Pseudomonas diminuta LPS with a new endotoxic lipid A structure

Volatile Metabolites from Brevundimonas diminuta and Nematicidal Esters Inhibit Meloidogyne javanica

Brevundimonas diminuta is broadly distributed in terrestrial and aquatic environments and has various biological activities. In this study, we found that B. diminuta exhibited nematicidal activity against the plant root-knot nematode, Meloidogyne javanica. A total of 42 volatile organic compounds (VOCs) from B. diminuta were identified using gas chromatography-mass spectrometry (GC-MS). The nematicidal activity of the 10 main VOCs was tested against M. javanica. Butyl butanoate (4 µL) caused the mortality of 80.13% of M. javanica after 4 h. The nematicidal activity of an additional 38 butyl-butyrate-like volatile esters was also investigated. Of these, seven had strong nematicidal activity against M. javanica, five of which showed egg-hatching inhibitory activity. This study is the first to report that butyl butanoate, ethyl 2-methylbutanoate, ethyl 4-methylpentanoate, ethyl pent-4-enoate, and methyl undecanoate have nematicidal activity against M. javanica. The results indicated that B. diminuta could serve as a candidate microorganism for the biocontrol of plant root-knot nematodes, showing that volatile esters have great potential as nematicides.

Structural analysis of the lipid A derived from the lipopolysaccharide of Brucella abortus

Lipopolysaccharide (LPS) of Brucella abortus strain 45/20 was purified using a novel method. Monophosphoryl lipid A (MPLA) was prepared from this LPS, methylated, and purified by high performance liquid chromatography. Chemical, mass spectral, and nuclear magnetic resonance analyses showed that MPLA consists of heptaacyl lipid As with molecular weights of 2095, 2123, 2151 and 2179. They contained the β-1,6-linked 2,3-diamino-2,3,-dideoxy-glucose disaccharide backbone and a phosphate group at the 4' position. Bisphosphoryl lipid A was also prepared and completely O-deacylated. It contained an additional phosphate group, and either 2 hydroxyhexadecanoic, 1 hydroxytetradecanoic, 1 hydroxydodecanoic acids or 2 hydroxyhexadecanoic and 2 hydroxydodecanoic acids, all in amide linkage. The predominant ester-linked fatty acyl group in acyloxyacyl linkage was hexadecanoate.

The purified LPS, bisphosphoryl lipid A, and MPLA from B. abortus showed about 14%, 3% and 1%, respectively, of the B cell mitogen activity of ReLPS from Escherichia coli at 1.0 μg/ml.

Chemical structure of lipid A isolated from Flavobacterium meningosepticum lipopolysaccharide

The chemical structure of the lipid A of the lipopolysaccharide component isolated from Flavobacterium meningosepticum IFO 12535 was elucidated. Methylation and nuclear magnetic resonance analyses showed that two kinds of hydrophilic backbone exist in the free lipid A: a beta (1-->6)-linked 2-amino-2-deoxy-D-glucose, which is usually present in enterobacterial lipid A's, and a 2-amino-6-O-(2, 3-diamino-2,3-dideoxy-beta-D-glucopyranosyl)-2-deoxy-D-glucose, in a molar ratio of 1.00:0.35. Both backbones were alpha-glycosidically phosphorylated in position 1, and the hydroxyl groups at positions 4, 4', and 6' were unsubstituted. Liquid secondary ion-mass spectrometry revealed a pseudomolecular ion at m/z 1673 [M-H]- as a major monophosphoryl lipid A component carrying five acyl groups. Fatty acid analysis showed that the lipid A contained 1 mol each of amide-linked (R)-3-OH iC17:0, ester-linked (R)-3-OH iC15:0, amide-linked (R)-3-O-(iC15:0)-iC17:0, and both amide- and ester-linked (R)-3-OH C16:0. Fatty acid distribution analyses using several mass spectrometry determinations demonstrated that the former two constituents were distributed on positions 2 and 3 of the reducing terminal unit of the backbones and that the latter two were attached to the 2' and 3' positions in the nonreducing terminal residue.

Cellular fatty acyl and alkenyl residues in Megasphaera and Pectinatus species: contrasting profiles and detection of beer spoilage

The strictly anaerobic Gram-negative beer spoilage bacteria Megasphaera cerevisiae, Pectinatus cerevisiiphilus and P. frisingensis were subjected to cellular fatty acid analysis, employing acid- and base-catalysed cleavage, gas chromatography and mass spectrometry. M. cerevisiae contained 12:0, 16:0, 16:1, 18:1, 17:cyc, 19:cyc, 12:0(3OH), 14:0(3OH) as the main fatty acids, and alk-1-enyl chains instead of acyl chains were detected to a considerable extent (14% of total fatty acids), indicating the presence of plasmalogens. The fatty acid pattern of M. cerevisiae was almost identical to that of M. elsdenii, the only species previously assigned to this genus. P. cerevisiiphilus and P. frisingensis yielded fatty acids that were heavily dominated by odd-numbered chains; 11:0, 15:0, 17:1, 18:cyc and 13:0(3OH) were the main fatty acids detected in both species. Alk-1-enyl chains with similar chain lengths were also found. Both Pectinatus species contained six different 3-hydroxy fatty acids with chain lengths between 11 and 15 carbons, 13:0(3OH) being dominant and the others accounting for generally less than 1% of total fatty acids. Among the minor components, an unsaturated 3-hydroxy fatty acid was detected which was shown to be 13:1(30H). In addition, fatty acid analysis was shown to be applicable to detection of bacterial contamination of beer.

Lipopolysaccharide-lipophorin complex formation in insect hemolymph: a common pathway of lipopolysaccharide detoxification both in insects and in mammals

The formation of the lipophorin-lipopolysaccharide (LPS) complex in Bombyx mori hemolymph and its role in LPS detoxification were explored. LPS, an antibacterial protein inducer in insects, was injected into B. mori larvae. Analytical density gradient ultracentrifugation revealed that after injection the LPS peak shifts to a zone of lower density with time. The shifted peak was identified as the lipophorin-LPS complex. This complex formation was also achieved in an in vitro mixture of cell-free hemolymph and LPS at 25 degrees C but not at 1 degree C. The lipophorin-LPS complex had a significantly lower capacity to elicit the mRNA of cecropin B, an antibacterial protein. The biological activity of reextracted LPS from the complex was slightly reduced in the Limulus test and no structural modification was observed in sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE). These results suggested that the formation of lipophorin-LPS strikingly reduces the cecropin inducibility of LPS without any structural change in LPS. Similar serum lipoprotein-LPS complex formation and reduction of biological activities of LPS were also observed in mammals. We, therefore, suggest that the formation of the serum lipoprotein-LPS complex is a common pathway to inactivate LPS both in insects and in mammals.

Legionella pneumophila growth restriction and cytokine production by murine macrophages activated by a novel Pseudomonas lipid A

Peritoneal exudate macrophages from A/J mice activated by purified lipid A preparations from Pseudomonas vesicularis, which contain 2,3-diamino-2,3-dideoxy-D-glucose disaccharide phosphomonoester as the lipid A backbone, restricted the growth of Legionella pneumophila, an intracellular opportunistic bacteria which readily grows in otherwise permissive macrophages from susceptible A/J mice and induced production of the proinflammatory cytokines interleukin 1 and tumor necrosis factor alpha. Activation of the macrophages was similar to that which occurred after stimulation with more conventional lipid A from other bacteria such as salmonellae. A purified fraction A3 preparation from the Pseudomonas lipid A, which lacked only 1 mol of amide-linked fatty acid, in comparison with another fraction (A2), which contained the fatty acid, also markedly activated the usually permissive macrophages from susceptible A/J mice to resist growth of the legionellae. The fraction A3 also induced both interleukin and tumor necrosis factor alpha. These results show that this novel lipid A from P. vesicularis can activate macrophages to resist infection with an opportunistic bacterium in a manner similar to that induced by conventional enterobacterial lipid A and that the hydrophobic portion of this Pseudomonas molecule may have an important role in activation of macrophages.

Neutralization of Shwartzman-inducing activity by antibodies recognizing the Re core or lipid A structures of lipopolysaccharide from Salmonella minnesota R595 and Pseudomonas vesicularis JCM1477

Antibodies recognizing the Re core or lipid A structures of lipopolysaccharide (LPS) derived from Salmonella minnesota R595 and Pseudomonas vesicularis JCM1477 were tested for the ability to neutralize the preparatory activity of endotoxin using the local Shwartzman reaction. Shwartzman-inducing activity of R595 LPS (Re-form) was strongly suppressed when the LPS was incubated with the rabbit anti-R595 antiserum or the purified IgG antibody which recognizes core region of the LPS. The antiserum also suppressed the preparatory activity of LPS from S. typhimurium SL1102 (Re) and Escherichia coli F515 (Re), but not that of either S. typhimurium LT-2 (S) LPS or R595 lipid A. Moreover, it was found that the murine monoclonal antibody (MAb), SmRe100G (IgG2a) which recognizes the core region of R595 LPS, significantly suppressed the preparatory activity of R595 LPS. Both conventional antibodies specific to R595 lipid A, which contains a 1,4'-bisphosphorylated beta-D-glucosaminyl-alpha-D-glucosamine disaccharide structure, and JCM1477 lipid A, which contains a monophosphorylated 3-amino-D-glucosamine disaccharide structure, neutralized the preparatory activity of homologous and a closely related lipid A, but not that of LPS. In addition, it was observed that MAb Sm5G (IgG2b) specific to enterobacterial lipid A preparations (especially R595 lipid A) neutralized the preparatory activity of R595 lipid A, although the effect was somewhat weak as compared with that of rabbit antiserum. These results suggest that anti-Re LPS antibody binding to the core of Re LPS is involved in suppressing the endotoxic activity of Re LPS, and that the direct binding of anti-lipid A antibody to some specific epitopes of lipid A is important in neutralizing the endotoxic activity.

Structural analysis of the lipid A component of Campylobacter jejuni CCUG 10936 (serotype O:2) lipopolysaccharide. Description of a lipid A containing a hybrid backbone of 2-amino-2-deoxy-D-glucose and 2,3-diamino-2,3-dideoxy-D-glucose

The chemical structure of Campylobacter jejuni CCUG 10936 lipid A was elucidated. The hydrophilic backbone of the lipid A was shown to consist of three (1----6)-linked bisphosphorylated hexosamine disaccharides. Neglecting the phosphorylation pattern, a D-glucosamine (2-amino-2-deoxy-D-glucose) disaccharide [beta-D-glucosaminyl-(1----6)-D-glucosamine], a hybrid disaccharide of 2,3-diamino-2,3-dideoxy-D-glucose and D-glucosamine [2,3-diamino-2,3-dideoxy-beta-D-glucopyranosyl-(1----6)-D-glucosamine], and a 2,3-diamino-2,3-dideoxy-D-glucose disaccharide were present in a molar ratio of 1:6:1.2. Although the backbones are bisphosphorylated, heterogeneity exists in the substitution of the polar head groups. Phosphorylethanolamine is alpha-glycosidically bound to the reducing sugar residue of the backbone, though C-1 is also non-stoichiometrically substituted by diphosphorylethanolamine. Position 4' of the non-reducing sugar residue carries an ester-bound phosphate group or is non-stoichiometrically substituted by diphosphorylethanolamine. By methylation analysis it was shown that position 6' is the attachment site for the polysaccharide moiety in lipopolysaccharide. These backbone species carry up to six molecules of ester- and amide-bound fatty acids. Four molecules of (R)-3-hydroxytetradecanoic acid are linked directly to the lipid A backbone (at positions 2, 3, 2', and 3'). Laser desorption mass spectrometry showed that both (R)-3-hydroxytetradecanoic acids linked to the non-reducing sugar unit carry, at their 3-hydroxyl group, either two molecules of hexadecanoic acid or one molecule of tetradecanoic and one of hexadecanoic acid. It also suggested that the (R)-3-(tetradecanoyloxy)-tetradecanoic acid was attached at position 2', whereas (R)-3-(hexadecanoyloxy)-tetradecanoic acid was attached at position 3', or at positions 2' and 3'. Therefore, the occurrence of three backbone disaccharides differing in amino sugar composition and presence of a hybrid disaccharide differentiate the lipid A of this C. jejuni strain from enterobacterial and other lipids A described previously.

Chemical characterization of Campylobacter jejuni lipopolysaccharides containing N-acetylneuraminic acid and 2,3-diamino-2,3-dideoxy-D-glucose

Lipopolysaccharides (LPS) of four nonencapsulated strains of the human enteric pathogen Campylobacter jejuni were chemically characterized. When applied to two of the strains, extraction by a modified phenol-chloroform-petroleum ether method (H. Brade and C. Galanos, Eur. J. Biochem. 122:233-237, 1982) gave better yields of LPS than did extraction by the conventional hot phenol-water technique. Constituents common to all LPS were D-glucose, D-galactose, L-glycero-D-manno-heptose, 3-deoxy-D-manno-2-octulosonic acid, D-glucuronic acid, D-galactosamine, and phosphorylethanolamine. Phosphate was present in a relatively high amount. In addition, the LPS of three strains contained N-acetylneuraminic acid, whereas the LPS of the strain lacking this component contained 3-amino-3,6-dideoxy-D-glucose. The lipid A component contained phosphate with D-glucosamine and 2,3-diamino-2,3-dideoxy-D-glucose as the major amino sugars. Ethanolamine-phosphate was present also. The major fatty acids were ester- and amide-bound 3-hydroxytetradecanoic and ester-bound hexadecanoic acids, with a minor amount of ester-bound tetradecanoic acid. This is the first report of N-acetylneuraminic acid in the oligosaccharide moiety and diaminoglucose in the lipid A of C. jejuni LPS.

Cytokine induction by lipopolysaccharide (LPS) corresponds to lethal toxicity and is inhibited by nontoxic Rhodobacter capsulatus LPS

Many pathological effects of gram-negative bacteria are produced by their cell wall-derived lipopolysaccharides (LPSs). Differing pathogenicity of gram-negative LPSs, however, may depend on their capacities to induce cytokines. Thus, we studied the lethal toxicity of four nonenterobacterial LPSs and compared it with their capacity to induce mononuclear cell (MNC)-derived interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor (TNF). Unstimulated MNC did not release these cytokines. LPS from the phototrophic strain Rhodobacter capsulatus 37b4 elaborated little toxicity in galactosamine-treated mice (10 micrograms of LPS per mouse was the 100% lethal dose [LD100]) and induced IL-1 and IL-6 release only at high concentrations (10 to 50 micrograms of LPS per ml). R. capsulatus LPS failed to induce TNF activity even at the highest concentration tested (100 micrograms of LPS per ml). In contrast, LPS derived from Pseudomonas diminuta NCTC 8545 or the nodulating species Bradyrhizobium lupini DSM 30140 and Rhizobium meliloti 10406 expressed lethal toxicity (LD100, 1,000, 100, and 10 ng per mouse, respectively) and induced IL-1 or IL-6 (10 to 100, 10, and 1 ng of LPS per ml, respectively) at concentrations 1,000- to 10,000-fold lower than effective levels of R. capsulatus LPS. LPSs from P. diminuta, B. lupini, and R. meliloti also stimulated TNF production and release. MNC accumulated cell-associated IL-1 activities under circumstances in which released activity was readily detected. The cells contained only scant IL-6 activity, indicating release of this mediator rather than intracellular accumulation. Antisera to the respective cytokines inactivated biological activities of the samples selectively. The R. capsulatus LPS inhibited cytokine induction by LPS from P. diminuta, B. lupini, and R. meliloti in coincubation experiments. These results show that the in vivo lethality of the LPSs tested correlates with the induction of monocyte-derived cytokines in vitro. The results of this study suggest that the different lethality of various LPSs from gram-negative bacteria may be due to the differential ability of these LPSs to induce cytokine production.

Tumor necrosis factor changes sensitivity of differentiation of mouse leukemia M1 cells by lipopolysaccharide

A clone of mouse leukemia M1 cells was induced to differentiate by lipopolysaccharide (LPS) (LPS-sensitive clone) while another clone of the same cells was resistant (LPS-resistant clone). LPS and lipid A preparations from Pseudomonas diminuta and Pseudomonas vesicularis were as active as Escherichia coli LPS in the induction of differentiation of the LPS-sensitive clone. Synthetic lipid A precursor Ia (compound 406), which has no interleukin 1 (IL-1)-inducing activity toward monocytes, had strong differentiation-inducing activity toward the LPS-sensitive clone. The combined treatment of the LPS-sensitive clone with LPS and recombinant tumor necrosis factor (rTNF) did not further increase the degree of differentiation induced by LPS alone. By contrast, the LPS-resistant clone was markedly induced to differentiate by LPS in the presence of rTNF. Combined treatment of the LPS-resistant clone with LPS and other cytokines such as recombinant IL-1 alpha, recombinant granulocyte colony-stimulating factor, and interferon-gamma was not effective in inducing marked synergistic differentiation. These results raise the possibility that rTNF changes the sensitivity of M1 cells to induction of differentiation by LPS.

Structural analysis of the nontoxic lipid A of Rhodobacter capsulatus 37b4

Lipid A from Rhodobacter capsulatus 37b4 consists of a D-glucosaminyl-(beta 1-6)-D-glucosamine disaccharide backbone, carrying diphosphorylethanolamine at C-1 of the reducing glucosamine and phosphorylethanolamine at C-4' of the nonreducing glucosamine. 1,4'-Bisphosphorylated lipid A, lacking the polar head groups, was also encountered and contributed to the observed microheterogeneity in the phosphate substitution. The amino functions of both glucosamines are substituted almost entirely by the rare 3-oxotetradecanoic acid, which is a characteristic constituent of lipid A in the genus Rhodobacter. 3-Hydroxydecanoic acid is ester-bound at C-3 and C-3' of the glucosamine disaccharide and the one at the nonreducing glucosamine (C-3') is partially substituted by dodecenoic acid to form an ester-bound diester. In free lipid A, hydroxy groups at C-4 and C-6' of the glucosamine disaccharide are unsubstituted. C-6' being the putative attachment point of the lipopolysaccharide core. The nontoxic Rhodobacter capsulatus lipid A shows extensive serological cross-reaction with the toxic Salmonella lipid A. Structural similarities in the hydrophilic part of both types of lipid A, dissimilarities in the hydrophobic part and their impacts on serologic properties are discussed.

Structural heterogeneity regarding local Shwartzman activity of lipid A

The relation of chemical structure to local Shwartzman activity of lipid A preparations purified by thin-layer chromatography from five bacterial strains was examined. Two lipid A fractions from E. coli F515--Ec-A2 and Ec-A3--exhibited strong activity, similar to that of previous synthetic E. coli-type lipid A (compound 506 or LA-15-PP). The Ec-A3 fraction contained a component that appeared to be structurally identical to compound 506, and the main component of Ec-A2 fraction was structurally similar to compound 506 except that it carried a 3-hydroxytetradecanoyl group at the C-3' position of the backbone in place of a 3-tetradecanoyloxytetradecanoyl group. Free lipid A (12 C) and purified lipid A fractions, Ec-A2 (12 C) and Ec-A3 (12 C), respectively, obtained from bacteria grown at 12 C, exhibited activity comparable to Ec-A2 or Ec-A3. In these preparations, a large part of the 3-dodecanoyloxytetradecanoyl group might be replaced by 3-hexadecenoyloxytetradecanoyl group. Salmonella minnesota R595 free lipid A also contained at least two active lipid A components as seen in E. coli lipid A, but the third component corresponding to the synthetic Salmonella-type lipid A (compound 516 or LA-16-PP) exhibited low activity. A lipid A fraction, Cv-A4 from Chromobacterium violaceum IFO 12614, which was proposed to have two acyloxyacyl groups at the C-2 and C-2' positions with other acyl groups, exhibited weaker activity than the free lipid A or LPS. The purified lipid A fractions from Pseudomonas diminuta JCM 2788 and Pseudomonas vesicularis JCM 1477 contained an unusual backbone with 2,3-diamino-2,3-dideoxy-D-glucose disaccharide phosphomonoester, and these lipid A (Pd-A3 and Pv-A3) exhibited strong activity comparable to the E. coli lipid A. Thus, the present results show that the local Shwartzman reaction can be expressed by partly different lipid A structures in both hydrophilic backbone and fatty acyl residues; when they have the same backbone the potency varies markedly depending on the structure of the acyl residues.

Tumor necrosis factor-inducing activities of lipid A preparations from Pseudomonas diminuta and Pseudomonas vesicularis

Tumor necrosis factor (TNF)-inducing activities of lipid A preparations from P. diminuta and P. vesicularis, which contain mainly 2 mol of 2,3-diamino-2,3-dideoxy-D-glucose and 1 mol of nonglycosidic phosphate as the backbone component and have partly different fatty acid compositions, were examined. TNF was induced by injecting various lipid A fractions into mice that had previously been sensitized with Mycobacterium bovis BCG vaccine. A major component of lipid A of both strains, referred to as A3 fraction, exhibited stronger TNF-inducing activity than A2 fraction having incomplete acyl residues. The removal of ester-linked fatty acyl groups by mild hydrazinolysis of the P. diminuta lipid A results in a marked decrease of the activity. These results suggest that the structure of the hydrophobic part, including the amide-linked acyloxyacyl group(s), of the lipid A molecule play an important role in inducing TNF in the sera of mice.

Different lipid A types in lipopolysaccharides of phototrophic and related non-phototrophic bacteria

Lipid A analyses confirm not only the present taxa of the purple nonsulfur bacteria (formerly Rhodospirillaceae), but also phylogenetical relatedness of distinct phototrophic to distinct non-phototrophic bacteria, as was suggested by cataloguing 16S rRNA. For example, lipid A with ester-bound 3-OH-10:0 and the rare amide-linked 3-oxo-14:0 is common to the phototrophic Rhodobacter capsulatus and Rhodobacter sphaeroides and also to Paracoccus denitrificans and Thiobacillus versutus. 'Lipid ADAG' (lipid A with 2,3-diamino-D-glucose (DAG)) occurs in the phototrophic Rhodopseudomonas viridis and Rhodopseudomonas palustris and also in the related non-phototrophic species, e.g., Nitrobacter winogradskyi, Pseudomonas diminuta, or Thiobacillus ferrooxidans. The phylogenetically more coherent purple sulfur bacteria (Chromatiaceae) uniformly contain D-mannose in their phosphate-free lipid A. Among the green bacteria, only the Chlorobiaceae but not the likewise chlorosome-containing Chloroflexaceae contain lipopolysaccharide. Lipid ADAG from R. viridis is a structural analogue of a biosynthetic precursor (lipid X) of enterobacterial lipid A. Lipid A synthase from Salmonella accepts not only lipid X but also the synthetic di-N-acyl-2,3-diamino-D-glucose analogue as substrate (Raetz, C.R.H., unpublished results). More and more naturally occurring lipid A's with both, 2,3-diaminoglucose and glucosamine ('mixed' lipid A, with 2,3-diaminoglucose or glucosamine dominating) are being found. Newly recognized lipid A and lipid ADAG types might offer the possibility of differentially stimulating desired biological activities in animals without also having the undesired endotoxic activities. The non-toxic lipid A from Rhodopseudomonas viridis for example is able to stimulate prostaglandin secretion in peritoneal macrophages and can be used as an antagonist to the endotoxic shock caused by Salmonella lipopolysaccharide.