Structural studies on the hexose region of the lipopolysaccharide from Escherichia coli C

Interaction between phage G13 and its oligosaccharide receptor studied by equilibrium dialysis

The reversible binding of phage G13, a phi X174-like single-strand DNA phage, to a 3H-labelled nonasaccharide from the lipopolysaccharide of its natural host Escherichia coli C was studied with equilibrium dialysis. The binding constant (Ka) was determined to 1.3 x 10(7) M-1 in Scatchard and Lineweaver-Burk plots. Approximately one saccharide bound per G13 phage particle which suggests that only one of the 12 spikes in each G13 virion was engaged in the phage/receptor saccharide interaction. Equilibrium dialysis inhibition experiments with saccharides from lipopolysaccharides of an isogenic series of Salmonella typhimurium mutants showed that hepta- and pentasaccharides from two G13-sensitive bacteria, i.e., with efficiencies of plating of 0.1-1.0 compared to E. coli C, were efficient inhibitors with Ka-values greater than or equal to 1.2 x 10(7) M-1. The octa- and hexasaccharides from two G13 resistant strains, with efficiency of plating less than or equal to x 10(-4), were either greater than 1000-fold or greater than 15-fold less efficient as inhibitors with Ka-values less than or equal to 8.8 x 10(5) M-1. The results show that phage G13 binds in a specific and reversible way to penta-, hepta-, and nonasaccharides from G13 sensitive bacteria with the specificity residing in the hexose and heptose region of the core lipopolysaccharide.

Structural studies on the hexose region of the core in lipopolysaccharides from Enterobacteriaceae

The structures for the hexose regions of cores from Enterobacteriaceae lipopolysaccharides have been investigated, using specific degradations and 1H NMR studies as the principal methods. Complete structures for these regions in the Salmonella, the Escherichia coli R1, R2, R3, R4, the E. coli K12 and E. coli B cores are proposed. Some complementary information on the structure of the heptose region has also been obtained.

Structural studies on Shigella flexneri serotype 6 core region

The core structure of Shigella flexneri serotype 6 has been investigated. The methods used in these studies involved methylation analysis, periodate oxidation, Smith degradation and enzymic modifications of core oligosaccharides isolated from two smooth strains and four rough mutants. As a result the complete core region was established (Formula: see text) where DGalp = D-galactopyranose, DGlcp = D-glucopyranose, L alpha DHepp = L-glycero-D-mannoheptapyranose, dOclA = 3-deoxy-D-manno-octulosonic, DGlcNp = 2-amino-2-deoxy-D-glucopyranose and P--PEtN = pyrophosphorylethanolamine (partially substituted). In the R mutants examined two types of mutation have been observed: (1) defect in heptose region (lack of D-glucosamine) or (2) defects in hexose region of the core.

Structural studies on the hexose region of the Enterobacteriaceae type R3 core polysaccharide

The structure of the hexose region of the Enterobacteriaceae type R3 core polysaccharide, which is the common core in Shigella flexneri and some Escherichia coli lipopolysaccharides (LPS), has been investigated. The principal method used in these studies involved methylation analysis of the original and modified materials. The polysaccharide was modified by N-deacetylation-deamination and by Smith degradation. As a result of these studies, the following structure is proposed: alpha-D-Glcp-(1 leads to 2)-alpha-D-Glcp-(1 leads to 2)-[alpha-D-GlcNAcp-(1 leads to 3)]-alpha-D-Galp-(1 leads to 3)-alpha-D-Glcp-(1 leads to.

Structure of the hexose region of Shigella sonnei phase II lipopolysaccharide with 3-deoxy-D-manno-octulosonic acid as possible immunodeterminant and its relation to Escherichia coli R1 core

Comparative chemical analysis (methylation, gas chromatography/mass spectrometry, periodate oxidation, etc.) of the lipopolysaccharides and degraded polysaccharides derived from Shigella sonnei phase I, phase II and galactose-deficient R mutants revealed a structure as shown: (formula: see text) 3-Deoxy-D-manno-octulosonic acid (dOclA) as an immunodeterminant was observed in the passive hemolysis inhibition test by (a) selective inhibition of the phase II system by dOclA; (b) the kinetics of the change of serological activity during mild acid treatment: 1% acetic acid abolished serological activity; (c) a lack of activity in galactose-less R mutants and reactivity with Re mutants including Salmonella minnesota Re. An enhanced sensitivity of phase II lipopolysaccharide to galactose oxidase after prolonged treatment with 1% acetic acid suggests that dOclA is linked to C-6 of the terminal or subterminal galactose. dOclA as immunodeterminant could explain some different polysaccharide structures described for Escherichia coli R1 core.