MECHANISMS OF POLYSIALIC ACID ASSEMBLY IN E COLI

尽管半个多世纪以来的研究和重大进展 在抗菌治疗中，包裹体引起的疾病 细菌，包括脑膜炎双球菌、肺炎双球菌、嗜血杆菌、 B型流感、大肠埃希氏菌和B组链球菌， 仍然是一个主要的健康问题。对预防和预防的兴趣 对这些细菌引起的疾病的控制已经得到了促进 由这些引起的疾病的高发病率和死亡率 微生物，抗生素耐药菌株的出现， 以及地方病和流行病的威胁。大肠埃希菌是 新生儿脑膜炎最常见的原因与高压性脑膜炎有关 死亡率和严重的神经后遗症。吉隆坡 多糖在结构上与聚唾液酸相同 神经细胞黏附分子NCAM上的部分，它可能 解释大肠杆菌胶囊的弱免疫原性和 缺乏有效的疫苗，尽管密集的疫苗开发 努力。事实上，目前还不清楚针对KL的疫苗是否 胶囊是可取的。治疗疾病的另一种方法 控制将是旨在破坏细菌的治疗方法 唾液酸代谢。这种方法需要详细的 关于聚唾液酸合成及其基础的信息 基因调控。 我们目前对大肠杆菌K1中KPS基因簇的认识 是在一种复杂的水平上，其中分子描述 合成和调节机制可以在一个 统一规划。结合强大的微生物遗传方法 分子和生化方法表明，对于 这是第一次，对膜的完整描述 多糖的合成，潜在的遗传调控，以及 移位可能是可能的。这些信息将是相关的 到其他胶囊生物合成系统的医疗和工业 重要性。 在这里，我们建议进行实验以进一步定义聚合酶 负责合成聚唾液酸的复合体，以 阐明环境背后的遗传机制 调节胶囊的表达，并开始功能 聚合物组装和移位因子的重组。 这些新的方法是我们的 以前的研究推导出了一个功能性的遗传图谱 聚唾液酸基因簇。

Despite research for more than half a century and major advances in antimicrobial therapy, diseases caused by encapsulated bacteria, including meningococci, pneumococci, Haemophilus, influenzae type B, Escherichia coli, and group B streptococci, remain a major health problem. Interest in the prevention and control of disease caused by these bacteria has been stimulated by the high morbidity and mortality of disease caused by these microorganisms, the emergence of antibiotic resistant strains, and the threat of endemic and epidemic disease. E. coli is the most common cause of neonatal meningitis associated with high mortality and serious neurological sequelae. The Kl polysaccharide is structurally identical to polysialic acid moieties on the neural cell adhesion molecule, NCAM, which may explain the weak immunogenicity of the E. coli capsule and the lack of effective vaccines, despite intensive vaccine development efforts. Indeed, it is not clear whether vaccines against the Kl capsule would be desireable. An alternative approach to disease control would be therapeutics aimed at disrupting bacterial sialic acid metabolism. This approach requires detailed information about polysialic acid synthesis and its underlying genetic regulation. Our current understanding of the kps gene cluster in E. coli Kl is at a level of sophistication wherein molecular descriptions of synthetic and regulatory mechanisms can be investigated in a unified program. Combining powerful microbial genetic approaches with molecular and biochemical methodologies suggests, for the first time, that a complete description of a membrane polysaccharide's synthesis, underlying genetic regulation, and translocation may be possible. This information will be relevant to other capsule biosynthetic systems of medical and industrial importance. Here, we propose experiments to further define the polymerase complex that is responsible for polysialic acid synthesis, to elucidate the genetic mechanisms underlying environmental regulation of capsule expression, and to begin a functional reconstitution of polymer assembly and translocation factors. These new approaches are a direct and logical continuance of our previous research to deduce a functional genetic map of the polysialic acid gene cluster.