Elucidation of the O-antigen structure of Escherichia coli O93 and characterization of its biosynthetic genes.
Glycobiology
; 33(4): 289-300, 2023 05 17.
Article
em En
| MEDLINE
| ID: mdl-36239409
ABSTRACT
The structure of the O-antigen from the international reference strain Escherichia coli O93-H16 has been determined. A nonrandom modal chain-length distribution was observed for the lipopolysaccharide, a pattern which is typical when long O-specific polysaccharides are expressed. By a combination of (i) bioinformatics information on the gene cluster related to O-antigen synthesis including putative function on glycosyl transferases, (ii) the magnitude of NMR coupling constants of anomeric protons, and (iii) unassigned 2D 1H, 13C-HSQC, and 1H,1H-TOCSY NMR spectra it was possible to efficiently elucidate the structure of the carbohydrate polymer in an automated fashion using the computer program CASPER. The polysaccharide also carries O-acetyl groups and their locations were determined by 2D NMR experiments showing that ~½ of the population was 2,6-di-O-acetylated, ~» was 2-O-acetylated, whereas ~» did not carry O-acetyl group(s) in the 3-O-substituted mannosyl residue of the repeating unit. The structure of the tetrasaccharide repeating unit of the O-antigen is given by â2)-ß-d-Manp-(1â3)-ß-d-Manp2Ac6Ac-(1â4)-ß-d-GlcpA-(1â3)-α-d-GlcpNAc-(1â, which should also be the biological repeating unit and it shares structural elements with capsular polysaccharides from E. coli K84 and K50. The structure of the acidic O-specific polysaccharide from Cellulophaga baltica strain NN015840T differs to that of the O-antigen from E. coli O93 by lacking the O-acetyl group at O6 of the O-acetylated mannosyl residue.
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Bases de dados:
MEDLINE
Assunto principal:
Antígenos O
/
Escherichia coli
Idioma:
En
Revista:
Glycobiology
Assunto da revista:
BIOQUIMICA
Ano de publicação:
2023
Tipo de documento:
Article
País de afiliação:
Suécia