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  • 1
    Electronic Resource
    Electronic Resource
    The Neisseria gonorrhoeae lpxLII gene encodes for a late-functioning lauroyl acyl transferase, and a null mutation within the gene has a significant effect on the induction of acute inflammatory responses (2001)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 42 (2001), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: LPS is a fundamental constituent of the outer membrane of all Gram-negative bacteria, and the lipid A domain plays a central role in the induction of inflammatory responses. We identified genes of the Neisseria gonorrhoeae lipid A biosynthetic pathway by searching the complete gonococcal genome sequence with sequences of known enzymes from other species. The lpxLII gene was disrupted by an insertion–deletion in an attenuated aroA mutant of the gonococcal strain MS11. Lipopolysaccharide (LPS) and lipid A analysis demonstrated that the lpxLII mutant had synthesized an altered LPS molecule lacking a single lauric fatty acid residue in the GlcN II of the lipid A backbone. LPS of the lpxLII mutant had a markedly reduced ability to induce the proinflammatory cytokines tumour necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 and IL-8 from human macrophages and IL-8 from polymorphonuclear cells. This study demonstrates that the lpxLII gene in gonococci encodes for a late-functioning lauroyl acyl transferase that adds a lauric acid at position 2′ in the lipid A backbone. The presence of lauric acid at such a position appears to be crucial for the induction of full inflammatory responses by N. gonorrhoeae LPS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2001.02619.x
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  • 2
    Electronic Resource
    Electronic Resource
    Lipid A, the lipid component of bacterial lipopolysaccharides: Relation of chemical structure to biological activity (1982)
    Springer
    Journal of molecular medicine 60 (1982), S. 705-709 
    Details
    ISSN: 1432-1440
    Keywords: Lipid A ; Lipopolysaccharides ; Chemical structure ; Biological activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Lipopolysaccharides are integral components of the outer membrane of Gram-negative bacteria and they participate in various membrane functions essential for bacterial growth and survival. Lipopolysaccharides also represent the endotoxins of Gram-negative bacteria and possibly play a role for the pathogenesis and manifestations of bacterial infections. These biological activities are mediated mainly by the lipid component of lipopolysaccharides, termed lipid A. Chemically, lipid A consists of a β1,6-linkedD-glucosamine disaccharide which carries substituted phosphoryl groups and a range ofD-3-hydroxy andD-3-acyloxyacyl residues, the latter being arranged in a hexagonal dense packing. A number of experimental data allow the conclusion that the highly ordered and compact lipid A structure confers stability to the outer membrane, renders it less permeable to lipophilic molecules and by providing a proper fluidity stabilizes the conformation of biologically active membrane proteins. For endotoxic activities of lipid A the polar substituents of phosphate residues are dispensable. The presence ofD-3-hydroxy (or acyloxy) acyl-groups, linked to the glucosamine disaccharide, however, seems to be of importance. Analyses of now available synthetic lipid A analogues are expected to allow a more precise characterization of substructures and conformations required for the expression of physiological functions and endotoxic activities of lipid A.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01716559
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  • 3
    Electronic Resource
    Electronic Resource
    Chemical composition of lipopolysaccharides from Legionella bozemanii and Legionella longbeachae (1994)
    Springer
    Archives of microbiology 162 (1994), S. 215-221 
    Details
    ISSN: 1432-072X
    Keywords: Key words     Taxonomy ; Chemical analyses ; Long-chain fatty acids ; 2 ; 3-Diamino-2 ; 3-dideoxy-d-glucose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract      Lipopolysaccharides (LPS) from Legionella bozemanii serogroup 1 and Legionella longbeachae serogroup 1 were subjected to chemical analyses. The lipid A part of both LPSs contained 2,3-dideoxy-2,3-diamino-d-glucose as major constituents and d-glucosamine and glycerol as minor constituents of the sugar backbone structure. Both LPSs exhibited a very complex fatty acid compositio n. Twenty amide-linked 3-hydroxy fatty acids were detected in LPS of L. longbeachae, whereas seventeen were encountered in LPS of L. bozemanii. Both LPSs contained nine ester-linked nonhydroxy fatty acids and the unique long-chain fatty acids 27-oxo-octacosanoic acid, 29-oxo-triacontanoic acid, heptacosane-1,27-dioic acid and nonacosane-1,29-dioic acid. SDS-PAGE showed that L. bozemanii produced smooth-form LPS, whereas L. longbeachae LPS was mainly of the R-type. Composi tion analyses were in accordance with these electrophoretic patterns. d-Quinovosamine and l-fucosamine constituted 80 mol% of the polysaccharide part of L. bozemanii LPS. Other sugars identified were d-glucosamine, d-mannose, d-glucose, l-rhamnose, d-glycero-d-manno-heptose, l-glycero-d-manno-heptose, 2-keto-3-deoxy-octonic acid and glycerol. The polysaccharide chain from LPS of L. longbeachae appeared to be shorter, but composed of the same sugars except l-fucosamine. Both LPSs contained glycerol phosphate and glucosamine phosphate and L. longbeachae LPS contained in addition glucose phosphate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00301841
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  • 4
    Electronic Resource
    Electronic Resource
    Isolation and structural analysis of two lipid A precursors from a KDO deficient mutant of Salmonella typhimurium differing in their hexadecanoic acid content (1985)
    Springer
    Archives of microbiology 141 (1985), S. 353-358 
    Details
    ISSN: 1432-072X
    Keywords: KDO mutant ; Lipid A intermediates ; Hexadecanoic acid substitution ; Biosynthesis of lipid A
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The extraction, purification and structural characterization of two lipid A precursors (Ia and Ib) differing only in one hexadecanoic acid are described. Both precursors were synthesized at elevated temperatures by a new mutant of Salmonella typhimurium (mutant Ts5) which is conditionally defective in synthesis of the 3-deoxy-d-manno-octulosonic acid region of lipopolysaccharides. Both precursors were purified by repeated phenol/chloroform/petroleum ether (PCP) extractions followed by thin layer chromatography. Teh precursor preparation was free of lipopolysaccharides and phospholipids and contained less than 0.1% protein. Structural analysis which included chemical degradation procedures as well as positive ion laser desorption (LDMS) mass spectroscopy of dephosphorylated lipid A precursors showed together that precursor Ia represents a diphosphorylated glucosamine disaccharide containing two ester, two amide-linked residues of 3-hydroxytetradecanoic acid and lacks the ester-linked dodecanoic, tetradecanoic and hexadecanoic acid as well as 3-deoxy-d-manno-octulosonic acid. Precursor Ib has the same basic structure as precursor Ia, but contains in addition one mol of hexadecanoic acid per mol disaccharide which is linked to the 3-hydroxy group of the amide-bound 3-hydroxy-tetradecanoic acid of the reducing, terminal glucosamine residue. The structure of precursor Ib supports the conclusion that hexadecanoic acid incorporation occurs at an early stage in lipid A biosynthesis prior to the attachment of 3-deoxy-d-manno-octulosonic acid and/or other polar substituents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00428849
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  • 5
    Electronic Resource
    Electronic Resource
    Chemical composition of lipopolysaccharides from Legionella bozemanii and Legionella longbeachae (1994)
    Springer
    Archives of microbiology 162 (1994), S. 215-221 
    Details
    ISSN: 1432-072X
    Keywords: Taxonomy ; Chemical analyses ; Long-chain fatty acids ; 2,3-Diamino-2,3-dideoxy-d-glucose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lipopolysaccharides (LPS) from Legionella bozemanii serogroup 1 and Legionella longbeachae serogroup 1 were subjected to chemical analyses. The lipid A part of both LPSs contained 2,3-dideoxy-2,3-diamino-d-glucose as major constituents and d-glucosamine and glycerol as minor constituents of the sugar backbone structure. Both LPSs exhibited a very complex fatty acid composition. Twenty amide-linked 3-hydroxy fatty acids were detected in LPS of L. longbeachae, whereas seventeen were encountered in LPS of L. bozemanii. Both LPSs contained nine ester-linked nonhydroxy fatty acids and the unique long-chain fatty acids 27-oxo-octacosanoic acid, 29-oxotriacontanoic acid, heptacosane-1,27-dioic acid and nonacosane-1,29-dioic acid. SDS-PAGE showed that L. bozemanii produced smooth-form LPS, whereas L. longbeachae LPS was mainly of the R-type. Composition analyses were in accordance with these electrophoretic patterns. d-Quinovosamine and l-fucosamine constituted 80 mol% of the polysaccharide part of L. bozemanii LPS. Other sugars identified were d-glucosamine, d-mannose, d-glucose, l-rhamnose, d-glycero-d-manno-heptose, l-glycero-d-mannoheptose, 2-keto-3-deoxy-octonic acid and glycerol. The polysaccharide chain from LPS of L. longbeachae appeared to be shorter, but composed of the same sugars except l-fucosamine. Both LPSs contained glycerol phosphate and glucosamine phosphate and L. longbeachae LPS contained in addition glucose phosphate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00301841
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    Paper (German National Licenses)
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