Comparative and functional genomics of C. neoformans

项目概要/摘要。致病真菌新型隐球菌导致危及生命 艾滋病患者的感染，因此对全世界超过3400万艾滋病患者构成重大威胁。 感染了艾滋病病毒相关物种格特隐球菌（Cryptococcus gattii）最近已成为大肠杆菌的主要病原体。 免疫功能正常的人。这个项目的长期目标是获得知识，将导致新的 对抗真菌感染的策略。特别是，我们希望建立一个详细的了解， 病原体在哺乳动物宿主中生长所需的因子，并确定有用的治疗靶点。在这 就这一点而言，铁的可用性是宿主环境的一个关键指标，也是一种必需的营养素 病原体增殖此外，哺乳动物积极地阻止铁从病原体在一个过程中被称为 因此，营养免疫和病原体必须积极竞争铁。铁特别 对C.因为这种金属的可用性不仅影响 生长，但也是多糖胶囊的大小，这是主要的毒力因子。为了填补我们 了解真菌病原体竞争铁的机制，第一个具体目标是 确定细胞表面蛋白质的分子功能，支持从血红素铁收购。这些 每种蛋白质都有助于血红素上的稳健生长，包括一种分泌的甘露糖蛋白， 血红素结合蛋白以及三种铁还原酶。第二个具体目标将是 血红素运输和加工的细胞内机制。插入诱变筛选鉴定了25个 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血红素是通过内吞作用获得的假说， 运输到液泡中进行铁提取和回收。在已知基因组中特定步骤有缺陷的突变体 并且将构建候选运输函数并测试它们处理血红素的能力。最终 具体的目的是评估血红素和铁获得功能在C.新人类 缺乏铁获取功能组合的突变体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检查： 不同的铁源这些研究将提供一个全面的观点， 特异性宿主铁源与隐球菌病真菌摄取策略 !

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. !