Proteomic Analysis Reveals That Iron Availability Alters the Metabolic Status of the Pathogenic Fungus Paracoccidioides brasiliensis

Abstract

Paracoccidioides brasiliensis is a thermodimorphic fungus and the causative agent of paracoccidioidomycosis (PCM). The ability of P. brasiliensis to uptake nutrients is fundamental for growth, but a reduction in the availability of iron and other nutrients is a host defense mechanism many pathogenic fungi must overcome. Thus, fungal mechanisms that scavenge iron from host may contribute to P. brasiliensis virulence. In order to better understand how P. brasiliensis adapts to iron starvation in the host we compared the two-dimensional (2D) gel protein profile of yeast cells during iron starvation to that of iron rich condition. Protein spots were selected for comparative analysis based on the protein staining intensity as determined by image analysis. A total of 1752 protein spots were selected for comparison, and a total of 274 out of the 1752 protein spots were determined to have changed significantly in abundance due to iron depletion. Ninety six of the 274 proteins were grouped into the following functional categories; energy, metabolism, cell rescue, virulence, cell cycle, protein synthesis, protein fate, transcription, cellular communication, and cell fate. A correlation between protein and transcript levels was also discovered using quantitative RT-PCR analysis from RNA obtained from P. brasiliensis under iron restricting conditions and from yeast cells isolated from infected mouse spleens. In addition, western blot analysis and enzyme activity assays validated the differential regulation of proteins identified by 2-D gel analysis. We observed an increase in glycolytic pathway protein regulation while tricarboxylic acid cycle, glyoxylate and methylcitrate cycles, and electron transport chain proteins decreased in abundance under iron limiting conditions. These data suggest a remodeling of P. brasiliensis metabolism by prioritizing iron independent pathways.

The genome of opportunistic fungal pathogen Fusarium oxysporum carries a unique set of lineage-specific chromosomes

“…Enrichment of proteins with metal ion-binding functions. One of the most significantly enriched functional categories of NRRL 32931 LS genes was metal ion binding (Supplementary Data 8) related to iron homeostasis, a function reported for many human pathogenic fungi 45,46,47,48 . Among these were three secreted copper-binding proteins with oxidoreductase activities, all located on LS chromosomes and surrounded by transposable elements (FOYG_17133 and FOYG_17127 in chr13 and FOYG_16888 in chr15).…”

Analysis of the Secretomes of Paracoccidioides Mycelia and Yeast Cells

“…Spots of interest were manually excised and digested as previously described [32], [33]. Briefly, the gel pieces were resuspended in 100 μL acetonitrile (ACN) and dried in a speed vacuum.…”

Effects of iron limitation on growth and carbon metabolism in oceanic and coastal heterotrophic bacteria

“…The remodeling of the cellular metabolism in response to Fe availability has been extensively studied in organisms such as yeast (Kaplan et al 2006), fungi (Parente et al 2011;Philpott et al 2012), and phytoplankton (Strzepek et al 2011), but studies on marine heterotrophic bacteria have mainly been focused on Fe uptake systems (Armstrong et al 2004;Hopkinson and Barbeau 2011). To date, the understanding of how Fe limitation in marine heterotrophic bacteria affects the pathways of C metabolism is a major challenge.…”