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.

该提议的广泛目标是增加我们的理解 致病微生物中的细菌多糖合成。 这 K1抗原或多氨酸酸胶囊是α2,8-的均聚物 连接的siAlyl残基。 胶囊的合成取决于大约15 KPS致病基因座的基因至少有两个 收集转录的操纵子，其中一个由 热调节的KPSF启动子。 唾液的反识别功能 酸（抗吞噬作用；抑制抗体非依赖性补体 固定；宿主抗原的分子模仿）使这些独特的九个 碳羧酸酸重要的毒力决定因素 多样化的人类和动物病原体。 大肠杆菌K1是领先 新生儿脑膜炎的原因和经常引起尿路的原因 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，而且常规药物 治疗是有问题的。 替代或改进的疗法可能会出现 从更好地理解囊囊多糖表达。 应用的目标是了解分子机制 囊囊热调节和唾液酸前体生物合成。 此信息对于构建定义的突变体是必需的 将使我们明确确定胶囊之间的关联 疾病期间的脂多糖O抗原。 完成这些 目标，我们将追求三个具体目标。首先，温度调节 将使用设计用于的体外转录系统进行研究 确定KPSF启动子对温度的固有灵敏度。 阳性调节器的作用将由隔离和 不再调节KPSF启动子的突变体的表征。 其次，唾液酸生物合成前体的起源，n- 乙酰基诺胺将由遗传和生化确定 方法。 最后，胶囊的作用及其与 o抗原将在动物模型中使用定义的突变体确定 大肠杆菌脑膜炎和菌血症的大肠杆菌。 完成此过程 研究，我们期望清楚地描述了亲戚 细胞表面多糖对发病机理的贡献。 我们也是 期望确定潜在治疗的特定新目标 旨在阻断体内胶囊表达的发展。