The K1 capsular polysaccharide of Escherichia coli.
The K1 capsular polysaccharide of Escherichia coli.
复制标题
大肠杆菌K1荚膜多糖。
DOI：
10.1093/cid/10.supplement_2.s282
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
W. Vann
中科院分区：
文献类型：
--
作者：
R. P. Silver;W. Aaronson;W. Vann
流行病学、免疫学和遗传学证据表明 K1 荚膜多糖赋予大肠杆菌侵袭性。这种胶囊是一种 α-2----8 连接的唾液酸均聚物 (NeuNAc)，为细菌提供了物理抗吞噬屏障。 K1 和人体组织成分之间的结构相似性表明，免疫耐受也可能是 K1 疾病发病机制的一个因素。研究了 K1 多糖合成和输出中涉及的分子和遗传事件。克隆的 K1 基因编码至少 12 种参与荚膜生物合成的蛋白质。这些基因似乎是协调调节的并且在功能上聚集。一簇与 NeuNAc 的合成和激活相关，并包括编码 CMP-NeuNAc 合成酶的基因。该酶催化 NeuNAc 活化为 CMP-NeuNAc。第二个区域编码五种蛋白质，与多糖向细菌表面的易位有关。 K1 多糖在人体中是一种较差的免疫原，了解 K1 合成中涉及的关键反应可能有助于提供抗荚膜免疫的替代方案。
Epidemiologic, immunologic, and genetic evidence indicate that the K1 capsular polysaccharide confers invasiveness to Escherichia coli. The capsule, an alpha-2----8-linked homopolymer of sialic acid (NeuNAc), provides the bacterium with a physical antiphagocytic barrier. Structural similarities between K1 and human tissue components suggest that immune tolerance may also be a factor in pathogenesis of K1 disease. The molecular and genetic events involved in the synthesis and export of the K1 polysaccharide were examined. The cloned K1 genes encode at least 12 proteins involved in capsule biosynthesis. These genes appear to be coordinately regulated and functionally clustered. One cluster is associated with the synthesis and activation of NeuNAc and includes the gene encoding CMP-NeuNAc synthetase. This enzyme catalyzes the activation of NeuNAc to CMP-NeuNAc. A second region, encoding five proteins, is associated with translocation of polysaccharide to the bacterial surface. The K1 polysaccharide is a poor immunogen in humans, and an understanding of the key reactions involved in K1 synthesis may help in providing an alternative to anticapsular immunity.