Burrows L L, Charter D F, Lam J S
Department of Microbiology, University of Guelph, Ontario, Canada.
Mol Microbiol. 1996 Nov;22(3):481-95. doi: 10.1046/j.1365-2958.1996.1351503.x.
Pseudomonas aeruginosa co-expresses A-band lipopolysaccharide (LPS), a homopolymer of rhamnose, and B-band LPS, a heteropolymer with a repeating unit of 2-5 sugars which is the serotype-specific antigen. The gene clusters for A- and B-band biosynthesis in P. aeruginosa O5 (strain PAO1) have been cloned previously. Here we report the DNA sequence and molecular analysis of the B-band O-antigen biosynthetic cluster. Sixteen open reading frames (ORFs) thought to be involved in synthesis of the O5 O antigen were identified, including wzz (rol), wzy (rfc), and wbpA-wbpN. A further 3 ORFs not thought to be involved with LPS synthesis were identified (hisH, hisF, and uvrB). Most of the wbp genes are found only in serotypes O2, O5, O16, O18, and O20, which form a chemically and structurally related O-antigen serogroup. In contrast, wbpM and wbpN are common to all 20 serotypes of P. aeruginosa. Although wbpM is not serogroup-specific, knockout mutations confirmed it is necessary for O5 O-antigen biosynthesis. A novel insertion sequences, IS 1209, is present at the junction between the serogroup-specific and non-specific regions. We have predicted the functions of the proteins encoded in the wbp cluster based on their homologies to those in the databases, and provide a proposed pathway of P. aeruginosa O5 O-antigen biosynthesis.
铜绿假单胞菌共表达A带脂多糖（LPS），一种鼠李糖同聚物，以及B带LPS，一种具有2 - 5个糖重复单元的杂聚物，它是血清型特异性抗原。铜绿假单胞菌O5（菌株PAO1）中A带和B带生物合成的基因簇先前已被克隆。在此，我们报告B带O抗原生物合成簇的DNA序列和分子分析。鉴定出16个被认为参与O5 O抗原合成的开放阅读框（ORF），包括wzz（rol）、wzy（rfc）和wbpA - wbpN。还鉴定出另外3个被认为与LPS合成无关的ORF（hisH、hisF和uvrB）。大多数wbp基因仅在血清型O2、O5、O16、O18和O20中发现，它们形成一个化学和结构相关的O抗原血清群。相比之下，wbpM和wbpN在铜绿假单胞菌的所有20个血清型中都存在。尽管wbpM不是血清群特异性的，但基因敲除突变证实它对于O5 O抗原生物合成是必需的。一个新的插入序列IS 1209存在于血清群特异性和非特异性区域之间的交界处。我们基于它们与数据库中那些蛋白的同源性预测了wbp簇中编码蛋白的功能，并提供了铜绿假单胞菌O5 O抗原生物合成的拟议途径。
