A Cell Factory of a Fungicolous Fungus Calcarisporium arbuscula for Efficient Production of Natural Products

Abstract

Fungal natural products are rich sources of clinical drugs. Particularly, the fungicolous fungi have a large number of biosynthetic gene clusters (BGCs) to produce numerous bioactive natural products, but most BGCs are silent in the laboratory. We have shown that a fungicolous fungus Calcarisporium arbuscula NRRL 3705 predominantly produces the highly reduced polyketidetype mycotoxins aurovertins. Here after evaluation of the aurovertin-null mutant ΔaurA as an efficient host, we further screened two strong promoters aurBp and A07068p based on RNA-Seq, and successfully activated an endogenous gene cluster from C. arbuscula as well as three additional exogenous BGCs from other fungi to produce polyketide-type natural products. Thus, we showed an efficient expression system from the fungicolous fungus C. arbuscula, which will be highly beneficial and complementary to the conventional Aspergillus and Penicillium fungal cell factories, and provides a useful toolkit for genome-wide mining of bioactive natural products from fungicolous fungi.

Discovery of a Potential Liver Fibrosis Inhibitor from a Mushroom Endophytic Fungus by Genome Mining of a Silent Biosynthetic Gene Cluster

“…Since most zinc finger transcriptional factors are positive regulators, − we tried to ectopically express TF17 under a strong promoter tef1p in the C. arbuscula Δ aurA mutant to obtain Δ aurA - TF17 (named MCA17 ), since this strain showed null production of the main products aurovertins and a very clear metabolite background. , The parental strain Δ aurA was white, and some transformants with reddish brown pigment on PDA were obtained (Figure B). HPLC analysis of the MCA17 culture from PDB showed a new peak compared to the Δ aurA strain (Figure C), indicating mca17 should have been activated after overexpression of TF17 .…”