Mass Spectrometric Analysis of Intact Lipooligosaccharide: Direct Evidence for O-Acetylated Sialic Acids and Discovery of O-Linked Glycine Expressed by Campylobacter jejuni

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• 作者：Monika Dzieciatkowska ; Denis Brochu ; Alex van Belkum ; Astrid P. Heikema ; Nobuhiro Yuki ; R. Scott Houliston ; James C. Richards ; Michel Gilbert ; Jianjun Li
• 刊名：Biochemistry
• 出版年：2007
• 出版时间：December 18, 2007
• 年：2007
• 卷：46
• 期：50
• 页码：14704 - 14714
• 全文大小：185K
• 年卷期：v.46,no.50(December 18, 2007)
• ISSN：1520-4995

文摘

The lipooligosaccharides (LOS) of Campylobacter jejuni is an important virulence factor. Itscore oligosaccharide component is frequently sialylated and bears a close resemblance with hostgangliosides. The display of ganglioside mimics by this bacterium is believed to trigger the onset of theautoimmune condition Guillain-Barré syndrome (GBS) in some individuals. Considerable effort has beendirected toward the structural characterization of the glycan component of the LOS of C. jejuni strainsisolated from GBS patients. Capillary electrophoresis-mass spectrometry (CE-MS) has been a particularlyuseful analytical technique applied toward this task. Conventional analysis of bacterial LOS by CE-MShas generally involved the prior removal of O-acyl lipid chains, which is necessary for the effectivesolubilization and separation of the heterogeneous ensemble of LOS species. Unfortunately, O-deacylationcauses the undesired removal of important glycan-associated O-linked modifications, such as O-acetateand O-linked amino acids. In this report, we describe a CE-MS technique developed for the rapid analysisof fully intact LOS from C. jejuni. Using this method, we report the structural characterization of theglycan from 10 GBS-associated strains and two enteritis strains, using material isolated from as little asone colony. The application of this technique has enabled us to unambiguously identify LOS-boundO-acetylated sialic acid in a number of strains and has revealed for the first time that C. jejuni frequentlymodifies its core with O-linked glycine. Our studies demonstrate that MS-based structural analysis ofbacterial LOS can be optimized to the level where only a single-colony quantity of material is requiredand time-consuming chemical treatments can be avoided.