Structure and gene cluster of the O-antigen of Escherichia coli O165 containing 5-N-acetyl-7-N-[(R)-3-hydroxybutanoyl]pseudaminic acid

• Upon mild acid degradation of the lipopolysaccharide of Escherichia coli O165, the O-polysaccharide chain was cleaved at the glycosidic linkage of 5-N-acetyl-7-N-[(R)-3-hydroxybutanoyl]pseudaminic acid (Pse5Hb7Ac). Analysis of the resulting linear tetrasaccharide and alkali-treated lipopolysaccharide by 1H/13C 1D and 2D nuclear magnetic resonance spectroscopy enabled elucidation of the following structure of the O-polysaccharide: →8)-α-Psep5Hb7Ac-(2 → 6)-β-D-Galp-(1 → 4)-β-D-Glсp-(1 → 3)-α-DGlсpNAc-(1→. The β-D-Galp-(1 → 4)-β-D-Glсp-(1 → 3)-D-GlсpNAc structural element is also present in the O-polysaccharide of E. coli O82. The content of the O-antigen gene cluster of E. coli O165 was found to be consistent with the O-polysaccharide structure established. Functions of proteins encoded in the gene cluster, including enzymes involved in the Pse5Hb7Ac biosynthesis and glycosyltransferases, were putatively assigned by comparison with sequences in available databases.

Subject headings

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Keyword

bacterial polysaccharide structure

Escherichia coli

lipopolysaccharide

O-antigen gene cluster

Publication and Content Type

ref (subject category)

art (subject category)