Rapid structural elucidation of polysaccharides employing predicted functions of glycosyltransferases and NMR data: Application to the O-antigen of Escherichia coli O59
Rapid structural elucidation of polysaccharides employing predicted functions of glycosyltransferases and NMR data: Application to the O-antigen of Escherichia coli O59
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DOI：
10.1093/glycob/cwu011
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发表时间：
2014-05-01
期刊：
影响因子：
4.3
通讯作者：
Widmalm, Goran
中科院分区：
文献类型：
--
作者：
Fontana, Carolina;Lundborg, Magnus;Widmalm, Goran
利用糖基转移酶（GT）的预测功能，结合未分配的NMR数据的计算机方法已被开发用于细菌多糖（PS）的结构解析。在这种方法中，从大肠杆菌O-抗原数据库中提取有关GT作用的信息（包括用作供体和/或受体的可能的糖残基，以及相应糖苷键中的异头构型和/或取代位置），并与未分配的NMR数据一起提交给CASPER程序。这种节省时间的方法，这表明需要化学分析，成功地实施在结构解析的O-抗原PS的E。coli O59。O-特异性链的重复单元使用O-脱酰化的PS确定，并且具有支链结构，即，-> 6）[α-d-GalpA 3Ac/4Ac-（1 -> 3）]-α-d-Manp-（1 -> 3）-α-d-Manp-（1-> 3）-β-d-Manp-（1-> 3）-α-d-GlcpNAc-（1 -> 3）。O-乙酰化位置的鉴定有效地进行了比较的H-1，C-13 HSQC NMR光谱的O-脱酰化的脂多糖和无脂PS结合化学位移预测由CASPER程序。侧链d-GalpA残基在0 -3和0 -4位置分别携带1当量的0-乙酰基，以3：7的比例分布在LPS中。在E. coliO 59 PS与先前提出的O-抗原基因簇中的乙酰转移酶WclD一致。
A computerized method that uses predicted functions of glycosyltransferases (GTs) in conjunction with unassigned NMR data has been developed for the structural elucidation of bacterial polysaccharides (PSs). In this approach, information about the action of GTs (consisting of possible sugar residues used as donors and/or acceptors, as well as the anomeric configuration and/or substitution position in the respective glycosidic linkages) is extracted from the Escherichia coli O-antigen database and is submitted, together with the unassigned NMR data, to the CASPER program. This time saving methodology, which alleviates the need for chemical analysis, was successfully implemented in the structural elucidation of the O-antigen PS of E. coli O59. The repeating unit of the O-specific chain was determined using the O-deacylated PS and has a branched structure, namely, -> 6)[alpha-d-GalpA3Ac/4Ac-(1 -> 3)]-alpha-d-Manp-(1 -> 3)-alpha-d-Manp-(1 -> 3)-beta-d-Manp-(1 -> 3)-alpha-d-GlcpNAc-(1 ->. The identification of the O-acetylation positions was efficiently performed by comparison of the H-1,C-13 HSQC NMR spectra of the O-deacylated lipopolysaccharide and the lipid-free PS in conjunction with chemical shift predictions made by the CASPER program. The side-chain d-GalpA residue carries one equivalent of O-acetyl groups at the O-3 and O-4 positions distributed in the LPS in a 3:7 ratio, respectively. The presence of O-acetyl groups in the repeating unit of the E. coli O59 PS is consistent with the previously proposed acetyltransferase WclD in the O-antigen gene cluster.