The structures of the capsular polysaccharides (CPSs) of the two clinical isolates Acinetobacter baumannii SMAL and MG1 were elucidated. Hot phenol/water extractions of the dry biomasses, followed by enzymatic digestions and repeated ultracentrifugations led to the isolation of polysaccharides that were negative in Western blot analysis utilizing an anti-lipid A antibody, thus proving that they were not the LPS O-antigens but CPSs. Their structures were established on the basis of NMR spectroscopy and GC-MS analyses. The A. baumannii MG1 CPS consisted of a linear aminopolysaccharide with acyl substitution heterogeneity at the N-4 amino group of QuipN4N: 4)-α-D-GlcpNAc-(1→4)-α-L-GalpNAcA-(1→3)-β-D-QuipNAc4NR-(1→ R=3-hydroxybutyrryl or acetyl. The repeating unit of the CPS produced by strain SMAL is a pentasaccharide, already reported for the O-antigen moiety from A. baumannii strain ATCC 17961: (formula, see text).
Acinetobacter baumannii, capsular polysaccharide, structural analysis, Western blot
NCBI PubMed ID: 21463855Publication DOI: 10.1016/j.carres.2011.03.024Journal NLM ID: 0043535Publisher: Elsevier
Correspondence: decastro@unina.it
Institutions: Division of Structural Biochemistry, Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Borstel, Germany, Università di Napoli Federico II, Dipartimento di Chimica Organica e Biochimica, Complesso Universitario Monte Sant’Angelo, Napoli, Italy
Methods: 13C NMR, 1H NMR, SDS-PAGE, sugar analysis, deacylation, Western blotting, NMR-1D
Found