title: Functional Investigation of Iron-Responsive Microsomal Proteins, including MirC, inAspergillus fumigatus.
abstract: The functionality of many microsome-associated proteins which exhibit altered abundance in response to iron limitation inAspergillus fumigatusis unknown. Here, we generate and characterize eight gene deletion strains, and of most significance reveal that MirC (AFUA_2G05730) contributes to the maintenance of intracellular siderophore [ferricrocin (FC)] levels, augments conidiation, confers protection against oxidative stress, exhibits an intracellular localization and contributes to fungal virulence in theGalleria mellonellaanimal model system. FC levels were unaffected following deletion of all other genes encoding microsome-associated proteins. MirC does not appear to play a role in either siderophore export from, or uptake into,A. fumigatus. Label-free quantitative proteomic analysis unexpectedly revealed increased abundance of siderophore biosynthetic enzymes. In addition, increased expression ofhapX(7.2 and 13.8-fold at 48 and 72 h, respectively;p< 0.001) was observed in ΔmirCcompared to wild-type under iron-replete conditions by qRT-PCR. This was complemented by significantly elevated extracellular triacetylfusarinine C (TAFC;p< 0.01) and fusarinine C (FSC;p< 0.05) siderophore secretion. We conclude that MirC plays an important role in FC biosynthesis and contributes to the maintenance of iron homeostasis inA. fumigatus.
authors.affiliation: Department of Biology, Maynooth University Kildare, Ireland.
authors.forename: Eoin D
authors.initials: ED
authors.lastname: Mulvihill
authors.affiliation: Department of Biology, Maynooth University Kildare, Ireland.
authors.forename: Nicola M
authors.initials: NM
authors.lastname: Moloney
authors.affiliation: Department of Biology, Maynooth University Kildare, Ireland.
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Owens
authors.affiliation: Department of Biology, Maynooth UniversityKildare, Ireland; Department of Biochemistry, University of CambridgeCambridge, UK.
authors.forename: Stephen K
authors.initials: SK
authors.lastname: Dolan
authors.affiliation: Department of Biology, Maynooth University Kildare, Ireland.
authors.forename: Lauren
authors.initials: L
authors.lastname: Russell
authors.affiliation: Department of Biology, Maynooth University Kildare, Ireland.
authors.forename: Sean
authors.initials: S
authors.lastname: Doyle
keywords: NRPS; fungal proteomics; membrane proteins; oxidative stress; siderophore