Iron Deprivation Modulates the Exoproteome in Paracoccidioides brasiliensis

Abstract

Fungi of the Paracoccidioides genus are the etiological agents of the systemic mycosis paracoccidioidomycosis and, when in the host, they find a challenging environment that is scarce in nutrients and micronutrients, such as Fe, which is indispensable for the survival of the pathogen. Previous studies have shown that fungi of this genus, in response to Fe deprivation, are able to synthesize and capture siderophores (Fe3+ chelators), use Fe-containing host proteins as a source of the metal, and use a non-canonical reductive pathway for Fe3+ assimilation. Despite all of these findings, there are still gaps that need to be filled in the pathogen response to metal deprivation. To contribute to the knowledge related to this subject, we obtained the exoproteome of Paracoccidioides brasiliensis (Pb18) undergoing Fe deprivation and by nanoUPLC-MSE. One hundred forty-one proteins were identified, and out of these, 64 proteins were predicted to be secreted. We also identified the regulation of several virulence factors. Among the results, we highlight Cyb5 as a secreted molecule of Paracoccidioides in the exoproteome obtained during Fe deprivation. Cyb5 is described as necessary for the Fe deprivation response of Saccharomyces cerevisiae and Aspergillus fumigatus. Experimental data and molecular modeling indicated that Cyb5 can bind to Fe ions in vitro, suggesting that it can be relevant in the arsenal of molecules related to iron homeostasis in P. brasiliensis.

Molecular Interactions of the Copper Chaperone Atx1 of Paracoccidioides brasiliensis with Fungal Proteins Suggest a Crosstalk between Iron and Copper Homeostasis

“…These were previously obtained by Petito et al (2020) [ 15 ] and Souza et al (2022) [ 21 ], respectively, in our group.…”

“…A recent study of the exoproteome of P. brasiliensis demonstrated that Fe deprivation promotes the regulation of several proteins, including Pb Cyb5. In vitro interaction assays demonstrated that Pb Cyb5 is capable of binding to inorganic Fe, and this finding was supported by molecular dynamics analyses [ 21 ].…”

“…To validate the pull-down assay, we performed Western blot analysis with the eluted proteins using the polyclonal antibodies anti- Pb Cyb5, produced upon the immunization of BALB/c mice with the recombinant Pb Cyb5 protein [ 21 ] ( Figure 1 ). Anti- Pb Cyb5 reacted with the pull-down sample, thus corroborating the assay depicted in Table 1 , confirming that this protein is among Pb Atx1 partners.…”