Comparative and functional genomics of C. neoformans

项目摘要/摘要。致病真菌新生隐球菌导致生命危险 感染艾滋病患者，因此对全世界3400万人构成重大威胁 感染了艾滋病毒。最近，相关物种隐球菌已成为一种主要的致病菌。 有免疫能力的人。这个项目的长期目标是获得将导致新的 对抗真菌感染的战略。特别是，我们希望建立对 病原体在哺乳动物宿主中生长所需的因素，并确定有用的治疗靶点。在这 在这方面，铁的可获得性是宿主环境的一个关键指标，也是 病原体增殖。此外，哺乳动物主动阻止病原体接触铁的过程 因此，营养免疫和病原体必须积极地争夺铁。铁是特别的 对新生芽孢杆菌的发病机制很重要，因为这种金属的可用性不仅影响 生长，也是多糖壳的大小，这是主要的毒力因素。填补我们的空白 了解真菌病原体竞争铁的机制，第一个具体目标是 确定支持从血红素中获取铁的细胞表面蛋白的分子功能。这些 每种蛋白质都有助于血红素的强健生长，并包括一种分泌的甘露糖蛋白，这是一种候选蛋白 血红素结合蛋白以及三种铁还原酶。第二个具体目标将描述 用于血红素运输和加工的细胞内机械。插入突变筛选鉴定为25 突变导致血红素生长缺陷的基因，其中一些基因编码细胞内 贩卖机器。这一结果导致了一种假设，即血红素是通过内吞作用获得的，并且 被运送到真空中进行铁的提取和回收。已知的在特定步骤有缺陷的突变体 并将构建候选的运输功能，并测试它们处理血红素的能力。决赛 具体目的是评估血红素和铁的获取功能在新生葡萄球菌毒力中的作用。 缺乏铁获取功能组合的突变株将在小鼠吸入模型中进行测试 隐球菌病和巨噬细胞中突变体的增殖将在以下背景下进行研究 不同的铁源。这些研究将提供对以下各项相对重要性的全面看法 隐球菌病期间特定的宿主铁源和真菌摄取策略。 好了！

Project Summary/Abstract. The pathogenic fungus Cryptococcus neoformans causes life-threatening infections in AIDS patients and therefore poses a major threat to the >34 million people worldwide who are infected with HIV. The related species Cryptococcus gattii has recently emerged as a primary pathogen of immunocompetent people. The long-term goal of this project is to acquire knowledge that will lead to new strategies to combat fungal infections. In particular, we want to establish a detailed understanding of the factors required for pathogen growth in mammalian hosts and identify useful targets for therapy. In this regard, iron availability is a key indicator of the host environment as well as an essential nutrient for pathogen proliferation. In addition, mammals actively withhold iron from pathogens in a process termed nutritional immunity, and pathogens must therefore aggressively compete for iron. Iron is particularly important for the pathogenesis of C. neoformans because the availability of this metal not only influences growth but also the size of the polysaccharide capsule that is the major virulence factor. To fill gaps in our understanding of the mechanisms by which fungal pathogens compete for iron, the first specific aim is to determine the molecular functions of cell surface proteins that support iron acquisition from heme. These proteins each contribute to robust growth on heme and include a secreted mannoprotein that is a candidate heme-binding protein as well as three ferric reductases. A second specific aim will characterize the intracellular machinery for heme trafficking and processing. An insertional mutagenesis screen identified 25 genes in which mutations caused growth defects on heme, and some of these genes encode intracellular trafficking machinery. This result led to the hypothesis that heme is acquired by endocytosis and transported to the vacuole for iron extraction and recycling. Mutants with defects at specific steps in known and candidate transport functions will be constructed and tested for their ability to process heme. A final specific aim will evaluate the role of heme and iron acquisition functions in the virulence of C. neoformans. Mutants lacking combinations of iron acquisition functions will be tested in mouse inhalation models of cryptococcosis and the proliferation of the mutants in macrophages will be examined in the context of different iron sources. These studies will provide a comprehensive view of the relative importance of specific host iron sources and fungal uptake strategies during cryptococcosis. !