Discovery of branching meroterpenoid biosynthetic pathways in Aspergillus insuetus: involvement of two terpene cyclases with distinct cyclization modes

Abstract

The aromatic polyketide 3,5-dimethylorsellinic acid (DMOA) serves as a precursor for many fungal meroterpenoids. A large portion of DMOA-derived meroterpenoids are biosynthesized via the cyclization of (6R,10′R)-epoxyfarnesyl-DMOA methyl ester (1)....

Biosynthetic Characterization, Heterologous Production, and Genomics-Guided Discovery of GABA-Containing Fungal Heptapeptides

“…To further confirm the proposed biosynthetic pathway leading to 3 and 4 (Figure ), we conducted heterologous expression experiments in A. oryzae NSAR1, which is a robust platform for the heterologous biosynthesis of fungal natural products. − Due to its large size (∼29.3 kb), it was difficult to introduce the entire NRPS gene ungA into a standard fungal transformation vector. In a previous study, a large fungal NRPS gene was separated into two fragments and introduced into A. oryzae over two rounds of transformation .…”

“…The ungC and ungD genes were initially amplified from the genomic DNA of A. violaceofuscus CBS 115571 with the primers described in Table S3 and Table S4 and then introduced into the pTAex3 vector, using a ClonExpress Ultra one step cloning kit (Vazyme Biotech Co., Ltd.). Subsequently, the ungC gene was also introduced into the pPyrG-HR vector . For the construction of the plasmids with both ungC and ungD , ungC with the amyB terminator ( TamyB ) and ungD with the amyB promoter ( PamyB ) were amplified from the pTAex3-based plasmids and further introduced into the pPyrG-HR vector.…”

“…Subsequently, the ungC gene was also introduced into the pPyrG-HR vector. 28 For the construction of the plasmids with both ungC and ungD, ungC with the amyB terminator (TamyB) and ungD with the amyB promoter (PamyB) were amplified from the pTAex3-based plasmids and further introduced into the pPyrG-HR vector. Primer sequences and detailed methods for the constructions of each plasmid are summarized in Table S3 and Table S4.…”

Depside Bond Formation by the Starter-Unit Acyltransferase Domain of a Fungal Polyketide Synthase

“…To obtain the metabolites derived from the drc cluster, we heterologously expressed drc genes in the Aspergillus oryzae NSAR1 strain, which has been widely used to characterize orphan fungal biosynthetic gene clusters . The metabolites produced by A. oryzae transformed with drcA were analyzed by HPLC, which revealed the presence of a major metabolite, 1 , that was absent from the host strain (Figure B, traces i and ii).…”

Hot off the press

“…Genome mining of Aspergillus insuetus CBS 107.25 has led to the discovery of a new terpene cyclase (InsA7) of (6 R ,10′ R )-epoxyfarnesyl-3,5-dimethylorsellinic acid methyl ester 26 . 23 Unusually, InsA7 folds 26 into a boat-chair conformation, generating insuetusin A1 27 with a C3 axial hydroxyl group (Scheme 2). The gene cluster responsible for the biosynthesis of talaronoid C 28 has been characterised from the marine-derived fungus Aspergillus flavipes .…”