An O-polysaccharide was isolated by mild acid degradation of the lipopolysaccharide of Salmonella enterica O47 and studied by sugar analysis along with one- and two-dimensional 1H- and 13C-NMR spectroscopy. The following structure of the linear ribitol phosphate-containing repeating unit of the O-polysaccharide was established: →2)-D-Ribitol-5-P-(O→6)-α-D-Galp-(1→3)-α-L-FucpNAm(1→3)-β-D-GlcpNAc-(1→, where FucNAm stands for 2-acetimidoylamino-2,6-dideoxy-L-galactose. About 10% of Gal is O-acetylated at position 4 and another minor O-acetyl group is present at an undetermined position. Functions of the S. enterica O47 antigen biosynthetic genes were tentatively assigned by comparison with gene databases and found to be in agreement with the O-polysaccharide structure. A comparison of the O-antigen gene clusters of S. enterica O47 and E. coli O145 suggested their close evolutionary relationship.

Lipopolysaccharide, Ribitol phosphate, Salmonella enterica, bacterial polysaccharide structure, O-antigen gene cluster, acetimidoyl group

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
3,3,6,0	xDRib-ol	62.2	83.1	72.2	71.2	67.3
3,3,6	P
3,3	aDGalp	102.8	69.4	70.3	70.5	71.7	66.4
3,2	Am	167.7	20.6
3	aLFucpN	97.7	53.1	78.1	72.0	68.4	16.8
2	Ac	175.8	23.8
	bDGlcpN	102.7	56.9	80.0	69.5	76.9	62.0


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
3,3,6,0	xDRib-ol	3.76-3.88	3.84	3.83	3.79	3.92-4.00
3,3,6	P
3,3	aDGalp	5.06	3.79	3.86	4.02	4.22	3.98-4.08
3,2	Am	?	2.26
3	aLFucpN	5.18	4.05	4.05	4.10	4.45	1.21
2	Ac	-	2.03
	bDGlcpN	4.58	3.95	3.71	3.57	3.49	3.78-3.93


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
3,3,6,0	xDRib-ol	62.2/3.76-3.88	83.1/3.84	72.2/3.83	71.2/3.79	67.3/3.92-4.00
3,3,6	P
3,3	aDGalp	102.8/5.06	69.4/3.79	70.3/3.86	70.5/4.02	71.7/4.22	66.4/3.98-4.08
3,2	Am	167.7/?	20.6/2.26
3	aLFucpN	97.7/5.18	53.1/4.05	78.1/4.05	72.0/4.10	68.4/4.45	16.8/1.21
2	Ac		23.8/2.03
	bDGlcpN	102.7/4.58	56.9/3.95	80.0/3.71	69.5/3.57	76.9/3.49	62.0/3.78-3.93

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

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

765.656 g/mol (C₂₇H₄₈R₂N₃O₂₀P, R = next and previous repeats, not counted in mol weight)