Structure and Characterization of the Gene Cluster of the O-Antigen of Escherichia coli O49 Containing 4,6-Dideoxy-4-[(S)-3-hydroxybutanoylamino]-D-glucose

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A. V. Perepelov^1*, Quan Wang^2,3, S. N. Senchenkova¹, S. D. Shevelev¹, A. S. Shashkov¹, Lu Feng^2,3, Y. A. Knirel¹, and Lei Wang^2,3

¹Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky pr. 47, 119991 Moscow, Russia; fax: (495) 137-6148; E-mail: perepel@ioc.ac.ru

²TEDA School of Biological Sciences and Biotechnology and ³Tianjin Key Laboratory for Microbial Functional Genomics, TEDA College, Nankai University, 23 HongDa Street, TEDA, Tianjin 300457, P. R. China; E-mail: wangquan@mail.nankai.edu.cn

^* To whom correspondence should be addressed.

Received July 11, 2007

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An O-polysaccharide was isolated by mild acid degradation of the lipopolysaccharide of enteropathogenic Escherichia coli O49 and studied by sugar analysis along with one- and two-dimensional ¹H- and ¹³C-NMR spectroscopy. The following structure of the linear tetrasaccharide repeating unit of the O-polysaccharide was established:

where d-Qui4N(S3HOBut) stands for 4,6-dideoxy-4-[(S)-3-hydroxybutanoylamino]-d-glucose and O-acetylation of GlcNAc is partial (~30%). To our knowledge, no N-(3-hydroxybutanoyl) derivative of Qui4N has been hitherto found in bacterial polysaccharides. Gene functions of the O-antigen gene cluster of E. coli O49 were assigned by bioinformatics analysis and found to correspond to the O-polysaccharide structure. Two new genes were revealed and suggested to be responsible for synthesis and transfer of the 3-hydroxybutanoyl group.

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KEY WORDS: Escherichia coli, lipopolysaccharide, bacterial polysaccharide structure, 3-hydroxybutyrate, 4-amino-4,6-dideoxy-d-glucose, O-antigen gene cluster

DOI: 10.1134/S0006297908040044

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