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）：由新型隐球菌引起的脑膜炎每年导致超过 625,000 名免疫功能低下的个体死亡。这种真菌的多糖荚膜和其他糖复合物对于其在环境中的生存及其作为人类严重病原体的成功至关重要。尽管这些结构很重要，但我们对它们的制造方式知之甚少。我们的长期目标是确定新型隐球菌中聚糖合成的主要途径，既可以用于基本的生化理解，也可以作为潜在的治疗靶点。聚糖的各个成分来自核苷酸糖，核苷酸糖是活化的糖供体，在生物合成反应中充当底物。这些带电化合物存在于细胞质中，这意味着它们必须跨膜转运到大多数真核聚糖合成发生的分泌细胞器中。因此，实现这一目标的蛋白质，即核苷酸糖转运蛋白（NST），是促进隐球菌发病机制的关键生物合成途径的必需和限制性成分。该提案的目的是确定一种新型核苷酸糖转运蛋白 NSTX 的功能，我们已经发现它并与真菌毒力密切相关。我们假设 NSTX 介导一种或多种酸性单糖的活化供体的运输。我们将通过两个目标来检验这个假设。在第一个目标中，我们将通过比较从野生型和突变细胞中分离的荚膜多糖、糖蛋白和糖脂的组成，确定删除编码 NSTX 的基因对隐球菌糖缀合物的影响。在第二个目标中，我们将直接测定 NSTX 的体外转运活性。这些互补的目标发挥了研究团队在新型隐球菌生物化学、糖生物学和细胞生物学方面的独特优势。确定 NSTX 的活性将有助于确定新型隐球菌如何定位制造胶囊和其他与毒力有关的重要糖缀合物所需的前体，并且还可能解决有关这些细胞使用唾液酸的长期存在的问题。该应用的创新之处在于提出了关于 NSTX 功能的新假设，并通过独特且尚未充分研究的糖复合物直接研究了生物体中的核苷酸糖转运。它很重要，因为它有望增进我们对聚糖合成过程中限制步骤的理解，而聚糖合成过程对于人类重要的病原体至关重要。这项探索性工作将进一步产生广泛的影响，因为它将为基础糖生物学、隐球菌生物学和发病机制的未来研究奠定基础。