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

• DOI: 10.1128/aem.01209-16
• Publication Date: 2016-07-16T03:19:05Z
• Authors: Massimo Ferrara; Giancarlo Perrone; Lucia Gambacorta; Filomena Epifani; Michele Solfrizzo; Antonia Gallo
• Keywords: Gene cluster; Ochratoxins

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