Comparative and functional genomics of C. neoformans

新型隐球菌的比较和功能基因组学

• 批准号: 9020184
• 负责人: JAMES W KRONSTAD
• 金额: $ 29.04万
• 依托单位: UNIVERSITY OF BRITISH COLUMBIA
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-01 至 2019-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9020184
• 关键词: AIDS/HIV problem; Acquired Immunodeficiency Syndrome; Affinity; Anabolism; Antifungal Agents; Azoles; Breathing; Cell Surface Proteins; Cell surface; Centers for Disease Control and Prevention (U.S.); Cryptococcus gattii; Cryptococcus neoformans; Cryptococcus neoformans infection; Defect; Disease; Drug usage; Endocytosis; Environment; Ergosterol; Evaluation; Funding; Genes; Goals; Growth; HIV; Health; Heme; Heme Iron; Hemoglobin; Human; Immune system; Immunity; Immunocompetent; In Vitro; Infection; Infection Control; Insertional Mutagenesis; Iron; Iron-Binding Proteins; Knowledge; Lead; Life; Mammals; Melanins; Meningoencephalitis; Metalloporphyrins; Metals; Modeling; Molecular; Mus; Mutation; Mycoses; Nutrient; Nutritional; Pathogenesis; Patients; Pharmaceutical Preparations; Polysaccharides; Predisposition; Process; Proteins; Protoporphyrins; Recycling; Regulation; Research; Resistance; Rewards; Role; Source; System; Testing; Therapeutic; Toxic effect; Vacuole; Virulence; Virulence Factors; capsule; combat; comparative genomics; disorder prevention; extracellular; functional genomics; fungus; heme-binding protein; iron (III) reductase; macrophage; mannoproteins; mutant; novel; novel therapeutic intervention; pandemic disease; pathogen; response; targeted treatment; therapeutic target; trafficking; trait; uptake

DESCRIPTION (provided by applicant): 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 availabilit 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 roe 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.

描述（申请人提供）：病原性真菌新型隐球菌会导致艾滋病患者出现危及生命的感染，因此对全球超过3400万艾滋病毒感染者构成重大威胁。相关物种隐球菌gattii最近已成为免疫功能正常的人的主要病原体。该项目的长期目标是获得知识，这将导致新的战略，以打击真菌感染。特别是，我们希望建立一个详细的了解所需的哺乳动物宿主中的病原体生长的因素，并确定有用的治疗目标。在这方面，铁的可利用性是宿主环境的关键指标，也是病原体增殖的必需营养素。此外，哺乳动物在一个称为营养免疫的过程中积极地阻止病原体吸收铁，因此病原体必须积极地竞争铁。铁在C.这是因为这种金属的可利用性不仅影响生长，而且影响作为主要毒力因子的多糖荚膜的大小。为了填补我们对真菌病原体竞争铁的机制的理解中的空白，第一个具体目标是确定支持从血红素获得铁的细胞表面蛋白的分子功能。这些蛋白质各自有助于血红素上的稳健生长，并且包括作为候选血红素结合蛋白的分泌甘露糖蛋白以及三种铁还原酶。第二个具体目标将表征血红素运输和加工的细胞内机制。插入突变筛选确定了25个基因，其中突变导致血红素生长缺陷，其中一些基因编码细胞内运输机械。这一结果导致了血红素通过内吞作用获得并运输到液泡中进行铁提取和再循环的假设。将构建在已知和候选转运功能的特定步骤具有缺陷的突变体，并测试其处理血红素的能力。最后一个具体的目的是评估血红素和铁的获得在C.新人类将在隐球菌病的小鼠吸入模型中测试缺乏铁获取功能组合的突变体，并将在不同铁源的背景下检查巨噬细胞中突变体的增殖。这些研究将提供一个全面的观点，在隐球菌病的相对重要性，特定的主机铁源和真菌的摄取策略。