A single nucleotide exchange in the wzy gene is responsible for the semirough O6 lipopolysaccharide phenotype and serum sensitivity of Escherichia coli strain Nissle 1917
A single nucleotide exchange in the wzy gene is responsible for the semirough O6 lipopolysaccharide phenotype and serum sensitivity of Escherichia coli strain Nissle 1917
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DOI：
10.1128/jb.184.21.5912-5925.2002
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发表时间：
2002-11-01
影响因子：
3.2
通讯作者：
Dobrindt, U
中科院分区：
文献类型：
--
作者：
Grozdanov, L;Zähringer, U;Dobrindt, U
对从半粗、血清敏感的大肠杆菌菌株 Nissle 1917（DSM 6601，血清型 O6:K5:H1）分离的脂多糖 (LPS) 进行结构分析表明，该菌株的 LPS 含有双磷酸化六酰基脂质 A 和由连接到 R1 型核心的一个大肠杆菌 06 抗原重复单元组成的十四糖。 O-抗原寡糖和核心（β）之间的GlcNAc糖苷键的构型不同于大肠杆菌O6抗原多糖（α）中重复单元的相互连接。对 Nissle 1917 菌株的 wa* 和 wb* 基因簇（LPS 核心和 O6 重复单元生物合成所需）进行了亚克隆和测序。 wa* 决定簇 (11.8 kb) 的 DNA 序列与其他 R1 核心类型特异性 wa* 基因簇具有 97% 的同一性。 wb* 基因簇 (11 kb) 的 DNA 序列与除 manC 和 manB 之外的已知 DNA 序列没有同源性。菌株 Nissle 1917 和平滑且具有血清抗性的尿路致病性大肠杆菌 O6 菌株 536 的 wb*(06)（来自血清型 O6 的 wb*）决定簇的遗传结构的比较表明，编码菌株 Nissle 1917 的 O 抗原聚合酶 Wzy 的假定开放阅读框由于点突变而被截短。与大肠杆菌菌株 536 的功能性 wzy 拷贝的互补证实，菌株 Nissle 1917 的半粗糙表型是由于非功能性 wzy 基因造成的。大肠杆菌菌株 Nissle 1917 中功能性 wzy 基因的表达增加了其抵抗血清抗菌防御机制的能力。这些结果强调了 LPS 对于大肠杆菌血清抗性或敏感性的重要性。
Structural analysis of lipopolysaccharide (LPS) isolated from semirough, serum-sensitive Escherichia coli strain Nissle 1917 (DSM 6601, serotype O6:K5:H1) revealed that this strain's LPS contains a bisphosphorylated hexaacyl lipid A and a tetradecasaccharide consisting of one E. coli 06 antigen repeating unit attached to the R1-type core. Configuration of the GlcNAc glycosidic linkage between O-antigen oligosaccharide and core (beta) differs from that interlinking the repeating units in the E. coli O6 antigen polysaccharide (alpha). The wa* and wb* gene clusters of strain Nissle 1917, required for LPS core and O6 repeating unit biosyntheses, were subcloned and sequenced. The DNA sequence of the wa* determinant (11.8 kb) shows 97% identity to other R1 core type-specific wa* gene clusters. The DNA sequence of the wb* gene cluster (11 kb) exhibits no homology to known DNA sequences except manC and manB. Comparison of the genetic structures of the wb*(06) (wb* from serotype O6) determinants of strain Nissle 1917 and of smooth and serum-resistant uropathogenic E. coli O6 strain 536 demonstrated that the putative open reading frame encoding the O-antigen polymerase Wzy of strain Nissle 1917 was truncated due to a point mutation. Complementation with a functional wzy copy of E. coli strain 536 confirmed that the semirough phenotype of strain Nissle 1917 is due to the nonfunctional wzy gene. Expression of a functional wzy gene in E. coli strain Nissle 1917 increased its ability to withstand antibacterial defense mechanisms of blood serum. These results underline the importance of LPS for serum resistance or sensitivity of E. coli.