GLYCAN PRECURSOR TRANSPORT IN CRYPTOCOCCUS NEOFORMANS

新生隐球菌中的聚糖前体运输

• 批准号: 8709197
• 负责人: Tamara L Doering
• 金额: $ 22.85万
• 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 2016-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8709197
• 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; public health relevance; research study; sialic acid permease; success; sugar; sugar nucleotide; 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。该真菌的多糖荚膜和其他糖复合物是其在环境中生存和成功成为人类严重病原体的关键。尽管这些结构很重要，但我们对它们是如何形成的了解有限。我们的长期目标是确定C.新型人，无论是对于基本的生化理解还是作为潜在的治疗目标。聚糖的单个组分来自核苷酸糖，核苷酸糖是在生物合成反应中充当底物的活化糖供体。这些带电化合物存在于细胞胞质溶胶中，这意味着它们必须穿过膜转运到分泌细胞器中，在分泌细胞器中发生大多数真核聚糖合成。实现这一点的蛋白质，核苷酸糖转运蛋白（NST），因此是关键的生物合成途径，有助于隐球菌发病的重要和限制性的组成部分。这个建议的目的是确定一种新的核苷酸糖转运蛋白，NSTX，我们已经发现，并强烈牵连在真菌毒力的功能。我们假设NSTX介导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来检验这一假设。在第一个目标中，我们将通过比较从野生型和突变型细胞分离的荚膜多糖、糖蛋白和糖脂的组合物来确定删除编码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C研究团队在生物化学、糖生物学和细胞生物学方面的独特优势。新人类确定NSTX的活性将有助于确定C. neoformans定位了制造荚膜和其他与毒力有关的重要糖缀合物所需的前体，并且还可能解决关于这些细胞使用唾液酸的长期问题。该应用程序是创新的，提出了一个新的假设NSTX功能和直接研究的核苷酸糖转运的生物体与独特的和未充分研究的糖缀合物。这是重要的，因为它预计将促进我们的理解，在聚糖合成过程中的一个限制步骤，是至关重要的一个重要的人类病原体。这项探索性的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。