Protein Composition of Infectious Spores Reveals Novel Sexual Development and Germination Factors in Cryptococcus.
Protein Composition of Infectious Spores Reveals Novel Sexual Development and Germination Factors in Cryptococcus.
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DOI：
10.1371/journal.pgen.1005490
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发表时间：
2015-08
期刊：
影响因子：
4.5
通讯作者：
Hull CM
中科院分区：
文献类型：
--
作者：
Huang M;Hebert AS;Coon JJ;Hull CM
孢子是生命树中不同生物长期生存所需的基本细胞类型，也是真菌繁殖、持久和扩散的标志。在人类真菌病原体中，孢子被认为是有感染性的颗粒，但对这种强大的细胞类型知之甚少。在这里，我们使用引起脑膜炎的真菌新生隐球菌来确定孢子驻留蛋白在孢子生物学中的作用。利用高灵敏的纳米级液相色谱/质谱仪，我们比较了孢子和营养细胞(酵母)的蛋白质组，鉴定了18个在孢子中特异富含的蛋白质。编码这些蛋白质的基因被删除，结果菌株被评估可识别的表型。我们推测，富含孢子的蛋白质将优先参与孢子特有的过程，如休眠、抗逆性和萌发。然而，令人惊讶的是，大多数突变体在性发育方面存在缺陷，性发育是孢子形成的过程。队列中的一个突变体在孢子特有的萌发过程中存在缺陷，特别是在营养生长的启动方面表现出延迟。因此，通过使用这种深入的蛋白质组学方法作为筛选细胞类型特异性蛋白的工具，并将其与分子遗传学相结合，我们成功地鉴定了新生隐孢子虫的第一个萌发因子。我们还鉴定了许多在性发育和孢子组成中具有未知功能的蛋白质。我们的发现首次提供了对感染孢子的基本蛋白质成分的洞察，并揭示了致病真核生物中感染颗粒产生和孢子组成之间意想不到的分子联系。孢子是一种关键的细胞类型，它允许从细菌到真菌再到植物的各种生物长期生存。在真菌中，孢子通常是在生长条件较差的时候形成的，然后孢子可以分散到更有利的环境中，重新开始生长。一些环境真菌的孢子会导致人类患上致命疾病。在这里，我们使用了引起脑膜炎的新生隐球菌来确定富含孢子的蛋白在孢子生物学中的作用。使用蛋白质组学和遗传学相结合的方法，我们鉴定了18种富含孢子的蛋白质，敲除了每一种蛋白质的编码基因，并在广泛的一系列分析中评估了所产生的菌株的表型。我们预测突变菌株可能会在孢子特有的过程中表现出缺陷，但相反，我们发现大多数菌株在有性发育过程中存在缺陷，有性发育是形成孢子的过程。只有一个突变体在孢子特有的过程(萌发)中表现出缺陷。我们的数据显示，许多孢子代表的蛋白质与孢子前发育过程有关，而不是与孢子固有的特性或过程有关。这些发现表明，导致孢子生物发生的发育过程与侵染孢子的组成之间存在着以前未知的分子联系。
Spores are an essential cell type required for long-term survival across diverse organisms in the tree of life and are a hallmark of fungal reproduction, persistence, and dispersal. Among human fungal pathogens, spores are presumed infectious particles, but relatively little is known about this robust cell type. Here we used the meningitis-causing fungus Cryptococcus neoformans to determine the roles of spore-resident proteins in spore biology. Using highly sensitive nanoscale liquid chromatography/mass spectrometry, we compared the proteomes of spores and vegetative cells (yeast) and identified eighteen proteins specifically enriched in spores. The genes encoding these proteins were deleted, and the resulting strains were evaluated for discernable phenotypes. We hypothesized that spore-enriched proteins would be preferentially involved in spore-specific processes such as dormancy, stress resistance, and germination. Surprisingly, however, the majority of the mutants harbored defects in sexual development, the process by which spores are formed. One mutant in the cohort was defective in the spore-specific process of germination, showing a delay specifically in the initiation of vegetative growth. Thus, by using this in-depth proteomics approach as a screening tool for cell type-specific proteins and combining it with molecular genetics, we successfully identified the first germination factor in C. neoformans. We also identified numerous proteins with previously unknown functions in both sexual development and spore composition. Our findings provide the first insights into the basic protein components of infectious spores and reveal unexpected molecular connections between infectious particle production and spore composition in a pathogenic eukaryote. Spores are a critical cell type that allow long-term survival of diverse organisms from bacteria to fungi to plants. Among fungi, spores are often formed when growth conditions are poor; spores can then disperse to more favorable environments and reinitiate growth. Spores of some environmental fungi can cause fatal disease in humans. Here we used the meningitis-causing yeast Cryptococcus neoformans to determine the roles of spore-enriched proteins in spore biology. Using a combined proteomics-genetics approach, we identified eighteen spore-enriched proteins, knocked out the genes encoding each of them, and assessed the resulting strains for phenotypes in a broad array of assays. We predicted that mutant strains would be likely to show defects in spore-specific processes, but instead, we discovered that the majority harbored defects in sexual development, the process by which spores are formed. Only one mutant exhibited a defect in a spore-specific process (germination). Our data reveal that many spore-represented proteins are associated with pre-spore developmental processes, rather than intrinsic spore-specific properties or processes. These findings indicate a previously unknown molecular connection between the developmental process that results in spore biogenesis and the composition of infectious spores.