Sammanfattning

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 H-1, C-13-HSQC, and H-1,H-1-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 similar to 1/2 of the population was 2,6-di-O-acetylated, similar to 1/4 was 2-O-acetylated, whereas similar to 1/4 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: -> 2)-beta-D-Manp-(1 -> 3)-beta-D-Manp2Ac6Ac-(1 -> 4)-beta-D-GlcpA-(1 -> 3)-alpha-D-GlcpNAc-(1 ->, 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 NN015840(T) 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.

Nyckelord

bioinformatics; CarbBuilder; CASPER; lipopolysaccharide; NMR spectroscopy

Publicerad i

Glycobiology
2023, Volym: 33, nummer: 4, sidor: 289-300
Utgivare: OXFORD UNIV PRESS INC

SLU författare

• Udekwu, Klas

  • Institutionen för vatten och miljö, Sveriges lantbruksuniversitet
    
  • Stockholms Universitet

UKÄ forskningsämne

Bioinformatik (beräkningsbiologi)
Organisk kemi


Publikationens identifierare

DOI: https://doi.org/10.1093/glycob/cwac069

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/122097