Fontana Carolina, Weintraub Andrej, Widmalm Göran
Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden.
Karolinska Institute, Department of Laboratory Medicine, Division of Clinical Microbiology, Karolinska University Hospital, S-141 86 Stockholm, Sweden.
Carbohydr Res. 2015 Feb 11;403:174-81. doi: 10.1016/j.carres.2014.05.003. Epub 2014 May 17.
The structure of the O-antigen polysaccharide (PS) from Escherichia coli O42 has been investigated by NMR spectroscopy as the main method, which was complemented with sugar analysis, mass spectrometry, and analysis of biosynthetic information. The O-specific chain of the O-deacylated lipopolysaccharide (LPS-OH) consists of branched tetrasaccharide-glycerol repeating units joined by phosphodiester linkages. The lipid-free polysaccharide contains 0.8equiv of O-acetyl groups per repeating unit and has the following teichoic acid-like structure: Based on biosynthetic aspects, this should also be the biological repeating unit. This O-antigen structure is remarkably similar to that of E. coli O28ac, differing only in the presence or absence, respectively, of a glucose residue at the branching point. The structural similarity explains the serological cross-reactivity observed between strains of these two serogroups, and also their almost identical O-antigen gene cluster sequences.
已通过核磁共振光谱法作为主要方法对来自大肠杆菌O42的O抗原多糖（PS）的结构进行了研究，同时辅以糖分析、质谱分析以及生物合成信息分析。去酰基脂多糖（LPS-OH）的O特异性链由通过磷酸二酯键连接的分支四糖-甘油重复单元组成。无脂多糖每个重复单元含有0.8当量的O-乙酰基，具有以下类磷壁酸结构：基于生物合成方面的考虑，这也应该是生物学重复单元。这种O抗原结构与大肠杆菌O28ac的结构非常相似，仅在分支点处分别存在或不存在葡萄糖残基方面有所不同。结构上的相似性解释了在这两个血清群的菌株之间观察到的血清学交叉反应性，以及它们几乎相同的O抗原基因簇序列。
