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首页> 外文期刊>Eukaryotic cell >Lipid Rafts in Cryptococcus neoformans Concentrate the Virulence Determinants Phospholipase B1 and Cu/Zn Superoxide Dismutase
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Lipid Rafts in Cryptococcus neoformans Concentrate the Virulence Determinants Phospholipase B1 and Cu/Zn Superoxide Dismutase

机译：新型隐球菌的脂质筏集中了毒性决定因素磷脂酶B1和铜/锌超氧化物歧化酶

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Lipid rafts have been identified in the membranes of mammalian cells, the yeast Saccharomyces cerevisiae, and the pathogenic fungus Candida albicans. Formed by a lateral association of sphingolipids and sterols, rafts concentrate proteins carrying a glycosylphosphatidylinositol (GPI) anchor. We report the isolation of membranes with the characteristics of rafts from the fungal pathogen Cryptococcus neoformans. These characteristics include insolubility in Triton X-100 (TX100) at 4°C, more-buoyant density within a sucrose gradient than the remaining membranes, and threefold enrichment with sterols. The virulence determinant phospholipase B1 (PLB1), a GPI-anchored protein, was highly concentrated in raft membranes and could be displaced from them by treatment with the sterol-sequestering agent methyl-β-cyclodextrin (MβCD). Phospholipase B enzyme activity was inhibited in the raft environment and increased 15-fold following disruption of rafts with TX100 at 37°C. Treatment of viable cryptococcal cells in suspension with MβCD also released PLB1 protein and enzyme activity, consistent with localization of PLB1 in plasma membrane rafts prior to secretion. The antioxidant virulence factor Cu/Zn superoxide dismutase (SOD1) was concentrated six- to ninefold in raft membrane fractions compared with nonraft membranes, whereas the cell wall-associated virulence factor laccase was not detected in membranes. We hypothesize that raft membranes function to cluster certain virulence factors at the cell surface to allow efficient access to enzyme substrate and/or to provide rapid release to the external environment.
机译：已经在哺乳动物细胞，酵母菌，致病真菌白念珠菌的膜中鉴定出了脂筏。木筏由鞘脂和固醇的侧向缔合形成，浓缩了带有糖基磷脂酰肌醇（GPI）锚的蛋白质。我们报道了真菌病原体新型隐球菌的筏板分离特征。这些特征包括Triton X-100（TX100）在4°C下的不溶性，蔗糖梯度内的浮力比其余膜高，并且固醇含量提高了三倍。决定力的磷脂酶B1（PLB1）是一种GPI锚定蛋白，高度浓缩在筏膜上，可以通过固醇-螯合剂甲基-β-环糊精（MβCD）处理将其置换。磷脂酶B酶活性在木筏环境中受到抑制，并在37°C下用TX100破坏木筏后增加了15倍。用MβCD处理悬浮液中的活隐球菌细胞也会释放PLB1蛋白和酶活性，这与分泌前PLB1在质膜筏中的定位一致。与非筏板膜相比，筏板膜部分中的抗氧化剂毒力因子Cu / Zn超氧化物歧化酶（SOD1）浓缩了6至9倍，而在膜中未检测到与细胞壁相关的毒因子漆酶。我们假设筏膜的功能是将某些毒力因子聚集在细胞表面，以有效利用酶底物和/或提供向外部环境的快速释放。

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