Top-Down Strategies for the Structural Elucidation of Intact Gram-Negative Bacterial Endotoxins

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Date

2014-07

Authors

O'Brien, John P.
Needham, Brittany D.
Brown, Dusty B.
Trent, M. Stephen
Brodbelt, Jennifer S.

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Abstract

Re-modelling of lipopolysaccharides, which are the primary constituent of the outer cell membrane of Gram-negative bacteria, modulates pathogenesis and resistance to microbials. Reported herein is the characterization of intact Gram-negative bacterial lipooligosaccharides (LOS) via a new strategy utilizing online liquid chromatography (LC) coupled with ultraviolet photodissociation (UVPD) mass spectrometry. Compared to collision-based MS/MS methods, UVPD and UVPD/HCD promoted a greater array of cleavages within both the glycan and lipid moieties, including C-C, C-N, C-O cleavages in the acyl chains as well as glycosidic and cross-ring cleavages, thus providing the most far-reaching structural characterization of LOS. This LC-MS/MS strategy affords a robust analytical method to structurally characterize complex mixtures of bacterial endotoxins that maintains the integrity of the core oligosaccharide and lipid A domains of LOS, providing direct feedback about the cell envelope architectures and LOS modification strategies involved in resistance of the host innate immune defense.

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O'Brien, John P., Brittany D. Needham, Dusty B. Brown, M. Stephen Trent, and Jennifer S. Brodbelt. "Top-down strategies for the structural elucidation of intact Gram-negative bacterial endotoxins." Chemical Science 5, no. 11 (Jul., 2014): 4291-4301.