RESUMO
O-specific polysaccharide was obtained from the lipopolysaccharide of Pseudomonas chlororaphis subsp. chlororaphis UCM B-106 and studied by composition analysis along with 1D and 2D (1)H and (13)C NMR spectroscopy. The polysaccharide was found to contain a derivative of pseudaminic acid (Pse) and the following structure of the trisaccharide repeating unit was established: â4)-ß-Psep5Ac7Hb-(2 â 6)-ß-d-Galf-(1 â 3)-ß-d-Galp-(1â where Pse5Ac7Hb indicates 5-acetamido-3,5,7,9-tetradeoxy-7-[(R)-3-hydroxybutanoylamino]-l-glycero-l-manno-non-2-ulosonic acid.
Assuntos
Antígenos O/química , Pseudomonas chlororaphis/metabolismo , Sequência de Carboidratos , Espectroscopia de Ressonância Magnética , Polissacarídeos Bacterianos/química , Pseudomonas chlororaphis/química , Pseudomonas chlororaphis/imunologiaRESUMO
Escherichia coli L-19 isolated from a healthy individual did not agglutinate with any of 21 polyvalent antisera that cover 174 E. coli O-serogroups. The strain was studied in respect to the O-antigen (O-specific polysaccharide, OPS) structure and genetics. The LPS was isolated by phenol-water extraction of bacterial cells and cleaved by mild acid hydrolysis to yield the OPS. The OPS was studied by sugar and methylation analyses, along with 1D and 2D (1)H and (13)C NMR spectroscopy. The established structure of the linear tetrasaccharide repeating unit was found to be unique among known bacterial polysaccharide structures. A peculiar component of the L-19 OPS was an amide of glucuronic acid with 2-amino-1,3-propanediol (2-amino-2-deoxyglycerol) (GroN). The O-antigen gene cluster of L-19 between the conserved genes galF and gnd was sequenced, and gene functions were tentatively assigned by a comparison with sequences in the available databases and found to be in agreement with the OPS structure. Except for putative genes for synthesis and transfer of GroN, the sequences in the L-19 O-antigen gene cluster were little related to those of reference strains of the 174 known E. coli O-serogroups. The data obtained suggest that L-19 can be considered as a candidate for a new E. coli O-serogroup.