Chitosan in Cryptococcus

隐球菌中的壳聚糖

• 批准号: 7994194
• 负责人: Jennifer K. Lodge
• 金额: $ 34.03万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-12-15 至 2012-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7994194
• 关键词: Acetylation; Acquired Immunodeficiency Syndrome; Anabolism; Antifungal Agents; Antifungal Therapy; Area; Carbohydrate Linkages; Cell Wall; Cells; Chitin; Chitin Synthase; Chitin deacetylase; Chitosan; Critiques; Cryptococcus; Cryptococcus neoformans; Data; Deacetylase; Defect; Eukaryotic Cell; Fungal Components; Genes; Goals; Graph; Growth; Health; Human; Immunocompromised Host; Infection; Link; Lung; Manuscripts; Mass Spectrum Analysis; Measurement; Measures; Melanins; Methods; Minor; Modeling; Mus; Mycoses; Nomenclature; Nose; Organ Transplantation; Organelles; Organism; Paper; Pathway interactions; Phenotype; Polymers; Polysaccharides; Production; Proteins; Published Comment; Publishing; Role; Structure; Testing; Text; Tissues; Virulence; chemotherapy; flexibility; improved; mutant; novel; pathogen; patient population; polysaccharide deacetylase; response

DESCRIPTION (provided by applicant): The cell wall of the fungal pathogen C. neoformans is an essential organelle that incorporates chitin as a rigid, insoluble, polysaccharide polymer. De-acetylation converts chitin to chitosan, a more flexible and soluble polymer. While chitin is an essential component of fungal cell walls, the importance of chitosan to cell wall integrity is unclear. The overall goal of this project is to identify key steps in Cryptococcus cell wall biosynthesis that will make attractive targets for antifungal drugs. Our preliminary data indicate that chitosan is an abundant component of Cryptococcus cell walls, both during vegetative growth and during infection of mouse lungs. We have explored genes that contribute to chitosan production, and shown that only one of eight putative chitin synthases, and one of three putative chitin synthase regulators substantially impact chitosan levels. In addition, we have demonstrated that three of four potential polysaccharide deacetylases produce chitosan. The shared phenotypes among strains deleted of genes in the chitosan biosynthetic pathway, include defects in cell integrity and leaky melanin, and suggest that these phenotypes are the result of substantial reduction of chitosan. Data obtained from this project will establish the role of chitosan in C. neoformans cell wall integrity and virulence, how chitosan is attached to the cell wall, and identify critical steps in this aspect of cell wall biosynthesis that could serve as antifungal targets. This project has three specific aims. In the first, we will determine the composition of chitosan and how it is linked to the cell wall during growth in the mammalian host. In the second, we will test the roles of the three chitin deacetylases in chitosan biosynthesis, cell wall integrity and virulence. In the third aim, we will test our current model that one chitin synthase and its regulator together synthesize the chitin that is deacetylated by the three chitin deacetylases to generate chitosan and determine the interactions among the these proteins that are critical for chitosan production. The results of these studies should provide a better understanding of chitosan biosynthesis and function in C. neoformans, and determine if chitosan production would be a viable antifungal target for novel anti-cryptococcal therapy. Fungal infections have become more prevalent in recent years due to the increase in the immunocompromised patient population from AIDS, organ transplants and chemotherapies. Systemic fungal infections are serious health threats, and safe, highly effective antifungal therapies are not available. Biosynthesis of the fungal cell wall is an attractive target for antifungal therapies because the cell wall is an essential organelle that is not present in the human host, and this project will delineate the biosynthesis of the cell wall of a fungal pathogen, Cryptococcus neoformans, and determine if one of its components, chitosan, is a potential antifungal target.

描述（由申请人提供）：真菌病原体新型隐球菌的细胞壁是一种重要的细胞器，其中包含几丁质作为刚性的、不溶性的多糖聚合物。脱乙酰化作用将甲壳素转化为壳聚糖，这是一种更灵活、更可溶的聚合物。虽然几丁质是真菌细胞壁的重要组成部分，但壳聚糖对细胞壁完整性的重要性尚不清楚。该项目的总体目标是确定隐球菌细胞壁生物合成的关键步骤，这将为抗真菌药物提供有吸引力的靶点。我们的初步数据表明，壳聚糖是隐球菌细胞壁的丰富成分，无论是在营养生长期间还是在小鼠肺部感染期间。我们探索了有助于壳聚糖生产的基因，并表明只有八种假定的几丁质合酶中的一种和三种假定的几丁质合酶调节剂中的一种会显着影响壳聚糖水平。此外，我们还证明了四种潜在的多糖脱乙酰酶中的三种可以产生壳聚糖。壳聚糖生物合成途径中基因缺失的菌株之间共有的表型，包括细胞完整性缺陷和黑色素渗漏，并表明这些表型是壳聚糖大量减少的结果。从该项目获得的数据将确定壳聚糖在新型隐球菌细胞壁完整性和毒力中的作用、壳聚糖如何附着在细胞壁上，并确定细胞壁生物合成这一方面可作为抗真菌靶标的关键步骤。该项目有三个具体目标。首先，我们将确定壳聚糖的成分以及它在哺乳动物宿主生长过程中如何与细胞壁连接。在第二部分中，我们将测试三种甲壳素脱乙酰酶在壳聚糖生物合成、细胞壁完整性和毒力中的作用。在第三个目标中，我们将测试我们当前的模型，即一种几丁质合酶及其调节剂共同合成由三种几丁质脱乙酰酶脱乙酰化的几丁质以产生壳聚糖，并确定这些对壳聚糖生产至关重要的蛋白质之间的相互作用。这些研究的结果应有助于更好地了解新型隐球菌中壳聚糖的生物合成和功能，并确定壳聚糖的产生是否会成为新型抗隐球菌疗法的可行抗真菌靶标。近年来，由于艾滋病、器官移植和化疗导致免疫功能低下的患者人数增加，真菌感染变得更加普遍。全身性真菌感染是严重的健康威胁，目前尚无安全、高效的抗真菌疗法。真菌细胞壁的生物合成是抗真菌治疗的一个有吸引力的目标，因为细胞壁是人类宿主中不存在的重要细胞器，该项目将描述真菌病原体、新型隐球菌和确定其成分之一壳聚糖是否是潜在的抗真菌靶点。