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首页> 外文期刊>Infection and immunity >Identification of N-acetylneuraminic acid and its 9-O-acetylated derivative on the cell surface of Cryptococcus neoformans: influence on fungal phagocytosis.
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Identification of N-acetylneuraminic acid and its 9-O-acetylated derivative on the cell surface of Cryptococcus neoformans: influence on fungal phagocytosis.

机译：新型隐球菌细胞表面N-乙酰神经氨酸及其9-O-乙酰化衍生物的鉴定：对真菌吞噬作用的影响。

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Sialic acids from sialoglycoconjugates present at the cell surface of Cryptococcus neoformans yeast forms were analyzed by high-performance thin-layer chromatography, binding of influenza A and C virus strains, enzymatic treatment, and flow cytofluorimetry with fluorescein isothiocyanate-labeled lectins. C. neoformans yeast forms grown in a chemically defined medium contain N-acetylneuraminic acid and its 9-O-acetylated derivative. A density of 3 x 10(6) residues of sialic acid per cell was found in C. neoformans. Sialic acids in cryptococcal cells are glycosidically linked to galactopyranosyl units as inferred from the increased reactivity of neuraminidase-treated yeasts with peanut agglutinin. N-Acetylneuraminic acids are alpha-2,6 and alpha-2,3 linked, as indicated by using virus strains M1/5 and M1/5 HS8, respectively, as agglutination probes. The alpha-2,6 linkage markedly predominated. These findings were essentially confirmed by the interaction of cryptococcal cells with the lectins Sambucus nigra agglutinin and Maackia amurensis agglutinin. We also investigated whether the sialyl residues present in C. neoformans are involved in the fungal interaction with a cationic solid-phase substrate and with mouse resident macrophages. Adhesion of yeast cells to poly-L-lysine was mediated, in part, by sialic acid residues, since the number of adherent cells was markedly reduced after treatment with bacterial neuraminidase. The enzymatic removal of sialic acids also made C. neoformans yeast cells more susceptible to endocytosis by macrophages. The results show that sialic acids are components of the cryptococcal cell surface that contribute to its negative charge and protect yeast forms against phagocytosis.
机译：通过高效薄层色谱，甲型和丙型流感病毒株的结合，酶处理以及用荧光素异硫氰酸酯标记的凝集素进行流式细胞荧光分析，分析了新隐球菌酵母形式细胞表面存在的唾液酸共轭物的唾液酸。在化学成分确定的培养基中生长的新孢梭菌酵母形式含有N-乙酰神经氨酸及其9-O-乙酰化衍生物。在新形成梭状芽胞杆菌中发现每个细胞的唾液酸残基密度为3 x 10（6）。从神经氨酸酶处理过的酵母与花生凝集素的反应性增加可以推断，隐球菌细胞中的唾液酸与半乳糖吡喃糖基单元糖基连接。如分别使用病毒株M1 / 5和M1 / 5 HS8作为凝集探针所示，N-乙酰神经氨酸是α-2,6和α-2,3连接的。 alpha-2,6连锁明显占优势。这些发现基本上由隐球菌细胞与凝集素黑接骨木凝集素和黑毛黑麦凝集素的相互作用所证实。我们还调查了新孢子虫中存在的唾液酸残基是否参与与阳离子固相底物和小鼠驻留巨噬细胞的真菌相互作用。酵母细胞对聚-L-赖氨酸的粘附部分地由唾液酸残基介导，因为在用细菌神经氨酸酶处理后，粘附细胞的数量明显减少。唾液酸的酶促去除也使新孢梭菌酵母细胞更易于被巨噬细​​胞内吞。结果表明，唾液酸是隐球菌细胞表面的组分，有助于其负电荷并保护酵母形式免于吞噬作用。

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