GLYCAN PRECURSOR TRANSPORT IN CRYPTOCOCCUS NEOFORMANS

新生隐球菌中的聚糖前体运输

• 批准号: 8823633
• 负责人: Tamara L Doering
• 金额: $ 19.06万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-03-15 至 2017-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8823633
• 关键词: Acids; Anabolism; Antifungal Agents; Area; Biochemical; Biochemistry; Biological Assay; Biology; Carbohydrates; Cells; Cellular biology; Cessation of life; Characteristics; Charge; Complement; Complex; Cryptococcus; Cryptococcus neoformans; Cytidine Monophosphate N-Acetylneuraminic Acid; Cytosol; Data; Defect; Disease; Encapsulated; Endoplasmic Reticulum; Environment; Exhibits; Future; Genes; Glucuronic Acids; Glycobiology; Glycoconjugates; Glycolipids; Glycoproteins; Goals; Golgi Apparatus; Growth; Guanosine Diphosphate Mannose; Health; Human; Immune; Immunocompromised Host; In Vitro; Individual; Infection; Knowledge; Mediating; Membrane; Meningitis; Meningoencephalitis; Monosaccharides; Nucleotides; Organelles; Organism; Pathogenesis; Pathway interactions; Play; Polysaccharides; Process; Proteins; Public Health; Reaction; Reporting; Research; Resources; Sialic Acids; Staging; Structure; System; Testing; Uridine Diphosphate Glucuronic Acid; Virulence; Virulence Factors; Work; base; capsule; chemotherapy; design; fungus; innovation; insight; killings; link protein; mouse model; mutant; novel; pathogen; research study; sialic acid permease; success; sugar; sugar nucleotide; targeted treatment; transport inhibitor

DESCRIPTION (provided by applicant): Meningitis caused by Cryptococcus neoformans kills over 625,000 immunocompromised individuals each year. The polysaccharide capsule and other glycoconjugates of this fungus are critical to its survival in the environment and its succes as a serious pathogen of humans. Despite the importance of these structures, we have only limited knowledge of how they are made. Our long-term goal is to define the major pathways of glycan synthesis in C. neoformans, both for fundamental biochemical understanding and as potential targets for therapy. The individual components of glycans come from nucleotide sugars, which are activated sugar donors that serve as substrates in biosynthetic reactions. These charged compounds are present in the cell cytosol, which means that they must be transported across membranes into the secretory organelles where most eukaryotic glycan synthesis occurs. The proteins that accomplish this, nucleotide sugar transporters (NSTs), are thus essential and limiting components of key biosynthetic pathways that contribute to cryptococcal pathogenesis. The objective of this proposal is to determine the function of a novel nucleotide sugar transporter, NSTX, which we have discovered and strongly implicated in fungal virulence. We hypothesize that NSTX mediates transport of the activated donor of one or more acidic monosaccharides. We will test this hypothesis through two aims. In the first aim, we will determine the effects of deleting the gene encoding NSTX on cryptococcal glycoconjugates by comparing the compositions of capsule polysaccharides, glycoproteins, and glycolipids isolated from wild type and mutant cells. In the second aim, we will directly determine the in vitro transport activity of NSTX. These complementary aims play to the unique strengths of the research team in biochemistry, glycobiology, and cell biology of C. neoformans. Determining the activity of NSTX will help establish how C. neoformans localizes the precursors required to make capsule and other important glycoconjugates implicated in virulence, and may also settle a long-standing question about sialic acid use by these cells. The application is innovative in terms of proposing a novel hypothesis about NSTX function and direct studies of nucleotide sugar transport in an organism with unique and understudied glycoconjugates. It is significant because it is expected to advance our understanding of a limiting step in glycan synthetic processes that are vital to an important pathogen of humans. This exploratory work will further be of broad impact because it will set the stage for future studies of fundamental glycobiology, cryptococcal biology, and pathogenesis.

描述（由申请人提供）：由加密型新象征引起的脑膜炎每年杀死625,000多名免疫功能低下的个体。这种真菌的多糖胶囊和其他糖缀合物对于其在环境中的生存至关重要，并且是人类的严重病原体。尽管这些结构很重要，但我们对它们的制造方式只有有限的了解。我们的长期目标是定义新生梭菌中聚糖合成的主要途径，既是基本的生化理解，又是治疗的潜在靶标。聚糖的各个成分来自核苷酸糖，它们是活化的糖供体，它们是生物合成反应的底物。这些带电的化合物存在于细胞胞质中，这意味着它们必须在大多数真核聚糖合成的分泌细胞器中运输到分泌细胞器中。因此，实现此目的的蛋白质是核苷酸糖转运蛋白（NST），因此是重要的生物合成途径的必不可少的成分，有助于加密局球发病机理。该建议的目的是确定新型核苷酸转运蛋白NSTX的功能，我们发现并与真菌毒力相关。我们假设NSTX介导了一种或多种酸性单糖的活化供体的转运。我们将通过两个目标检验这一假设。在第一个目标中，我们将通过比较胶囊多糖，糖蛋白和与野生型和突变细胞分离的胶囊多糖，糖蛋白和糖脂的组成来确定删除编码NSTX对隐球菌糖缀合物的影响。在第二个目标中，我们将直接确定NSTX的体外运输活性。这些互补的目的涉及研究小组在生物化学，糖生物学和细胞生物学的独特优势。确定NSTX的活性将有助于建立新梭状芽孢杆菌如何定位使胶囊和其他重要的糖缀合物所需的前体涉及毒力，并且还可能解决有关这些细胞使用唾液酸使用的长期问题。在提出关于NSTX功能的新假设以及对具有独特和研究的糖缀合物中核苷酸糖转运的直接研究方面，该应用具有创新性。这很重要，因为期望我们对聚糖合成过程中对人类重要病原体至关重要的聚糖合成过程的有限步骤的理解。这项探索性工作将进一步产生广泛的影响，因为它将为未来的基础糖生物学，加密局生物学和发病机理奠定阶段。