Identification of a Halogenase Involved in the Biosynthesis of Ochratoxin A in Aspergillus carbonarius

Torna indietro

Abstract

Aspergillus carbonarius is the main responsible fungus of ochratoxin A (OTA) contamination of grapes and derived products. Todate, the biosynthetic mechanism of this mycotoxin has been partially elucidated. Availability of genome sequence of A. carbonariushas allowed the identification of a putative gene cluster involved in OTA biosynthesis. This region hosts the previouslycharacterized AcOTAnrps and AcOTApks genes encoding two key enzymes of the biosynthetic pathway. At about 4,400 nucleotidesdownstream of these loci, a gene encoding a putative flavin dependent-halogenase came out from the annotation data. Itsproximity to OTA biosynthetic genes and its sequence analysis have suggested a role in the biosynthesis of OTA, directed to theintroduction of the chlorine atom in the C-5 position of the final molecular structure of this mycotoxin. The deduced proteinsequence of the halogenase gene, we designated AcOTAhal, shows a high similarity to a halogenase that is located in the OTAcluster of A. niger. The deletion of the halogenase gene completely eliminated the production of ochratoxin A in A. carbonariusand determined a significant increase of ochratoxin B, as confirmed by mass spectrometry analysis. Moreover, its expressionprofile was similar to the two biosynthetic genes previously identified, AcOTApks and AcOTAnrps, indicating a strong correlationof the AcOTAhal gene with the kinetics of OTA accumulation in A. carbonarius. Therefore, experimental evidence confirmedthat the chlorination step which converts OTB in OTA represents the final stage of the biosynthetic pathway, supportingour earlier hypothesis on the order of enzymatic steps of OTA biosynthesis in A. carbonarius.

Autore Pugliese

Tutti gli autori

  • Ferrara M.; Perrone G.; Gambacorta L.; Epifani F.; Solfrizzo M.; Gallo A.

Titolo volume/Rivista

Applied and environmental microbiology

Anno di pubblicazione

2016

ISSN

0099-2240

ISBN

Non Disponibile

Numero di citazioni Wos

Nessuna citazione

Ultimo Aggiornamento Citazioni

Non Disponibile

Numero di citazioni Scopus

Non Disponibile

Ultimo Aggiornamento Citazioni

Non Disponibile

Settori ERC

Non Disponibile

Codici ASJC

Non Disponibile