The structural and genetic organization of the Escherichia coli O52 O antigen was studied. As identified by sugar and methylation analysis and nuclear magnetic resonance spectroscopy, the O antigen of E. coli O52 has a partially O-acetylated disaccharide repeating unit (O unit) containing D-fucofuranose and 6-deoxy-D-manno-heptopyranose, as well as a minor 6-deoxy-3-O-methylhexose (most likely, 3-O-methylfucose). The O-antigen gene cluster of E. coli O52, which is located between the galF and gnd genes, was found to contain putative genes for the synthesis of the O-antigen constituents, sugar transferase genes, and ABC-2 transporter genes. Further analysis confirmed that O52 employs an ATP-binding cassette (ABC) transporter-dependent pathway for translocation and polymerization of the O unit. This is the first report of an ABC transporter being involved in translocation of a heteropolysaccharide O antigen in E. coli. Genes specific for E. coli O52 were also identified.

genetic, structure, gene, O-antigen, O antigen, Escherichia coli, ABC transporter

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6	C7
3	bDFucf	105.9	81.2	85.8	87.3	68.4	19.9
	bD6dmanHepp	100.5	68.7	78.5	70.1	74.2	35.1	59.5


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6	H7
3	bDFucf	5.18	4.29	4.17	4.06	3.97	1.26
	bD6dmanHepp	4.86	4.24	3.75	3.52	3.43	1.75-2.13	3.76


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6	C7/H7
3	bDFucf	105.9/5.18	81.2/4.29	85.8/4.17	87.3/4.06	68.4/3.97	19.9/1.26
	bD6dmanHepp	100.5/4.86	68.7/4.24	78.5/3.75	70.1/3.52	74.2/3.43	35.1/1.75-2.13	59.5/3.76

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

*O[C@H]1[C@H]([C@@H](C)O)O[C@@H](O[C@@H]2[C@H](O)[C@H](*)O[C@H](CCO)[C@H]2O)[C@@H]1O

322.31 g/mol (C₁₃H₂₂R₂O₉, R = next and previous repeats, not counted in mol weight)