Taxonomic group: bacteria / Proteobacteria
(Phylum: Proteobacteria)
Host organism: Homo sapiens
Associated disease: bacillary dysentery (shigellosis) [ICD11:
1A02 
, ICD11:
SA56 , ICD11:
XN7HG ];
infection due to Shigella flexneri [ICD11:
XN7Y2 ]
The structure was elucidated in this paperPublication DOI: 10.1002/ejoc.201300180Journal NLM ID: 9805750Publisher: Wiley-VCH
Correspondence: Laurence A. Mulard <laurence.mulard
pasteur.fr>
Institutions: Institut Pasteur, Unité de Chimie des Biomolécules, 28 rue du Dr Roux, 75015 Paris, France, CNRS UMR3523, Institut Pasteur, 28 rue du Dr Roux, 75015 Paris, France, Université Paris Descartes Sorbonne Paris Cité, Institut Pasteur, rue du Dr Roux, 75015 Paris, France, Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm, Sweden, Institut Pasteur, Pathogénie Microbienne Moléculaire, 28 rue du Dr Roux, 75015 Paris, France, INSERM U786, Institut Pasteur, 28 rue du Dr Roux, 75015 Paris, France
Extensive analysis by NMR spectroscopy of the delipidated lipopolysaccharide of Shigella flexneri serotype 6 strain MDC 2924-71 confirmed the most recently reported structure of the O-antigen repeating unit as {→4)-β-D-GalpA-(1→3)-β-D-GalpNAc-(1→2)-α-L-Rhap3Ac/4Ac-(1→2)-α-L-Rhap-(1→}, and revealed the non-stoichiometric acetylation at O-3C/4C. Input from the CASPER program helped to ascertain the fine distribution of the three possible patterns of O-acetylation. The non-O-acetylated repeating unit (ABCD) corresponded to about 2/3 of the population, while 1/4 was acetylated at O-3C (3AcCDAB), and 1/10 at O-4C (4AcCDAB). Di- to tetrasaccharides with a GalpA residue (A) at their reducing end were synthesized as their propyl glycosides following a multistep linear strategy relying on late-stage acetylation at O-3C. Thus, the 3C-O-acetylated and non-O-acetylated targets were synthesized from common protected intermediates. Rhamnosylation was most efficiently achieved by using imidate donors, including at O-4 of a benzyl galacturonate acceptor. In contrast, a thiophenyl 2-deoxy-2-trichloroacetamido-D-galactopyranoside precursor was preferred for chain elongation involving residue B. Final Pd/C-mediated deprotection ensured O-acetyl stability. All of the target molecules represent parts of the O-antigen of S. flexneri 6, a prevalent serotype. Non-O-acetylated oligosaccharides are also fragments of the Escherichia coli O147 O-antigen.
carbohydrates, Oligosaccharides, NMR spectroscopy, structure elucidation, polysaccharides, glycosylation
Structure type: polymer chemical repeating unit
Location inside paper: p.4086, fig.1
Compound class: O-polysaccharide
Contained glycoepitopes: IEDB_130648,IEDB_133754,IEDB_136105,IEDB_137473,IEDB_225177,IEDB_885823
Methods: 1H NMR, chemical synthesis, chemical methods
Synthetic data: chemical
Comments, role: 70% of the polysaccharide are non-O-acetylated. 1H NMR data of the minor form repeating units O-acetylated at C-4 Rhap residue: #2,2,2_Ac - 2.207// #2,2_bDGalpN 4.716 4.055 3.868 4.301 3.685 ?// #2,4_10%Ac - 2.158// #2_aLRhap 5.159 4.238 4.095 4.823 3.857 1.151//
Related record ID(s): 29447, 29448, 29449, 29450, 29451, 29937
NCBI Taxonomy refs (TaxIDs): 424719
Show glycosyltransferases
NMR conditions: in D2O; pH 6 at 290(H) K
[as TSV]
13C NMR data:
missing...
1H NMR data:
Linkage Residue H1 H2 H3 H4 H5 H6
2,2,3 bDGalpA
2,2,2 Ac - 2.086
2,2 bDGalpN 4.512 4.014 3.899 4.300 3.633 ?
2 aLRhap 5.164 4.282 5.071 3.540 3.800 1.289
aLRhap
2,3 25%Ac - 2.207
2,4 10%Ac - 2.158
1H NMR data:
| Linkage | Residue | H1 | H2 | H3 | H4 | H5 | H6 |
|---|
| 2,2,3 | bDGalpA | |
| 2,2,2 | Ac |
| 2.086 | |
| 2,2 | bDGalpN | 4.512 | 4.014 | 3.899 | 4.300 | 3.633 | ? |
| 2 | aLRhap | 5.164 | 4.282 | 5.071 | 3.540 | 3.800 | 1.289 |
| | aLRhap | |
| 2,3 | 25%Ac |
| 2.207 | |
| 2,4 | 10%Ac |
| 2.158 | |
|
There is only one chemically distinct structure:
Found 
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