Structure of the Hafnia alvei strain PCM 1188 O-specific polysaccharide

Structure of the O-specific polysaccharide from the lipopolysaccharide of Aeromonas sobria strain Pt312

The O-specific polysaccharide (OPS) obtained by mild-acid degradation of the lipopolysaccharide from Aeromonas sobria strain Pt312 was studied by sugar and methylation analyses along with 1H and 13C NMR spectroscopy, including 2D 1H,1H COSY, TOCSY, NOESY, 1H-detected 1H,13C HSQC, and HMBC experiments. The sequence of the sugar residues was determined using 1H,1H NOESY and 1H,13C HMBC experiments. It was found that the OPS was built up of disaccharide repeating units composed of GlcpNAc and non-stoichiometrically O-acetylated Rhap residues, and had the structure.

Structure and serological analysis of the Hafnia alvei 481-L O-specific polysaccharide containing phosphate in the backbone chain

The lipopolysaccharide was extracted from cells of Hafnia alvei 481-L bacterial strain and, after mild acid hydrolysis, the O-specific polysaccharide was isolated and characterised. On the basis of chemical analyses and NMR spectroscopic studies of the polysaccharide and oligosaccharides obtained after Smith degradation, or hydrogen fluoride treatment, it was found that the repeating unit of the O-specific polysaccharide is a phosphorylated hexasaccharide: [see text]. The biological repeating unit of the H. alvei 481-L O-antigen has galactose phosphate at the nonreducing terminus. Serological tests indicate that this strain represents an individual serotype in the H. alvei genus.

Structures of the biological repeating units in the O-chain polysaccharides ofHafnia alveistrains having a typical lipopolysaccharide outer core region

Earlier, the structures of the O-chain polysaccharides of the lipopolysaccharides (LPS) of a number of Hafnia alvei strains have been established. However, it remained unknown, which is the first and the last monosaccharide of the O-chain. This is defined by the structure of the so-called biological repeating unit (O-unit), which is pre-assembled and then polymerised in the course of biosynthesis of bacterial polysaccharides by the Wzy-dependent pathway. Now we report on the structures of the O-units in 10 H. alvei strains. The LPS were cleaved by mild acid hydrolysis and oligosaccharide fractions IIIa and IIIb were isolated by gel chromatography subsequently on Sephadex G-50 and BioGel P-2 and studied by methylation analysis and NMR spectroscopy. Fraction IIIb was found to represent the core oligosaccharide containing a terminal upstream alpha-d-Glc-(1-->3)-alpha-d-Glc or alpha-d-Gal-(1-->3)-alpha-d-Glc disaccharide in the outer region that is typical of H. alvei. Fraction IIIa consists of the LPS core with one O-unit linked by a 3-substituted beta-d-GalNAc residue (in strains PCM 1189 and PCM 1546) or a 3-substituted beta-d-GlcNAc residue (in the other strains studied). In most strains examined the beta-configuration of the d-GlcNAc linkage in the first O-unit attached to the core is the same and in some strains is opposite to that found in the interior O-units of the O-chain polysaccharide. Various monosaccharides, including d-Glc, d-Gal, d-GlcA and acyl derivatives of 3-amino-3,6-dideoxy-d-glucose or 4-amino-4,6-dideoxy-d-glucose, occupy the non-reducing end of the O-unit.

Structure of the major glycolipid from Rothia dentocariosa

Structural studies of the major glycolipid isolated from Rothia dentocariosa were carried out by specific chemical degradation and nuclear magnetic resonance spectroscopy. The glycolipid was found to be a dimannosylacylmonoglyceride in which the carbohydrate part was the glycerol-linked dimannoside alpha-D-Manp-(1-->3)-alpha-D-Manp-(1-->3)-sn-Gro, and the internal mannose was esterified at C-6 by fatty acid residue. The other fatty acyl chain substituted the primary methylene position of glycerol. The occurrence of this glycolipid is limited to the related microorganisms. The structural characteristics can facilitate the differentiation of some genera.

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.

Structure of the O-specific polysaccharide of Hafnia alvei PCM 1222 containing 2-aminoethyl phosphate

The O-specific polysaccharide of H. alvei strain PCM 1222 has a branched hexasaccharide repeating unit containing D-galactose, L-rhamnose, D-ribose, D-galacturonic acid, and 2-acetamido-2-deoxy-D-glucose in the ratios 1:2:1:1:1, as well as 2-aminoethyl phosphate (EtNP) and O-acetyl groups in nonstoichiometric amounts. The polysaccharide was modified by carboxyl reduction, O-deacetylation, and dephosphorylation with 48% hydrofluoric acid, the last reaction being accompanied by removal of the lateral residue of beta-galactofuranose. The modified polysaccharides were studied by methylation analysis and 1H and 13C NMR spectroscopy, including 2D correlation spectroscopy (COSY), H-detected 1H,13C and 1H,31P heteronuclear multiple-quantum coherence (HMQC), 1D NOE, 2D rotating-frame NOE spectroscopy (ROESY), and 2D combined total correlation spectroscopy (TOCSY) and ROESY (TORO). The following structure of the O-deacetylated polysaccharide was established: [formula: see text] In different batches of the polysaccharide, the content of EtNP varied from 0.35 to 0.55 and that of the O-acetyl groups from 0.05 to 0.4 per repeating unit. It was tentatively suggested that the O-acetyl group is located at position 4 of a rhamnosyl residue.

Structural study and serological characterisation of the O-specific polysaccharide of Hafnia alvei PCM 1185, another Hafnia O-antigen that contains 3,6-dideoxy-3-[(R)-3-hydroxybutyramido]-D-glucose

The O-specific polysaccharide of H. alvei strain PCM 1185 contains D-glucose, D-glucuronic acid, 2-acetamido-2-deoxy-D-glucose, and 3,6-dideoxy-3-[(R)-3-hydroxybutyramido]-D-glucose (Qui3NAcyl) in the ratios 2:1:1:1 as well as O-acetyl groups. On the basis of sugar and methylation analyses of the polysaccharide before and after chemical modifications (O-deacetylation, carboxyl reduction, Smith degradation), as well as 1H and 13C NMR spectroscopy, including 1D sequential, selective spin-decoupling, 2D homonuclear and 13C,1H heteronuclear correlation spectroscopy (COSY), and 2D rotating-frame NOE spectroscopy, it was found that the polysaccharide has a pentasaccharide repeating unit with the following structure: [formula: see text] with O-acetyl groups present in nonstoichiometric amounts, mainly at position 2 of GlcA and position 6 of GlcNAc or lateral Glc. Serological study showed that H. alvei strain PCM 1185 can be placed in a new serotype D and that an O-acetyl group can be a part of its epitope.

Structural studies of the O-specific chain of Hafnia alvei strain 32 lipopolysaccharide

The structure of the O-specific side chain of the Hafnia alvei strain 32 lipopolysaccharide has been investigated. Methylation analysis, partial acid hydrolysis, Smith degradations, NMR spectroscopy, MALDI-TOF and FAB mass spectrometry in combination with collision-induced decomposition MS/MS were the principal methods used. It is concluded that the polysaccharide is composed of pentasaccharide repeating units having the following structure which is partially O-acetylated in the 2- (20%) and 3- (50%) position of the-->4)-alpha-D-GalpA-(1-->residue. [sequence :see text] A MALDI-TOF mass spectrum of the O-specific chains indicated that they consisted of up to 16 repeating units.