title: Nonribosomal peptide synthetase genes pesL and pes1 are essential for Fumigaclavine C production in Aspergillus fumigatus.
abstract: The identity of metabolites encoded by the majority of nonribosomal peptide synthetases in the opportunistic pathogen, Aspergillus fumigatus, remains outstanding. We found that the nonribosomal peptide (NRP) synthetases PesL and Pes1 were essential for fumigaclavine C biosynthesis, the end product of the complex ergot alkaloid (EA) pathway in A. fumigatus. Deletion of either pesL (ΔpesL) or pes1 (Δpes1) resulted in complete loss of fumigaclavine C biosynthesis, relatively increased production of fumitremorgins such as TR-2, fumitremorgin C and verruculogen, increased sensitivity to H(2)O(2), and increased sensitivity to the antifungals, voriconazole, and amphotericin B. Deletion of pesL resulted in severely reduced virulence in an invertebrate infection model (P < 0.001). These findings indicate that NRP synthesis plays an essential role in mediating the final prenylation step of the EA pathway, despite the apparent absence of NRP synthetases in the proposed EA biosynthetic cluster for A. fumigatus. Liquid chromatography/diode array detection/mass spectrometry analysis also revealed the presence of fumiquinazolines A to F in both A. fumigatus wild-type and ΔpesL strains. This observation suggests that alternative NRP synthetases can also function in fumiquinazoline biosynthesis, since PesL has been shown to mediate fumiquinazoline biosynthesis in vitro. Furthermore, we provide here the first direct link between EA biosynthesis and virulence, in agreement with the observed toxicity associated with EA exposure. Finally, we demonstrate a possible cluster cross-talk phenomenon, a theme which is beginning to emerge in the literature.
authors.affiliation: Department of Biology and National Institute for Cellular Biotechnology, National University of Ireland Maynooth, County Kildare, Ireland.
authors.forename: Karen A
authors.initials: KA
authors.lastname: O'Hanlon
authors.forename: Lorna
authors.initials: L
authors.lastname: Gallagher
authors.forename: Markus
authors.initials: M
authors.lastname: Schrettl
authors.forename: Christoph
authors.initials: C
authors.lastname: Jöchl
authors.forename: Kevin
authors.initials: K
authors.lastname: Kavanagh
authors.forename: Thomas O
authors.initials: TO
authors.lastname: Larsen
authors.forename: Sean
authors.initials: S
authors.lastname: Doyle
mesh_terms: D001232:Aspergillus fumigatus / Q000201:enzymology* / Q000235:genetics*; D004876:Ergot Alkaloids / Q000096:biosynthesis*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D026121:Indole Alkaloids; D010453:Peptide Synthases / Q000235:genetics* / Q000378:metabolism*; D011799:Quinazolines / Q000378:metabolism; D037521:Virulence Factors / Q000096:biosynthesis
chemical_list: D004876:Ergot Alkaloids; D005656:Fungal Proteins; D026121:Indole Alkaloids; D011799:Quinazolines; D037521:Virulence Factors; C492995:fumigaclavine C; C512459:Pes1 protein, Aspergillus fumigatus; D010453:Peptide Synthases; C104385:non-ribosomal peptide synthase