title: A nonribosomal peptide synthetase (Pes1) confers protection against oxidative stress in Aspergillus fumigatus.
abstract: Aspergillus fumigatus is an important human fungal pathogen. The Aspergillus fumigatus genome contains 14 nonribosomal peptide synthetase genes, potentially responsible for generating metabolites that contribute to organismal virulence. Differential expression of the nonribosomal peptide synthetase gene, pes1, in four strains of Aspergillus fumigatus was observed. The pattern of pes1 expression differed from that of a putative siderophore synthetase gene, sidD, and so is unlikely to be involved in iron acquisition. The Pes1 protein (expected molecular mass 698 kDa) was partially purified and identified by immunoreactivity, peptide mass fingerprinting (36% sequence coverage) and MALDI LIFT-TOF/TOF MS (four internal peptides sequenced). A pes1 disruption mutant (delta pes1) of Aspergillus fumigatus strain 293.1 was generated and confirmed by Southern and western analysis, in addition to RT-PCR. The delta pes1 mutant also showed significantly reduced virulence in the Galleria mellonella model system (P < 0.001) and increased sensitivity to oxidative stress (P = 0.002) in culture and during neutrophil-mediated phagocytosis. In addition, the mutant exhibited altered conidial surface morphology and hydrophilicity, compared to Aspergillus fumigatus 293.1. It is concluded that pes1 contributes to improved fungal tolerance against oxidative stress, mediated by the conidial phenotype, during the infection process.
authors.affiliation: National Institute for Cellular Biotechnology, Department of Biology, National University of Ireland Maynooth, Co. Kildare, Ireland.
authors.forename: Emer P
authors.initials: EP
authors.lastname: Reeves
authors.forename: Kathrin
authors.initials: K
authors.lastname: Reiber
authors.forename: Claire
authors.initials: C
authors.lastname: Neville
authors.forename: Olaf
authors.initials: O
authors.lastname: Scheibner
authors.forename: Kevin
authors.initials: K
authors.lastname: Kavanagh
authors.forename: Sean
authors.initials: S
authors.lastname: Doyle
mesh_terms: D001232:Aspergillus fumigatus / Q000201:enzymology*; D001483:Base Sequence; D003001:Cloning, Molecular; D005656:Fungal Proteins / Q000737:chemistry* / Q000502:physiology*; D005800:Genes, Fungal; D016681:Genome, Fungal; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D010453:Peptide Synthases / Q000737:chemistry* / Q000502:physiology*; D010641:Phenotype; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013997:Time Factors
chemical_list: D005656:Fungal Proteins; C512459:Pes1 protein, Aspergillus fumigatus; D010453:Peptide Synthases