Chemical structure of  -galactofuranose-containing polysaccharide and O-linked oligosaccharides obtained from the cell wall of pathogenic dematiaceous fungus Fonsecaea pedrosoi

The trypsinized cell walls of Group C streptococci contain two components, the group-specific carbohydrate and a mucopeptide polymer. Hot formamide extraction of Group C cell walls results in a soluble group-specific carbohydrate fraction and an insoluble mucopeptide residue. This mucopeptide, similar in composition to that of Groups A and A-variant streptococci, contains N-acetylglucosamine, N-acetylmuramic acid, alanine, glutamic acid, lysine, and glycine. It is dissolved by the muralytic enzymes, including lysozyme, which does not attack the whole cell wall. Lysis of the cell wall by phage-associated lysin results in the release of soluble fragments composed of the elements of mucopeptide. Group C carbohydrate extracted with formamide is composed primarily of N-acetylgalactosamine and rhamnose. Serological studies suggest that the specificity of Group C carbohydrate is determined by the N-acetylgalactosamine.

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Structure, Cellular Distribution, Antigenicity, and Biological Functions of Fonsecaea pedrosoi Ceramide Monohexosides

Infection and Immunity ◽

10.1128/iai.73.12.7860-7868.2005 ◽

2005 ◽

Vol 73 (12) ◽

pp. 7860-7868 ◽

Cited By ~ 35

Author(s):

Leonardo Nimrichter ◽

Mariana D. Cerqueira ◽

Eduardo A. Leitão ◽

Kildare Miranda ◽

Ernesto S. Nakayasu ◽

...

Keyword(s):

Cell Wall ◽

Structural Difference ◽

Structural Diversity ◽

Fungal Species ◽

Hydroxyl Group ◽

Current Evidence ◽

Fonsecaea Pedrosoi ◽

Fungal Cell ◽

Long Chain Base ◽

Antifungal Action

ABSTRACT Monohexosylceramides (CMHs, or cerebrosides) have been reported as membrane and cell wall constituents of both pathogenic and nonpathogenic fungi, presenting remarkable differences in their ceramide moiety compared to mammalian CMHs. Current evidence suggests that CMHs are involved in fungal differentiation and growth and contribute to host immune response. Here we describe a structural diversity between cerebrosides obtained from different forms of the human pathogen Fonsecaea pedrosoi. The major CMH species produced by conidial forms displayed the same structure previously demonstrated by our group for mycelia, an N-2′-hydroxyhexadecanoyl-1-β-d-glucopyranosyl-9-methyl-4,8-sphingadienine. However, the major cerebroside species purified from sclerotic cells carries an additional hydroxyl group, bound to its long-chain base. The structural difference between cerebrosides from mycelial and sclerotic cells was apparently not relevant for their antigenicity, since they were both recognized at similar levels by sera from individuals with chromoblastomycosis and a monoclonal antibody to a conserved cerebroside structure. Preincubation of fungal cells with anti-CMH monoclonal antibodies had no effect on the interaction of F. pedrosoi sclerotic cells with murine macrophages. In contrast to what has been described for other fungal species, sclerotic bodies are resistant to the antifungal action of anti-CMH antibodies. Immunofluorescence analysis showed that recognition of sclerotic cells by these antibodies only occurs at cell wall regions in which melanization is not evident. Accordingly, melanin removal with alkali results in an increased reaction of fungal cells with anti-CMH antibodies. Our results indicate that cerebroside expression in F. pedrosoi cells is associated with dimorphism and melanin assembly on the fungal cell wall.

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