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Taxonomic group: bacteria / Proteobacteria (Phylum: Proteobacteria)
Associated disease: infection due to Escherichia coli [ICD11: XN6P4

]

The structure was elucidated in this paper
NCBI PubMed ID: 24909379
Publication DOI: 10.1016/j.carres.2014.05.003
Journal NLM ID: 0043535
Publisher: Elsevier
Correspondence: G. Widmalm <gw

organ.su.se>
Institutions: Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm, Sweden

The structure of the O-antigen polysaccharide (PS) from Escherichia coli O42 has been investigated by NMR spectroscopy as the main method, which was complemented with sugar analysis, mass spectrometry, and analysis of biosynthetic information. The O-specific chain of the O-deacylated lipopolysaccharide (LPS-OH) consists of branched tetrasaccharide-glycerol repeating units joined by phosphodiester linkages. The lipid-free polysaccharide contains 0.8equiv of O-acetyl groups per repeating unit and has the following teichoic acid-like structure: Based on biosynthetic aspects, this should also be the biological repeating unit. This O-antigen structure is remarkably similar to that of E. coli O28ac, differing only in the presence or absence, respectively, of a glucose residue at the branching point. The structural similarity explains the serological cross-reactivity observed between strains of these two serogroups, and also their almost identical O-antigen gene cluster sequences.

NMR, O-antigen, Escherichia coli, O-acetylation

Structure type: polymer biological repeating unit
Location inside paper: p.177, fig.5
Compound class: O-antigen
Contained glycoepitopes: IEDB_130695,IEDB_135813,IEDB_136095,IEDB_137340,IEDB_137472,IEDB_141807,IEDB_142488,IEDB_144998,IEDB_146664,IEDB_151531,IEDB_190606,IEDB_983931,SB_192

Methods: 13C NMR, 1H NMR, NMR-2D, HF solvolysis, de-O-acylation, sugar analysis, 31P NMR, ESI-MS, acid hydrolysis, GLC, NMR-1D
Comments, role: O-deacylated polysaccharide

Related record ID(s): 30057, 30237, 30238
NCBI Taxonomy refs (TaxIDs): 562
Reference(s) to other database(s): GTC:G79899UZ
Show glycosyltransferases

NMR conditions: in D2O at 315 K [as TSV]

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
3,3,4,0	xRGro	65.53	78.12	62.13
3,3,4	P
3,3,2	Ac	175.15	23.46
3,3,3	aDGlcp	100.00	72.52	73.36	69.89	73.13	60.99
3,3	bDGlcpN	101.28	55.53	79.67	74.92	75.80	61.35
3	bDGalf	109.08	80.76	85.36	82.53	71.29	63.85
2	Ac	175.05	22.98
	aDGlcpN	97.91	53.92	78.59	69.19	73.12	61.48


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
3,3,4,0	xRGro	4.036-4.084	3.931	3.771
3,3,4	P
3,3,2	Ac	-	2.077
3,3,3	aDGlcp	5.329	3.495	3.693	3.457	3.638	3.813
3,3	bDGlcpN	4.701	3.818	3.969	4.222	3.588	3.830-3.919
3	bDGalf	5.076	4.031	4.205	4.181	3.915	3.656-3.688
2	Ac	-	2.103
	aDGlcpN	5.043	4.081	3.852	3.493	3.878	3.811-3.870


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
3,3,4,0	xRGro	65.53/4.036-4.084	78.12/3.931	62.13/3.771
3,3,4	P
3,3,2	Ac		23.46/2.077
3,3,3	aDGlcp	100.00/5.329	72.52/3.495	73.36/3.693	69.89/3.457	73.13/3.638	60.99/3.813
3,3	bDGlcpN	101.28/4.701	55.53/3.818	79.67/3.969	74.92/4.222	75.80/3.588	61.35/3.830-3.919
3	bDGalf	109.08/5.076	80.76/4.031	85.36/4.205	82.53/4.181	71.29/3.915	63.85/3.656-3.688
2	Ac		22.98/2.103
	aDGlcpN	97.91/5.043	53.92/4.081	78.59/3.852	69.19/3.493	73.12/3.878	61.48/3.811-3.870

¹H NMR data:

Linkage	Residue	H1	H2	H3	H4	H5	H6
3,3,4,0	xRGro	4.036 4.084	3.931	3.771
3,3,4	P
3,3,2	Ac		2.077
3,3,3	aDGlcp	5.329	3.495	3.693	3.457	3.638	3.813
3,3	bDGlcpN	4.701	3.818	3.969	4.222	3.588	3.830 3.919
3	bDGalf	5.076	4.031	4.205	4.181	3.915	3.656 3.688
2	Ac		2.103
	aDGlcpN	5.043	4.081	3.852	3.493	3.878	3.811 3.870

¹³C NMR data:

Linkage	Residue	C1	C2	C3	C4	C5	C6
3,3,4,0	xRGro	65.53	78.12	62.13
3,3,4	P
3,3,2	Ac	175.15	23.46
3,3,3	aDGlcp	100.00	72.52	73.36	69.89	73.13	60.99
3,3	bDGlcpN	101.28	55.53	79.67	74.92	75.80	61.35
3	bDGalf	109.08	80.76	85.36	82.53	71.29	63.85
2	Ac	175.05	22.98
	aDGlcpN	97.91	53.92	78.59	69.19	73.12	61.48

There is only one chemically distinct structure:

*O[C@H](CO)COP(=O)(O)O[C@@H]1[C@@H](CO)O[C@@H](O[C@H]2[C@H]([C@H](O)CO)O[C@@H](O[C@@H]3[C@@H](NC(C)=O)[C@@H](*)O[C@H](CO)[C@H]3O)[C@@H]2O)[C@H](NC(C)=O)[C@H]1O[C@H]1O[C@H](CO)[C@@H](O)[C@H](O)[C@H]1O

SVG MW SMILES 3D mol Ionize