Cryptococcus neoformans: synthesis of the polysaccharide capsule

新型隐球菌：多糖胶囊的合成

• 批准号: RGPIN-2016-04782
• 负责人: Brockhausen, Inka
• 金额: $ 2.26万
• 依托单位: Queen's University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=615297
• 关键词: Cryptococcus; neoformans; synthesis; polysaccharide; capsule

Cryptococcus is a fungus having a thick polysaccharide capsule, and infections (cryptococcosis) are an emerging problem in Canada. Especially individuals with a suppressed immune system are at risk. An outbreak of cryptococcosis in British Columbia demonstrated that strains of this fungus can be transferred world-wide and also infect individuals with a normal immune system. The capsule surrounding this fungus is a major virulence factor and can circumvent immune defenses and phagocytosis. The structures of C. neoformans capsule polysaccharides have been analyzed and the genome of several Cryptococcus species has been sequenced. However, the enzymes and mechanisms to assemble capsule polysaccharides remain to be elucidated. A number of capsule-associated genes are known that are required for the proper structure or size of the capsule but their specific functions are still unclear. This is a major knowledge gap in Canada and world-wide and we hope to fill this gap. The short term goal of this proposal is to use information from the capsule-associated genes and the capsule structures to identify the enzymes involved in capsule synthesis, to characterize these proteins and to determine the pathways of capsule synthesis in Cryptococcus. The sequence and control mechanisms of glycosyltransferases and O-acetyltransferases involved in capsule assembly will be studied in vitro and in fungal cells. This includes studies of protein structures and functions of specific amino acids in substrate binding and catalysis. The long term goal of this program is to acquire the knowledge and basic understanding of fungal polysaccharide synthesis and to train scientists in the field of fungal glycobiology and glycomics. Our previous expertise in the glycosyltransferases and glycosylation of mammalian cells and in bacteria is the basis for a successful outcome of this project. In addition, the P.I. has assembled a team of experts in Cryptococcus genetics and biology, synthesis of enzyme substrate analogs, protein structure determination and fungal biochemistry. These ground breaking discovery studies will establish a unique, needed expertise in fungal research in Canada. The research team will include at least two graduate and ten undergraduate students and three postdoctoral fellows. Our trainees will acquire a unique multidisciplinary expertise that can find applications in basic research and discovery, in biotechnology and drug development. The benefits are highly valuable for research laboratories and industry. It is essential to have this basic expertise in Canada.

隐球菌是一种具有厚厚多糖胶囊的真菌，感染（隐球菌病）是加拿大的一个新问题。尤其是免疫系统受到抑制的个体处于危险之中。不列颠哥伦比亚省爆发的隐球菌病表明，这种真菌菌株可以在世界范围内传播，也可以感染免疫系统正常的个体。这种真菌周围的荚膜是主要的毒力因子，可以绕过免疫防御和吞噬作用。已经分析了新型隐球菌荚膜多糖的结构，并对几种隐球菌属物种的基因组进行了测序。然而，组装荚膜多糖的酶和机制仍有待阐明。已知许多胶囊相关基因是胶囊适当结构或大小所必需的，但它们的具体功能仍不清楚。这是加拿大和世界范围内的一个重大知识空白，我们希望填补这一空白。该提案的短期目标是利用来自荚膜相关基因和荚膜结构的信息来识别荚膜合成中涉及的酶，表征这些蛋白质并确定隐球菌中荚膜合成的途径。将在体外和真菌细胞中研究参与胶囊组装的糖基转移酶和 O-乙酰转移酶的序列和控制机制。这包括对底物结合和催化中特定氨基酸的蛋白质结构和功能的研究。该计划的长期目标是获得真菌多糖合成的知识和基本了解，并培训真菌糖生物学和糖组学领域的科学家。我们之前在哺乳动物细胞和细菌的糖基转移酶和糖基化方面的专业知识是该项目取得成功的基础。此外，P.I.组建了隐球菌遗传学和生物学、酶底物类似物合成、蛋白质结构测定和真菌生物化学方面的专家团队。这些突破性的发现研究将为加拿大真菌研究建立独特的、所需的专业知识。研究团队将包括至少两名研究生、十名本科生和三名博士后。我们的学员将获得独特的多学科专业知识，可以在基础研究和发现、生物技术和药物开发中找到应用。这些好处对于研究实验室和工业界来说非常有价值。在加拿大拥有这些基本专业知识至关重要。