Izquierdo Luis, Coderch Núria, Piqué Nuria, Bedini Emiliano, Corsaro Maria Michela, Merino Susana, Fresno Sandra, Tomás Juan M, Regué Miguel
Departamento de Microbiología y Parasitología Sanitarias, División de Ciencias de la Salud, Facultad de Farmacia,Universidad de Barcelona, Barcelona, Spain.
J Bacteriol. 2003 Dec;185(24):7213-21. doi: 10.1128/JB.185.24.7213-7221.2003.
To determine the function of the wabG gene in the biosynthesis of the core lipopolysaccharide (LPS) of Klebsiella pneumoniae, we constructed wabG nonpolar mutants. Data obtained from the comparative chemical and structural analysis of LPS samples obtained from the wild type, the mutant strain, and the complemented mutant demonstrated that the wabG gene is involved in attachment to alpha-L-glycero-D-manno-heptopyranose II (L,D-HeppII) at the O-3 position of an alpha-D-galactopyranosyluronic acid (alpha-D-GalAp) residue. K. pneumoniae nonpolar wabG mutants were devoid of the cell-attached capsular polysaccharide but were still able to produce capsular polysaccharide. Similar results were obtained with K. pneumoniae nonpolar waaC and waaF mutants, which produce shorter LPS core molecules than do wabG mutants. Other outer core K. pneumoniae nonpolar mutants in the waa gene cluster were encapsulated. K. pneumoniae waaC, waaF, and wabG mutants were avirulent when tested in different animal models. Furthermore, these mutants were more sensitive to some hydrophobic compounds than the wild-type strains. All these characteristics were rescued by reintroduction of the waaC, waaF, and wabG genes from K. pneumoniae.
为了确定wabG基因在肺炎克雷伯菌核心脂多糖（LPS）生物合成中的功能，我们构建了wabG非极性突变体。对野生型、突变株和互补突变体的LPS样品进行比较化学和结构分析所获得的数据表明，wabG基因参与了在α-D-吡喃半乳糖醛酸（α-D-GalAp）残基的O-3位与α-L-甘油-D-甘露庚糖II（L,D-HeppII）的连接。肺炎克雷伯菌非极性wabG突变体缺乏细胞附着的荚膜多糖，但仍能产生荚膜多糖。肺炎克雷伯菌非极性waaC和waaF突变体也得到了类似的结果，它们产生的LPS核心分子比wabG突变体短。waa基因簇中的其他肺炎克雷伯菌外核心非极性突变体被包裹。在不同动物模型中测试时，肺炎克雷伯菌waaC、waaF和wabG突变体无毒力。此外，这些突变体比野生型菌株对一些疏水化合物更敏感。通过重新导入肺炎克雷伯菌的waaC、waaF和wabG基因，所有这些特性都得到了恢复。
