The O-polysaccharide from the lipopolysaccharide of Providencia stuartii O44 contains L-quinovose, a 6-deoxy sugar rarely occurring in bacterial polysaccharides

The O-polysaccharide (O-antigen) of Providencia stuartii O44:H4 (strain 3768/51) was obtained by mild acid degradation of the lipopolysaccharide and studied by sugar and methylation analyses along with (1)H and (13)C NMR spectroscopy, including 2D (1)H,(1)H COSY, TOCSY, ROESY, and H-detected (1)H,(13)C HSQC, and HMQC-TOCSY experiments. The O-polysaccharide was found to have a branched hexasaccharide repeating unit of the following structure: [Formula: see text].     

The two-pathway model for the catch-slip transition in biological adhesion

Some recently studied biological noncovalent bonds have shown increased lifetime when stretched by mechanical force. In each case these counterintuitive "catch-bonds" have transitioned into ordinary "slip-bonds" that become increasingly shorter lived as the tensile force on the bond is further increased. We describe analytically how these results are supported by a physical model whereby the ligand escapes the receptor binding site via two alternative routes, a catch-pathway that is opposed by the applied force and a slip-pathway that is promoted by force. The model predicts under what conditions and at what critical force the catch-to-slip transition would be observed, as well as the degree to which the bond lifetime is enhanced at the critical force. The model is applied to four experimentally studied systems taken from the literature, involving the binding of P- and L-selectins to sialyl Lewis(X) oligosaccharide-containing ligands. Good quantitative fit to the experimental data is obtained, both for experiments with a constant force and for experiments where the force increases linearly with time.     

The structure of the O-polysaccharide from the lipopolysaccharide of Providencia stuartii O57 containing an amide of D-galacturonic acid with L-alanine

The O-polysaccharide (O-antigen) was obtained by mild acid degradation of the lipopolysaccharide of Providencia stuartii O57:H29. Studies by sugar and methylation analyses along with (1)H and (13)C NMR spectroscopy, including two-dimensional (1)H,(1)H COSY, TOCSY, ROESY, H-detected (1)H,(13)C HSQC, and HMBC experiments, showed that the polysaccharide contains an amide of D-galacturonic acid with L-alanine and has the following pentasaccharide repeating unit: [formula: see text]     

Temperature-dependent variations and intraspecies diversity of the structure of the lipopolysaccharide of Yersinia pestis

Yersinia pestis spread throughout the Americas in the early 20th century, and it occurs predominantly as a single clone within this part of the world. However, within Eurasia and parts of Africa there is significant diversity among Y. pestis strains, which can be classified into different biovars (bv.) and/or subspecies (ssp.), with bv. orientalis/ssp. pestis most closely related to the American clone. To determine one aspect of the relatedness of these different Y. pestis isolates, the structure of the lipopolysaccharide (LPS) of four wild-type and one LPS-mutant Eurasian/African strains of Y. pestis was determined, evaluating effects of growth at mammalian (37 degrees C) or flea (25 degrees C) temperatures on the structure and composition of the core oligosaccharide and lipid A. In the wild-type clones of ssp. pestis, a single major core glycoform was synthesized at 37 degrees C whereas multiple core oligosaccharide glycoforms were produced at 25 degrees C. Structural differences occurred primarily in the terminal monosaccharides. Only tetraacyl lipid A was made at 37 degrees C, whereas at 25 degrees C additional pentaacyl and hexaacyl lipid A structures were produced. 4-Amino-4-deoxyarabinose levels in lipid A increased with lower growth temperatures or when bacteria were cultured in the presence of polymyxin B. In Y. pestis ssp. caucasica, the LPS core lacked D-glycero-D-manno-heptose and the content of 4-amino-4-deoxyarabinose showed no dependence on growth temperature, whereas the degree of acylation of the lipid A and the structure of the oligosaccharide core were temperature dependent. A spontaneous deep-rough LPS mutant strain possessed only a disaccharide core and a slightly variant lipid A. The diversity and differences in the structure of the Y. pestis LPS suggest important contributions of these variations to the pathogenesis of this organism, potentially related to innate and acquired immune recognition of Y. pestis and epidemiologic means to detect, classify, control and respond to Y. pestis infections.     

Structure of the O-polysaccharide of Providencia alcalifaciens O19

Studies of the O-polysaccharide chain of the lipopolysaccharide (O-antigen) of Providencia alcalifaciens O19 by sugar and methylation analyses along with NMR spectroscopy, including 2D 1H,1H COSY, TOCSY, NOESY and 1H,13C HSQC experiments, showed that the pentasaccharide repeating unit of the polysaccharide has the following structure: [structure: see text] where Fuc3NAc is 3-acetamido-3,6-dideoxygalactose. The unique structure of the O-antigen and serological data are in consistence with classification of this bacterium in a separate Providencia serogroup.     

The O-polysaccharide of Pseudomonas syringae pv. mori NCPPB 1656 is a beta-(1-->2)-linked homopolymer of L-rhamnose

The O-polysaccharide from the lipopolysaccharide of the phytopathogenic bacterium Pseudomonas syringae pv. mori NCPPB 1656 was studied by sugar analysis along with 1H and 13C NMR spectroscopy and found to be a new beta-(1-->2)-linked homopolymer of L-rhamnose.     

Structure of the O-polysaccharide of Providencia stuartii O49

The O-specific polysaccharide chain (O-antigen) of the lipopolysaccharide (LPS) of Providencia stuartii O49 was studied using sugar and methylation analyses along with 1H and 13C NMR spectroscopy, including two-dimensional COSY, TOCSY, ROESY, H-detected 1H, 13C HSQC and HMBC experiments. The polysaccharide was found to have the trisaccharide repeating unit with the following structure: -->6)-beta-D-Galp(1-->3)-beta-D-GalpNAc(1-->4)-alpha-D-Galp(1-->     

Structure of the O-polysaccharide of Proteus serogroup O34 containing 2-acetamido-2-deoxy-alpha-D-galactosyl phosphate

On mild acid degradation of the lipopolysaccharide of Proteus vulgaris O34, strain CCUG 4669, the O-polysaccharide was cleaved at a glycosyl-phosphate linkage that is present in the main chain. The resultant phosphorylated oligosaccharides and an alkali-treated lipopolysaccharide were studied by sugar and methylation analyses along with 1H and 13C NMR spectroscopy, and the following structure of the branched tetrasaccharide phosphate repeating unit of the O-polysaccharide was established: [carbohydrate structure: see text]The O-polysaccharide of Proteus mirabilis strain TG 276 was found to have the same structure and, based on the structural and serological data, this strain was proposed to be classified into the same Proteus serogroup O34.