Search

Gliotoxin is a virulence factor of the human pathogen Aspergillus fumigatus, the leading cause of invasive aspergillosis. The activity of this metabolite is mediated by a transannular disulfide bond, a hallmark of the epipolythiodiketopiperazine (ETP) family. Through the creation of fungal gene deletion mutants and heterologous protein expression, we unveiled the critical role of the cytochrome P450 monooxygenase (CYP450) GliC for the stepwise bishydroxylation of the diketopiperazine (DKP) core. We show for the first time the formation of the C-S bond from the DKP in a combined assay of GliC and the glutathione- S-transferase (GST) GliG in vitro. Furthermore, we present experimental evidence for an intermediary imine species. The flexible substrate scope of GliC and GliG in combination parallels P450/GST pairs used in eukaryotic phase I/II detoxification pathways.

Enzyme quartet: Isolation of the first sulfur-bearing intermediate of the gliotoxin pathway in Aspergillus fumigatus and successful in vitro conversion of the bisglutathione adduct into an intact epidithiodiketopiperazine by a four-enzyme cascade (including glutamyltransferase GliK and dipeptidase GliJ) revealed an outstanding adaptation of a primary metabolic pathway into natural product biosynthesis that is widespread in fungi., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Gliotoxin is a virulence factor of the human pathogen Aspergillus fumigatus , the leading cause of invasive aspergillosis. Its toxicity is mediated by the unusual transannular disulfide bridge of the epidithiodiketopiperazine (ETP) scaffold. Here we disclose the critical role of a specialized glutathione S-transferase (GST), GliG, in enzymatic sulfurization. Furthermore, we show that bishydroxylation of the diketopiperazine by the oxygenase GliC is a prerequisite for glutathione adduct formation. This is the first report of the involvement of a GST in enzymatic C-S bond formation in microbial secondary metabolism.