The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Yuriy A. Knirel - One of the best experts on this subject based on the ideXlab platform.
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structure of the alanopine containing o polysaccharide and serological cross reactivity of the Lipopolysaccharide of proteus vulgaris hsc 438 classified into a new proteus serogroup o76
Microbiology, 2013Co-Authors: Malgorzata Siwinska, Alexander S Shashkov, Anna N Kondakova, Dominika Drzewiecka, Agnieszka Zablotni, Nikolay P Arbatsky, Olga A Valueva, Krystyna Zych, Zygmunt Sidorczyk, Yuriy A. KnirelAbstract:The O-polysaccharide was isolated by mild acid hydrolysis of the Lipopolysaccharide of Proteus vulgaris HSC 438, and the following structure was established by chemical methods and one- and two-dimensional 1H and 13C NMR spectroscopy: →3)-β-d-Quip4NAlo-(1→3)-α-d-Galp6Ac-(1→6)-α-d-Glcp-(1→3)-α-l-FucpNAc-(1→3)-β-d-GlcpNAc-(1→, where d-Qui4N stands for 4-amino-4,6-dideoxy-d-glucose and Alo for N-((S)-1-carboxyethyl)-l-alanine (alanopine); only about half of the Gal residues are O-acetylated. This structure is unique among the Proteus O-polysaccharides, and therefore it is proposed to classify P. vulgaris HSC 438 into a new Proteus serogroup, O76. A serological cross-reactivity of HSC 438 O-antiserum and Lipopolysaccharides of some other Proteus serogroups was observed and accounted for by shared epitopes on the O-polysaccharides or Lipopolysaccharide core regions, including that associated with d-Qui4NAlo.
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bacterial Lipopolysaccharides structure chemical synthesis biogenesis and interaction with host cells
2011Co-Authors: Yuriy A. Knirel, Miguel A. ValvanoAbstract:-1. Lipid A structure (A. Silipo, A. Molinaro).- 2. Structure of the Lipopolysaccharide core region (O. Holst).- 3. Structure of O-antigens (Y.A. Knirel).- 4. Chemical synthesis of lipid A and analogues (S. Kusumoto).- 5. Chemical synthesis of Lipopolysaccharide core (P. Kosma, A. Zamyatina).- 6. Genetics and biosynthesis of lipid A (C.M. Stead, A.C. Pride, M.S. Trent).- 7. Pathways for the biosynthesis of NDP sugars (Y. Hao, J. Lam).- 8. Lipopolysaccharide core oligosaccharide biosynthesis and assembly (U. Mamat, M. Skurnik, J.A. Bengoechea).- 9. Genetics, biosynthesis and assembly of O-antigen (M.A. Valvano, S.E. Furlong, K.B. Patel).- 10. Lipopolysaccharide export to the outer membrane (P. Sperandeo, G. Deho, A. Polissi).- 11. Evolution of Lipopolysaccharide biosynthesis genes (M.M. Cunneen, P.R. Reeves).- 12. The molecular basis of lipid A and Toll-like receptor 4 interactions (G.L. Hold, C.E. Bryant).- 13. Modulation of Lipopolysaccharide signalling through TLR4 agonists and antagonists (F. Peri, M. Piazza, V. Calabrese, R. Cighetti).- 14. Lipopolysaccharide interactions with plants (G. Erbs, M.-A. Newman)
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bacterial Lipopolysaccharides structure chemical synthesis biogenesis and interaction with host cells
2011Co-Authors: Yuriy A. Knirel, Miguel A. ValvanoAbstract:-1. Lipid A structure (A. Silipo, A. Molinaro).- 2. Structure of the Lipopolysaccharide core region (O. Holst).- 3. Structure of O-antigens (Y.A. Knirel).- 4. Chemical synthesis of lipid A and analogues (S. Kusumoto).- 5. Chemical synthesis of Lipopolysaccharide core (P. Kosma, A. Zamyatina).- 6. Genetics and biosynthesis of lipid A (C.M. Stead, A.C. Pride, M.S. Trent).- 7. Pathways for the biosynthesis of NDP sugars (Y. Hao, J. Lam).- 8. Lipopolysaccharide core oligosaccharide biosynthesis and assembly (U. Mamat, M. Skurnik, J.A. Bengoechea).- 9. Genetics, biosynthesis and assembly of O-antigen (M.A. Valvano, S.E. Furlong, K.B. Patel).- 10. Lipopolysaccharide export to the outer membrane (P. Sperandeo, G. Deho, A. Polissi).- 11. Evolution of Lipopolysaccharide biosynthesis genes (M.M. Cunneen, P.R. Reeves).- 12. The molecular basis of lipid A and Toll-like receptor 4 interactions (G.L. Hold, C.E. Bryant).- 13. Modulation of Lipopolysaccharide signalling through TLR4 agonists and antagonists (F. Peri, M. Piazza, V. Calabrese, R. Cighetti).- 14. Lipopolysaccharide interactions with plants (G. Erbs, M.-A. Newman)
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Structure of the O-polysaccharide of Providencia alcalifaciens O8 containing (2S,4R)-2,4-dihydroxypentanoic acid, a new non-sugar component of bacterial glycans.
Carbohydrate Research, 2008Co-Authors: Filip V Toukach, Agnieszka Maszewska, Nina A. Kocharova, Yuriy A. Knirel, Alexander S Shashkov, Antoni RozalskiAbstract:Abstract A glycerol teichoic acid-like O-polysaccharide was obtained by mild acid degradation of the Lipopolysaccharide of Providencia alcalifaciens O8 and studied by chemical methods and NMR spectroscopy, including 2D ROESY, {1H,13C} HSQC, and HMQC-TOCSY experiments. It was found that the compound contains a new component of bacterial Lipopolysaccharides: ether-linked (2S,4R)-2,4-dihydroxypentanoic acid (Dhpa), which was identified by NMR spectroscopy. The following structure of the repeating unit of the polysaccharide was established:
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structure and biological activity of the short chain Lipopolysaccharide from bartonella henselae atcc 49882t
Journal of Biological Chemistry, 2004Co-Authors: Ulrich Zahringer, Yuriy A. Knirel, Buko Lindner, Willem M R Van Den Akker, Rosemarie Hiestand, Holger Heine, Christoph DehioAbstract:Abstract The facultative intracellular pathogen Bartonella henselae is responsible for a broad range of clinical manifestations, including the formation of vascular tumors as a result of increased proliferation and survival of colonized endothelial cells. This remarkable interaction with endotoxin-sensitive endothelial cells and the apparent lack of septic shock are considered to be due to a reduced endotoxic activity of the B. henselae Lipopolysaccharide. Here, we show that B. henselae ATCC 49882T produces a deep-rough-type Lipopolysaccharide devoid of O-chain and report on its complete structure and Toll-like receptor-dependent biological activity. The major short-chain Lipopolysaccharide was studied by chemical analyses, electrospray ionization, and matrix-assisted laser desorption/ionization mass spectrometry, as well as by NMR spectroscopy after alkaline deacylation. The carbohydrate portion of the Lipopolysaccharide consists of a branched trisaccharide containing a glucose residue attached to position 5 of an α-(2→4)-linked 3-deoxy-d-manno-oct-2-ulosonic acid disaccharide. Lipid A is a pentaacylated β-(1′→6)-linked 2,3-diamino-2,3-dideoxy-glucose disaccharide 1,4′-bisphosphate with two amide-linked residues each of 3-hydroxydodecanoic and 3-hydroxyhexadecanoic acids and one residue of either 25-hydroxyhexacosanoic or 27-hydroxyoctacosanoic acid that is O-linked to the acyl group at position 2′. The Lipopolysaccharide studied activated Toll-like receptor 4 signaling only to a low extent (1,000–10,000-fold lower compared with that of Salmonella enterica sv. Friedenau) and did not activate Toll-like receptor 2. Some unusual structural features of the B. henselae Lipopolysaccharide, including the presence of a long-chain fatty acid, which are shared by the Lipopolysaccharides of other bacteria causing chronic intracellular infections (e.g. Legionella and Chlamydia), may provide the molecular basis for low endotoxic potency.
Maria Michela Corsaro - One of the best experts on this subject based on the ideXlab platform.
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lipid a structural characterization from the lps of the siberian psychro tolerant psychrobacter arcticus 273 4 grown at low temperature
Extremophiles, 2018Co-Authors: Angela Casillo, Rosa Lanzetta, Buko Lindner, Marcello Ziaco, Ermenegilda Parrilli, Dominik Schwudke, Aurora Holgado, Rudi Beyaert, Maria Luisa Tutino, Maria Michela CorsaroAbstract:Psychrobacter arcticus 273-4 is a Gram-negative bacterium isolated from a 20,000-to-30,000-year-old continuously frozen permafrost in the Kolyma region in Siberia. The survival strategies adopted to live at subzero temperatures include all the outer membrane molecules. A strategic involvement in the well-known enhancement of cellular membrane fluidity is attributable to the Lipopolysaccharides (LPSs). These molecules covering about the 75% of cellular surface contribute to cold adaptation through structural modifications in their portions. In this work, we elucidated the exact structure of lipid A moiety obtained from the Lipopolysaccharide of P. arcticus grown at 4 °C, to mimic the response to the real environment temperatures. The lipid A was obtained from the LPS by mild acid hydrolysis. The lipid A and its partially deacylated derivatives were exhaustively characterized by chemical analysis and by means of ESI Q-Orbitrap mass spectrometry. Moreover, biological assays indicated that P. arcticus 273-4 lipid A may behave as a weak TLR4 agonist.
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structural investigation of the antagonist lps from the cyanobacterium oscillatoria planktothrix fp1
Carbohydrate Research, 2014Co-Authors: Sara Carillo, Giuseppina Pieretti, Rosa Lanzetta, Emiliano Bedini, Michelangelo Parrilli, Maria Michela CorsaroAbstract:Abstract Cyanobacteria are aquatic and photosynthetic microorganisms, which contribute up to 30% of the yearly oxygen production on the earth. They have the distinction of being the oldest known fossils, more than 3.5 billion years old, and are one of the largest and most important groups of bacteria on earth. Cyanobacteria are an emerging source of potentially pharmacologically active products and, among these, there are the Lipopolysaccharides. Despite their significant and well documented activity, very little is known about the cyanobacteria Lipopolysaccharides (LPS) structure. The aim of this work is to investigate the structure of the highly TLR4-antagonist Lipopolysaccharide from the cyanobacterium Oscillatoria plankthotrix FP1. The LPS was purified and analysed by means of chemical analysis and 1 H and 13 C NMR spectroscopy. The LPS was then degraded by Smith degradation, HF and acetic acid hydrolyses. All the obtained products were investigated in detail by chemical analysis, NMR spectroscopy and by mass spectrometry. The LPS consists of a high molecular mass and very complex molecule lacking Kdo and heptose residues, where the polysaccharide chain is mainly constituted by a backbone of 3-substituted α- l -rhamnose units. The core region is rich in galacturonic acid and mannose residues. Moreover a glycolipid portion, similar to Gram-negative lipid A, was identified. This was built up of a non phosphorylated (1′→6) linked glucosamine disaccharide, acylated with 3-hydroxylated fatty acids. In particular 3-hydroxypentadecanoic and 3-hydroxyesadecanoic acids were found, together with esadecanoic and tetradecanoic ones. Finally the presence of a galacturonic acid residue at 6-position of the distal glucosamine in place of the Kdo residue is suggested.
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structural characterization of the core oligosaccharide isolated from the Lipopolysaccharide of the haloalkaliphilic bacterium salinivibrio sharmensis strain bagt
Carbohydrate Research, 2013Co-Authors: Sara Carillo, Giuseppina Pieretti, Rosa Lanzetta, Michelangelo Parrilli, Barbara Nicolaus, Ida Romano, Buko Lindner, Maria Michela CorsaroAbstract:Abstract Salinivibrio genus is included in the family Vibrionaceae and up to now is constituted by only five members. All the species are moderately halophilic bacteria found in salted meats, brines, and several hypersaline environments. Halophilic microorganisms are good sources of biomolecules, such as proteases, that have a great industrial interest as demonstrated by recent studies. All these bacteria possess on their outer membrane amphiphilic molecules named Lipopolysaccharides, which are of great interest because of their involvement in the mechanisms of interaction between the microbial life and environmental factors. A novel haloalkaliphilic, facultative anaerobic and Gram-negative Salinivibrio-like microorganism, named S. sharmensis strain BAGT, was recovered from a saline lake in Ras Mohammed Park (Egypt). The aim of this work is the isolation and structural characterization of the core oligosaccharidic fraction of the Lipopolysaccharide from this bacterium. By means of HPAEC-PAD we were able to purify two glycoforms, fully depicted by ESI FT-ICR mass spectrometry, chemical analysis, and NMR spectroscopy. Like other haloalkaliphilic bacteria, the core region was found to be characterized by the presence of several negatively charged residues, such as uronic acids. All the data contributed to give the following structure .
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structural determination of the o chain polysaccharide from the Lipopolysaccharide of the haloalkaliphilic halomonas pantelleriensis bacterium
European Journal of Organic Chemistry, 2006Co-Authors: Maria Michela Corsaro, Rosa Lanzetta, Agata Gambacorta, Alfonso Iadonisi, Teresa Naldi, Barbara Nicolaus, Ida Romano, Salvatore Ummarino, Michelangelo ParrilliAbstract:The structural determination of the O-chain repeating unit of the Lipopolysaccharide from the haloalkaliphilic Halomonas pantelleriensis bacterium is described. The structure of the repeating unit was suggested on the basis of chemical analysis and NMR and MS data. The 4-O-[(S)-1-carboxyethyl]-D-GlcA residue has been found for the first time in a Lipopolysaccharide, being previously only found in capsular polysaccharides. A comparison of the O-chain structures of Halomonas magadiensis and H. pantelleriensis is also reported. The results show that both bacteria present Lipopolysaccharides containing a high number of carboxylate groups whose salification might determine a protective buffer effect on bacterium against extreme life conditions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Nobuhiro Yuki - One of the best experts on this subject based on the ideXlab platform.
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infectious origins of and molecular mimicry in guillain barre and fisher syndromes
Lancet Infectious Diseases, 2001Co-Authors: Nobuhiro YukiAbstract:Guillain-Barre syndrome (GBS), characterised by limb weakness and areflexia, is the prototype of postinfectious autoimmune diseases, and Campylobacter jejuni is the most frequent antecedent pathogen. GBS subsequent to C jejuni enteritis is associated with a severe, pure motor axonal variant and IgG antibodies against GM1, GM1b, GD1a, or GalNAc-GDla, gangliosides expressed in human peripheral nerves. Lipopolysaccharides of C jejuni isolated from GBS patients have ganglioside-like epitopes. Cytomegalovirus is the most common viral antecedent infection. Patients with demyelinating GBS who have had a recent CMV infection have severe sensory deficits and anti-GM2 IgM antibody. CMV-infected fibroblasts express the GM2 epitope. Fisher syndrome (FS), characterised by ophthalmoplegia, ataxia, and areflexia, is a GBS variant associated with anti-GQ1b IgG antibody. GQ1b is enriched in the cranial nerves that innervate the extraocular muscles. Some patients develop FS after C jejuni infection, and the Lipopolysaccharide present bears the GQ1b epitope. Molecular mimicry is a possible cause of GBS and FS.
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molecular mimicry between gangliosides and Lipopolysaccharides of campylobacter jejuni isolated from patients with guillain barre syndrome and miller fisher syndrome
The Journal of Infectious Diseases, 1997Co-Authors: Nobuhiro YukiAbstract:Some patients developed Guillain-Barre syndrome (GBS) after being given bovine gangliosides. Patients with GBS subsequent to Campylobacter jejuni enteritis frequently have IgG antibody to GM 1 ganglioside. Miller Fisher syndrome (MFS), a variant of GBS, is associated with IgG antibody to GQ 1b ganglioside. The existence of molecular mimicry between GM 1 and Lipopolysaccharide of C. jejuni isolated from a GBS patient and that between GQ 1b and C. jejuni Lipopolysaccharides from patients with MFS are shown herein. The molecular mimicry between infectious agents and gangliosides may function in the production of anti-ganglioside antibodies and the development of GBS and MFS.
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molecular mimicry between gq1b ganglioside and Lipopolysaccharides of campylobacter jejuni isolated from patients with fisher s syndrome
Annals of Neurology, 1994Co-Authors: Nobuhiro Yuki, Kahiko Saito, H. Yoshino, Takao Taki, Shizuo Handa, Masaki Takahashi, Tadashi MiyatakeAbstract:We isolated Campylobacter jejuni from 2 patients with Fisher's syndrome subsequent to enteritis. Crude Lipopolysaccharide fractions were extracted from the bacteria and separated by thin-layer chromatography. Monoclonal antibodies to GQ1b ganglioside (GMR 13 and 7F5) reacted with both Lipopolysaccharide fractions, indicating that the Lipopolysaccharides bear the GQ1b epitope. This is the first report of molecular mimicry between neural tissue components and the antecedent infectious agents of Fisher's syndrome.
Yihua Huang - One of the best experts on this subject based on the ideXlab platform.
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structural basis for Lipopolysaccharide extraction by abc transporter lptb2fg
Nature Structural & Molecular Biology, 2017Co-Authors: Xu Yang, Dianfan Li, Le Xiao, Shan Yu, Tingting Li, Xinzheng Zhang, Kun Wang, Min Zhou, Yihua HuangAbstract:The crystal structure of LptB2FG, an ABC transporter that extracts LPS from the bacterial inner membrane and transports it to the outer membrane, indicates a transport mechanism distinct from classical ABC transporters. After biosynthesis, bacterial Lipopolysaccharides (LPS) are transiently anchored to the outer leaflet of the inner membrane (IM). The ATP-binding cassette (ABC) transporter LptB2FG extracts LPS molecules from the IM and transports them to the outer membrane. Here we report the crystal structure of nucleotide-free LptB2FG from Pseudomonas aeruginosa. The structure reveals that Lipopolysaccharide transport proteins LptF and LptG each contain a transmembrane domain (TMD), a periplasmic β-jellyroll-like domain and a coupling helix that interacts with LptB on the cytoplasmic side. The LptF and LptG TMDs form a large outward-facing V-shaped cavity in the IM. Mutational analyses suggest that LPS may enter the central cavity laterally, via the interface of the TMD domains of LptF and LptG, and is expelled into the β-jellyroll-like domains upon ATP binding and hydrolysis by LptB. These studies suggest a mechanism for LPS extraction by LptB2FG that is distinct from those of classical ABC transporters that transport substrates across the IM.
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Structural basis for Lipopolysaccharide insertion in the bacterial outer membrane
Nature, 2014Co-Authors: Shuai Qiao, Qingshan Luo, Yan Zhao, Xuejun Cai Zhang, Yihua HuangAbstract:Lipopolysaccharide, an essential component of the Gram-negative bacteria outer membrane, is inserted by LptD–LptE, a protein complex with a unique ‘barrel and plug’ architecture; the structure of the LptD–LptE complex of Shigella flexneri determined here shows LptD forming a 26-stranded β-barrel with LptE located inside the barrel of LptD, the first two β-strands are distorted by two proline residues, creating a potential portal in the barrel wall that might allow lateral diffusion of Lipopolysaccharide into the outer membrane. Haohao Dong et al. and Shuai Qiao et al. present X-ray crystal structures of the complex between the Lipopolysaccharide transport proteins LptD and LptE from the bacteria Salmonella typhimurium and Shigella flexneri, respectively. The two papers report a unique two-protein plug-and-barrel architecture for the LptD–LptE complex that reveals the mechanism by which the cell-wall Lipopolysaccharide is delivered and inserted into the external leaflet of the outer membrane of Gram-negative bacteria. As well as providing new detail on the nature of outer membrane biogenesis, this work will provide data relevant to the design of new antibiotic strategies targeting the bacterial outer membrane, much needed in the fight against multi-drug resistant pathogens. One of the fundamental properties of biological membranes is the asymmetric distribution of membrane lipids. In Gram-negative bacteria, the outer leaflet of the outer membrane is composed predominantly of Lipopolysaccharides (LPS)1. The export of LPS requires seven essential Lipopolysaccharide transport (Lpt) proteins to move LPS from the inner membrane, through the periplasm to the surface2. Of the seven Lpt proteins, the LptD–LptE complex is responsible for inserting LPS into the external leaflet of the outer membrane3,4. Here we report the crystal structure of the ∼110-kilodalton membrane protein complex LptD–LptE from Shigella flexneri at 2.4 A resolution. The structure reveals an unprecedented two-protein plug-and-barrel architecture with LptE embedded into a 26-stranded β-barrel formed by LptD. Importantly, the secondary structures of the first two β-strands are distorted by two proline residues, weakening their interactions with neighbouring β-strands and creating a potential portal on the barrel wall that could allow lateral diffusion of LPS into the outer membrane. The crystal structure of the LptD–LptE complex opens the door to new antibiotic strategies targeting the bacterial outer membrane.
Rosa Lanzetta - One of the best experts on this subject based on the ideXlab platform.
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lipid a structural characterization from the lps of the siberian psychro tolerant psychrobacter arcticus 273 4 grown at low temperature
Extremophiles, 2018Co-Authors: Angela Casillo, Rosa Lanzetta, Buko Lindner, Marcello Ziaco, Ermenegilda Parrilli, Dominik Schwudke, Aurora Holgado, Rudi Beyaert, Maria Luisa Tutino, Maria Michela CorsaroAbstract:Psychrobacter arcticus 273-4 is a Gram-negative bacterium isolated from a 20,000-to-30,000-year-old continuously frozen permafrost in the Kolyma region in Siberia. The survival strategies adopted to live at subzero temperatures include all the outer membrane molecules. A strategic involvement in the well-known enhancement of cellular membrane fluidity is attributable to the Lipopolysaccharides (LPSs). These molecules covering about the 75% of cellular surface contribute to cold adaptation through structural modifications in their portions. In this work, we elucidated the exact structure of lipid A moiety obtained from the Lipopolysaccharide of P. arcticus grown at 4 °C, to mimic the response to the real environment temperatures. The lipid A was obtained from the LPS by mild acid hydrolysis. The lipid A and its partially deacylated derivatives were exhaustively characterized by chemical analysis and by means of ESI Q-Orbitrap mass spectrometry. Moreover, biological assays indicated that P. arcticus 273-4 lipid A may behave as a weak TLR4 agonist.
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structural investigation of the antagonist lps from the cyanobacterium oscillatoria planktothrix fp1
Carbohydrate Research, 2014Co-Authors: Sara Carillo, Giuseppina Pieretti, Rosa Lanzetta, Emiliano Bedini, Michelangelo Parrilli, Maria Michela CorsaroAbstract:Abstract Cyanobacteria are aquatic and photosynthetic microorganisms, which contribute up to 30% of the yearly oxygen production on the earth. They have the distinction of being the oldest known fossils, more than 3.5 billion years old, and are one of the largest and most important groups of bacteria on earth. Cyanobacteria are an emerging source of potentially pharmacologically active products and, among these, there are the Lipopolysaccharides. Despite their significant and well documented activity, very little is known about the cyanobacteria Lipopolysaccharides (LPS) structure. The aim of this work is to investigate the structure of the highly TLR4-antagonist Lipopolysaccharide from the cyanobacterium Oscillatoria plankthotrix FP1. The LPS was purified and analysed by means of chemical analysis and 1 H and 13 C NMR spectroscopy. The LPS was then degraded by Smith degradation, HF and acetic acid hydrolyses. All the obtained products were investigated in detail by chemical analysis, NMR spectroscopy and by mass spectrometry. The LPS consists of a high molecular mass and very complex molecule lacking Kdo and heptose residues, where the polysaccharide chain is mainly constituted by a backbone of 3-substituted α- l -rhamnose units. The core region is rich in galacturonic acid and mannose residues. Moreover a glycolipid portion, similar to Gram-negative lipid A, was identified. This was built up of a non phosphorylated (1′→6) linked glucosamine disaccharide, acylated with 3-hydroxylated fatty acids. In particular 3-hydroxypentadecanoic and 3-hydroxyesadecanoic acids were found, together with esadecanoic and tetradecanoic ones. Finally the presence of a galacturonic acid residue at 6-position of the distal glucosamine in place of the Kdo residue is suggested.
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structural characterization of the core oligosaccharide isolated from the Lipopolysaccharide of the haloalkaliphilic bacterium salinivibrio sharmensis strain bagt
Carbohydrate Research, 2013Co-Authors: Sara Carillo, Giuseppina Pieretti, Rosa Lanzetta, Michelangelo Parrilli, Barbara Nicolaus, Ida Romano, Buko Lindner, Maria Michela CorsaroAbstract:Abstract Salinivibrio genus is included in the family Vibrionaceae and up to now is constituted by only five members. All the species are moderately halophilic bacteria found in salted meats, brines, and several hypersaline environments. Halophilic microorganisms are good sources of biomolecules, such as proteases, that have a great industrial interest as demonstrated by recent studies. All these bacteria possess on their outer membrane amphiphilic molecules named Lipopolysaccharides, which are of great interest because of their involvement in the mechanisms of interaction between the microbial life and environmental factors. A novel haloalkaliphilic, facultative anaerobic and Gram-negative Salinivibrio-like microorganism, named S. sharmensis strain BAGT, was recovered from a saline lake in Ras Mohammed Park (Egypt). The aim of this work is the isolation and structural characterization of the core oligosaccharidic fraction of the Lipopolysaccharide from this bacterium. By means of HPAEC-PAD we were able to purify two glycoforms, fully depicted by ESI FT-ICR mass spectrometry, chemical analysis, and NMR spectroscopy. Like other haloalkaliphilic bacteria, the core region was found to be characterized by the presence of several negatively charged residues, such as uronic acids. All the data contributed to give the following structure .
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structural determination of the o chain polysaccharide from the Lipopolysaccharide of the haloalkaliphilic halomonas pantelleriensis bacterium
European Journal of Organic Chemistry, 2006Co-Authors: Maria Michela Corsaro, Rosa Lanzetta, Agata Gambacorta, Alfonso Iadonisi, Teresa Naldi, Barbara Nicolaus, Ida Romano, Salvatore Ummarino, Michelangelo ParrilliAbstract:The structural determination of the O-chain repeating unit of the Lipopolysaccharide from the haloalkaliphilic Halomonas pantelleriensis bacterium is described. The structure of the repeating unit was suggested on the basis of chemical analysis and NMR and MS data. The 4-O-[(S)-1-carboxyethyl]-D-GlcA residue has been found for the first time in a Lipopolysaccharide, being previously only found in capsular polysaccharides. A comparison of the O-chain structures of Halomonas magadiensis and H. pantelleriensis is also reported. The results show that both bacteria present Lipopolysaccharides containing a high number of carboxylate groups whose salification might determine a protective buffer effect on bacterium against extreme life conditions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
