pks63787, a Polyketide Synthase Gene Responsible for the Biosynthesis of Benzenoids in the Medicinal Mushroom Antrodia cinnamomea

Abstract

Antrodia cinnamomea, a unique resupinate basidiomycete endemic to Taiwan, has potent medicinal activities. The reddish basidiocarps and mycelia generally exhibit abundant metabolites and higher biological activity. To investigate the pigments of A. cinnamomea, polyketide synthase (PKS) genes were characterized based on its partially deciphered genome and the construction of a fosmid library. Furthermore, a gene disruption platform was established via protoplast transformation and homologous recombination. Of four putative polyketide synthase genes, pks63787 was selected and disrupted in the monokaryotic wild-type (wt) strain f101. Transformant Δpks63787 was deficient in the synthesis of several aromatic metabolites, including five benzenoids and two benzoquinone derivatives. Based on these results, a biosynthetic pathway for benzenoid derivatives was proposed. The pks63787 deletion mutant not only displayed a reduced red phenotype compared to the wt strain but also displayed less 1,1-biphenyl-2-picrylhydrazyl free radical scavenging activity. This finding suggests that PKS63787 is responsible for the biosynthesis of pigments and metabolites related to the antioxidant activity of A. cinnamomea. The present study focuses on the functional characterization of the PKS gene, the fluctuations of its profile of secondary metabolites, and interpretation of the biosynthesis of benzenoids.

Optimization of Protoplast Preparation and Regeneration of a Medicinal Fungus Antrodia cinnamomea

“…Under the conditions obtained, it showed that the mycelial cell wall was almost completely digested, and no further filtration step was required to remove the cell wall debris ( Figure S1). The number of protoplasts obtained was 2.1 Â 10 8 cells mL À1 which was much higher than earlier studies when compared with the literature on the preparation of protoplasts of A. cinnamomea [18].…”

“…As shown in Figure 9, it had the highest regeneration rate of 71.3% at 80 mM citrate buffer in this experiment. The protoplast regeneration rate is dramatically increased from earlier report of 6.8% [18] to 71.3%. Based on the above optimal condition for protoplast regeneration of A. cinnamomea, it is easier for observation of subsequent results of protoplast regeneration, such as shown in Figure 10.…”

Analysis of the Sequences, Structures, and Functions of Product-Releasing Enzyme Domains in Fungal Polyketide Synthases

“…Similarly, the TE domain of A. nidulans OrsA in group I catalyzes an intermolecular transesterification during biosynthesis of lecanoric acid ( Gressler et al, 2015 ). Besides cross-coupling activity, the TE domains of NR-PKSs in group VIII often perform hydrolysis activity to produce orsellinic acid ( Lackner et al, 2013 ; Yu et al, 2016 ). The complex phylogeny revealed that the evolution of TE domains was accompanied by functional divergence from hydrolysis to cross-coupling to macrolactone closure.…”

Induced Chemical Defense of a Mushroom by a Double‐Bond‐Shifting Polyene Synthase

“…Very few PKSs from mushrooms have been investigated. All of them were identified as orsellinic acid synthases, [13,20] that is, none of them represents a HR-PKS and none of the previous studies investigated the interrelation between an enzyme, its product, and the function for the producing organism.Therefore, our results highlight that a single PKS gene is sufficient to induce chemical defense (Figure 4). Genes for highly similar synthases were identified in basidiomycetes of various evolutionary clades.…”