Structure of a new N-acetylisomuramic acid-containing O-specific polysaccharide of Proteus penneri strains 19 and 35

Structure and serology of O-antigens as the basis for classification of Proteus strains

This review is devoted to structural and serological characteristics of the O-antigens (O-polysaccharides) of the lipopolysaccharides of various Proteus species, which provide the basis for classifying Proteus strains to Oserogroups. The antigenic relationships of Proteus strains within and beyond the genus as well as their O-antigenrelated bioactivities are also discussed.

N-acetylmuramic acid as capping element of alpha-D-fucose-containing S-layer glycoprotein glycans from Geobacillus tepidamans GS5-97T

Geobacillus tepidamans GS5-97(T) is a novel Gram-positive, moderately thermophilic bacterial species that is covered by a glycosylated surface layer (S-layer) protein. The isolated and purified S-layer glycoprotein SgtA was ultrastructurally and chemically investigated and showed several novel properties. By SDS-PAGE, SgtA was separated into four distinct bands in an apparent molecular mass range of 106-166 kDa. The three high molecular mass bands gave a positive periodic acid-Schiff staining reaction, whereas the 106-kDa band was nonglycosylated. Glycosylation of SgtA was investigated by means of chemical analyses, 600-MHz nuclear magnetic resonance spectroscopy, and electrospray ionization quadrupole time-of-fight mass spectrometry. Glycopeptides obtained after Pronase digestion revealed the glycan structure [-->2)-alpha-L-Rhap-(1-->3)-alpha-D-Fucp-(1-->](n=approximately 20), with D-fucopyranose having never been identified before as a constituent of S-layer glycans. The rhamnose residue at the nonreducing end of the terminal repeating unit of the glycan chain was di-substituted. For the first time, (R)-N-acetylmuramic acid, the key component of prokaryotic peptidoglycan, was found in an alpha-linkage to carbon 3 of the terminal rhamnose residue, serving as capping motif of an S-layer glycan. In addition, that rhamnose was substituted at position 2 with a beta-N-acetylglucosamine residue. The S-layer glycan chains were bound via the trisaccharide core -->2)-alpha-L-Rhap-(1-->3)-alpha-L-Rhap-(1-->3)-alpha-L-Rhap-(1--> to carbon 3 of beta-D-galactose, which was attached in O-glycosidic linkage to serine and threonine residues of SgtA of G. tepidamans GS5-97(T).

Structure of the O-polysaccharide ofProteus penneri28 andProteus vulgarisO31 and classification ofP. penneri26 and 28 inProteusserogroup O31

The lipopolysaccharides (LPS) of Proteus penneri 28 and Proteus vulgaris O31 (PrK 55/57) were degraded with dilute acetic acid and structurally identical high-molecular-mass O-polysaccharides were isolated by gel-permeation chromatography. Sugar analysis and nuclear magnetic resonance (NMR) spectroscopic studies showed that both polysaccharides contain D-GlcNAc, 2-acetamido-2,6-dideoxy-L-glucose (L-2-acetamido-2,6-dideoxyglucose (N-acetylquinovosamine)) and 2-acetamido-3-O-[(S)-1-carboxyethyl]-2-deoxy-D-glucose (N-acetylisomuramic acid) and have the following structure: [carbohydrate structure: see text] where (S)-1-carboxyethyl [a residue of (S)-lactic acid] (S-Lac) is an ether-linked residue of (S)-lactic acid. The O-polysaccharide studied is structurally similar to that of P. penneri 26, which differs only in the absence of S-Lac from the GlcNAc residue. Based on the O-polysaccharide structures and serological data of the LPS, it was suggested classifying these strains in one Proteus serogroup, O31, as two subgroups: O(31a), 31b for P. penneri 28 and P. vulgaris PrK 55/57 and O31a for P. penneri 26. A serological relatedness of the LPS of Proteus O(31a), 31b and P. penneri 62 was revealed and substantiated by sharing epitope O31b, which is associated with N-acetylisomuramic acid. It was suggested that a cross-reactivity of P. penneri 28 O-antiserum with the LPS of several other P. penneri strains is due to a common epitope(s) on the LPS core.

Structure of the O-specific polysaccharide of Providencia alcalifaciens O16 containing N-acetylmuramic acid

The O-specific polysaccharide of Providencia alcalifaciens O16 was obtained by mild-acid degradation of the lipopolysaccharide and studied by chemical methods and NMR spectroscopy, including 2D 1H,(1)H COSY, TOCSY, NOESY, and 1H,(13)C HSQC experiments. It was found that the polysaccharide contains N-acetylmuramic acid, which was isolated by solvolysis with trifluoromethanesulfonic acid and identified by the specific optical rotation and NMR spectroscopy. The following structure of the trisaccharide repeating-unit of the polysaccharide was established:

Structure of the O-specific polysaccharide of Proteus penneri 71 and classification of cross-reactive P. penneri strains to a new proposed serogroup O64

A neutral O-specific polysaccharide (O-antigen) was isolated from the lipopolysaccharide (LPS) of the bacterium Proteus penneri 71. On the basis of sugar analysis and 1H- and 13C-NMR spectroscopic studies, including two-dimensional COSY, 13C,1H heteronuclear COSY and ROESY, the following structure of the trisaccharide repeating unit of the polysaccharide was established: -->3)-beta-D-GlcpNAc-(1-->4)-beta-D-GlcpNAc-(1-->3)-alpha-D-Galp-(1-- > The polysaccharide has the same carbohydrate backbone as the O-specific polysaccharide of P. penneri 19 and both are similar to that of P. penneri 62 studied by us previously. A cross-reactivity of anti-P. penneri 71, 19 and 62 O-antisera with 11 P. penneri strains was revealed and substantiated at the level of the O-antigen structures. These strains could be divided into three subgroups within a new proposed Proteus O64 serogroup containing P. penneri strains only.

Structure of the O-specific polysaccharide of a serologically separate strain Proteus penneri 2 from a new proposed serogroup O66

O-specific polysaccharide chain of Proteus penneri strain 2 lipopolysaccharide was studied by full and partial acid hydrolysis, Smith degradation, methylation analysis, and NMR spectroscopy, including two-dimensional rotating-frame NOE spectroscopy (ROESY) and 1H,13C heteronuclear multiple-quantum coherence (HMQC) experiments. Together with D-glucose and 2-acetamido-2-deoxy-D-glucose, the polysaccharide was found to contain two rarely occurring sugars, 6-deoxy-L-talose (L-6dTal) and 2,3-diacetamido-2,3,6-trideoxy-L-mannose (L-RhaNAc3NAc), and the following structure of a non-stoichiometrically O-acetylated tetrasaccharide repeating unit was established: [equation: see text] The O-specific polysaccharide studied has a unique composition and structure and, accordingly, P. penneri 2 is serologically separate among Proteus strains. Therefore, we propose for P. penneri 2 a new Proteus O-serogroup O66 where this strain is at present the single representative.

Structure of a new neutral O-specific polysaccharide of Proteus penneri 34

The O-specific polysaccharide of Proteus penneri strain 34 was studied using 1H and 13C NMR spectroscopy, including 2D COSY, TOCSY, NOESY, and H-detected 1H, 13C HMQC experiments. The following structure was established, which is unique among the known structures of Proteus O-antigens:-->4)-beta-D-Glcp-(1-->3)-beta-D-GalpNAc-(1-->4)-beta- D-GalpNAc-(1-->4)-beta-D-Galp-(1-->. Accordingly, no cross-reaction was observed between P. penneri 34 O-antiserum and O-antigens of other Proteus strains. Therefore, the strain studied should belong to a new Proteus serogroup O65.

Structure of the O-specific polysaccharide of a serologically separate Proteus penneri strain 22

The O-specific polysaccharide chain (O-antigen) of Proteus penneri strain 22 lipopolysaccharide was studied using chemical methods, including partial acid hydrolysis and Smith degradation, as well as one- and two-dimensional 1H and 13C NMR spectroscopy. The following structure of the pentasaccharide repeating unit was established: [sequence: see text] The O-specific polysaccharide contains a GalNAc residue in the furanose form which has not been hitherto found in bacterial polysaccharides. The O-antigen studied is serologically and structurally unique among Proteus strains and, therefore, a new Proteus serogroup O63 is proposed for P. penneri strain 22.

Structure of a muramic acid containing capsular polysaccharide from the pathogenic strain of Vibrio vulnificus ATCC 27562

Vibrio vulnificus strains isolated from septicemia cases and from the environment show a wide variety of capsular types. In an attempt to find common structural features which can be correlated with pathogenicity and toxicity, we have determined structures of the capsular polysaccharides (CPS) from several pathogenic strains. We report the complete structure of the polysaccharide from the pathogenic V. vulnificus strain ATCC 27562 using a combination of homonuclear and heteronuclear one-dimensional and two dimensional NMR experiments. The 13C and 1H NMR spectra, including the exchangeable amide proton resonances, have been completely assigned. The amide linkage between Ser and C6 of GalA has been unambiguously determined by water-suppressed 2D NOESY. To verify the structure established by NMR, we have fragmented the polymer employing the Smith degradation procedure. The Smith product identified by NMR and matrix-assisted laser desorption mass spectrometry is consistent with the proposed structure for the CPS, which is composed of D-GlcNAc, MurNAc, D-GalA, L-Rha and is serine-linked as shown: [formula: see text]

Structure of the O-specific polysaccharide of Proteus penneri strain 41 from a new proposed serogroup O62

O-specific polysaccharide of Proteus penneri strain 41 was studied using 1H- and 13C-NMR spectroscopy, including two-dimensional COSY, heteronuclear 13C,1H-correlation (HETCOR) and one-dimensional NOE spectroscopy, and the following structure of a non-stoichiometrically O-acetylated hexasaccharide repeating unit was established:[structure: see text] where RGlcNAc is 2-acetamido-4-O-[(S)-1-carboxyethyl]-2-deoxyglucose. Cross-reactivity of anti-P. penneri 41 O-serum with other P. penneri strains is discussed, and a new, separate O62 serogroup is proposed which is the next Proteus O-serogroup containing P. penneri strains only.

Structure of the O-specific polysaccharide of Proteus vulgaris O25 containing 3-O-[(R)-1-carboxyethyl]-D-glucose

The O-specific polysaccharide of Proteus vulgaris O25 was studied by acid hydrolysis and by 1H-NMR and 13C-NMR spectroscopies, including one-dimensional NOE and two-dimensional COSY and heteronuclear 13C,1H correlation (HETCOR) spectroscopy. The polysaccharide was found to contain 3-O-[(R)-1-carboxyethyl]-D-glucose (D-RGlc), and the following structure of the pentasaccharide repeating unit was established: [structure in text]

Structural characterisation of the exocellular polysaccharide produced by Streptococcus thermophilus OR 901

The exocellular polysaccharide of Streptococcus thermophilus OR 901, isolated from partially deproteinised whey, is a heteropolymer of D-galactopyranose and L-rhamnopyranose residues in the molar ratio 5:2. The structure was established by methylation analysis and 1D and 2D NMR spectroscopy of the native polysaccharide, in combination with characterisation of oligosaccharide fragments, obtained by partial acid hydrolysis, using methylation analysis and 1D 1H NMR spectroscopy. The polysaccharide has a branched heptasaccharide repeating unit with the following structure: [sequence: see text]

Structure of the O-specific polysaccharide of Proteus penneri strain 25 containing N-(L-alanyl) and multiple O-acetyl groups in a tetrasaccharide repeating unit

Based on sugar and methylation analyses, O-deacetylation, Smith degradation, and 1H and 13C NMR spectroscopy, including 2D COSY, 1H-detected 1H, 13C heteronuclear single-quantum coherence (HSQC), and 1H-detected 1H, 13C heteronuclear multiple-bond connectivity (HMBC) experiments, the following structure of the O-specific polysaccharide of Proteus penneri strain 25 was established: [formula: see text] where D-GlcN(L-Ala) is 2-(L-alanylamido)-2-deoxy-D-glucose.