Characterisation and heterologous biosynthesis of burnettiene A, a new polyene-decalin polyketide from Aspergillus burnettii

Abstract

Burnettiene A is a novel cytotoxic tridecaketide decalin polyketide from Aspergillus burnettii. Its biosynthesis was elucidated by heterologous expression in fungi.

Trichoderma reesei Contains a Biosynthetic Gene Cluster That Encodes the Antifungal Agent Ilicicolin H

“…Likewise, oxygenation of the terminal methyl of 12 to a carboxylic acid is newly observed in A. oryzae. This is similar to the BueE-catalysed oxidation recently observed by Piggott and coworkers in the case of the fungal polyketide decalin burnettiene A in Aspergillus burnettii [33]. It also appears that a spontaneous (or A. oryzae-catalysed) Diels-Alder reaction can occur to produce a decalin that is then oxidised to a carboxylic acid at the terminal methyl to generate new compound 12.…”

Cre/lox-Mediated Chromosomal Integration of Biosynthetic Gene Clusters for Heterologous Expression in Aspergillus nidulans

“…Protoplasts of A. nidulans LO8030 LP1 or LP2 were prepared from germlings, 51 For the activation of the chromosomally integrated bue genes by TF overexpression, protoplasts were prepared from the strains A. nidulans LO8030-LP1-bueA/B/C/D/E/R and A. nidulans LO8030-LP2-bueA/B/C/D/E/R. Protoplasts were transformed with the vector pYFAC-bueG-PgpdA-bueR 38 or pYFAC-PgpdA-bueR and selected on SMM u−r+p−. Diagnostic PCRs.…”

“…The bue BGC has recently been characterized by heterologous episomal expression in A. nidulans to produce burnettiene A. 38 As the complete BGC led to production of multiple metabolite derivatives along with the final product, we decided to evaluate instead the integration of the partial BGC containing bueA/B/C/D/E/R (without bueF) whose expression results in the production of a single peak corresponding to the penultimate pathway product, preburnettiene B (1). 38 As the bue cluster is active in the native host 42 and episomal expression of bue genes under native promoters in A. nidulans leads to compound production, 38 we hypothesized that if the partial bue BGC was chromosomally integrated into A. nidulans we would observe the production of 1 (Figure S2B).…”

“…We previously demonstrated that overexpression of the bue cluster-specific transcription factor (TF) bueR increased the production of burnettienes in an episomal context. 38 Therefore, we hypothesized that overexpression of the TF bueR would activate the expression of the chromosomal bue genes in the recombinant A. nidulans strains (Figure 4A). Effectively, we observed the production of 1 in strains harboring bue genes integrated by RMCE at either LP1 or LP2 when further transformed with an AMA1-based vector encoding P gpdA -bueR and the transporter gene bueG 38 (Figure 4B,C).…”

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“…Bioinformatic analysis of the genome sequence from Aspergillus burnettii has allowed the identification of the biosynthetic gene cluster involved in the production of the polyene-decalin polyketide, burnettiene A 32 . 24 Some of the tailoring enzymes were also characterised, such as BueE, a cytochrome P450 enzyme that catalyses regioselective oxidation of methyl groups to carboxylic acids.…”