Proteinas de superficie de Paracoccidioides brasiliensis / Proteinas de superficie de Paracoccidioides brasiliensis

AUTOR(ES)

Nadya da Silva Castro

DATA DE PUBLICAÇÃO

2008

RESUMO

Paracoccidioides brasiliensis is a temperature dependent dimorphic fungus, the etiological agent of paracoccidioidomycosis. In human, infection starts by inhalation of fungal propagules reaching the pulmonary epithelium, where the morphogenetic conversion is correlated with changes in the cell wall composition, organization and structure. The cell wall constitute an important reservoir of immunoreactive molecules and potential target for the search of vaccine candidates. In many pathogens, the proteins with glicosilfosfatidilinositol (GPI)-anchors are immunogenic and important virulence factors. Thus, P. brasiliensis transcriptome data were analyzed for potential GPI-anchored proteins localized in plasma membrane or cell wall, as well as for proteins involved in synthesis, attachment and cleavage of the GPI anchor. The proteins were identified in several functional categories: (i) enzymes: glucanosyltransferases(1- 3), (ii) probable surface antigens, (iii) proteins involved in cell wall biosynthesis and structural role. It was identificated transcript encoding to proteins involved in GPI anchor biosynthesis and hydrolysis. In an effort to elucidate the molecular mechanisms involved in the fungus cell wall-assembling and morphogenesis it was performed the study of the β-1,3-glucanosyltransferase 3 (PbGel3). PbGel3 showed one copy in genome of this fungus with the highest level of transcript and protein in the mycelium phase. The protein was immunolocalized at the surface in both mycelium and yeast phase. The potential role of PbGel3p in cell wall biosynthesis and remodeling was evidenced by its ability to rescue the phenotype of the Saccharomyces cerevisiae gas1∆ mutant. The DFG5 (defective in filamentous growth) homologue of P. brasiliensis, a probably glycosylated and β-glucan linked cell-wall protein was also studied. Studies demonstrated that the recombinant PbDfg5p binds to extracellular matrix components, indicating that it can be important for initial steps leading of P. brasiliensis attachment and colonization of host tissues. Because of its essential biological role, unique biochemistry, structural organization and the absence of the most of their constituents in mammalians cells, the cell wall is an attractive target for the development of new antifungal agents and essential for understanding the fungal pathogenesis.

ASSUNTO(S)

paracoccidioides brasiliensis proteínas de superfície -1,3-glicanosiltransferas proteínas gpi ancoradas β medicina deficiente para o crescimento filamentoso 5 (dfg5)

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