Fungal Indole Alkaloid Biosynthesis: Genetic and Biochemical Investigation of the Tryptoquialanine Pathway inPenicillium aethiopicum

Citations Over TimeTop 10% of 2011 papers

Abstract

Tremorgenic mycotoxins are a group of indole alkaloids which include the quinazoline-containing tryptoquivaline (2) that are capable of eliciting intermittent or sustained tremors in vertebrate animals. The biosynthesis of this group of bioactive compounds, which are characterized by an acetylated quinazoline ring connected to a 6-5-5 imidazoindolone ring system via a 5-membered spirolactone, has remained uncharacterized. Here, we report the identification of a gene cluster (tqa) from P. aethiopicum that is involved in the biosynthesis of tryptoquialanine (1), which is structurally similar to 2. The pathway has been confirmed to go through an intermediate common to the fumiquinazoline pathway, fumiquinazoline F, which originates from a fungal trimodular nonribosomal peptide synthetase (NRPS). By systematically inactivating every biosynthetic gene in the cluster, followed by isolation and characterization of the intermediates, we were able to establish the biosynthetic sequence of the pathway. An unusual oxidative opening of the pyrazinone ring by an FAD-dependent berberine bridge enzyme-like oxidoreductase has been proposed based on genetic knockout studies. Notably, a 2-aminoisobutyric acid (AIB)-utilizing NRPS module has been identified and reconstituted in vitro, along with two putative enzymes of unknown functions that are involved in the synthesis of the unnatural amino acid by genetic analysis. This work provides new genetic and biochemical insights into the biosynthesis of this group of fungal alkaloids, including the tremorgens related to 2.

Related Papers

• → Design of α-Keto Carboxylic Acid Dimers by Domain Recombination of Nonribosomal Peptide Synthetase (NRPS)-Like Enzymes(2019)53 cited
• → Identification and Characterization of the Althiomycin Biosynthetic Gene Cluster in Myxococcus xanthus DK897(2011)35 cited
• → Total Biosynthesis of the Pyrrolo[4,2]benzodiazepine Scaffold Tomaymycin on an In Vitro Reconstituted NRPS System(2017)24 cited
• → Involvement of both PKS and NRPS in antibacterial activity inLysobacter enzymogenesOH11(2014)30 cited
• → Identification of the Biosynthetic Gene Cluster for Pyracrimycin A, an Antibiotic Produced by Streptomyces sp.(2022)9 cited