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1. (Article ID: 664)
 
Grozdanov L, Zähringer U, Blum-Oehler G, Brade L, Henne A, Knirel YA, Schombel U, Schulze J, Sonnenborn U, Gottschalk G, Hacker J, Rietschel ET, Dobrindt U
A single nucleotide exchange in the wzy gene is responsible for the semirough O6 lipopolysaccharide phenotype and serum sensitivity of Escherichia coli strain Nissle 1917
Journal of Bacteriology 184(21) (2002) 5912-5925
 

Structural analysis of lipopolysaccharide (LPS) isolated from semirough, serum-sensitive Escherichia coli strain Nissle 1917 (DSM 6601, serotype O6:K5:H1) revealed that this strain's LPS contains a bisphosphorylated hexaacyl lipid A and a tetradecasaccharide consisting of one E. coli O6 antigen repeating unit attached to the R1-type core. Configuration of the GlcNAc glycosidic linkage between O-antigen oligosaccharide and core (b) differs from that interlinking the repeating units in the E. coli O6 antigen polysaccharide (a). The wa* and wb* gene clusters of strain Nissle 1917, required for LPS core and O6 repeating unit biosyntheses, were subcloned and sequenced. The DNA sequence of the wa* determinant (11.8 kb) shows 97% identity to other R1 core type-specific wa* gene clusters. The DNA sequence of the wb* gene cluster (11 kb) exhibits no homology to known DNA sequences except manC and manB. Comparison of the genetic structures of the wb*O6 (wb* from serotype O6) determinants of strain Nissle 1917 and of smooth and serum-resistant uropathogenic E. coli O6 strain 536 demonstrated that the putative open reading frame encoding the O-antigen polymerase Wzy of strain Nissle 1917 was truncated due to a point mutation. Complementation with a functional wzy copy of E. coli strain 536 confirmed that the semirough phenotype of strain Nissle 1917 is due to the nonfunctional wzy gene. Expression of a functional wzy gene in E. coli strain Nissle 1917 increased its ability to withstand antibacterial defense mechanisms of blood serum. These results underline the importance of LPS for serum resistance or sensitivity of E. coli.

Lipopolysaccharide, antigen, core, gene, O-antigen, Escherichia, Escherichia coli, lipid A, SR-type LPS

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2. (Article ID: 665)
 
Grzeszczyk B, Holst O, Zamojski A
The synthesis of five L-glycero-D-manno-heptose monophosphates
Carbohydrate Research 290(1) (1996) 1-15
 

Five monophosphates of L-glycero-D-manno-heptose having the PO(OH)2 residue at O-2,3, 4, 6, and 7 have been synthesized starting from suitably protected benzyl D-mannopyranoside derivatives. The synthesis involved chain elongation by the reaction of D-mannoside 6-aldehyde with alkoxymethylmagnesium chloride resulting in the desired L-glycero-D-manno-heptopyranoside as the main product. The blocking groups pattern enabled selective deprotection of the hydroxyl groups at C-2, 3, 4, and 7. These substrates were phosphitylated with 2-dimethylamino-5,6-benzo-1,3,2-dioxaphosphepan and oxidized in situ to phosphates. The resulting products were hydrogenolytically deprotected and converted to di(cyclohexylammonium) salts which were characterized by 13C NMR spectra.

synthesis, L-glycero-D-manno-heptose, Bacterial sugars, L-glycero-D-manno-Heptose monophosphate, Heptose synthesis, monophosphate

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3. (Article ID: 666)
 
Grzeszczyk B, Holst O, Müller-Loennies S, Zamojski A
Five monophosphates of methyl L-glycero-a-D-manno-heptopyranoside: synthesis, hydrolysis and migrations
Carbohydrate Research 307(1-2) (1998) 55-67
 

From suitably protected methyl a-d-mannopyranosides five methyl L-glycero-a-D--manno-heptopyranosides were synthesized by the one-carbon-atom chain elongation at C-6 and converted to five monophosphates (1-5) having the PO(OH)2 group at O-2, -3, -4, -6 and -7. Compounds 1-5 were exposed to acidic and basic hydrolytic conditions used in lipopolysaccharide analysis and the products and their proportion were determined. Under acidic conditions, besides hydrolysis of the glycoside, migrations and hydrolytic cleavage of the phosphate residue were found. Under basic conditions the phosphates were stable.

synthesis, L-glycero-D-manno-heptose, heptose, phosphate, hydrolysis, 13C NMR, glycoside, 1H NMR, methyl, migration, monophosphate

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4. (Article ID: 989)
 
Mieszala M, Kogan G, Jennings HJ
Conjugation of meningococcal lipooligosaccharides through their lipid A terminus conserves their inner epitopes and results in conjugate vaccines having improved immunological properties
Carbohydrate Research 338(2) (2003) 167-175
 

The importance of conserved inner saccharide epitopes to the immune performance of meningococcal lipooligosaccharide-protein conjugate vaccines was demonstrated in the following experiments. Two different oligosaccharides were obtained by chemical degradations of the same L7 lipooligosaccharide, and both were linked terminally to tetanus toxoid. One was a truncated oligosaccharide in which the inner epitopes were incomplete and was obtained by mild acid hydrolysis of the L7 lipooligosaccharide. This oligosaccharide was conjugated by direct reductive amination through its newly exposed terminal Kdo residue. The second, a full-length oligosaccharide, was obtained by O-deacylation of the L7 lipooligosaccharide, with subsequent removal of phosphate substituents from its lipid A moiety using alkaline phosphatase. This permitted the full-length oligosaccharide to be conjugated directly to tetanus toxoid by reductive amination through its newly exposed terminal 2-N-acyl-2-deoxy-D-glucopyranose residue. Comparison of the immune performance of the two conjugates in mice revealed, that while both were able to induce significant levels of L7-lipooligosaccharide- specific IgG antibody, the conjugate made with the full-length saccharide was able to induce antibodies with increased bactericidal activity against homologous meningococci

oligosaccharide, Lipooligosaccharide, meningococcal, meningococci, terminal, linked, Research, property, acid, Kdo, antibodies, antibody, conserved, epitope, lipid, lipid A, phosphate, Oligosaccharides, IgG, immunological, level, mice, epitopes, specific, hydrolysis, biological, activity, chemical, alkaline, degradation, vaccines, lipooligosaccharides, comparison, vaccine, bactericidal, conjugate, conjugates, conjugate vaccines, conjugate vaccine, tetanus toxoid, bactericidal activity, immune, O-deacylation, saccharide, terminus, phosphatase, tetanus, toxoid, alkaline phosphatase, amination, homologous, importance, reductive, removal

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