title: Structures and gene clusters of the O-specific polysaccharides of the lipopolysaccharides of Escherichia coli O69 and O146 containing glycolactilic acids: ether conjugates of D-GlcNAc and D-Glc with (R)- and (S)-lactic acid.
abstract: Based on the O-specific polysaccharides of the lipopolysaccharides (O-polysaccharides, O-antigens), strains of a clonal species Escherichia coli are classified into 184 O serogroups. In this work, structures of the O-polysaccharides of E. coli O69 and O146 were elucidated and gene clusters for their biosynthesis were characterized. The O-polysaccharides were released from the lipopolysaccharides by mild acid hydrolysis and studied by sugar analysis and one- and two-dimensional1H and13C NMR spectroscopy before and after O-deacetylation. The O146 polysaccharide was also studied by Smith degradation. The O69 and O146 polysaccharides were found to contain ether conjugates of monosaccharides with lactic acid called glycolactilic acids: 2-acetamido-2-deoxy-4-O-[(R)-1-carboxyethyl]-D-glucose (D-GlcNAc4Rlac) and 3-O-[(S)-1-carboxyethyl]-D-glucose (D-Glc3Slac), respectively. Structures of the pentasaccharide repeats of the O-polysaccharides were established, and that of E. coli O69 was found to differ in the presence of D-GlcNAc4Rlac from the structure reported for this bacterium earlier (Erbing C, Kenne L, Lindberg B. 1977. Carbohydr Res. 56:371-376). The O-antigen gene clusters of E. coli O69 and O146 between conserved genes galF and gnd were analyzed taking into account the O-polysaccharide structures established, and functions of putative genes for synthesis of D-Glc3Slac and D-GlcNAc4Rlac and for glycosyltransferases were assigned based on homology with O-antigen biosynthesis genes of other enteric bacteria. It was found that in E. coli and Shigella spp. predicted enolpyruvate reductases of the biosynthesis pathway of glycolactilic acids, LarR and LarS, which catalyze formation of conjugates with (R)- or (S)-lactic acid, respectively, are distinguished by sequence homology and size.
authors.affiliation: N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 199991, Moscow, Russia. yknirel@gmail.com.
authors.forename: Yuriy A
authors.initials: YA
authors.lastname: Knirel
authors.affiliation: Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, 300457, Tianjin, People's Republic of China.
authors.forename: Xi
authors.initials: X
authors.lastname: Guo
authors.affiliation: N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 199991, Moscow, Russia.
authors.forename: Sof'ya N
authors.initials: SN
authors.lastname: Senchenkova
authors.affiliation: N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 199991, Moscow, Russia.
authors.forename: Andrei V
authors.initials: AV
authors.lastname: Perepelov
authors.affiliation: Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, 300457, Tianjin, People's Republic of China.
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.affiliation: N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 199991, Moscow, Russia.
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Shashkov
mesh_terms: D000117:Acetylglucosamine / Q000031:analogs & derivatives* / Q000378:metabolism; D004926:Escherichia coli / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D005947:Glucose / Q000031:analogs & derivatives / Q000378:metabolism; D005964:Glucosyltransferases / Q000235:genetics; D019344:Lactic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D008070:Lipopolysaccharides / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics
chemical_list: D008070:Lipopolysaccharides; D019344:Lactic Acid; D005964:Glucosyltransferases; D005947:Glucose; D000117:Acetylglucosamine
keywords: Gene cluster; Glycolactilic acid; Lactic acid ether; Lipopolysaccharide; O-antigen; O-specific polysaccharide