title: Disruption of a nonribosomal peptide synthetase in Aspergillus fumigatus eliminates gliotoxin production.
abstract: The fungal secondary metabolite gliotoxin produced by Aspergillus fumigatus has been hypothesized to be important in the development of invasive aspergillosis. In this study, we addressed this hypothesis by disrupting a nonribosomal peptide synthetase (NRPS) (encoded by gliP) predicted to be involved in gliotoxin production. Mutants with a disrupted gliP locus failed to produce gliotoxin, which confirmed the role of the NRPS encoded by gliP in gliotoxin biosynthesis. We found no morphological, developmental, or physiological defects in DeltagliP mutant strains. In addition, disruption of gliP resulted in down regulation of gene expression in the gliotoxin biosynthesis gene cluster, which was restored with addition of exogenous gliotoxin. This interesting result suggests a role for gliotoxin in regulating its own production. Culture filtrates from the DeltagliP mutant were unable to inhibit ionomycin-dependent degranulation of mast cells, suggesting a role for gliotoxin in suppressing mast cell degranulation and possibly in disease development. However, the DeltagliP mutant did not have an impact on survival or tissue burden in a murine inhalational model of invasive aspergillosis. This result suggests that gliotoxin is not required for virulence in an immunosuppressed host with an invasive pulmonary infection.
authors.affiliation: Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA. rcramer@duke.edu
authors.forename: Robert A
authors.initials: RA
authors.lastname: Cramer
authors.forename: Michael P
authors.initials: MP
authors.lastname: Gamcsik
authors.forename: Rhea M
authors.initials: RM
authors.lastname: Brooking
authors.forename: Laura K
authors.initials: LK
authors.lastname: Najvar
authors.forename: William R
authors.initials: WR
authors.lastname: Kirkpatrick
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Patterson
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Balibar
authors.forename: John R
authors.initials: JR
authors.lastname: Graybill
authors.forename: John R
authors.initials: JR
authors.lastname: Perfect
authors.forename: Soman N
authors.initials: SN
authors.lastname: Abraham
authors.forename: William J
authors.initials: WJ
authors.lastname: Steinbach
mesh_terms: D000818:Animals; D021461:Animals, Outbred Strains; D001228:Aspergillosis; D001232:Aspergillus fumigatus / Q000378:metabolism* / Q000472:pathogenicity*; D015550:Cell Degranulation; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D015536:Down-Regulation; D016681:Genome, Fungal; D005912:Gliotoxin / Q000096:biosynthesis*; D016867:Immunocompromised Host; D008297:Male; D008407:Mast Cells / Q000166:cytology / Q000276:immunology; D051379:Mice; D005810:Multigene Family; D009154:Mutation; D009503:Neutropenia; D010453:Peptide Synthases / Q000235:genetics* / Q000378:metabolism; D010641:Phenotype; D051381:Rats; D037521:Virulence Factors
chemical_list: D037521:Virulence Factors; D005912:Gliotoxin; D010453:Peptide Synthases; C104385:non-ribosomal peptide synthase