A fungal NRPS-PKS enzyme catalyses the formation of the flavonoid naringenin

Abstract

Biosynthesis of the flavonoid naringenin in plants and bacteria is commonly catalysed by a type III polyketide synthase (PKS) using one p-coumaroyl-CoA and three malonyl-CoA molecules as substrates. Here, we report a fungal non-ribosomal peptide synthetase -polyketide synthase (NRPS-PKS) hybrid FnsA for the naringenin formation. Feeding experiments with isotope-labelled precursors demonstrate that FnsA accepts not only p-coumaric acid (p-CA), but also p-hydroxybenzoic acid (p-HBA) as starter units, with three or four malonyl-CoA molecules for elongation, respectively. In vitro assays and MS/MS analysis prove that both p-CA and p-HBA are firstly activated by the adenylation domain of FnsA. Phylogenetic analysis reveals that the PKS portion of FnsA shares high sequence homology with type I PKSs. Refactoring the biosynthetic pathway in yeast with the involvement of fnsA provides an alternative approach for the production of flavonoids such as isorhamnetin and acacetin.

Identification and Functional Characterization of Fungal Chalcone Synthase and Chalcone Isomerase

“…A similar chimeric AT-PKS, P168DRAFT_323099 (CfvA in this study), was proposed to be involved in the biosynthesis of chlorflavonin, which is the first example of a fungal flavonoid, the producer of which was confirmed to be Aspergillus candidus (Figure B) . More recently, Zhang et al demonstrated that this type of AT-PKS catalyzes the formation of 1 and naringenin ( 2 ) . Herein, we report the functional characterization of DiapA, showing that this enzyme also catalyzes the formation of 1 and that its TE domain is responsible for the characteristic Claisen-type cyclization.…”

“…Heterologous expression in A. oryzae , isolation and structural analysis of the metabolites, and structural prediction of the terminal TE domain and molecular docking analysis clearly indicated that DiapA is a dedicated chalcone synthase distinct from plant type III PKS. The previous study also identified FnsA, a DiapA homologue, synthesized 1 and 2 . However, it remains unclear whether the cyclization of 1 to 2 is an enzymatic process or not.…”

“…The previous study also identified FnsA, a DiapA homologue, synthesized 1 and 2 . 19 However, it remains unclear whether the cyclization of 1 to 2 is an enzymatic process or not. We identified a fungal CHI that is also distinct from plant CHI, demonstrating that fungi adopt unique biosynthetic machineries for the synthesis of plant-like metabolites.…”

“… 18 More recently, Zhang et al demonstrated that this type of AT-PKS catalyzes the formation of 1 and naringenin ( 2 ). 19 Herein, we report the functional characterization of DiapA, showing that this enzyme also catalyzes the formation of 1 and that its TE domain is responsible for the characteristic Claisen-type cyclization. In addition to its natural substrate, DiapA accepted benzoic acid analogues and gave unnatural flavanones as products.…”

Fungal NRPS-PKS Hybrid Enzymes Biosynthesize New γ-Lactam Compounds, Taslactams A-D, Analogous to Actinomycete Proteasome Inhibitors

“…The TAS1 PKS part has a KS domain alone with a unique sequence. After discovery of TAS1, some fungal NRPS-PKS enzymes (SwnK (A-PCP-KS-AT-KR-ACP-R), , HispS20 (A-PCP-KS-AT-ACP), AnATPKS21 (A-PCP-KS-AT-ACP), HppS (A-PCP-KS-AT-ACP), AcdB (A-PCP-KS-AT-KR 0 -ACP-R 0 ), and FnsA (A-PCP-KS-AT-DH-KR-ACP-TE)) have been reported. All these enzymes have AT and ACP domains and lack C domain.…”