Isolation and partial characterization of an adhesin from Fonsecaea pedrosoi.

Abstract

We showed previously that mannose and N-acetylglucosamine (GlcNAc) residues are involved in the process of adhesion of Fonsecaea pedrosoi, the causative agent of chromoblastomycosis, to epithelial cells. It was then suggested that lectin-like molecules would be involved in the interaction. In the present study, we used fluorescein isothiocyanate-labeled neoglycoproteins (bovine serum albumin [BSA]-mannose and BSA-GlcNAc) to analyze the presence of sugar-binding proteins on the surface of conidia of F. pedrosoi grown at 28 and 37 degrees C. Binding of the neoglycoproteins was measured using flow cytometry. Fungal conidia expressed high levels of binding sites for BSA-mannose and BSA-GlcNAc when grown at 37 degrees C rather than 28 degrees C. Binding was inhibited by previous incubation of the conidia in the presence of chloroquine and trypsin. Chloroquine treatment also inhibited the interaction of fungal conidia with Chinese hamster ovary cells. Extracts from the conidia, obtained using a mechanical cell homogenizer, were purified by affinity chromatography using mannose-agarose or GlcNAc-agarose column. Polyacrylamide gel electrophoresis of the purified material from both columns showed a single protein band of 50 kDa, suggesting that the same lectin-like protein recognizes both carbohydrates.