Comparative and functional genomics of C. neoformans

项目概要/摘要。最近的估计表明，由病原体引起的脑膜脑炎 真菌新型隐球菌占艾滋病患者死亡的15%。沿着其它真菌 病原体、C.因此，新型艾滋病毒感染者是全世界3700万艾滋病毒感染者的主要威胁。一 一个最初被命名为加特隐球菌的相关物种的复合体最近成为了一个主要的 免疫力正常的人的病原体。我们研究计划的长期目标是获得 这些知识将导致对抗隐球菌感染的新策略。特别是，我们正在努力 详细了解真菌在脊椎动物宿主中增殖所需的因素。在 特别是，我们寻求确定新的治疗靶点。我们的重点是铁作为一种必需的营养素， 病原体增殖和宿主环境的重要指标。铁尤其重要 因为哺乳动物通过一种称为营养免疫的过程主动地将铁从病原体中保留下来。 因此，病原体必须能够成功地竞争铁才能引起疾病。我们有 结果表明，铁对C.以及多糖胶囊的大小， 是主要的毒力因子。我们的努力集中在表征铁传感机制 以及利用所述调节信息来鉴定铁获取所需的靶。第一个具体目标 是表征单硫醇谷氧还蛋白Grx 4作为铁可用性的关键传感器。Grx 4与 铁调节因子Cir 1和蛋白质调节铁稳态和毒力因子的表达。 我们试图了解铁传感的机制以及铁信号如何影响基因表达。 第二个具体目标将研究Grx 4与转录因子网络的相互作用。两 已经确定了强有力的候选者（HapX和Gat 201），以及 这些具有Grx 4的蛋白质将被表征。最后一个具体目标是基于高产的遗传 筛选确定血红素运输的细胞内机制的组成部分。缺乏突变体 血红素获取的运输函数将在小鼠吸入模型中构建和测试， 隐球菌病此外，已经开发了血红素传感器来检测血红素在贩运中的可用性 突变体的培养和隐球菌细胞在不同的宿主组织位置增殖期间。总的来说， 这些研究将提供一个综合的观点，铁的感应与吸收的调节 在隐球菌病期间至关重要的策略。 !

Project Summary/Abstract. Recent estimates indicate that meningoencephalitis caused by the pathogenic fungus Cryptococcus neoformans is responsible 15% of deaths in AIDS patients. Along with other fungal pathogens, C. neoformans is therefore a major threat to the 37 million people worldwide living with HIV. A complex of related species originally designated Cryptococcus gattii has recently emerged as a primary pathogen of immunocompetent people. The long-term goal of our research program is to acquire knowledge that will lead to new strategies to combat cryptococcal infections. In particular, we are working to acquire a detailed understanding of the factors required for fungi to proliferate in vertebrate hosts. In particular, we seek to identify new targets for therapy. Our focus is on iron as an essential nutrient for pathogen proliferation and an important indicator of the host environment. Iron is especially important because mammals actively withhold iron from pathogens through a process called nutritional immunity. Pathogens must therefore be able to successfully compete for iron in order to cause disease. We have shown that iron influences the growth of C. neoformans and also the size of the polysaccharide capsule that is the major virulence factor. Our efforts have focused on characterizing the mechanisms of iron sensing and exploiting the regulatory information to identify targets required for iron acquisition. The first specific aim is to characterize the monothiol glutaredoxin Grx4 as a key sensor of iron availability. Grx4 interacts with the iron regulator Cir1 and the proteins regulate iron homeostasis and the expression of virulence factors. We seek to understand the mechanisms of iron sensing and how the iron signal influences gene expression. A second specific aim will investigate the interaction of Grx4 with a network of transcription factors. Two strong candidates have been identified (HapX and Gat201) and the interactions and regulatory influences of these proteins with Grx4 will be characterized. A final specific aim is based on highly productive genetic screens that identified components of the intracellular machinery for heme trafficking. Mutants lacking trafficking functions for heme acquisition will be constructed and tested in mouse inhalation models of cryptococcosis. Additionally, a heme sensor has been developed to detect heme availability in trafficking mutants in culture and in cryptococcal cells during proliferation in different host tissue locations. Overall, these studies will provide a comprehensive view the integration of iron sensing with the regulation of uptake strategies that are critical during cryptococcosis. !