Structure of the O-Specific Polysaccharide ofHafnia Alvei23 Having an Oligosaccharide-Phosphate Repeating Unit

Genome Analysis and Characterisation of the Exopolysaccharide Produced by Bifidobacterium longum subsp. longum 35624™

The Bifibobacterium longum subsp. longum35624^™ strain (formerly named Bifidobacterium longum subsp. infantis) is a well described probiotic with clinical efficacy in Irritable Bowel Syndrome clinical trials and induces immunoregulatory effects in mice and in humans. This paper presents (a) the genome sequence of the organism allowing the assignment to its correct subspeciation longum; (b) a comparative genome assessment with other B. longum strains and (c) the molecular structure of the 35624 exopolysaccharide (EPS₆₂₄). Comparative genome analysis of the 35624 strain with other B. longum strains determined that the sub-speciation of the strain is longum and revealed the presence of a 35624-specific gene cluster, predicted to encode the biosynthetic machinery for EPS₆₂₄. Following isolation and acid treatment of the EPS, its chemical structure was determined using gas and liquid chromatography for sugar constituent and linkage analysis, electrospray and matrix assisted laser desorption ionization mass spectrometry for sequencing and NMR. The EPS consists of a branched hexasaccharide repeating unit containing two galactose and two glucose moieties, galacturonic acid and the unusual sugar 6-deoxy-L-talose. These data demonstrate that the B. longum35624 strain has specific genetic features, one of which leads to the generation of a characteristic exopolysaccharide.

Structure of the β-l-fucopyranosyl phosphate-containing O-specific polysaccharide of Escherichia coli O84

Fine structure of the O-polysaccharide chain of the lipopolysaccharide (O-antigen) defines the serospecificity of bacterial cells, which is the basis for O-serotyping of medically and agriculturally important gram-negative bacteria including Escherichia coli. In order to obtain the O-polysaccharide for structural analysis, the lipopolysaccharide was isolated from cells of E. coli O84a by phenol/water extraction and degraded with mild acid. However, the O-polysaccharide was cleaved at a highly acid-labile β-l-fucopyranosyl phosphate (β-l-Fucp-1-P) linkage to give mainly a pentasaccharide that corresponded to the O-polysaccharide repeat. Therefore, the lipopolysaccharide and the pentasaccharide as well as their O-deacylated derivatives were studied using sugar analysis, NMR spectroscopy, and (for oligosaccharides) ESI HR MS, and the O84-polysaccharide structure was established. The O-polysaccharide is distinguished by the presence of β-l-Fucp-1-P and randomly di-O-acetylated 6-deoxy-d-talose, which are found for the first time in natural carbohydrates. The gene cluster for the O84-antigen biosynthesis was analysed and its content was found to be consistent with the O-polysaccharide structure.

New functional ligands for ficolin-3 among lipopolysaccharides of Hafnia alvei

Ficolin-1 (M), ficolin-2 (L), ficolin-3 (H) and mannan-binding lectin (MBL) activate the complement system and have opsonic activity. The specificity of ficolin-3 is poorly characterized and currently limited to a few ligands only. We present new specific targets for human ficolin-3, identified among lipopolysaccharides (LPSs, endotoxin) of Hafnia alvei. The interaction was restricted to LPSs of four strains: 23, Polish Collection of Microorganisms (PCM) 1200, PCM 1203 and PCM 1205 and limited to their O-specific polysaccharides (O-specific PSs) composed of different numbers of oligosaccharide (OS) repeating units (RUs). Moreover, these LPS/ficolin-3 complexes activated the lectin pathway of complement in a C4b-deposition assay in a calcium- and magnesium-dependent way. A neoglycoconjugate of the O-specific PS fraction of H. alvei 1200 LPS with bovine serum albumin (BSA) was prepared and used as a tool for the determination of ficolin-3 concentration and activity in serum. To confirm a structure of the O-specific PS 1200 selected for the conjugate preparation, structural analysis was performed on a series of O-specific PSs released by the mild acid hydrolysis of the LPS. The isolated O-specific PSs, showing the different length distributions, were devoid of a major part of the core OS region and had Hep-Kdo disaccharide at a reducing end. The neoglycoconjugate was a highly selective tool for the determination of ficolin-3 concentration and activity in serum (lectin pathway activation in the C4b deposition assay) and was not affected by MBL, ficolin-1 and ficolin-2 or natural antibodies.

Natural phosphoglycans containing glycosyl phosphate units: structural diversity and chemical synthesis

An anomeric phosphodiester linkage formed by a glycosyl phosphate unit and a hydroxyl group of another monosaccharide is found in many glycopolymers of the outer membrane in bacteria (e.g., capsular polysaccharides and lipopolysaccharides), yeasts and protozoa. The polymers (phosphoglycans) composed of glycosyl phosphate (or oligoglycosyl phosphate) repeating units could be chemically classified as poly(glycosyl phosphates). Their importance as immunologically active components of the cell wall and/or capsule of numerous microorganisms upholds the need to develop routes for the chemical preparation of these biopolymers. In this paper, we (1) present a review of the primary structures (known to date) of natural phosphoglycans from various sources, which contain glycosyl phosphate units, and (2) discuss different approaches and recent achievements in the synthesis of glycosyl phosphosaccharides and poly(glycosyl phosphates).

Structure of the O-specific polysaccharide of Hafnia alvei PCM 1196

An acidic O-specific polysaccharide was isolated from Hafnia alvei PCM 1196 lipopolysaccharide and studied by sugar and methylation analyses along with one- and two-dimensional 1H and 13C NMR spectroscopy, including NOESY and HMBC experiments. The following structure of the pentasaccharide repeating unit was established: -->4)-alpha-D-GalpA-(1-->3)-beta-D-GlcpNAc-(1-->2)-beta-D-Galp-(1-->6)-alpha-D-Glcp-(1-->6)-alpha-D-GlcpNAc-(1-->.

Immunochemical aspects of Hafnia alvei O antigens

In the article the composition and structure of the O-specific polysaccharide chains and core region of the O antigens isolated from over 20 H. alvei strains is overviewed. Moreover, the correlation between the structure and immunospecificity of the O antigens is presented and discussed.