scholarly journals Ergot Alkaloids of the Family Clavicipitaceae

2017 ◽  
Vol 107 (5) ◽  
pp. 504-518 ◽  
Author(s):  
Simona Florea ◽  
Daniel G. Panaccione ◽  
Christopher L. Schardl

Ergot alkaloids are highly diverse in structure, exhibit diverse effects on animals, and are produced by diverse fungi in the phylum Ascomycota, including pathogens and mutualistic symbionts of plants. These mycotoxins are best known from the fungal family Clavicipitaceae and are named for the ergot fungi that, through millennia, have contaminated grains and caused mass poisonings, with effects ranging from dry gangrene to convulsions and death. However, they are also useful sources of pharmaceuticals for a variety of medical purposes. More than a half-century of research has brought us extensive knowledge of ergot-alkaloid biosynthetic pathways from common early steps to several taxon-specific branches. Furthermore, a recent flurry of genome sequencing has revealed the genomic processes underlying ergot-alkaloid diversification. In this review, we discuss the evolution of ergot-alkaloid biosynthesis genes and gene clusters, including roles of gene recruitment, duplication and neofunctionalization, as well as gene loss, in diversifying structures of clavines, lysergic acid amides, and complex ergopeptines. Also reviewed are prospects for manipulating ergot-alkaloid profiles to enhance suitability of endophytes for forage grasses.

Author(s):  
Abigail M. Jones ◽  
Chey R. Steen ◽  
Daniel G. Panaccione

Ergot alkaloids derived from lysergic acid have impacted humanity as contaminants of crops and as the bases of pharmaceuticals prescribed to treat dementia, migraines, and other disorders. Several plant-associated fungi in the Clavicipitaceae produce lysergic acid derivatives, but many of these fungi are difficult to culture and manipulate. Some Aspergillus species, which may be more ideal experimental and industrial organisms, contain an alternate branch of the ergot alkaloid pathway but none were known to produce lysergic acid derivatives. We mined genomes of Aspergillus species for ergot alkaloid synthesis ( eas ) gene clusters and discovered three species–– A. leporis, A. homomorphus, and A. hancockii ––had eas clusters indicative of the capacity to produce a lysergic acid amide. In culture, A. leporis, A. homomorphus, and A. hancockii produced lysergic acid amides, predominantly lysergic acid α-hydroxyethylamide (LAH). Aspergillus leporis and A. homomorphus produced high concentrations of LAH and secreted most of their ergot alkaloid yield into the culture medium. Phylogenetic analyses indicated genes encoding enzymes leading to the synthesis of lysergic acid were orthologous to those of the lysergic acid amide-producing Clavicipitaceae; however, genes to incorporate lysergic acid into an amide derivative evolved from different ancestral genes in the Aspergillus species. Our data demonstrate fungi outside the Clavicipitaceae produce lysergic acid amides and indicate the capacity to produce lysergic acid evolved once, but the ability to insert it into LAH evolved independently in Aspergillus species and the Clavicipitaceae. The LAH-producing Aspergillus species may be useful for study and production of these pharmaceutically important compounds. IMPORTANCE Lysergic acid derivatives are specialized metabolites with historical, agricultural, and medical significance and were known heretofore only from fungi in one family, the Clavicipitaceae. Our data show that several Aspergillus species, representing a different family of fungi, also produce lysergic acid derivatives and that the ability to put lysergic acid into its amide forms evolved independently in the two lineages of fungi. From microbiological and pharmaceutical perspectives, the Aspergillus species may represent better experimental and industrial organisms than the currently employed, lysergic acid producers of the plant-associated Clavicipitaceae. The observation that both lineages independently evolved the derivative lysergic acid α-hydroxyethylamide (LAH), among many possible lysergic acid amides, suggests a selection for this metabolite.


2007 ◽  
Vol 73 (22) ◽  
pp. 7185-7191 ◽  
Author(s):  
Nicole Lorenz ◽  
Ella V. Wilson ◽  
Caroline Machado ◽  
Christopher L. Schardl ◽  
Paul Tudzynski

ABSTRACT The grass parasites Claviceps purpurea and Claviceps fusiformis produce ergot alkaloids (EA) in planta and in submerged culture. Whereas EA synthesis (EAS) in C. purpurea proceeds via clavine intermediates to lysergic acid and the complex ergopeptines, C. fusiformis produces only agroclavine and elymoclavine. In C. purpurea the EAS gene (EAS) cluster includes dmaW (encoding the first pathway step), cloA (elymoclavine oxidation to lysergic acid), and the lpsA/lpsB genes (ergopeptine formation). We analyzed the corresponding C. fusiformis EAS cluster to investigate the evolutionary basis for chemotypic differences between the Claviceps species. Other than three peptide synthetase genes (lpsC and the tandem paralogues lpsA1 and lpsA2), homologues of all C. purpurea EAS genes were identified in C. fusiformis, including homologues of lpsB and cloA, which in C. purpurea encode enzymes for steps after clavine synthesis. Rearrangement of the cluster was evident around lpsB, which is truncated in C. fusiformis. This and several frameshift mutations render CflpsB a pseudogene (CflpsB Ψ ). No obvious inactivating mutation was identified in CfcloA. All C. fusiformis EAS genes, including CflpsB Ψ and CfcloA, were expressed in culture. Cross-complementation analyses demonstrated that CfcloA and CflpsB Ψ were expressed in C. purpurea but did not encode functional enzymes. In contrast, CpcloA catalyzed lysergic acid biosynthesis in C. fusiformis, indicating that C. fusiformis terminates its EAS pathway at elymoclavine because the cloA gene product is inactive. We propose that the C. fusiformis EAS cluster evolved from a more complete cluster by loss of some lps genes and by rearrangements and mutations inactivating lpsB and cloA.


2020 ◽  
Vol 86 (14) ◽  
Author(s):  
Caroline E. Leadmon ◽  
Jessi K. Sampson ◽  
Matthew D. Maust ◽  
Angie M. Macias ◽  
Stephen A. Rehner ◽  
...  

ABSTRACT Genomic sequence data indicate that certain fungi in the genus Metarhizium have the capacity to produce lysergic acid-derived ergot alkaloids, but accumulation of ergot alkaloids in these fungi has not been demonstrated previously. We assayed several Metarhizium species grown under different conditions for accumulation of ergot alkaloids. Isolates of M. brunneum and M. anisopliae accumulated the lysergic acid amides lysergic acid α-hydroxyethyl amide, ergine, and ergonovine on sucrose-yeast extract agar but not on two other tested media. Isolates of six other Metarhizium species did not accumulate ergot alkaloids on sucrose-yeast extract agar. Conidia of M. brunneum lacked detectable ergot alkaloids, and mycelia of this fungus secreted over 80% of their ergot alkaloid yield into the culture medium. Isolates of M. brunneum, M. flavoviride, M. robertsii, M. acridum, and M. anisopliae produced high concentrations of ergot alkaloids in infected larvae of the model insect Galleria mellonella, but larvae infected with M. pingshaense, M. album, M. majus, and M. guizhouense lacked detectable ergot alkaloids. Alkaloid concentrations were significantly higher when insects were alive (as opposed to killed by freezing or gas) at the time of inoculation with M. brunneum. Roots of corn and beans were inoculated with M. brunneum or M. flavoviride and global metabolomic analyses indicated that the inoculated roots were colonized, though no ergot alkaloids were detected. The data demonstrate that several Metarhizium species produce ergot alkaloids of the lysergic acid amide class and that production of ergot alkaloids is tightly regulated and associated with insect colonization. IMPORTANCE Our discovery of ergot alkaloids in fungi of the genus Metarhizium has agricultural and pharmaceutical implications. Ergot alkaloids produced by other fungi in the family Clavicipitaceae accumulate in forage grasses or grain crops; in this context they are considered toxins, though their presence also may deter or kill insect pests. Our data report ergot alkaloids in Metarhizium species and indicate a close association of ergot alkaloid accumulation with insect colonization. The lack of accumulation of alkaloids in spores of the fungi and in plants colonized by the fungi affirms the safety of using Metarhizium species as biocontrol agents. Ergot alkaloids produced by other fungi have been exploited to produce powerful pharmaceuticals. The class of ergot alkaloids discovered in Metarhizium species (lysergic acid amides) and their secretion into the growth medium make Metarhizium species a potential platform for future studies on ergot alkaloid synthesis and modification.


2020 ◽  
Vol 86 (19) ◽  
Author(s):  
Kyle A. Davis ◽  
Jessi K. Sampson ◽  
Daniel G. Panaccione

ABSTRACT Ergot alkaloids are important specialized fungal metabolites that are used to make potent pharmaceuticals for neurological diseases and disorders. Lysergic acid (LA) and dihydrolysergic acid (DHLA) are desirable lead compounds for pharmaceutical semisynthesis but are typically transient intermediates in the ergot alkaloid and dihydroergot alkaloid pathways. Previous work with Neosartorya fumigata demonstrated strategies to produce these compounds as pathway end products, but their percent yield (percentage of molecules in product state as opposed to precursor state) was low. Moreover, ergot alkaloids in N. fumigata are typically retained in the fungus as opposed to being secreted. We used clustered regularly interspaced short palindromic repeat (CRISPR)–CRISPR-associated protein 9 (Cas9) and heterologous expression approaches to engineer these compounds in Metarhizium brunneum, representing an alternate expression host from a different lineage of fungi. The relative percent yields of LA (86.9%) and DHLA (72.8%) were much higher than those calculated here for previously engineered strains of N. fumigata (2.6% and 2.0%, respectively). Secretion of these alkaloids also was measured, with averages of 98.4% of LA and 87.5% of DHLA being secreted into the growth medium; both values were significantly higher than those measured for the N. fumigata derivatives (both of which were less than 5.6% secreted). We used a similar approach to engineer a novel dihydroergot alkaloid in M. brunneum and, through high-performance liquid chromatography-mass spectrometry (LC-MS) analyses, provisionally identified it as the dihydrogenated form of lysergic acid α-hydroxyethylamide (dihydro-LAH). The engineering of these strains provides a strategy for producing novel and pharmaceutically important chemicals in a fungus more suitable for their production. IMPORTANCE Ergot alkaloids derived from LA or DHLA are the bases for numerous pharmaceuticals with applications in the treatment of dementia, migraines, hyperprolactinemia, and other conditions. However, extraction of ergot alkaloids from natural sources is inefficient, and their chemical synthesis is expensive. The ability to control and redirect ergot alkaloid synthesis in fungi may allow more efficient production of these important chemicals and facilitate research on novel derivatives. Our results show that Metarhizium brunneum can be engineered to efficiently produce and secrete LA and DHLA and, also, to produce a novel derivative of DHLA not previously found in nature. The engineering of dihydroergot alkaloids, including a novel species, is important because very few natural sources of these compounds are known. Our approach establishes a platform with which to use M. brunneum to study the production of other ergot alkaloids, specifically those classified as lysergic acid amides and dihydroergot alkaloids.


2007 ◽  
Vol 13 ◽  
pp. 477-479
Author(s):  
S. Florea ◽  
C. Machado ◽  
D. Zhang ◽  
D.G. Panaccione ◽  
C.L. Schardl

Neotyphodium coenophialum strain e19 from tall fescue cv. Kentucky 31 carries dmaW1 and dmaW2, two gene homologues that encode dimethylallyltryptophan synthase, the enzyme for the first step in ergot-alkaloid biosynthesis. In our effort to disrupt both homologues and ultimately obtain marker-free mutants, we are using a marker-exchange strategy employing the Cre/ loxP site-specific recombination system. Of 1522 transformants obtained and screened, three were likely dmaW2 disruptants because they gave no PCR product from the wild-type locus, but yielded the larger PCR fragment from the disruption construct. The putative dmaW2-knockouts were also transformed with pKAES186, a plasmid with a cassette containing the cre and ble genes in between loxP sequences. The transformants obtained were screened for the presence of hph, cre and ble genes. The preliminary results indicate a loop-out of the hph gene. The transformants inoculated into endophyte-free tall fescue preserved their compatibility with the plant. The fungus grown from these plants will be further analysed for the presence of hph, cre and ble genes. Keywords: Cre/LoxP, dimethylallyltryptophan synthase, dmaW, Epichloë, ergot alkaloids, Festuca arundinacea, gene knockouts, Lolium arundinaceum, Neotyphodium coenophialum, tall fescue


Toxins ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 153
Author(s):  
Simona Florea ◽  
Jolanta Jaromczyk ◽  
Christopher L. Schardl

The Epichloë species of fungi include seed-borne symbionts (endophytes) of cool-season grasses that enhance plant fitness, although some also produce alkaloids that are toxic to livestock. Selected or mutated toxin-free endophytes can be introduced into forage cultivars for improved livestock performance. Long-read genome sequencing revealed clusters of ergot alkaloid biosynthesis (EAS) genes in Epichloë coenophiala strain e19 from tall fescue (Lolium arundinaceum) and Epichloë hybrida Lp1 from perennial ryegrass (Lolium perenne). The two homeologous clusters in E. coenophiala—a triploid hybrid species—were 196 kb (EAS1) and 75 kb (EAS2), and the E. hybrida EAS cluster was 83 kb. As a CRISPR-based approach to target these clusters, the fungi were transformed with ribonucleoprotein (RNP) complexes of modified Cas9 nuclease (Cas9-2NLS) and pairs of single guide RNAs (sgRNAs), plus a transiently selected plasmid. In E. coenophiala, the procedure generated deletions of EAS1 and EAS2 separately, as well as both clusters simultaneously. The technique also gave deletions of the EAS cluster in E. hybrida and of individual alkaloid biosynthesis genes (dmaW and lolC) that had previously proved difficult to delete in E. coenophiala. Thus, this facile CRISPR RNP approach readily generates non-transgenic endophytes without toxin genes for use in research and forage cultivar improvement.


Toxins ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 342
Author(s):  
Maximilian Kuner ◽  
Susanne Kühn ◽  
Hajo Haase ◽  
Klas Meyer ◽  
Matthias Koch

Ergot alkaloids are mycotoxins formed by fungi of the Claviceps genus, which are some of the most common contaminants of food and feed worldwide. These toxins are a structurally heterogeneous group of compounds, sharing an ergoline backbone. Six structures and their corresponding stereoisomers are typically quantified by either HPLC-FLD or HPLC-MS/MS and the values subsequently summed up to determine the total ergot alkaloid content. For the development of a screening method targeting all ergot alkaloids simultaneously, the alkaloids need to be transferred to one homogeneous structure: a lysergic acid derivative. In this study, two promising cleaving methods—acidic esterification and hydrazinolysis—are compared, using dihydroergocristine as a model compound. While the acidic esterification proved to be unsuitable, due to long reaction times and oxidation sensitivity, hydrazinolysis reached a quantitative yield in 40‒60 min. Parallel workup of several samples is possible. An increasing effect on the reaction rate by the addition of ammonium iodide was demonstrated. Application of hydrazinolysis to a major ergot alkaloid mix solution showed that all ergopeptines were cleaved, but ergometrine/-inine was barely affected. Still, hydrazinolysis is a suitable tool for the development of a sum parameter screening method for ergot alkaloids in food and feed.


2018 ◽  
Vol 84 (19) ◽  
Author(s):  
Samantha J. Fabian ◽  
Matthew D. Maust ◽  
Daniel G. Panaccione

ABSTRACTErgot alkaloids are specialized fungal metabolites with potent biological activities. They are encoded by well-characterized gene clusters in the genomes of producing fungi.Penicillium camembertiplays a major role in the ripening of Brie and Camembert cheeses. TheP. camembertigenome contains a cluster of five genes shown in other fungi to be required for synthesis of the important ergot alkaloid intermediate chanoclavine-I aldehyde and two additional genes (easHandeasQ) that may control modification of chanoclavine-I aldehyde into other ergot alkaloids. We analyzed samples of Brie and Camembert cheeses, as well as cultures ofP. camemberti, and did not detect chanoclavine-I aldehyde or its derivatives. To create a functioning facsimile of theP. camembertieascluster, we expressedP. camemberti easHandeasQin a chanoclavine-I aldehyde-accumulatingeasAknockout mutant ofNeosartorya fumigata. TheeasH-easQ-engineeredN. fumigatastrain accumulated a pair of compounds ofm/z269.1288 in positive-mode liquid chromatography-mass spectrometry (LC-MS). The analytes fragmented in a manner typical of the stereoisomeric ergot alkaloids rugulovasine A and B, and the related rugulovasine producerPenicillium biformeaccumulated the same isomeric pair of analytes. TheP. camemberti easgenes were transcribed in culture, but comparison of theP. camemberti eascluster with the functional cluster fromP. biformeindicated 11 polymorphisms. Whereas otherP. camembertieasgenes functioned when expressed inN. fumigata,P. camembertieasCdid not restore ergot alkaloids when expressed in aneasCmutant. The data indicate thatP. camembertiformerly had the capacity to produce the ergot alkaloids rugulovasine A and B.IMPORTANCEThe presence of ergot alkaloid synthesis genes in the genome ofPenicillium camembertiis significant, because the fungus is widely consumed in Brie and Camembert cheeses. Our results show that, although the fungus has several functional genes from the ergot alkaloid pathway, it produces only an early pathway intermediate in culture and does not produce ergot alkaloids in cheese.Penicillium biforme, a close relative ofP. camemberti, contains a similar but fully functional set of ergot alkaloid synthesis genes and produces ergot alkaloids chanoclavine-I, chanoclavine-I aldehyde, and rugulovasine A and B. Our reconstruction of theP. camembertipathway in the model fungusNeosartorya fumigataindicated thatP. camembertiformerly had the capacity to produce these same ergot alkaloids. NeitherP. camembertinorP. biformeproduced ergot alkaloids in cheese, indicating that nutritionally driven gene regulation prevents these fungi from producing ergot alkaloids in a dairy environment.


1981 ◽  
Vol 59 (12) ◽  
pp. 2534-2538 ◽  
Author(s):  
Charles W. Bacon ◽  
James K. Porter ◽  
Joe D. Robbins

Two endophytic clavicipitaceous fungi, Balansia epichloë and B. henningsiana, were isolated from several grasses, cultured on laboratory media, and assessed for their ability to produce the major ergot alkaloids agroclavine, chanoclavine (I), ergonovine, and ergonovinine. Data indicated that the ability of these two species of fungi to biosynthesize ergot alkaloids was host related. All isolates of B. epichloë from smut-grass (Sporobolus poiretii) and 59% of the isolates of B. henningsiana from broom-sedge (Andropogon virginicus) produced the major alkaloids in culture. All isolates of B. epichloë from Eragrostis secundiflora and E. hirsuta, and all isolates of B. henningsiana from Panicum tenerum failed to produce alkaloids. The total yield and chemical species of individual alkaloids varied among isolates from a sampling site.


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