Burkholderia (Pseudomonas) pseudomallei is the causative agent of melioidosis, a bacterial infection of considerable morbidity in areas of endemicity of Southeast Asia and northern Australia. Clinical isolates of B. pseudomallei have been demonstrated to produce a lipopolysaccharide (LPS) containing two separate and chemically distinct antigenic O polysaccharides against which infected patients produced antibodies. A putative capsular polysaccharide (CPS) has also been reported and is thought to be antigenically conserved based on results of serological studies with clinical B. pseudomallei isolates. In the present study, the CPS isolated from B. pseudomallei 304b from northeastern Thailand was found to have an [α]D of +99 degrees (water), was composed of D-galactose (D-Gal), 3-deoxy-D-manno-2-octulosonic acid (KDO), and O-acetyl 3:1:1), and was a linear unbranched polymer of repeating tetrasaccharide units having the following structure: -3)-2-O-Ac-β-D-Galp-(1-4)-α-D-Galp-(1-3)-β-D-Galp-(1-5)-β-D-KDOp-(2-. Sera from 13 of 15 patients with different clinical manifestations of melioidosis but not normal controls recognize the CPS, which suggests that it is immunogenic and raises the possibility that it may have a role as a vaccine candidate and/or diagnostic agent.

structure, capsular, characterization, polysaccharide, Burkholderia, Pseudomonas, Kdo, capsular polysaccharide

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6	C7	C8
5,3,4	bDGalp	105.16	70.79	79.04	69.30	75.39	61.41
5,3	aDGalp	96.32	69.80	70.80	79.45	71.05	61.82
5	bDGalp	105.16	70.59	78.40	65.72	75.78	61.67
	bXKdop	175.30	104.70	36.74	68.30	76.07	74.28	69.94	64.70


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6	H7	H8
5,3,4	bDGalp	4.62	3.63	3.78	4.12	3.70	?
5,3	aDGalp	5.15	3.93	4.03	4.27	4.26	3.72-3.83
5	bDGalp	4.69	3.77	3.79	4.16	3.72	?
	bXKdop	-	-	1.97-2.54	3.87	4.19	3.86	4.07	3.68-3.77


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6	C7/H7	C8/H8
5,3,4	bDGalp	105.16/4.62	70.79/3.63	79.04/3.78	69.30/4.12	75.39/3.70	61.41/?
5,3	aDGalp	96.32/5.15	69.80/3.93	70.80/4.03	79.45/4.27	71.05/4.26	61.82/3.72-3.83
5	bDGalp	105.16/4.69	70.59/3.77	78.40/3.79	65.72/4.16	75.78/3.72	61.67/?
	bXKdop			36.74/1.97-2.54	68.30/3.87	76.07/4.19	74.28/3.86	69.94/4.07	64.70/3.68-3.77

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

*O[C@@H]1[C@@H](O)[C@H](O[C@H]2[C@@H](CO)O[C@H](O[C@H]3[C@@H](O)[C@@H](CO)O[C@@H](O[C@@H]4[C@H](O)C[C@@](*)(C(=O)O)O[C@@H]4[C@H](O)CO)[C@@H]3O)[C@H](O)[C@H]2O)O[C@H](CO)[C@@H]1O

706.6 g/mol (C₂₆H₄₂R₂O₂₂, R = next and previous repeats, not counted in mol weight)