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

描述（由申请人提供）：哺乳动物肠道是一个复杂多样的生态系统，定植有数百种不同的细菌。人类与其肠道微生物群的共同进化导致了合作关系，这些合作关系塑造了这些共生伙伴的生物学和基因组。关于肠道微生物群的主要成员在人类肠道中建立共生关系的机制知之甚少。本提案中概述的实验旨在表征由哺乳动物肠道的主要细菌（即拟杆菌）合成的一类新的和丰富的细菌糖蛋白。这些分子在许多方面都是独一无二的。首先，它们是唯一被证明含有L-岩藻糖的细菌糖蛋白。其次，它们代表了报道的由细菌合成的最大数量的糖蛋白。最后，它们的合成涉及一种独特的细菌酶，仅由拟杆菌合成，以使用从宿主分子中清除的岩藻糖。在这个建议中概述的实验将解决三个方面的岩藻糖基化糖蛋白的拟杆菌。第一个目标是鉴定B的岩藻糖基化糖蛋白。fragilis和B. distasonis，并表征这些分子的聚糖部分。第二个目标的目标是确定哪些岩藻糖基转移酶和其他基因产物参与聚糖与蛋白质的合成和连接。第三个目标是在体外和体内功能上表征这些糖蛋白对细菌的功能及其对与宿主的共生相互作用的贡献。最终，这些研究将使我们能够更好地了解这些微生物如何影响宿主，无论是有益的（益生菌，免疫调节和耐受性，上皮表面的成熟）还是有害的（抗生素耐药性的转移和炎症性肠病的参与）影响。B。脆壁菌也是一种重要的机会致病菌。B。脆壁菌在腹腔内脓肿和厌氧菌血症病例中占优势，并且已从骨和软组织感染患者中分离出来，并且已被鉴定为早产发生率增加的一个促成因素。因此，对B. fragilis也将有助于我们了解这种生物体的致病潜力。

DESCRIPTION (provided by applicant): 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.