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  • 1
    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.
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  • 2
    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.
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  • 3
    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.
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  • 4
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Escherichia coli strains harbouring the plasmid pIE636 are able to synthesize acetylcoenzyme A: streptothricin acetyltransferase (ACSAT). The (enzymatic) N-acetylation of streptothricin F is known to contribute significantly towards the loss of antibacterial activity. 13C-NMR analysis of [14C]N-acetyl-labelled streptothricin F, produced by ACSAT-catalysed acetylation of streptothricin F and subsequent purification by various chromatographical steps, unequivocally revealed streptothricin F to be acetylated at the β-amino group (C16) (and not at the ε-amino group (C19)).
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  • 5
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Salmonella infections in naturally susceptible mice grow rapidly, with death occurring only after bacterial numbers in vivo have reached a high threshold level, commonly called the lethal load. Despite much speculation, no direct evidence has been available to substantiate a role for any candidate bacterial components in causing death. One of the most likely candidates for the lethal toxin in salmonellosis is endotoxin, specifically the lipid A domain of the lipopolysaccharide (LPS) molecule. Consequently, we have constructed a Salmonella mutant with a deletion–insertion in its waaN gene, which encodes the enzyme that catalyses one of the two secondary acylation reactions that complete lipid A biosynthesis. The mutant biosynthesizes a lipid A molecule lacking a single fatty acyl chain and is consequently less able to induce cytokine and inducible nitric oxide synthase (iNOS) responses both in vivo and in vitro. The mutant bacteria appear healthy, are not sensitive to increased growth temperature and synthesize a full-length O-antigen-containing LPS molecule lacking only the expected secondary acyl chain. On intravenous inoculation into susceptible BALB/c mice, wild-type salmonellae grew at the expected rate of approximately 10-fold per day in livers and spleens and caused the death of the infected mice when lethal loads of approximately 108 were attained in these organs. Somewhat unexpectedly, waaN mutant bacteria grew at exactly the same rate as wild-type bacteria in BALB/c mice but, when counts reached 108 per organ, mice infected with mutant bacteria survived. Bacterial growth continued until unprecedentedly high counts of 109 per organ were attained, when approximately 10% of the mice died. Most of the animals carrying these high bacterial loads survived, and the bacteria were slowly cleared from the organs. These experiments provide the first direct evidence that death in a mouse typhoid infection is directly dependent on the toxicity of lipid A and suggest that this may be mediated via pro-inflammatory cytokine and/or iNOS responses.
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  • 6
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We have isolated the ypfP gene (accession number P54166) from genomic DNA of Bacillus subtilis Marburg strain 60015 (Freese and Fortnagel, 1967) using PCR. After cloning and expression in E. coli, SDS–PAGE showed strong expression of a protein that had the predicted size of 43.6 kDa. Chromatographic analysis of the lipids extracted from the transformed E. coli revealed several new glycolipids. These glycolipids were isolated and their structures determined by nuclear magnetic resonance (NMR) and mass spectrometry. They were identified as 3-[O-β-D-glucopyranosyl-(1→6)-O-β-D-glucopyranosyl]-1,2-diacylglycerol, 3-[O-β-D-glucopyranosyl-(1→6)-O-β-D-glucopyranosyl-(1→6)-O-β-D-glucopyranosyl]-1,2-diacylglycerol and 3-[O-β-D-glucopyranosyl-(1→6)-O-β-D-glucopyranosyl-(1→6)-O-β-D-glucopyranosyl-(1→6)-O-β-D-glucopyranosyl]-1,2-diacylglycerol. The enzymatic activity expected to catalyse the synthesis of these compounds was confirmed by in vitro assays with radioactive substrates. In these assays, one additional glycolipid was formed and tentatively identified as 3-[O-β-D-glucopyranosyl]-1,2-diacylglycerol, which was not detected in the lipid extract of transformed cells. Experiments with some of the above-described glycolipids as 14C-labelled sugar acceptors and unlabelled UDP-glucose as glucose donor suggest that the ypfP gene codes for a new processive UDP-glucose: 1,2-diacylglycerol-3-β-D-glucosyl transferase. This glucosyltransferase can use diacylglycerol, monoglucosyl-diacylglycerol, diglucosyldiacylglycerol or triglucosyldiacylglycerol as sugar acceptor, which, apart from the first member, are formed by repetitive addition of a glucopyranosyl residue in β (1→6) linkage to the product of the preceding reaction.
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  • 7
    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.
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  • 8
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A sialic acid-specific lectin was isolated from the albumin glands of the garden snail Cepaea hortensis by affinity chromatography on fetuin-Sepharose following gel filtration on Superdex 200. The purified native lectin showed a molecular mass of about 95 kDa by gel filtration and 100 kDa by SDS electrophoresis. It was cleaved by boiling in buffer containing SDS in three serological identical bands corresponding to molecular masses of about 24, 20 and 16 kDa, respectively. From these three fragments, only the 24- and the 20-kDa bands were found to be glycosylated. Only the three sugars mannose, galactose and N-acetylglucosamine could be detected in a molar ratio of 3:8.6:2. The oligosaccharide moieties seem to be N- and partially O-glycosidic bound. Isoelectric focusing (IEF) of the purified lectin revealed a heterogeneous pattern with bands in the pH range of 4.3–5.0. Isolated bands of different isoelectric points showed in SDS electrophoresis the same three fragments with molecular masses of 24, 20 or 16 kDa. The heterogeneity of the lectin was revealed either by IEF or amino acid sequencing of internal tryptic peptides.
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 199 (2001), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Mycoplasma fermentans strains differ in the profile of choline-containing phosphoglycolipids (PGL) present in their cell membrane. MfGL-II [Zähringer et al. (1997) J. Biol. Chem. 272, 26262–26270] was found to be the major PGL in most strains tested. However, in the pulmonary isolates, M52 and M39 the major choline-containing PGLs were MfGL-I [Matsuda et al. (1994) J. Biol. Chem. 269, 33123–33129] and MfEL, a unique choline-containing ether lipid recently identified by us [Wagner et al. (2000) Eur. J. Biochem. 267, 6276–6286]. Both MfGL-I and MfEL were metabolically labeled by growing the cells with radioactive choline but only MfGL-I reacted with anti-phosphocholine antibodies. All tested strains fused with Molt-3 cells at almost the same rate and to about the same extent and in all the strains membrane proteins that reacted with anti-phosphocholine antibodies were detected, indicating that some membrane proteins are decorated with phosphocholine moieties.
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  • 10
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The choline-containing phosphoglycolipid, MfGL-II, is the major polar lipid of Mycoplasma fermentans PG18. Anti-MfGL-II antisera raised in rabbits using the purified MfGL-II as an immunogen were employed in immunogold electron microscopic and immunofluorescence studies showing that MfGL-II is uniformly distributed and exposed on the cell surface of M. fermentans cells. The specificity of the antibodies was determined by immunostaining of lipid extracts separated by thin layer chromatography. The antibodies recognize lipids specific to M. fermentans but did not cross-react with lipid extracts of M. penetrans, M. capricolum, M. gallisepticum or Acholeplasma laidlawii. As phosphocholine almost completely abolished antibody interaction with MfGL-II in an ELISA assay it is suggested that the anti-MfGL-II repertoire is composed primarily of anti-phosphocholine antibodies. The anti-MfGL-II antisera inhibit the attachment of M. fermentans to Molt-3 lymphocytes suggesting that MfGL-II plays a major role in M. fermentans-host cell interaction.
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