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Structure and Biosynthesis Gene Cluster of the O-Antigen of Escherichia coli O12

S. N. Senchenkova1, Yuanyuan Zhang2, A. V. Perepelov1, Xi Guo2, A. S. Shashkov1, Bin Liu2, and Yu. A. Knirel1*

1Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russia; fax: +7 (499) 135-5328; E-mail: yknirel@gmail.com

2Nankai University, TEDA Institute of Biological Sciences and Biotechnology, 300457 Tianjin, P. R. China; E-mail: striker198126@aliyun.com

* To whom correspondence should be addressed.

Received October 5, 2015; Revision received November 21, 2015
Two polysaccharides were isolated from Escherichia coli O12, the major being identified as the O12-antigen and the minor as the K5-antigen. The polysaccharides were studied by sugar analysis, Smith degradation, and one- and two-dimensional 1H and 13C NMR spectroscopy. As a result, the following structure of the O12-polysaccharide was elucidated, which, to our knowledge, has not been hitherto found in bacterial carbohydrates: →2)-β-d-Glcp-(1→6)-α-d-GlcpNAc-(1→3)-α-l-FucpNAc-(1→3)-β-d-GlcpNAc-(1→. The →4)-β-d-GlcpA-(1→4)-α-d-GlcpNAc-(1→ structure established for the K5-polysaccharide (heparosan) is previously known. Functions of genes in the O-antigen biosynthesis gene cluster of E. coli O12 were assigned by comparison with sequences in the available databases and found to be consistent with the O12-polysaccharide structure.
KEY WORDS: Escherichia coli, O-polysaccharide structure, O-antigen gene cluster, glycosyltransferase

DOI: 10.1134/S0006297916040106