Resumo

Paracoccicoidioides is the etiological agent of paracoccidioidomycosis (PCM), which is considered the first cause of disease mortality among the systemic mycoses in Brazil. To establish infection the fungus has to adhere to host components. The interaction with components of the extracellular matrix (ECM) has been correlated with the ability of adhesion and invasion of different organisms during the infection. Human plasminogen (hPlg) is a proenzyme of blood plasma that presents fibrinolytic activity when it activated into plasmin, and ability to degrade ECM components, favoring the spread of microorganisms to deeper tissues. Pathogens interact with human plasminogen through proteins called adhesins. Enolase was identified on the surface of Paracoccidioides and features the ability to bind to plasminogen, to activate it into plasmin and to participate in the degradation of ECM components and of adherence to macrophages. Thus, it is important to identify other plasminogen binding proteins of Paracoccidioides, which is a significant contribution to the study the virulence of the fungus. In this work, we identified through Far Western and proteomic analysis (2D gels), 30 proteins from the soluble and secreted fractions of Paracoccidioides that are plasminogen binding molecules. The protein fructose 1,6-bisphosphate aldolase (FBA) was detected in the two analyzed fractions and has been described in other organisms as a plasminogen binding protein. For validation tests, a recombinant protein FBA (rFBA) of Paracoccidioides was produced that presents ability to bind to plasminogen and promotes the generation of plasmin in the presence of the plasminogen activator (tPA). This binding favored degradation of fibrinogen, a substrate of plasmin, suggesting the involvement of FBA in fibrinolytic activity of the fungus. The FBA was also detected in the cell wall, where it can act to capture plasminogen, facilitating the process of adhesion and spread of the fungus. The protein was also detected in the secretome of Paracoccidioides during infection of macrophages evidencing its function adhesin and reports of its importance in the host-parasite relationship in pathogens. The data suggest that FBA of Paracoccidioides can be involved in the process of adhesion, invasion and spread of the fungus during infection.