Structural, genetic, and functional analyses of the glycoproteins of Bacteroides

哺乳动物的肠道是一个复杂而多样的生态系统，寄生着数百种不同的细菌。 物种。人类与肠道微生物区系的共同进化导致了合作关系 塑造了这些共生伙伴的生物学和基因组。人们对此知之甚少 肠道微生物区系的主要成员用来建立共生关系的机制 人类的肠道。本提案中概述的实验旨在描述一种新的和 细菌糖蛋白丰富的一类细菌糖蛋白，由优势细菌合成 哺乳动物的肠道，即拟杆菌。这些分子在许多方面都是独一无二的。首先，他们是 唯一证明含有L岩藻糖的细菌糖蛋白。其次，它们代表着最大的 据报道由细菌合成的糖蛋白的数量。最后，他们的合成涉及到一个独特的 仅由类杆菌合成的细菌酶，使用从宿主分子中清除的岩藻糖。这个 本提案中概述的实验将涉及类杆菌岩藻糖化糖蛋白的三个方面。 第一个目标是鉴定脆弱芽孢杆菌和稻瘟杆菌的岩藻糖化糖蛋白，并 描述这些分子的葡聚糖部分。第二个目标的目标是确定哪一个 岩藻糖基转移酶和其他基因产物参与了多糖的合成和与 蛋白质。第三个目标的目标是从功能上表征。在体外和体内， 这些糖蛋白对细菌及其与宿主的共生作用有贡献。 最终，这些研究将使我们能够更好地了解这些微生物是如何影响宿主的 有益的(益生菌、免疫调节和耐受、上皮表面成熟)或 有害的(抗生素耐药性的转移和炎症性肠病的参与)影响。胡麻B. 脆性杆菌也是一种重要的条件致病菌。脆弱杆菌在腹内脓肿中占主导地位 和厌氧菌血症的病例，并已从骨骼和软组织感染的患者中分离出来， 并已被确定为早产发生率增加的一个促成因素。因此， 对脆弱芽胞杆菌岩藻糖化糖蛋白的分析也将有助于我们理解 这种生物的致病潜能。

The mammalian gut is a complex and diverse ecosystem colonized with hundreds of different bacterial species. The coevolution of humans with their intestinal microbiota has resulted in cooperative relationships that have shaped the biology and the genomes of these symbiotic partners. Little is known about the mechanisms used by the predominant members of the gut microbiota to establish symbiotic relationships in the human intestine. The experiments outlined in this proposal are designed to characterize a novel and abundant class of bacterial glycoproteins that are synthesized by the predominant bacteria of the mammalian intestine, namely the Bacteroides. These molecules are unique in many regards. First, they are the only bacterial glycoproteins demonstrated to contain L-fucose. Second, they represent the largest number of glycoproteins reported to be synthesized by bacteria. Lastly, their synthesis of involves a unique bacterial enzyme, synthesized only by the Bacteroides, to use fucose scavenged from host molecules. The experiments outlined in this proposal will address three aspects of fucosylated glycoproteins of Bacteroides. The goal of the first aim is to identify the fucosylated glycoproteins of B. fragilis and B. distasonis, and to characterize the glycan portion of these molecules. The goal of the second aim is to determine which fucosyltransferases and other gene products are involved in the synthesis and linkage of the glycans to the proteins. The goal of the third aim is to functionally characterize,.both in vitro and in vivo, the functions of these glycoproteins to the bacteria and their contribution to the symbiotic interaction with the host. Ultimately, these studies will allow us to better understand how these microorganisms are affecting the host with either beneficial (probiotics, immune regulation and tolerance, maturation of the epithelial surface) or deleterious (transfer of antibiotic resistance and involvement in inflammatory bowel disease) effects. B. fragilis is also an important opportunistic pathogen. B. fragilis predominates in intraabdominal abscesses and cases of anaerobic bacteremia, and has been isolated from patients with bone and soft tissue infections, and has been identified as a contributing factor to increased incidence of preterm labor. Therefore, the analysis of the fucosylated glycoproteins of B. fragilis will also contribute to our understanding of the pathogenic potential of this organism.