Nina A. Kocharova

Conserved and variable structural features in the lipopolysaccharide of Pseudomonas aeruginosa.

The review is devoted to recent progress in the structural elucidation of the lipopolysaccharide of the bacterium Pseudomonas aeruginosa, including O-antigen biological repeats, core oligosaccharide, and lipid A. Data on biosynthesis, genetics and serology of the lipopolysaccharide isolated from various P. aeruginosa O-serogroups are discussed in relation to the chemical structures.

The core structure of the lipopolysaccharide from the causative agent of plague, Yersinia pestis.

The rough-type lipopolysaccharide (LPS) of the plague pathogen, Yersinia pestis, was studied after mild-acid and strong-alkaline degradations by chemical analyses, NMR spectroscopy and electrospray-ionization mass spectrometry, and the following structure of the core region was determined:where L-alpha-D-Hep stands for L-glycero-alpha-D-manno-heptose, Sug1 for either 3-deoxy-alpha-D-manno-oct-2-ulosonic acid (alpha-Kdo) or D-glycero-alpha-D-talo-oct-2-ulosonic acid (alpha-Ko), and Sug2 for either beta-D-galactose or D-glycero-alpha-D-manno-heptose. A minority of the LPS molecules lacks GlcNAc.

Intraspecies and temperature-dependent variations in susceptibility of Yersinia pestis to the bactericidal action of serum and to polymyxin B

ABSTRACT Lipopolysaccharide (LPS) structure impacts the bactericidal action of cationic peptides, such as polymyxin B (PMB), and sensitivity to killing by normal human serum (NHS). Cultivation of different subspecies strains of Yersinia pestis isolated from unrelated geographic origins at various temperatures (mammals, 37°C; fleas, 25°C; or winter hibernation, 6°C) affects LPS composition and structure. We tested the susceptibilities of various strains of Y. pestis grown at these different temperatures to PMB and serum bactericidal killing. Both properties varied significantly in response to temperature changes. In Y. pestis subsp. pestis (the main subspecies causing human plague), high levels of resistance to PMB and NHS were detected at 25°C. However, at the same temperature, Y. pestis subsp. caucasica was highly sensitive to PMB. At both of the extreme temperatures, all strains were highly susceptible to PMB. At 25°C and 37°C, Y. pestis subsp. caucasica strain 1146 was highly susceptible to the bactericidal activity of 80% NHS. All Y. pestis strains studied were able to grow in heat-inactivated human serum or in 80% normal mouse serum. At 6°C, all strains were highly sensitive to NHS. Variations in the PMB resistance of different bacterial cultures related to both the content of cationic components (4-amino-4-deoxyarabinose in lipid A and glycine in the core) and a proper combination of terminal monosaccharides in the LPS. The NHS resistance correlated with an elevated content of N-acetylglucosamine in the LPS. Structural variation in the LPS of Y. pestis correlates with the organisms ability to resist innate immunity in both fleas and mammals.

Structure of the capsular polysaccharide of Klebsiella ozaenae serotype K4 containing 3-deoxy-d-glycero-d-galacto-nonulosonic acid

The acidic capsular polysaccharide from the museum strain 2211 of Klebsiella ozaenae serotype K4 is built up of pentasaccharide repeating-units that contain residues of D-glucose, D-mannose, D-glucuronic acid, and 3-deoxy-D-glycero-D-galacto-nonulosonic acid (Kdn) in the ratios 2:1:1:1, as well as an O-acetyl group. The last-named sugar, which is reported in bacterial polysaccharides for the first time, was identified as the methyl (methyl 3-deoxynonulopyranosid)onate obtained by methanolysis of the polysaccharide. On the basis of the results of partial acid hydrolysis, Smith degradation, and computer-assisted 13C-n.m.r. analysis, it was concluded that the capsular polysaccharide has the following structure: (formula see text)

Structural features and structural variability of the lipopolysaccharide of Yersinia pestis, the cause of plague

Data on the structure and temperature-dependent variations of the lipopolysaccharide (LPS) of Yersinia pestis are summarized and compared with data of other enteric bacteria, including other Yersinia spp. A correlation between the LPS structure and properties of the LPS and bacterial cultures as well as the LPS biosynthesis control are briefly discussed.

The structure of glycerol teichoic acid-like O-specific polysaccharide of Hafnia alvei 1205

The O-specific polysaccharide of Hafnia alvei 1205 contained D-glucose, D-galactose, 2-acetamido-2-deoxy-D-glucose, 4-acetamido-4,6-dideoxy-D-glucose (Qui4NAc), glycerol, phosphate, and O-acetyl groups. On the basis of 1D and 2D shift-correlated homonuclear and 13C-1H heteronuclear NMR spectroscopy, methylation analysis, Smith degradation, and dephosphorylation with hydrofluoric acid, it was concluded that the O-antigen was a partially O-acetylated teichoic acid-like polysaccharide having the following structure: [formula: see text]

Structure of the lipopolysaccharide of Pseudomonas aeruginosa O-12 with a randomly O-acetylated core region

The lipopolysaccharide of Pseudomonas aeruginosa O-12 was studied by strong alkaline and mild acid degradations and dephosphorylation followed by fractionation of the products by GPC and high-performance anion-exchange chromatography and analyses by ESI FT-MS and NMR spectroscopy. The structures of the lipopolysaccharide core and the O-polysaccharide repeating unit were elucidated and the site and the configuration of the linkage between the O-polysaccharide and the core established. The core was found to be randomly O-acetylated, most O-acetyl groups being located on the terminal rhamnose residue of the outer core region.

Relationship of the Lipopolysaccharide Structure of Yersinia bpestis to Resistance to Antimicrobial Factors

Disruption of lipopolysaccharide (LPS) biosynthesis genes in an epidemiologically significant Yersinia pestis strain showed that the ability to synthesize the full inner core of the LPS is crucial for resistances to the bactericidal action of antimicrobial peptides and to complement-mediated serum killing. Resistance to polymyxin B also requires a high content of the cationic sugar, 4-amino-4-deoxy-L-arabinose, in lipid A.

Pleiotropic effects of the lpxM mutation in Yersinia pestis resulting in modification of the biosynthesis of major immunoreactive antigens

Deletion mutants in the lpxM gene in two Yersinia pestis strains, the live Russian vaccine strain EV NIIEG and a fully virulent strain, 231, synthesise a less toxic penta-acylated lipopolysaccharide (LPS). Analysis of these mutants revealed they possessed marked reductions in expression and immunoreactivity of numerous major proteins and carbohydrate antigens, including F1, Pla, Ymt, V antigen, LPS, and ECA. Moreover, both mutants demonstrated altered epitope specificities of the antigens as determined in immunodot-ELISAs and immunoblotting analyses using a panel of monoclonal antibodies. The strains also differed in their susceptibility to the diagnostic plague bacteriophage L-413C. These findings indicate that the effects of the lpxM mutation on reduced virulence and enhanced immunity of the Y. pestis EV DeltalpxM is also associated with these pleiotropic changes and not just to changes in the lipid A acylation.

Structure of the O-specific polysaccharide of Citrobacter freundii O3a,3b,1c

The following structure of the O-specific polysaccharide of Citrobacter braakii O7a,3b,1c was established using sugar and methylation analyses and NMR spectroscopy, including 2D COSY, TOCSY, NOESY, and 1H, 13C heteronuclear single-quantum coherence (HSQC) experiments: (struture: see text). The main D-mannan chain of the polysaccharide studied has the same structure as the O-specific polysaccharide of Escherichia coli O9, Klebsiella pneumoniae O3, and Hafnia alvei PCM 1223.