Structure of the oligosaccharide region (core) of the lipopolysaccharides of Shigella flexneri types 2a and 5b

Abstract

The full structure of the lipopolysaccharide core of bacteria Shigella flexneri types 2a and 5b, the causative agents of bacillary dysentery (shigellosis), was established by chemical methods, high-resolution electrospray ionization mass spectrometry, and two-dimensional NMR spectroscopy. The structure of the O-antigen repeating unit and the configuration and position of the linkage between the O-antigen and the core were determined in the lipopolysaccharide of S. flexneri type 2a.

Bacteriophage-mediated Glucosylation Can Modify Lipopolysaccharide O-Antigens Synthesized by an ATP-binding Cassette (ABC) Transporter-dependent Assembly Mechanism

“…Consistent with this proposal, the LPS products of wzy mutants, which contain a single O-repeat unit, are not modified in Salmonella (50,51). Likewise, the first repeat unit of S. flexneri O-antigen is not subject to glucosylation (7,53,54). However, in bacteria producing full-length LPS forms, both glucosylated and nonglycosylated glycans can be produced by the same culture, and when they were separated, the modification was confined to LPS molecules with O-antigens exceeding ϳ6 repeat units in length (55).…”

Lipopolysaccharide core structures and their correlation with genetic groupings of Shigella strains. A novel core variant in Shigella boydii type 16

“…ESI FT-ICR MS of the oligosaccharides from B16 ( Figure 2B) showed also minor peaks for M + P, M + PEtN, M − P and M − Hex. The M + P compound may represent a variant of 1 with an additional phosphate group on Hep F (GlcN + P + inner core), which has been reported earlier in F2 and F5 (Kondakova et al 2010) and SS (Kübler-Kielb et al 2010). The M + PEtN compound is evidently another variant with a di-PEtN group on Hep E. This conclusion was confirmed by the presence of a major signal at δ P −2.2 ppm for a phosphate group and a minor signal at δ P −9.8 ppm for a diphosphate group in the 31 P NMR spectrum as well as minor signals at δ H 3.29 and δ C 41.6 for NH 2 CH 2 of ethanolamine in the 1 H and 13 C NMR spectra, respectively.…”

“…LDHep is a component of the outer core of E. coli K-12 (Müller-Loennies et al 2003) but no DDHep has been hitherto found in the core of the E. coli/Shigella group. Glc L, which bears the DDHep extension in B16, serves also as the site of attachment of the O-antigen to the R3 core in F2 (Kondakova et al 2010;Kübler-Kielb et al 2010). A biological significance of the core extension in B16 remains to be elucidated.…”

“…The core is a negatively charged LPS region, which strengthens the rigidity of the Gram-negative cell wall by intermolecular cationic bridging. In Shigella, the core structure has been studied in detail only in S. flexneri (Holst 1999;Kondakova et al 2010) representing cluster 1 (F6) and cluster 3 (all others) and in two outliers: S. sonnei (Gamian and Romanowska 1982) and S. dysenteriae type 1 (Kübler-Kielb et al 2010). In Shigella, as in all enterobacteria, the conserved inner-core part located closer to lipid A consists of two residues of 3-deoxy-D-manno-oct-2-ulosonic acid (Kdo) and three residues of L-glycero-D-manno-heptose (Hep).…”

Bacteriophage Sf6 Tailspike Protein for Detection of Shigella flexneri Pathogens

“…In contrast, oligosaccharides released from the 2a strains in this work contained high amounts of non-O-acetylated decasaccharides ( Figure 2 e–f). Moreover, minor peaks were detected with masses corresponding to oligosaccharides that lacked one glucose moiety resulting from the glucosylation process of the undecaprenyl pyrophosphate-O-antigen conjugate as non-glucosylated first repeating unit, what provides a measure for the amount of O-antigen chains [ 50 , 51 ]. Thus, oligosaccharide release analysis from strains with serotype Y and 2a O-antigens confirmed that Sf6TSP enzymatic digest is allowed for different degrees of O-acetylation, as naturally found in strains encountered in the field.…”