The novel family of superoxide dismutase enzymes in Candida albicans

白色念珠菌中超氧化物歧化酶的新家族

• 批准号: 8383200
• 负责人: Valeria C Culotta
• 金额: $ 24.3万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-02 至 2014-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8383200
• 关键词: Address; Basic Science; Binding; Biochemistry; Biological Assay; Biological Availability; Biology; Candida albicans; Cell Wall; Cells; Charge; Copper; Cuprozinc Superoxide Dismutase; Cytosol; Development; Disulfides; Environment; Enzymes; Eukaryota; Exhibits; Exploratory/Developmental Grant; Family; Fluorescent Probes; Fostering; Free Radicals; Growth; Immune; Immune response; Immunocompromised Host; Individual; Infection; Iron; Laboratories; Lead; Manganese; Metals; Methods; Mission; Monitor; Names; Oxygen; Pathogenicity; Phagolysosome; Phase; Population; Proteins; Public Health; Reactive Oxygen Species; Recombinants; Research; Respiratory Burst; Seeds; Site; Staging; Superoxide Dismutase; Superoxides; System; Testing; Virulence; Virulence Factors; Yeasts; Zinc; assay development; extracellular; factor C; killings; macrophage; member; novel; novel therapeutics; oxidation; pathogen; prevent; programs; research study; stem; tool

DESCRIPTION (provided by applicant): The infectious yeast Candida albicans remains an important concern in public health, particularly with immune-compromised individuals. One set of virulence factors for C. albicans includes a family of copper containing superoxide dismutase (SOD) enzymes that scavenge toxic superoxide free radicals. In spite of their established importance in virulence, virtually nothing is known about the biochemistry of C. albicans SODs or how these enzymes are activated in cells through insertion of the copper co-factor. In this research application, we plan to develop new systems for monitoring the effects of the host on intracellular copper and copper containing SODs of C. albicans . Two types of Cu-containing SODs in C. albicans will be examined: a Cu/Zn SOD in the cytosol (SOD1), and an extracellular member of the Cu/Zn SOD family attached to the cell wall through GPI anchors (SOD5). Both are important for virulence and in our preliminary analyses, both exhibit some distinctive features not seen in other Cu/Zn SODs. For example, under normal (non-infectious) laboratory growth conditions, the intracellular SOD1 protein is inactive and the yeast instead uses an unusual cytosolic manganese-SOD3 to remove superoxide. The extracellular SOD5 is also unique in that it appears to bind only copper, and is lacking the zinc site that is invariant among other eukaryotic Cu/Zn SODs. We propose that these unusual Cu-SODs have evolved to exploit the host effects on metals. During infection, the macrophage phagolysosome starves pathogens of manganese, zinc and iron, while attempting to kill pathogens with high levels of copper and reactive oxygen. This particular environment of the host seems ideal for activating copper requiring SODs. We hypothesize that during infection, both the intracellular SOD1 and extracellular SOD5 are immediately charged with copper, representing the first line of defense against the oxidative burst of the host. We will begin to test this hypothesis by developing systems in which we can monitor changes in intracellular copper and Cu/Zn SOD activity that occur in C. albicans during infection of macrophages. We will also develop a system for recovering enzymatically active SOD5 from the cell wall or secreted from yeast, a tool that will prove invaluable for monitoring extracellular SOD activation during macrophage infection. Through metal analysis of recombinant SOD5, we will address whether this enzyme is truly a copper-only SOD. These studies are in the exploratory, assay-development phase. The findings and new systems that stem from this 2 year program will foster our more long-term mechanistic studies geared towards understanding host effects on pathogen metals and SOD enzymes. These basic research studies have the potential to seed development of new therapies that target copper and prevent activation of the C. albicans SODs essential for virulence. PUBLIC HEALTH RELEVANCE: The pathogenic yeast Candida albicans remains a critical threat to the population, particularly with immunocompromised individuals. In this application, we shall explore the biology of copper containing superoxide dismutase (SOD) enzymes in C. albicans that are important virulence factors. Specifically we shall test the hypothesis that the novel SOD enzymes of C. albicans have evolved the capacity to become fully charged with copper during the immune response.

描述（由申请人提供）：传染性酵母菌白色念珠菌仍然是公共卫生中的一个重要问题，特别是对免疫功能低下的个体。白色念珠菌的一组毒力因子包括一个含铜的超氧化物歧化酶（SOD）酶家族，它可以清除有毒的超氧化物自由基。尽管白念珠菌sod在毒力中具有重要作用，但人们对其生物化学性质以及这些酶如何通过铜辅助因子的插入在细胞中被激活仍知之甚少。在本研究应用中，我们计划开发新的系统来监测宿主对白色念珠菌细胞内铜和含铜sod的影响。我们将研究白色念珠菌中两种类型的含铜SOD：细胞质中的Cu/Zn SOD （SOD1）和通过GPI锚点附着在细胞壁上的Cu/Zn SOD家族的胞外成员（SOD5）。两者对毒力都很重要，在我们的初步分析中，两者都表现出其他Cu/Zn sod所没有的一些独特特征。例如，在正常（非感染性）的实验室生长条件下，细胞内的SOD1蛋白是无活性的，而酵母则使用一种不寻常的细胞质锰- sod3来去除超氧化物。胞外SOD5也很独特，因为它似乎只结合铜，而缺乏锌位点