Identification of an Escherichia coli operon required for formation of the O-antigen capsule
Identification of an Escherichia coli operon required for formation of the O-antigen capsule
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DOI：
10.1128/jb.187.15.5259-5266.2005
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发表时间：
2005-08-01
影响因子：
3.2
通讯作者：
Rosenshine, I
中科院分区：
文献类型：
--
作者：
Peleg, A;Shifrin, Y;Rosenshine, I
大肠杆菌产生的多糖胶囊，根据其合成和组装机制，已被分为四组。第4组被膜（G4 C）多糖通常与同源脂多糖O侧链的多糖相同，因此也被称为O抗原被膜。参与第1、2和3组胶囊组装的基因已被描述，但G4 C组装所需的基因仍不清楚。我们发现肠致病性E.大肠杆菌（EPEC）产生G4 C，并且我们鉴定了含有形成荚膜所需的7个基因ymcD、ymcC、ymcB、ymcA、yccZ、etp和etk的操纵子。编码的蛋白质似乎构成了多糖分泌系统。G4 C操纵子在肠聚集性大肠杆菌基因组中缺失。大肠杆菌和尿路致病性大肠杆菌。杆菌E. coliK-12含有G4 C操纵子，但不表达，因为在其启动子区存在IS 1。EPEC、肠出血性E.大肠杆菌和志贺氏菌具有完整的G4 C操纵子。
Escherichia coli produces polysaccharide capsules that, based on their mechanisms of synthesis and assembly, have been classified into four groups. The group 4 capsule (G4C) polysaccharide is frequently identical to that of the cognate lipopolysaccharide O side chain and has, therefore, also been termed the O-antigen capsule. The genes involved in the assembly of the group 1, 2, and 3 capsules have been described, but those required for G4C assembly remained obscure. We found that enteropathogenic E. coli (EPEC) produces G4C, and we identified an operon containing seven genes, ymcD, ymcC, ymcB, ymcA, yccZ, etp, and etk, which are required for formation of the capsule. The encoded proteins appear to constitute a polysaccharide secretion system. The G4C operon is absent from the genomes of enteroaggregative E. coli and uropathogenic E. coli. E. coli K-12 contains the G4C operon but does not express it, because of the presence of IS1 at its promoter region. In contrast, EPEC, enterohemorrhagic E. coli, and Shigella species possess an intact G4C operon.