During infection, invading microorganism and host enter a struggle for iron on which the outcome of infection is decided. Aspergillus fumigatus is the predominant causative agent of life-threatening Invasive Aspergillosis and possesses sophisticated adaptations to iron starvation. Importantly, the production of iron-chelating siderophores in vivo is essential to virulence. Characterisation of the iron-starved proteome of A. fumigatus is, therefore, warranted to understand the role of iron at this host: pathogen interface and to dissect the basis of siderophores as therapeutic targets.
A. fumigatus was grown in iron-replete and -deplete conditions, and secreted, microsomal, and mycelial protein fractions were extracted and analysed by Label-Free Quantitative proteomics. Microsomal (n = 96), mycelial (n = 789), and secreted (n = 182) proteins with increased abundance (p < 0.05) under iron limitation were identified. Additionally, microsomal (n = 135), mycelial (n = 512), and secreted (n = 238) proteins with decreased abundance were identified. Functional categories significantly represented (p < 0.05) in the ironstarved proteome included cell wall organisation, secondary metabolite production, cellular respiration and transport, including putative siderophore transporters. Siderophore, fusarinine C (FSC) was RP-HPLC purified and fluorescently derivatized. This permitted visualisation of the uptake and subsequent fate of the iron: siderophore complex, and provides a method to evaluate the therapeutic strategies that impede siderophoreuptake.
This work has shed light on the networks of proteins affected by iron limitation in A. fumigatus. Specifically, the cellular localisation and putative proteins mediating the fate of siderophores in A. fumigatus have been further unveiled.
Full conference title:
- MS 2017