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

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A. V. Perepelov^1*, Bin Liu^2,3, S. N. Senchenkova¹, A. S. Shashkov¹, S. D. Shevelev¹, Lu Feng^2,3, Lei Wang^2,3, 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

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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.

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KEY WORDS: Escherichia coli, lipopolysaccharide, O-antigen, biosynthesis, O-polysaccharide structure, O-antigen gene cluster, nonulosonic acid

DOI: 10.1134/S0006297910010037

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