam Sharkey
- Department of Microbiology and Immunology at the Doherty InstituteUniversity of Melbourne Melbourne VIC 3000 Australia
| | - Liselle Atkin
- School of ChemistryThe Bio21 Molecular Science and Biotechnology InstituteUniversity of Melbourne Melbourne VIC 3000 Australia
| | - Jessica L. Porter
- Department of Microbiology and Immunology at the Doherty InstituteUniversity of Melbourne Melbourne VIC 3000 Australia
| | - Torsten Seemann
- Department of Microbiology and Immunology at the Doherty InstituteUniversity of Melbourne Melbourne VIC 3000 Australia
- Microbioloigical Diagnostic UnitUniversity of Melbourne Melbourne VIC 3000 Australia
| | - Benjamin P. Howden
- Department of Microbiology and Immunology at the Doherty InstituteUniversity of Melbourne Melbourne VIC 3000 Australia
- Microbioloigical Diagnostic UnitUniversity of Melbourne Melbourne VIC 3000 Australia
| | - Mark A. Rizzacasa
- School of ChemistryThe Bio21 Molecular Science and Biotechnology InstituteUniversity of Melbourne Melbourne VIC 3000 Australia
| | - Timothy P. Stinear
- Department of Microbiology and Immunology at the Doherty InstituteUniversity of Melbourne Melbourne VIC 3000 Australia
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16
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Pidot SJ, Herisse M, Sharkey L, Atkin L, Porter JL, Seemann T, Howden BP, Rizzacasa MA, Stinear TP. Biosynthesis and Ether‐Bridge Formation in Nargenicin Macrolides. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201900290] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Sacha J. Pidot
- Department of Microbiology and Immunology at the Doherty InstituteUniversity of Melbourne Melbourne VIC 3000 Australia
| | - Marion Herisse
- Department of Microbiology and Immunology at the Doherty InstituteUniversity of Melbourne Melbourne VIC 3000 Australia
| | - Liam Sharkey
- Department of Microbiology and Immunology at the Doherty InstituteUniversity of Melbourne Melbourne VIC 3000 Australia
| | - Liselle Atkin
- School of ChemistryThe Bio21 Molecular Science and Biotechnology InstituteUniversity of Melbourne Melbourne VIC 3000 Australia
| | - Jessica L. Porter
- Department of Microbiology and Immunology at the Doherty InstituteUniversity of Melbourne Melbourne VIC 3000 Australia
| | - Torsten Seemann
- Department of Microbiology and Immunology at the Doherty InstituteUniversity of Melbourne Melbourne VIC 3000 Australia
- Microbioloigical Diagnostic UnitUniversity of Melbourne Melbourne VIC 3000 Australia
| | - Benjamin P. Howden
- Department of Microbiology and Immunology at the Doherty InstituteUniversity of Melbourne Melbourne VIC 3000 Australia
- Microbioloigical Diagnostic UnitUniversity of Melbourne Melbourne VIC 3000 Australia
| | - Mark A. Rizzacasa
- School of ChemistryThe Bio21 Molecular Science and Biotechnology InstituteUniversity of Melbourne Melbourne VIC 3000 Australia
| | - Timothy P. Stinear
- Department of Microbiology and Immunology at the Doherty InstituteUniversity of Melbourne Melbourne VIC 3000 Australia
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17
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Schramm S, Köhler N, Rozhon W. Pyrrolizidine Alkaloids: Biosynthesis, Biological Activities and Occurrence in Crop Plants. Molecules 2019; 24:E498. [PMID: 30704105 PMCID: PMC6385001 DOI: 10.3390/molecules24030498] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 01/28/2019] [Accepted: 01/29/2019] [Indexed: 12/13/2022] Open
Abstract
Pyrrolizidine alkaloids (PAs) are heterocyclic secondary metabolites with a typical pyrrolizidine motif predominantly produced by plants as defense chemicals against herbivores. They display a wide structural diversity and occur in a vast number of species with novel structures and occurrences continuously being discovered. These alkaloids exhibit strong hepatotoxic, genotoxic, cytotoxic, tumorigenic, and neurotoxic activities, and thereby pose a serious threat to the health of humans since they are known contaminants of foods including grain, milk, honey, and eggs, as well as plant derived pharmaceuticals and food supplements. Livestock and fodder can be affected due to PA-containing plants on pastures and fields. Despite their importance as toxic contaminants of agricultural products, there is limited knowledge about their biosynthesis. While the intermediates were well defined by feeding experiments, only one enzyme involved in PA biosynthesis has been characterized so far, the homospermidine synthase catalyzing the first committed step in PA biosynthesis. This review gives an overview about structural diversity of PAs, biosynthetic pathways of necine base, and necic acid formation and how PA accumulation is regulated. Furthermore, we discuss their role in plant ecology and their modes of toxicity towards humans and animals. Finally, several examples of PA-producing crop plants are discussed.
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Affiliation(s)
- Sebastian Schramm
- Biotechnology of Horticultural Crops, TUM School of Life Sciences Weihenstephan, Technical University of Munich, Liesel-Beckmann-Straße 1, 85354 Freising, Germany.
| | - Nikolai Köhler
- Biotechnology of Horticultural Crops, TUM School of Life Sciences Weihenstephan, Technical University of Munich, Liesel-Beckmann-Straße 1, 85354 Freising, Germany.
| | - Wilfried Rozhon
- Biotechnology of Horticultural Crops, TUM School of Life Sciences Weihenstephan, Technical University of Munich, Liesel-Beckmann-Straße 1, 85354 Freising, Germany.
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18
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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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19
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Ushimaru R, Ruszczycky MW, Chang WC, Yan F, Liu YN, Liu HW. Substrate Conformation Correlates with the Outcome of Hyoscyamine 6β-Hydroxylase Catalyzed Oxidation Reactions. J Am Chem Soc 2018; 140:7433-7436. [PMID: 29870653 PMCID: PMC6488034 DOI: 10.1021/jacs.8b03729] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Hyoscyamine 6β-hydroxylase (H6H) is an α-ketoglutarate dependent mononuclear nonheme iron enzyme that catalyzes C6-hydroxylation of hyoscyamine and oxidative cyclization of the resulting product to give the oxirane natural product scopolamine. Herein, the chemistry of H6H is investigated using hyoscyamine derivatives with modifications at the C6 or C7 position as well as substrate analogues possessing a 9-azabicyclo[3.3.1]nonane core. Results indicate that hydroxyl rebound is unlikely to take place during the cyclization reaction and that the hydroxylase versus oxidative cyclase activity of H6H is correlated with the presence of an exo-hydroxy group having syn-periplanar geometry with respect to the adjacent H atom to be abstracted.
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Affiliation(s)
- Richiro Ushimaru
- Department of Chemistry, and Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712, United States
| | - Mark W. Ruszczycky
- Department of Chemistry, and Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712, United States
| | - Wei-chen Chang
- Department of Chemistry, and Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712, United States
| | - Feng Yan
- Department of Chemistry, and Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712, United States
| | - Yung-nan Liu
- Department of Chemistry, and Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712, United States
| | - Hung-wen Liu
- Department of Chemistry, and Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712, United States
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20
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Ogawara H. Comparison of Strategies to Overcome Drug Resistance: Learning from Various Kingdoms. Molecules 2018; 23:E1476. [PMID: 29912169 PMCID: PMC6100412 DOI: 10.3390/molecules23061476] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 06/13/2018] [Accepted: 06/15/2018] [Indexed: 11/16/2022] Open
Abstract
Drug resistance, especially antibiotic resistance, is a growing threat to human health. To overcome this problem, it is significant to know precisely the mechanisms of drug resistance and/or self-resistance in various kingdoms, from bacteria through plants to animals, once more. This review compares the molecular mechanisms of the resistance against phycotoxins, toxins from marine and terrestrial animals, plants and fungi, and antibiotics. The results reveal that each kingdom possesses the characteristic features. The main mechanisms in each kingdom are transporters/efflux pumps in phycotoxins, mutation and modification of targets and sequestration in marine and terrestrial animal toxins, ABC transporters and sequestration in plant toxins, transporters in fungal toxins, and various or mixed mechanisms in antibiotics. Antibiotic producers in particular make tremendous efforts for avoiding suicide, and are more flexible and adaptable to the changes of environments. With these features in mind, potential alternative strategies to overcome these resistance problems are discussed. This paper will provide clues for solving the issues of drug resistance.
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Affiliation(s)
- Hiroshi Ogawara
- HO Bio Institute, Yushima-2, Bunkyo-ku, Tokyo 113-0034, Japan.
- Department of Biochemistry, Meiji Pharmaceutical University, Noshio-2, Kiyose, Tokyo 204-8588, Japan.
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21
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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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22
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Robertson J, Stevens K. Pyrrolizidine alkaloids: occurrence, biology, and chemical synthesis. Nat Prod Rep 2017; 34:62-89. [PMID: 27782262 DOI: 10.1039/c5np00076a] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Covering: 2013 up to the end of 2015This review covers the isolation and structure of new pyrrolizidines; pyrrolizidine biosynthesis; biological activity, including the occurrence of pyrrolizidines as toxic components or contaminants in foods and beverages; and formal and total syntheses of naturally-occurring pyrrolizidine alkaloids and closely related non-natural analogues.
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Affiliation(s)
- Jeremy Robertson
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA, UK.
| | - Kiri Stevens
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA, UK.
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23
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[Dedicated to Prof. T. Okada and Prof. T. Nishioka: data science in chemistry]Classification of Alkaloid Compounds Based on Subring Skeleton (SRS) Profiling: On Finding Relationship of Compounds with Metabolic Pathways. JOURNAL OF COMPUTER AIDED CHEMISTRY 2017. [DOI: 10.2751/jcac.18.58] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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24
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Saikkonen K, Young CA, Helander M, Schardl CL. Endophytic Epichloë species and their grass hosts: from evolution to applications. PLANT MOLECULAR BIOLOGY 2016; 90:665-75. [PMID: 26542393 PMCID: PMC4819788 DOI: 10.1007/s11103-015-0399-6] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 10/26/2015] [Indexed: 05/21/2023]
Abstract
The closely linked fitness of the Epichloë symbiont and the host grass is presumed to align the coevolution of the species towards specialization and mutually beneficial cooperation. Ecological observations demonstrating that Epichloë-grass symbioses can modulate grassland ecosystems via both above- and belowground ecosystem processes support this. In many cases the detected ecological importance of Epichloë species is directly or indirectly linked to defensive mutualism attributable to alkaloids of fungal-origin. Now, modern genetic and molecular techniques enable the precise studies on evolutionary origin of endophytic Epichloë species, their coevolution with host grasses and identification the genetic variation that explains phenotypic diversity in ecologically relevant characteristics of Epichloë-grass associations. Here we briefly review the most recent findings in these areas of research using the present knowledge of the genetic variation that explains the biosynthetic pathways driving the diversity of alkaloids produced by the endophyte. These findings underscore the importance of genetic interplay between the fungus and the host in shaping their coevolution and ecological role in both natural grass ecosystems, and in the agricultural arena.
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Affiliation(s)
- Kari Saikkonen
- Management and Production of Renewable Resources, Natural Resources Institute Finland (Luke), Itäinen Pitkäkatu 3, 20520, Turku, Finland.
| | - Carolyn A Young
- The Samuel Roberts Noble Foundation, Ardmore, OK, 73401, USA
| | - Marjo Helander
- Management and Production of Renewable Resources, Natural Resources Institute Finland (Luke), Itäinen Pitkäkatu 3, 20520, Turku, Finland
- Section of Ecology, Department of Biology, University of Turku, 20014, Turku, Finland
| | - Christopher L Schardl
- Department of Plant Pathology, University of Kentucky, Lexington, KY, 40546-0312, USA
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25
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Xie Z, Zhou L, Guo L, Yang X, Qu G, Wu C, Zhang S. Grisemycin, a Bridged Angucyclinone with a Methylsulfinyl Moiety from a Marine-Derived Streptomyces sp. Org Lett 2016; 18:1402-5. [DOI: 10.1021/acs.orglett.6b00332] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Zeping Xie
- The Key Laboratory of Traditional Chinese Medicine Prescription Effect
and Clinical Evaluation of State Administration of Traditional Chinese
Medicine, School of Pharmacy, ‡School of Enology, and §School of Gerontology, Binzhou Medical University, Yantai 264003, China
| | - Ling Zhou
- The Key Laboratory of Traditional Chinese Medicine Prescription Effect
and Clinical Evaluation of State Administration of Traditional Chinese
Medicine, School of Pharmacy, ‡School of Enology, and §School of Gerontology, Binzhou Medical University, Yantai 264003, China
| | - Lin Guo
- The Key Laboratory of Traditional Chinese Medicine Prescription Effect
and Clinical Evaluation of State Administration of Traditional Chinese
Medicine, School of Pharmacy, ‡School of Enology, and §School of Gerontology, Binzhou Medical University, Yantai 264003, China
| | - Xiaoping Yang
- The Key Laboratory of Traditional Chinese Medicine Prescription Effect
and Clinical Evaluation of State Administration of Traditional Chinese
Medicine, School of Pharmacy, ‡School of Enology, and §School of Gerontology, Binzhou Medical University, Yantai 264003, China
| | - Guiwu Qu
- The Key Laboratory of Traditional Chinese Medicine Prescription Effect
and Clinical Evaluation of State Administration of Traditional Chinese
Medicine, School of Pharmacy, ‡School of Enology, and §School of Gerontology, Binzhou Medical University, Yantai 264003, China
| | - Changjing Wu
- The Key Laboratory of Traditional Chinese Medicine Prescription Effect
and Clinical Evaluation of State Administration of Traditional Chinese
Medicine, School of Pharmacy, ‡School of Enology, and §School of Gerontology, Binzhou Medical University, Yantai 264003, China
| | - Shumin Zhang
- The Key Laboratory of Traditional Chinese Medicine Prescription Effect
and Clinical Evaluation of State Administration of Traditional Chinese
Medicine, School of Pharmacy, ‡School of Enology, and §School of Gerontology, Binzhou Medical University, Yantai 264003, China
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Moore JR, Pratley JE, Mace WJ, Weston LA. Variation in Alkaloid Production from Genetically Diverse Lolium Accessions Infected with Epichloë Species. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2015; 63:10355-65. [PMID: 26550846 DOI: 10.1021/acs.jafc.5b03089] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Widespread infection of Epichloë occultans in annual ryegrass in Australia suggests that infection provides its weedy host, Lolium rigidum, some ecological advantage. Initial studies determined the distribution and profiles of known Epichloë alkaloids (epoxy-janthitrems, ergovaline, lolines, lolitrem B, and peramine) in plant extracts using a combination of GC-FID and HPLC techniques utilizing a single accession of Australian L. rigidum. However, the lolines N-acetylnorloline (NANL) and N-formylloline (NFL) were the only alkaloids detected and were highly concentrated in the immature inflorescences of mature plants. Additional glasshouse studies subjected a wide range of Australian L. rigidum haplotypes and international annual Lolium accessions to a suite of analyses to determine alkaloid levels and profiles. Again, NFL and NANL were the key lolines produced, with NFL consistently predominating. Considerable variation in alkaloid production was found both within and between biotypes and accessions evaluated under identical conditions, at the same maturation stage and on the same tissue type. The pyrrolopyrazine alkaloid peramine was also present in 8 out of 17 Australian biotypes of L. rigidum and 7 out of 33 international accessions infected with Epichloë spp.; the highest peramine concentrations were observed in seed extracts from L. rigidum collected from Australia. This study represents the first report of alkaloids from a geographically diverse collection of annual ryegrass germplasm infected with Epichloë spp. when grown under identical controlled conditions.
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Affiliation(s)
- Joseph R Moore
- Graham Centre for Agricultural Innovation (An alliance between NSW Department of Primary Industries and Charles Sturt University), School of Agricultural and Wine Sciences, Charles Sturt University , Wagga Wagga, New South Wales 2650, Australia
| | - James E Pratley
- Graham Centre for Agricultural Innovation (An alliance between NSW Department of Primary Industries and Charles Sturt University), School of Agricultural and Wine Sciences, Charles Sturt University , Wagga Wagga, New South Wales 2650, Australia
| | - Wade J Mace
- Grasslands Research Centre, AgResearch Limited , Palmerston North 4442, New Zealand
| | - Leslie A Weston
- Graham Centre for Agricultural Innovation (An alliance between NSW Department of Primary Industries and Charles Sturt University), School of Agricultural and Wine Sciences, Charles Sturt University , Wagga Wagga, New South Wales 2650, Australia
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Genetics, genomics and evolution of ergot alkaloid diversity. Toxins (Basel) 2015; 7:1273-302. [PMID: 25875294 PMCID: PMC4417967 DOI: 10.3390/toxins7041273] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 04/02/2015] [Accepted: 04/08/2015] [Indexed: 01/18/2023] Open
Abstract
The ergot alkaloid biosynthesis system has become an excellent model to study evolutionary diversification of specialized (secondary) metabolites. This is a very diverse class of alkaloids with various neurotropic activities, produced by fungi in several orders of the phylum Ascomycota, including plant pathogens and protective plant symbionts in the family Clavicipitaceae. Results of comparative genomics and phylogenomic analyses reveal multiple examples of three evolutionary processes that have generated ergot-alkaloid diversity: gene gains, gene losses, and gene sequence changes that have led to altered substrates or product specificities of the enzymes that they encode (neofunctionalization). The chromosome ends appear to be particularly effective engines for gene gains, losses and rearrangements, but not necessarily for neofunctionalization. Changes in gene expression could lead to accumulation of various pathway intermediates and affect levels of different ergot alkaloids. Genetic alterations associated with interspecific hybrids of Epichloë species suggest that such variation is also selectively favored. The huge structural diversity of ergot alkaloids probably represents adaptations to a wide variety of ecological situations by affecting the biological spectra and mechanisms of defense against herbivores, as evidenced by the diverse pharmacological effects of ergot alkaloids used in medicine.
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Berry D, Takach JE, Schardl CL, Charlton ND, Scott B, Young CA. Disparate independent genetic events disrupt the secondary metabolism gene perA in certain symbiotic Epichloë species. Appl Environ Microbiol 2015; 81:2797-807. [PMID: 25681180 PMCID: PMC4375322 DOI: 10.1128/aem.03721-14] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 02/05/2015] [Indexed: 01/23/2023] Open
Abstract
Peramine is an insect-feeding deterrent produced by Epichloë species in symbiotic association with C3 grasses. The perA gene responsible for peramine synthesis encodes a two-module nonribosomal peptide synthetase. Alleles of perA are found in most Epichloë species; however, peramine is not produced by many perA-containing Epichloë isolates. The genetic basis of these peramine-negative chemotypes is often unknown. Using PCR and DNA sequencing, we analyzed the perA genes from 72 Epichloë isolates and identified causative mutations of perA null alleles. We found nonfunctional perA-ΔR* alleles, which contain a transposon-associated deletion of the perA region encoding the C-terminal reductase domain, are widespread within the Epichloë genus and represent a prevalent mutation found in nonhybrid species. Disparate phylogenies of adjacent A2 and T2 domains indicated that the deletion of the reductase domain (R*) likely occurred once and early in the evolution of the genus, and subsequently there have been several recombinations between those domains. A number of novel point, deletion, and insertion mutations responsible for abolishing peramine production in full-length perA alleles were also identified. The regions encoding the first and second adenylation domains (A1 and A2, respectively) were common sites for such mutations. Using this information, a method was developed to predict peramine chemotypes by combining PCR product size polymorphism analysis with sequencing of the perA adenylation domains.
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Affiliation(s)
- Daniel Berry
- Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand
| | | | | | | | - Barry Scott
- Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand
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Miller KE, Wright AJ, Olesen MK, Hovey MT, Scheerer JR. Stereoselective Synthesis of (+)-Loline Alkaloid Skeleton. J Org Chem 2015; 80:1569-76. [DOI: 10.1021/jo502493e] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kelsey E. Miller
- Department of Chemistry, The College of William & Mary, P.O. Box 8795, Williamsburg, Virginia 23187, United States
| | - Anthony J. Wright
- Department of Chemistry, The College of William & Mary, P.O. Box 8795, Williamsburg, Virginia 23187, United States
| | - Margaret K. Olesen
- Department of Chemistry, The College of William & Mary, P.O. Box 8795, Williamsburg, Virginia 23187, United States
| | - M. Todd Hovey
- Department of Chemistry, The College of William & Mary, P.O. Box 8795, Williamsburg, Virginia 23187, United States
| | - Jonathan R. Scheerer
- Department of Chemistry, The College of William & Mary, P.O. Box 8795, Williamsburg, Virginia 23187, 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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Young CA, Charlton ND, Takach JE, Swoboda GA, Trammell MA, Huhman DV, Hopkins AA. Characterization of Epichloë coenophiala within the US: are all tall fescue endophytes created equal? Front Chem 2014; 2:95. [PMID: 25408942 PMCID: PMC4219521 DOI: 10.3389/fchem.2014.00095] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 10/14/2014] [Indexed: 11/13/2022] Open
Abstract
Tall fescue (Lolium arundinaceum) is a valuable and broadly adapted forage grass that occupies approximately 14 million hectares across the United States. A native to Europe, tall fescue was likely introduced into the US around the late 1800's. Much of the success of tall fescue can be attributed to Epichloë coenophiala (formerly Neotyphodium coenophialum) a seed borne symbiont that aids in host persistence. Epichloë species are capable of producing a range of alkaloids (ergot alkaloids, indole-diterpenes, lolines, and peramine) that provide protection to the plant host from herbivory. Unfortunately, most tall fescue within the US, commonly referred to as "Kentucky-31" (KY31), harbors the endophyte E. coenophiala that causes toxicity to grazing livestock due to the production of ergot alkaloids. Molecular analyses of tall fescue endophytes have identified four independent associations, representing tall fescue with E. coenophiala, Epichloë sp. FaTG-2, Epichloë sp. FaTG-3, or Epichloë sp. FaTG-4. Each of these Epichloë species can be further distinguished based on genetic variation that equates to differences in the alkaloid gene loci. Tall fescue samples were evaluated using markers to simple sequence repeats (SSRs) and alkaloid biosynthesis genes to determine endophyte strain variation present within continental US. Samples represented seed and tillers from the Suiter farm (Menifee County, KY), which is considered the originating site of KY31, as well as plant samples collected from 14 states, breeder's seed and plant introduction lines (National Plant Germplasm System, NPGS). This study revealed two prominent E. coenophiala genotypes based on presence of alkaloid biosynthesis genes and SSR markers and provides insight into endophyte variation within continental US across historical and current tall fescue samples.
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Affiliation(s)
- Carolyn A Young
- The Samuel Roberts Noble Foundation, Forage Improvement Division Ardmore, OK, USA
| | - Nikki D Charlton
- The Samuel Roberts Noble Foundation, Forage Improvement Division Ardmore, OK, USA
| | - Johanna E Takach
- The Samuel Roberts Noble Foundation, Forage Improvement Division Ardmore, OK, USA
| | - Ginger A Swoboda
- The Samuel Roberts Noble Foundation, Forage Improvement Division Ardmore, OK, USA
| | - Michael A Trammell
- The Samuel Roberts Noble Foundation, Forage Improvement Division Ardmore, OK, USA
| | - David V Huhman
- The Samuel Roberts Noble Foundation, Forage Improvement Division Ardmore, OK, USA
| | - Andrew A Hopkins
- The Samuel Roberts Noble Foundation, Forage Improvement Division Ardmore, OK, USA
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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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