Isolation, characterization, and localization of a capsule-associated gene, CAP10, of Cryptococcus neoformans
Isolation, characterization, and localization of a capsule-associated gene, CAP10, of Cryptococcus neoformans
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DOI：
10.1128/jb.181.18.5636-5643.1999
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发表时间：
1999-09-01
影响因子：
3.2
通讯作者：
Kwon-Chung, KJ
中科院分区：
文献类型：
--
作者：
Chang, YC;Kwon-Chung, KJ
新型隐球菌是一种致病真菌，最常影响中枢神经系统，并主要在艾滋病患者中引起致命的脑膜脑炎。这种真菌产生厚厚的胞外多糖胶囊，被公认为毒力因子。在这里，我们描述了胶囊形成所需的新基因 CAP10 的分离和表征。无荚膜 cap10 突变体的互补产生了有荚膜菌株，而从野生菌株中删除 CAP10 则产生了无荚膜表型。血凝素表位标记的 Cap10p 的分子量约为 73 kDa，与序列分析预测的大小相似。当 CRP10 与杂合绿色荧光蛋白构建体融合时，荧光信号在细胞质中以斑块的形式出现。使用报告基因构建体，我们发现 CAP10 在晚期稳定期细胞中高水平表达。此外，我们发现CAP10的表达水平受到转录因子STE12α的调节。删除 STE12 alpha！下调CAP10的表达水平，而STE12α的过表达则上调CAP10的表达水平。动物模型研究表明，CAP10 基因的缺失会导致毒力丧失，而 cap10 的无荚膜表型的补充可恢复毒力。因此，CAP10 是胶囊形成和毒力所必需的。
Cryptacoccus neoformans is a pathogenic fungus which most commonly affects the central nervous system and causes fatal meningoencephalitis primarily in patients with AIDS. This fungus produces a thick extracellular polysaccharide capsule which is well recognized as a virulence factor. Here, we describe the isolation and characterization of a novel gene, CAP10, which is required for capsule formation. Complementation of the acapsular cap10 mutant produced an encapsulated strain and the deletion of CAP10 from a wild strain resulted in an acapsular phenotype. The molecular mass of the hemagglutinin epitope-tagged Cap10p is about 73 kDa, which is similar to the size predicted from sequence analysis. When CRP10 was fused with a hybrid green fluorescent protein construct, the fluorescence signals appeared as patches in the cytoplasm. Using a reporter gene construct, we found that CAP10 was expressed at high levels in late-stationary-phase cells. In addition, we found that the expression levels of CAP10 are modulated by the transcriptional factor STE12 alpha. Deletion of STE12 alpha! downregulated the expression levels of CAP10 while overexpression of STE12 alpha upregulated the expression levels of CAP10. Animal model studies indicate that deletion of the CAP10 gene results in the loss of virulence, and complementation of the acapsular phenotype of cap10 restores virulence. Thus, CAP10 is required for capsule formation and virulence.