Biosynthesis of the Immunomodulatory Molecule Capsular Polysaccharide A

描述(由申请人提供)：细菌被膜多糖的作用和产生它们的途径在人类健康和疾病中是不可或缺的，在细菌发病机制以及与动物的基本共生关系中发挥着基础作用。对调控这些大分子产生的过程和因素的详细了解对于了解胶囊多糖如何影响健康和疾病状态是至关重要的。这项建议的重点是在共生原核生物脆弱类杆菌的细胞表面表达的荚膜多糖A。这是进行详细研究的一个重要目标，因为研究将提供工具和方法，以了解可用于增进人类健康的共生微生物中的荚膜多糖的作用。此外，这一途径代表了一种实验上易于处理的未知生物合成系统，将为获得病原菌和共生菌中细菌多糖的一般生物合成信息提供见解和新的方法学途径。研究人员已经确定了导致荚膜多糖A四糖重复单位生物合成的基因位点。然而，对该基因位点产生的蛋白质进行明确的生化分析还没有进行。基因位点分析已经确定了与四种糖基转移酶同源的蛋白质，一种半乳糖基转移酶，一种糖氨基转移酶，一种负责丙酮化的蛋白质，一种翻转酶和聚合酶。在这个项目中，我们将使用化学和动力学方法来确定胶囊多糖A的生物合成路线，这只能通过序列分析来部分预测。在这样做的过程中，我们将对目前知之甚少的二磷酸核苷酸糖修饰酶和寡糖糖基转移酶有更多的了解。 与公共卫生相关：细菌被膜多糖的作用和产生它们的途径在人类健康和疾病中是不可或缺的，在细菌发病机制以及与动物的基本共生关系中发挥着基础性作用。这项建议的重点是在共生原核生物脆弱类杆菌的细胞表面表达的荚膜多糖A。在这个项目中，我们将使用化学和动力学方法阐明胶囊多糖A的生物合成路线，增加利用这种生物分子治疗从多发性硬化症到炎症性肠病等各种疾病的机会。

DESCRIPTION (provided by applicant): The role of bacterial capsular polysaccharides and the pathways that produce them are integral in human health and disease playing a fundamental role in bacterial pathogenesis as well as essential symbiotic relationships with animals. A detailed understanding of the process and factors that regulate production of these macromolecules is of utmost importance to understanding how capsular polysaccharides affect healthy and diseased states. The focus of this proposal is on capsular polysaccharide A expressed on the cell surface of the symbiotic prokaryote Bacteroides Fragilis. This is an important target for detailed investigation since studies will provide tools and approaches for understanding the role of capsular polysaccharides in symbiotic microbes that may be used in enhancing human health. In addition, this pathway represents an uncharacterized biosynthetic system that is experimentally tractable and would offer insights and new methodological approaches for deriving information on the general biosynthesis of bacterial polysaccharides in pathogenic as well as symbiotic bacteria. The gene locus responsible for the biosynthesis of the tetrasaccharide repeat unit of capsular polysaccharide A has been identified. However, unambiguous biochemical analysis of the proteins produced from this gene locus has not been performed. Gene locus analysis has identified proteins homologous to four glycosyltransferases, a galactopyranose mutase, and a sugar aminotransferase, a protein responsible for pyruvation, a flippase and a polymerase. In this program we will use chemical and kinetic approaches to identify the biosynthetic route to capsular polysaccharide A, which can only be partially predicted by sequence analysis alone. In doing so, we will learn a great deal about nucleotide diphosphate sugar modifying enzymes and oligosaccharide glycosyltransferases that are currently poorly understood. PUBLIC HEALTH RELEVANCE: The role of bacterial capsular polysaccharides and the pathways that produce them are integral in human health and disease playing a fundamental role in bacterial pathogenesis as well as essential symbiotic relationships with animals. The focus of this proposal is on capsular polysaccharide A expressed on the cell surface of the symbiotic prokaryote Bacteroides Fragilis. In this program we will use chemical and kinetic approaches to elucidate the biosynthetic route to capsular polysaccharide A, enhancing the opportunity to utilize this biomolecule as a therapeutic for diseases ranging from Multiple Sclerosis to Inflammatory Bowel Disease.