Fusobacterium nucleatum is an anaerobic bacterium found in the human mouth where it causes periodontitis. It was also found in colorectal cancer tissues and is linked with pregnancy complications, including pre-term and still births. Cell surface structures of the bacterium could be implicated in pathogenesis. Here we report the following structure of the lipopolysaccharide O-chain of a spontaneous streptomycin resistant (SmR) mutant of F. nucleatum strain ATCC 23726: -4-β-Non5Am7Ac-4-β-d-GlcNAcyl3NFoAN-3-β-d-FucNAc4N- where GlcNAcyl3NFoAN indicates 2,3-diamino-2,3-dideoxyglucuronic acid amide with Fo at N-3 being formyl and Acyl at N-2 being propanoyl ( approximately 70%) or butanoyl ( approximately 30%); Non5Am7Ac indicates 7-acetamido-5-acetimidoylamino-3,5,7,9-tetradeoxy-l-gluco-non-2-ulosonic acid presumably having the d-glycero-l-gluco configuration. To our knowledge, no l-gluco isomer of higher sugars of this class as well as no N-propanoyl or N-butanoyl group have so far been found in bacterial polysaccharides.

Lipopolysaccharide, structure, polysaccharide, NMR spectroscopy, 2, 3-diamino-2, 3-dideoxyglucuronic acid, Fusobacterium nucleatum, Non-2-ulosonic acid

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6	C7	C8	C9
3,4,5	Am
3,4,7	Ac
3,4	bXDL3,9dglcNonp5N7N-ulosonic	173.0	98.4	35.5	66.9	48.2	70.4	54.0	66.1	19.1
3,2	Pp	179.5	30.2	10.6
3,3	Fo
3,6	NH2
3	bDGlcpN3NA	102.6	54.4	53.1	72.1	77.4	174.9
2	Ac
	Subst	61.2	54.2-55.6	77.5-78.0	41.0-41.8	65.0-65.3	23.3-23.6


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6	H7	H8	H9
3,4,5	Am
3,4,7	Ac
3,4	bXDL3,9dglcNonp5N7N-ulosonic	-	-	1.84-2.54	4.00	3.82	4.30	3.85	4.38	1.14
3,2	Pp	-	2.26-2.26	1.08
3,3	Fo
3,6	NH2
3	bDGlcpN3NA	1.74	3.91	4.20	4.27	4.09	-
2	Ac
	Subst	3.51-3.57	3.97-4.05	4.02-4.03	1.54-1.88	-	1.14-1.16


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6	C7/H7	C8/H8	C9/H9
3,4,5	Am
3,4,7	Ac
3,4	bXDL3,9dglcNonp5N7N-ulosonic			35.5/1.84-2.54	66.9/4.00	48.2/3.82	70.4/4.30	54.0/3.85	66.1/4.38	19.1/1.14
3,2	Pp		30.2/2.26-2.26	10.6/1.08
3,3	Fo
3,6	NH2
3	bDGlcpN3NA	102.6/1.74	54.4/3.91	53.1/4.20	72.1/4.27	77.4/4.09	
2	Ac
	Subst	61.2/3.51-3.57	54.2-55.6/3.97-4.05	77.5-78.0/4.02-4.03	41.0-41.8/1.54-1.88		23.3-23.6/1.14-1.16

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

CCC(=O)N[C@H]1[C@H](O[C@@H](CC(C)O)[C@H](CO)NC(C)=O)O[C@H](C(N)=O)[C@@H](O[C@]2(C(=O)O)C[C@@H](O)[C@H](NC(C)=N)[C@H]([C@@H](NC(C)=O)[C@@H](C)O)O2)[C@@H]1NC=O

763.799 g/mol (C₃₁H₅₃N₇O₁₅)