title: Characterisation of the laccase-encoding gene abr2 of the dihydroxynaphthalene-like melanin gene cluster of Aspergillus fumigatus.
abstract: Aspergillus fumigatus is an important pathogen of the immunocompromised host. Previously, it was shown that the polyketide synthase encoded by the pksP (alb1) gene represents a virulence determinant. pksP is part of a gene cluster involved in dihydroxynaphthalene (DHN)-like melanin biosynthesis. Because a putative laccase-encoding gene (abr2) is also part of the cluster and a laccase was found to represent a virulence factor in Cryptococcus neoformans, here, the Abr2 laccase was characterised. Deletion of the abr2 gene changed the gray-green conidial pigment to a brown color and the ornamentation of conidia was reduced compared with wild-type conidia. In contrast to the white pksP mutant, the susceptibility of the Deltaabr2 mutant against reactive oxygen species (ROS) was not increased, suggesting that the intermediate of DHN-like melanin produced up to the step catalysed by Abr2 already possesses ROS scavenging activity. In an intranasal mouse infection model, the Deltaabr2 mutant strain showed no reduction in virulence compared with the wild type. In the Deltaabr2 mutant, overall laccase activity was reduced only during sporulation, but not during vegetative growth. An abr2p-lacZ gene fusion was expressed during sporulation, but not during vegetative growth confirming the pattern of laccase activity due to Abr2.
authors.affiliation: Department of Microbiology and Molecular Biology, Friedrich-Schiller-University, Jena, Germany.
authors.forename: Venelina
authors.initials: V
authors.lastname: Sugareva
authors.forename: Albert
authors.initials: A
authors.lastname: Härtl
authors.forename: Matthias
authors.initials: M
authors.lastname: Brock
authors.forename: Katrin
authors.initials: K
authors.lastname: Hübner
authors.forename: Manfred
authors.initials: M
authors.lastname: Rohde
authors.forename: Thorsten
authors.initials: T
authors.lastname: Heinekamp
authors.forename: Axel A
authors.initials: AA
authors.lastname: Brakhage
mesh_terms: D000818:Animals; D001228:Aspergillosis / Q000382:microbiology; D001232:Aspergillus fumigatus / Q000235:genetics* / Q000472:pathogenicity; D005656:Fungal Proteins / Q000235:genetics*; D005800:Genes, Fungal; D042845:Laccase / Q000235:genetics*; D008543:Melanins / Q000235:genetics*; D051379:Mice; D005810:Multigene Family; D009284:Naphthols; D014774:Virulence / Q000235:genetics
chemical_list: C423455:1,8-dihydroxynaphthalene melanin; D005656:Fungal Proteins; D008543:Melanins; D009284:Naphthols; D042845:Laccase