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Poster Presentations
Day 3, June 24（Tue.）
Room P (Maesato East, Foyer, Ocean Wing)
- 3P-PM-12
Decoding O-Antigen Substructures in Pathogenic E. coli O111: Insights from MALDI Glycotyping of Cell Culture and Commercial LPS
(Hokkaido Univ.)
oJune Chelyn Lee, Shogo Urakami, Hinou Hiroshi
Escherichia coli O111 is a highly pathogenic strain linked to severe human infections. The O-antigen, a key component of lipopolysaccharides (LPS), is crucial for serogroup classification. However, traditional serotyping struggles to distinguish closely related structures. To overcome this limitation, our team has developed a novel matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) technique for ultra-rapid glycan analysis. This approach leverages a simple acid treatment and a DAN/DHB/Na matrix to detect O-antigen repeat units (RU) across various Gram-negative bacterial strains.
Using a modified acidic treatment in our MALDI glycotyping method, we identified two distinct O-antigen glycoforms in E. coli O111. The first, a well-characterized pentasaccharide RU with a mass of m/z 787, consists of two hexoses, one hexosamine, and two colitose residues. MALDI-MS analysis confirmed this structure in strain JNBP02191 (GTC16618). However, strain JNBP02254 (GTC14517) exhibited a second glycoform with an RU mass of m/z 828, featuring a hexose-to-hexosamine substitution. This structural variation was also observed in commercial LPS samples and further validated by LIFT-TOF/TOF analysis. The precise structure of the modified monosaccharide in the new glycoform was ultimately confirmed through NMR analysis.
Our findings highlight the power of MALDI glycotyping in resolving subtle O-antigen variations, providing a valuable tool for bacterial classification and pathogenicity studies.