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Structure of the O-Antigen and Characterization of the O-Antigen Gene Cluster of Escherichia coli O108 Containing 5,7-Diacetamido-3,5,7,9-tetradeoxy-l-glycero-d-galacto-non-2-ulosonic (8-Epilegionaminic) Acid

A. V. Perepelov1*, Bin Liu2,3, S. N. Senchenkova1, A. S. Shashkov1, S. D. Shevelev1, Lu Feng2,3, Lei Wang2,3, and Y. A. Knirel1

1Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninskii pr. 47, 119991 Moscow, Russia; fax: (499) 137-6148; E-mail: perepel@ioc.ac.ru

2TEDA School of Biological Sciences and Biotechnology, Nankai University, 23 HongDa Street, TEDA, Tianjin 300457, P. R. China

3Tianjin Key Laboratory for Microbial Functional Genomics, TEDA College, Nankai University, 23 HongDa Street, TEDA, Tianjin 300457, P. R. China

* To whom correspondence should be addressed.

Received March 20, 2009; Revision received June 3, 2009
On mild acid degradation of the lipopolysaccharide of Escherichia coli O108, the O-polysaccharide was isolated and studied by sugar analysis and one- and two-dimensional 1H- and 13C-NMR spectroscopy. The polysaccharide was found to contain an unusual higher sugar, 5,7-diacetamido-3,5,7,9-tetradeoxy-l-glycero-d-galacto-non-2-ulosonic acid (di-N-acetyl-8-epilegionaminic acid, 8eLeg5Ac7Ac). The following structure of the tetrasaccharide repeating unit of the polysaccharide was established: →4)-α-8eLegp5Ac7Ac-(2→6)-α-D-Galp-(1→3)-α-L-FucpNAc-(1→3)-α-D-GlcpNAc-(1→. Functions of the E. coli O108 antigen biosynthetic genes, including seven putative genes for synthesis of 8eLeg5Ac7Ac, were assigned by sequencing the O-antigen gene cluster along with comparison with gene databases and known biosynthetic pathways for related nonulosonic acids.
KEY WORDS: Escherichia coli, lipopolysaccharide, O-antigen, biosynthesis, O-polysaccharide structure, O-antigen gene cluster, nonulosonic acid

DOI: 10.1134/S0006297910010037