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: 8502621
• 负责人: Valeria C Culotta
• 金额: $ 19.04万
• 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 2015-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8502621
• 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.

描述（由申请人提供）：传染性的酵母白色念珠菌仍然是公共卫生中的重要关注点，尤其是在免疫受损的人群中。白色念珠菌的一组毒力因子包括一个含有超氧化物歧化酶（SOD）酶的铜系，可清除有毒的超氧化物自由基。尽管它们在毒力方面具有确定的重要性，但实际上对白色念珠菌索的生物化学或如何通过插入铜co因子在细胞中激活这些酶的生物化学几乎没有任何了解。在本研究应用程序中，我们计划开发新的系统，以监视宿主对含白色念珠菌的SOD的细胞内铜和铜的影响。将检查白色念珠菌中的两种类型的含Cu的SOD：细胞质中的Cu/Zn SOD（SOD1），以及通过GPI锚（SOD5）附着在细胞壁上的Cu/Zn SOD家族的细胞外成员（SOD5）。两者都对毒力很重要，在我们的初步分析中，两者都表现出在其他Cu/Zn SOD中看不见的一些独特特征。例如，在正常（非感染）实验室生长条件下，细胞内SOD1蛋白不活跃，而酵母则使用异常的胞质锰-SOD3去除超氧化物。细胞外SOD5也是独特的，因为它似乎仅粘合铜，并且缺少在 其他真核Cu/Zn Sods。我们建议这些不寻常的Cu-Sods已经演变以利用宿主对金属的影响。在感染期间，巨噬细胞吞噬体饥饿的锰，锌和铁的病原体，同时试图杀死具有高水平的铜和活性氧的病原体。主机的这种特殊环境似乎是激活需要草皮的铜的理想选择。我们假设在感染过程中，细胞内SOD1和细胞外SOD5均立即充电铜，代表了针对宿主的氧化爆发的第一道防线。我们将通过开发系统开始检验这一假设，在该系统中我们可以监视巨噬细胞感染期间白色念珠菌中发生的细胞内铜和Cu/Zn SOD活性的变化。我们还将开发一个系统，用于从细胞壁中恢复酶活性SOD5或从酵母中分泌，该工具对于监测巨噬细胞感染期间的细胞外SOD激活而言是无价的。通过对重组SOD5的金属分析，我们将解决该酶是否真正是仅铜的草皮。这些研究处于探索性测定开发阶段。源于这项两年计划的发现和新系统将促进我们更长期的机械研究，旨在了解宿主对病原体金属和SOD酶的影响。这些基础研究有可能播种靶向铜的新疗法，并防止白色念珠菌so虫的激活对毒力必不可少。