Sialylglycoconjugates and sialyltransferase activity in the fungus Cryptococcus neoformans

Sialylglycoconjugates and sialyltransferase activity in the fungus Cryptococcus neoformans

Autor Rodrigues, M. L. Google Scholar
Dobroff, ASS Google Scholar
Couceiro, ENDS Google Scholar
Alviano, C. S. Google Scholar
Schauer, R. Google Scholar
Travassos, L. R. Google Scholar
Instituição Universidade Federal do Rio de Janeiro (UFRJ)
Universidade Federal de São Paulo (UNIFESP)
Univ Kiel
Resumo Cryptococcus neoformans is a fungal pathogen associated with systemic mycoses in up to 10% of AIDS patients. C. neoformans yeasts express sialic acids on the cell wall, where they play an anti-phagocytic role, and may represent a virulence factor at the initial phase of infection. Since the nature of the sialic acid-carrying components is undefined in C. neoformans, our aim in the present work was to identify sialylated molecules in this fungus and study the sialylation process. C. neoformans yeast forms were cultivated in a chemically defined medium free of sialic acids, to search for autologous sialylglycoconjugates. Sialylated glycolipids were not detected. Two glycoproteins with molecular masses of 38 and 67 kDa were recognized by Sambucus nigra agglutinin, an alpha2,6-sialic acid-specific lectin. the 67 kDa glycoprotein also interacted with Influenza C virus, but not with Limax flavus agglutinin, suggesting the presence of the 9-O-acetylated sialic acid derivative as a constituent of the oligosaccharide chains. A partially purified protein fraction from cryptococcal yeast forms was able to transfer sialic acid from CMP-Neu5Ac to both N-(acetyl-1-C-14)-lactosamine and asialofetuin. Additional evidence for a sialyltransferase in C. neoformans was obtained through the reactivity of fungal proteins with rabbit anti-rat alpha2,6 sialyltransferase polyclonal antibody. Our results indicate that sialic acids in C. neoformans are linked to glycoproteins, which are sialylated by the action of a fungal sialyltransferase. This is the first demonstration of this biosynthetic step in pathogenic fungi. Published in 2003.
Assunto Cryptococcus neoformans
O-acetylated sialic acid
Idioma Inglês
Data 2002-03-01
Publicado em Glycoconjugate Journal. Dordrecht: Kluwer Academic Publ, v. 19, n. 3, p. 165-173, 2002.
ISSN 0282-0080 (Sherpa/Romeo, fator de impacto)
Editor Kluwer Academic Publ
Extensão 165-173
Direito de acesso Acesso restrito
Tipo Artigo
Web of Science WOS:000183555200002

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