REGULATION OF THE (POLY) SIALIC ACID VIRULENCE FACTOR

(聚)唾液酸毒力因子的调节

• 批准号: 2887612
• 负责人: Eric Ross Vimr
• 金额: $ 15.92万
• 依托单位: UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-07-01 至 2003-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2887612
• 关键词: Escherichia coli; bacterial capsules; bacterial genetics; bacterial polysaccharides; carbohydrate biosynthesis; genetic promoter element; genetic regulation; genetic transcription; operon; sialate; virulence

The broad objective of this proposal is to increase our understanding of bacterial polysaccharide synthesis in pathogenic microorganisms. The K1 antigen, or polysialic acid capsule is a homopolymer of alpha2,8- linked sialyl residues. Synthesis of the capsule depends on about 15 genes of the kps pathogenicity locus that is organized into at least two convergently transcribed operons, one of which is controlled by the thermoregulated kpsF promoter. The anti-recognition functions of sialic acids (anti-phagocytosis; inhibition of antibody-independent complement fixation; molecular mimicry of host antigens) make these unique nine- carbon carboxy sugar acids important determinants of virulence in diverse human and animal pathogens. Escherichia coli K1 is a leading cause of neonatal meningitis and a frequent cause of urinary tract infections in children and bacteremia in adults. Vaccination against these diseases may not always be practical, and conventional drug therapy is problematic. Alternative or improved therapies may emerge from a better understanding of capsular polysaccharide expression. Objectives of the application are to understand the molecular mechanisms of capsule thermoregulation and sialic acid precursor biosynthesis. This information is necessary for construction of defined mutants that will allow us to unambiguously determine the association between capsule and lipopolysaccharide O antigen during disease. To accomplish these objectives, we will pursue three specific aims. First, thermoregulation will be investigated with an in vitro transcription system designed to determine the intrinsic sensitivity of the kpsF promoter to temperature. The role of a positive regulator will be determined by isolation and characterization of mutants that no longer regulate the kpsF promoter. Second, the origin of sialic acid biosynthetic precursor, N- acetylmannosamine, will be determined by genetic and biochemical approaches. Finally, the role of the capsule and its association with O antigen will be determined using defined mutants in an animal model of E. coli K1 meningitis and bacteremia. At the completion of this research, we expect to have clearly delineated the relative contributions of cell surface polysaccharides to pathogenesis. We also expect to have identified specific new targets for potential therapeutic developments aimed at blocking capsule expression in vivo.

这项建议的主要目标是增进我们对 病原微生物中细菌多糖的合成。 的 K1抗原或聚唾液酸胶囊是α 2，8- 连接的唾液酸残基。 胶囊的合成取决于约15 KPS致病性基因座的基因，其被组织成至少两个 聚合转录操纵子，其中之一是由 温度调节的kpsF启动子。 唾液酸的抗识别功能 酸（抗吞噬作用;抑制抗体非依赖性补体 固定;宿主抗原的分子模拟）使这些独特的九- 碳羧基糖酸是毒力的重要决定因素 多种人类和动物病原体。 大肠杆菌K1是一种主要的 引起新生儿脑膜炎和泌尿道疾病的常见原因 儿童感染和成人菌血症。疫苗接种 这些疾病可能并不总是实用的， 治疗是有问题的。 可能会出现替代或改进的治疗方法 从更好地了解荚膜多糖的表达。 应用程序的目标是了解分子机制 囊体温度调节和唾液酸前体生物合成。 这些信息对于构建确定的突变体是必要的， 将使我们能够明确地确定胶囊 和脂多糖O抗原。 完成这些 我们将努力实现三个具体目标。第一，体温调节 将使用体外转录系统进行研究，该系统旨在 确定kpsF启动子对温度的固有敏感性。 正调节剂的作用将由隔离和 表征不再调节kpsF启动子的突变体。 第二，唾液酸生物合成前体N- 乙酰甘露糖胺，将由遗传和生化 接近。 最后，胶囊的作用及其与 将使用动物模型中确定的突变体测定O抗原 大肠coli K1脑膜炎和菌血症。 在完成此 研究，我们希望能清楚地描绘出相对的 细胞表面多糖对发病机制的贡献。 我们也 我希望已经确定了潜在治疗的特定新靶点， 旨在体内阻断胶囊表达的发展。