Isolation and partial characterization of an adhesin from Fonsecaea pedrosoi

We showed previously that mannose. and N-acetylglucosamine (GlcNAc) residue s are involved in the process of adhesion of Fonsecaea pedrosoi, the causat ive agent of chromoblastomycosis, to epithelial cells. It was then suggeste d that lectin-like molecules would be involved in the interaction. In the p resent study, we used fluorescein isothiocyanate-labeled neoglycoproteins ( bovine serum albumin [BSA]mannose and BSA-GlcNAc) to analyze the presence o f sugar-binding proteins on the surface of conidia of F. pedrosoi grown at 28 and 37 degreesC. Binding of the neoglycoproteins was measured using flow cytometry. Fungal conidia expressed high levels of binding sites for BSA-m annose and BSA-GlcNAc when grown at 37 degreesC rather than 28 degreesC. Bi nding was inhibited by previous incubation of the conidia in the presence o f chloroquine and trypsin. Chloroquine treatment also inhibited the interac tion of fungal conidia with Chinese hamster ovary cells. Extracts from the conidia, obtained using a mechanical cell homogenizer, were purified by aff inity chromatography using marmose-agarose or GlcNAc-agarose column. Polyac rylamide gel electrophoresis of the purified material from both columns sho wed a single protein band of 50 kDa, suggesting that the same lectin-like p rotein recognizes both carbohydrates.