Biochemical Outcome of Blocking the Ergot Alkaloid Pathway of a Grass Endophyte

Abstract

Neotyphodium sp. Lp1, an endophytic fungus from perennial ryegrass (Lolium perenne), produces the mycotoxin ergovaline in infected grasses, whereas a mutant in which a particular peptide synthetase gene is knocked out does not. We examined the impact of this knockout on other constituents of the ergot alkaloid pathway. Two simple lysergic acid amides, ergine and a previously undescribed amide, were eliminated by the knockout. Lysergic acid accumulated in the knockout endophyte, but quantities were only 13% of the total lysergic acid derivatives accumulated in the wild type. Concentrations of several clavines were not substantially affected. However, a novel clavine accumulated to higher concentrations in perennial ryegrass containing the knockout strain. The results indicate that production of simple lysergic acid amides requires the activity or products of the ergovaline-associated peptide synthetase and that the regulation of ergot alkaloid production is modified in response to the relatively late block in the pathway.

Epichloë hybrida, sp. nov., an emerging model system for investigating fungal allopolyploidy

“…Consistent with earlier MSMS analyses demonstrating that the ergovaline pathway is fully functional within E. hybrida (Panaccione et al 2003), all genes required for ergovaline production were identified in E. hybrida Lp1 from genomic reads and appear to have been inherited as single homeologs derived from the E. festucae progenitor. (This pathway is also absent in E. typhina E8.)…”

An Ergot Alkaloid Biosynthesis Gene and Clustered Hypothetical Genes from Aspergillus fumigatus

“…This result is not surprising since chanoclavine is an early pathway intermediate in the biosynthesis of all known ergot alkaloids and it accumulates to various degrees in different ergot alkaloid producers (7,8,14,15,25).…”

“…(15,19). However, none of the fumigaclavines produced by A. fumigatus has been detected in a member of the Clavicipitaceae.…”

“…The ergot alkaloid pathway is relatively long and may have alternate branches or spurs in some ergot alkaloid producers (7,8,14,15). Functions of three genes involved in the ergot alkaloid pathway have been demonstrated by gene knockout.…”

“…strain Lp1 (16). LPS1-deficient knockout mutants failed to produce ergopeptines and simple amides of lysergic acid but still produced clavine ergot alkaloids (15,16). A gene encoding lysergyl peptide synthetase 2 (LPS2), the lysergic acid-activating component of the lysergyl peptide synthetase complex, has been cloned and knocked out in C. purpurea, resulting in the loss of ergopeptines from the knockout mutant (5).…”