Phospholipids and a novel glycine-containing lipoamino acid in Cytophaga johnsonae Stanier strain C21

Construction of a Bacterial Lipidomics Analytical Platform: Pilot Validation with Bovine Paratuberculosis Serum

Lipidomics analyses of bacteria offer the potential to detect and monitor infections in a host since many bacterial lipids are not present in mammals. To evaluate this omics approach, we first built a database of bacterial lipids for representative Gram-positive and Gram-negative bacteria. Our lipidomics analysis of the reference bacteria involved high-resolution mass spectrometry and electrospray ionization with less than a 1.0 ppm mass error. The lipidomics profiles of bacterial cultures clearly distinguished between Gram-positive and Gram-negative bacteria. In the case of bovine paratuberculosis (PTB) serum, we monitored two unique bacterial lipids that we also monitored in Mycobacterium avian subspecies PTB. These were PDIM-B C82, a phthiodiolone dimycocerosate, and the trehalose monomycolate hTMM 28:1, constituents of the bacterial cell envelope in mycolic-containing bacteria. The next step will be to determine if lipidomics can detect subclinical PTB infections which can last 2-to-4 years in bovine PTB. Our data further suggest that it will be worthwhile to continue building our bacterial lipidomics database and investigate the further utility of this approach in other infections of veterinary and human clinical interest.

Polar lipid characterization and description of Chryseobacterium capnotolerans sp. nov., isolated from high CO2-containing atmosphere and emended descriptions of the genus Chryseobacterium, and the species C. balustinum, C. daecheongense, C. formosense, C. gleum, C. indologenes, C. joostei, C. scophthalmum and C. ureilyticum

Modified atmosphere (MA) packaging plays an important role in improving food quality and safety. By using different gas mixtures and packaging materials the shelf life of fresh produce can significantly be increased. A Gram-negative-staining, rod-shaped, orange-pigmented strain DH-B6T, has been isolated from MA packed raw pork sausage (20% CO2, 80% O2). The strain produced biofilms and showed growth at high CO2 levels of up to 40%. Complete 16S rRNA gene and whole-genome sequences revealed that strain DH-B6T belongs to the genus Chryseobacterium , being closely related to strain Chryseobacterium indologenes DSM 16777T (98.4%), followed by Chryseobacterium gleum NCTC11432T (98.3%) and Chryseobacterium lactis KC1864T (98.2%). Average nucleotide identity value between DH-B6T and C. indologenes DSM 16777T was 81.1% and digital DNA–DNA hybridisation was 24.9%, respectively. The DNA G+C content was 35.51 mol%. Chemotaxonomical analysis revealed the presence of the rare glycine lipid cytolipin, the serine-glycine lipid flavolipin and the sulfonolipid sulfobacin A, as well as phosphatidylethanolamine, monohexosyldiacylglycerol and ornithine lipid, including the hydroxylated forms. Major fatty acids were iC15 : 0 (50.7%) and iC17 : 1 cis 9 (28.7%), followed by iC15 : 0 2-OH (7.0%) and iC17 : 0 3-OH (6.2%). The isolated strain contained MK-6 as the only respiratory quinone and flexirubin-like pigments were detected as the major pigments. Based on the phenotypic, chemotaxonomic and phylogenetic characteristics, the strain DH-B6T (=DSM 110542T=LMG 31915T) represents a novel species of the genus Chryseobacterium , for which the name Chryseobacterium capnotolerans sp. nov. is proposed. Emended descriptions of the genus Chryseobacterium and eight species of this genus based on polar lipid characterisation are also proposed.

Serine/Glycine Lipid Recovery in Lipid Extracts From Healthy and Diseased Dental Samples: Relationship to Chronic Periodontitis

Toll-like receptor 2 (TLR2) activation has been implicated in the pathogenesis of periodontal disease but the identity of the TLR2 agonists has been an evolving story. The serine/glycine lipids produced by Porphyromonas gingivalis are reported to engage human TLR2 and will promote the production of potent pro-inflammatory cytokines. This investigation compared the recovery of serine/glycine lipids in periodontal organisms, teeth, subgingival calculus, subgingival plaque, and gingival tissues, either from healthy sites or periodontally diseased sites. Lipids were extracted using the phospholipid extraction procedure of Bligh and Dyer and were analyzed using liquid chromatography/mass spectrometry for all serine/glycine lipid classes identified to date in P. gingivalis. Two serine/glycine lipid classes, Lipid 567 and Lipid 1256, were the dominant serine/glycine lipids recovered from oral Bacteroidetes bacteria and from subgingival calculus samples or diseased teeth. Lipid 1256 was the most abundant serine/glycine lipid class in lipid extracts from P. gingivalis, Tannerella forsythia, and Prevotella intermedia whereas Lipid 567 was the most abundant serine/glycine lipid class recovered in Capnocytophaga species and Porphyromonas endodontalis. Serine/glycine lipids were not detected in lipid extracts from Treponema denticola, Aggregatibacter actinomycetemcomitans, or Fusobacterium nucleatum. Lipid 1256 was detected more frequently and at a significantly higher mean level in periodontitis tissue samples compared with healthy/gingivitis tissue samples. By contrast, Lipid 567 levels were essentially identical. This report shows that members of the Bacteroidetes phylum common to periodontal disease sites produce Lipid 567 and Lipid 1256, and these lipids are prevalent in lipid extracts from subgingival calculus and from periodontally diseased teeth and diseased gingival tissues.

Novel Glycerophospholipid, Lipo- and N-acyl Amino Acids from Bacteroidetes: Isolation, Structure Elucidation and Bioactivity

The 'core' metabolome of the Bacteroidetes genus Chitinophaga was recently discovered to consist of only seven metabolites. A structural relationship in terms of shared lipid moieties among four of them was postulated. Here, structure elucidation and characterization via ultra-high resolution mass spectrometry (UHR-MS) and nuclear magnetic resonance (NMR) spectroscopy of those four lipids (two lipoamino acids (LAAs), two lysophosphatidylethanolamines (LPEs)), as well as several other undescribed LAAs and N-acyl amino acids (NAAAs), identified during isolation were carried out. The LAAs represent closely related analogs of the literature-known LAAs, such as the glycine-serine dipeptide lipids 430 (2) and 654. Most of the here characterized LAAs (1, 5-11) are members of a so far undescribed glycine-serine-ornithine tripeptide lipid family. Moreover, this study reports three novel NAAAs (N-(5-methyl)hexanoyl tyrosine (14) and N-(7-methyl)octanoyl tyrosine (15) or phenylalanine (16)) from Olivibacter sp. FHG000416, another Bacteroidetes strain initially selected as best in-house producer for isolation of lipid 430. Antimicrobial profiling revealed most isolated LAAs (1-3) and the two LPE 'core' metabolites (12, 13) active against the Gram-negative pathogen M. catarrhalis ATCC 25238 and the Gram-positive bacterium M. luteus DSM 20030. For LAA 1, additional growth inhibition activity against B. subtilis DSM 10 was observed.

Identification of the Flavobacterium johnsoniae cysteate-fatty acyl transferase required for capnine synthesis and for efficient gliding motility

Sulfonolipids (SLs) are bacterial lipids that are structurally related to sphingolipids. Synthesis of this group of lipids seems to be mainly restricted to Flavobacterium, Cytophaga and other members of the phylum Bacteroidetes. These lipids have a wide range of biological activities: they can induce multicellularity in choanoflagellates, act as von Willebrand factor receptor antagonists, inhibit DNA polymerase, or function as tumour suppressing agents. In Flavobacterium johnsoniae, their presence seems to be required for efficient gliding motility. Until now, no genes/enzymes involved in SL synthesis have been identified, which has been limiting for the study of some of the biological effects these lipids have. Here, we describe the identification of the cysteate-fatty acyl transferase Fjoh_2419 required for synthesis of the SL precursor capnine in F. johnsoniae. This enzyme belongs to the α-oxoamine synthase family similar to serine palmitoyl transferases, 2-amino-3-oxobutyrate coenzyme A ligase and 8-amino-7-oxononanoate synthases. Expression of the gene fjoh_2419 in Escherichia coli caused the formation of a capnine-derived molecule. Flavobacterium johnsoniae mutants deficient in fjoh_2419 lacked SLs and were more sensitive to many antibiotics. Mutant growth was not affected in liquid medium but the cells exhibited defects in gliding motility.

Glycine Lipids of Porphyromonas gingivalis Are Agonists for Toll-Like Receptor 2

The serine-glycine dipeptide lipid classes, including lipid 430 and lipid 654, are produced by the periodontal pathogen Porphyromonas gingivalis and can be detected in lipid extracts of diseased periodontal tissues and teeth of humans. Both serine-glycine lipid classes were previously shown to engage human and mouse Toll-like receptor 2 (TLR2) and to inhibit mouse osteoblast differentiation and function through engagement of TLR2. It is not clear if other lipids related to serine-glycine lipids are also produced by P. gingivalis The goal of this investigation was to determine whether P. gingivalis produces additional lipid classes similar to the serine-glycine lipids that possess biological properties. P. gingivalis (ATCC 33277) was grown in broth culture, and lipids were extracted and fractionated by high-performance liquid chromatography (HPLC). Lipids were separated using semipreparative HPLC, and specific lipid classes were identified using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and liquid chromatography-multiple reaction monitoring (LC-MRM) mass spectrometric approaches. Two glycine lipid classes were identified, termed lipid 567 and lipid 342, and these lipid classes are structurally related to the serine-glycine dipeptide lipids. Both glycine lipid classes were shown to promote TLR2-dependent tumor necrosis factor alpha (TNF-α) release from bone marrow macrophages, and both were shown to activate human embryonic kidney (HEK) cells through TLR2 and TLR6 but not TLR1. These results demonstrate that P. gingivalis synthesizes glycine lipids and that these lipids engage TLR2 similarly to the previously reported serine-glycine dipeptide lipids.

The Glycine Lipids of Bacteroides thetaiotaomicron Are Important for Fitness during Growth In Vivo and In Vitro

Acylated amino acids function as important components of the cellular membrane in some bacteria. Biosynthesis is initiated by the N-acylation of the amino acid, and this is followed by subsequent O-acylation of the acylated molecule, resulting in the production of the mature diacylated amino acid lipid. In this study, we use both genetics and liquid chromatography-mass spectrometry (LC-MS) to characterize the biosynthesis and function of a diacylated glycine lipid (GL) species produced in Bacteroides thetaiotaomicron We, and others, have previously reported the identification of a gene, named glsB in this study, that encodes an N-acyltransferase activity responsible for the production of a monoacylated glycine called N-acyl-3-hydroxy-palmitoyl glycine (or commendamide). In all of the Bacteroidales genomes sequenced so far, the glsB gene is located immediately downstream from a gene, named glsA, that is also predicted to encode a protein with acyltransferase activity. We use LC-MS to show that the coexpression of glsB and glsA results in the production of GL in Escherichia coli We constructed a deletion mutant of the glsB gene in B. thetaiotaomicron, and we confirm that glsB is required for the production of GL in B. thetaiotaomicron Moreover, we show that glsB is important for the ability of B. thetaiotaomicron to adapt to stress and colonize the mammalian gut. Therefore, this report describes the genetic requirements for the biosynthesis of GL, a diacylated amino acid species that contributes to fitness in the human gut bacterium B. thetaiotaomicronIMPORTANCE The gut microbiome has an important role in both health and disease of the host. The mammalian gut microbiome is often dominated by bacteria from the Bacteroidales, an order that includes Bacteroides and Prevotella In this study, we have identified an acylated amino acid, called glycine lipid, produced by Bacteroides thetaiotaomicron, a beneficial bacterium originally isolated from the human gut. In addition to identifying the genes required for the production of glycine lipids, we show that glycine lipids have an important role during the adaptation of B. thetaiotaomicron to a number of environmental stresses, including exposure to either bile or air. We also show that glycine lipids are important for the normal colonization of the murine gut by B. thetaiotaomicron This work identifies glycine lipids as an important fitness determinant in B. thetaiotaomicron and therefore increases our understanding of the molecular mechanisms underpinning colonization of the mammalian gut by beneficial bacteria.

Linear Aminolipids with Moderate Antimicrobial Activity from the Antarctic Gram-Negative Bacterium Aequorivita sp

The combination of LC-MS/MS based metabolomics approach and anti-MRSA activity-guided fractionation scheme was applied on the Gram-negative bacterium Aequorivita sp. isolated from shallow Antarctic sea sediment using a miniaturized culture chip technique. This methodology afforded the isolation of three new (1⁻3) and four known (4⁻7) N-terminal glycine- or serine-bearing iso-fatty acid amides esterified with another iso-fatty acid through their C-3 hydroxy groups. The chemical structures of the new compounds were elucidated using a set of spectroscopic (NMR, [α]_D and FT-IR) and spectrometric (HRMS, HRMS/MS) methods. The aminolipids possessing an N-terminal glycine unit (1, 2, 4, 5) showed moderate in vitro antimicrobial activity against MRSA (IC₅₀ values 22⁻145 μg/mL). This is the first in-depth chemistry and biological activity study performed on the microbial genus Aequorivita.

Synthesis of N-acyl derivatives of Pro-Gly-Pro-Leu peptide: Proteolytic stability in vitro and effects on mouse macrophage cells RAW264.7

Acetyl, oleoyl, arachidonoyl, and docosahexaenoyl derivatives of the Pro-Gly-Pro-Leu peptide with a chemical purity of 99.8% were synthesized. The degradation kinetics of the Pro-Gly-Pro-Leu derivatives under the action of leucine aminopeptidase, nasal mucus, and microsomal fraction of the brain and blood of rats was studied. It was shown that the N-acyl derivatives of Pro-Gly-Pro-Leu proved to be more resistant to the action of leucine aminopeptidase and other enzyme systems. The study of the cytotoxic and anti-inflammatory activity of preparations on the mouse macrophage cell line RAW264.7 showed that acylation with oleic and arachidonic acid makes the peptide cytotoxic with LC50 in the range of 70-15 μM and gives it anti-inflammatory properties with EC50 of 32 and 36 μM, respectively.

Molecular basis for lipopolysaccharide mimetic action of Taxol™ and flavolipin

We previously reported that Taxol™, which mimics the action of LPS on murine macrophages, induces signals via mouse TLR4/MD-2, but not via human TLR4/MD-2. Here we investigated the molecular basis for this species-specific action of Taxol™. Expression of mouse MD-2 conferred both LPS and Taxol™ responsiveness on HEK293 cells expressing mouse TLR4, whereas expression of human MD-2 conferred LPS responsiveness alone, suggesting that MD-2 is responsible for the species-specificity of Taxol™ responsiveness. Furthermore, mouse MD-2 mutants, in which Gln-22 was changed to other amino acids, showed dramatically reduced ability to confer Taxol™ responsiveness, although their ability to confer LPS responsiveness was not affected. These results indicated that Gln-22 of mouse MD-2 is essential for Taxol™ signaling, but not for LPS signaling. In this study, we also found that the TLR4/MD-2 complex, together with CD14, mediated signal transduction induced by flavolipin, an amino acid-containing lipid unique to Flavobacterium meningosepticum.

Elucidation and identification of amino acid containing membrane lipids using liquid chromatography/high-resolution mass spectrometry

RATIONALE

Intact polar lipids (IPLs) are the building blocks of cell membranes, and amino acid containing IPLs have been observed to be involved in response to changing environmental conditions in various species of bacteria. High-performance liquid chromatography/mass spectrometry (HPLC/MS) has become the primary method for analysis of IPLs. Many glycerol-free amino acid containing membrane lipids (AA-IPLs), which are structurally different than abundant aminophospholipids, have not been characterized using HPLC/MS. This results in many lipids remaining unrecognized in IPL analysis of microbial cultures and environmental samples, hampering the study of their occurrence and functionality.

METHODS

We analyzed the amino acid containing IPLs of a number of bacteria (i.e. Gluconobacter cerinus, Cyclobacterium marinus, Rhodobacter sphaeroides, and Pedobacter heparinus) in order to decipher fragmentation pathways, and explore potential novel lipid structures using HPLC/electrospray ionization ion trap MS (HPLC/ESI-IT-MS) and HPLC/high-resolution MS (HPLC/HRMS).

RESULTS

We report differentiation between glutamine and lysine lipids with the same nominal masses, novel MS fragmentation pathways of cytolipin, the lipopeptides cerilipin and flavolipin, head group hydroxylated ornithine lipids, and the novel identification of cerilipin with a hydroxylated fatty acid.

CONCLUSIONS

Non-glycerol AA lipids can be readily recognized as their fragmentation follows a clear pattern with initial dehydration or other loss from the head group, followed by fatty acid losses resulting in a diagnostic fragment ion. Higher level MSn and HRMS are valuable tools in characterizing AA lipid head group structural components.

Lysine and novel hydroxylysine lipids in soil bacteria: amino acid membrane lipid response to temperature and pH in Pseudopedobacter saltans

Microbial decomposition of organic matter is an essential process in the global carbon cycle. The soil bacteria Pseudopedobacter saltans and Flavobacterium johnsoniae are both able to degrade complex organic molecules, but it is not fully known how their membrane structures are adapted to their environmental niche. The membrane lipids of these species were extracted and analyzed using high performance liquid chromatography-electrospray ionization/ion trap/mass spectrometry (HPLC-ESI/IT/MS) and high resolution accurate mass/mass spectrometry (HRAM/MS). Abundant unknown intact polar lipids (IPLs) from P. saltans were isolated and further characterized using amino acid analysis and two dimensional nuclear magnetic resonance (NMR) spectroscopy. Ornithine IPLs (OLs) with variable (hydroxy) fatty acid composition were observed in both bacterial species. Lysine-containing IPLs (LLs) were also detected in both species and were characterized here for the first time using HPLC-MS. Novel LLs containing hydroxy fatty acids and novel hydroxylysine lipids with variable (hydroxy) fatty acid composition were identified in P. saltans. The confirmation of OL and LL formation in F. johnsoniae and P. saltans and the presence of OlsF putative homologs in P. saltans suggest the OlsF gene coding protein is possibly involved in OL and LL biosynthesis in both species, however, potential pathways of OL and LL hydroxylation in P. saltans are still undetermined. Triplicate cultures of P. saltans were grown at three temperature/pH combinations: 30°C/pH 7, 15°C/pH 7, and 15°C/pH 9. The fractional abundance of total amino acid containing IPLs containing hydroxylated fatty acids was significantly higher at higher temperature, and the fractional abundance of lysine-containing IPLs was significantly higher at lower temperature and higher pH. These results suggest that these amino acid-containing IPLs, including the novel hydroxylysine lipids, could be involved in temperature and pH stress response of soil bacteria.

Novel mono-, di-, and trimethylornithine membrane lipids in northern wetland planctomycetes

Northern peatlands represent a significant global carbon store and commonly originate from Sphagnum moss-dominated wetlands. These ombrotrophic ecosystems are rain fed, resulting in nutrient-poor, acidic conditions. Members of the bacterial phylum Planctomycetes are highly abundant and appear to play an important role in the decomposition of Sphagnum-derived litter in these ecosystems. High-performance liquid chromatography coupled to high-resolution accurate-mass mass spectrometry (HPLC-HRAM/MS) analysis of lipid extracts of four isolated planctomycetes from wetlands of European north Russia revealed novel ornithine membrane lipids (OLs) that are mono-, di-, and trimethylated at the ε-nitrogen position of the ornithine head group. Nuclear magnetic resonance (NMR) analysis of the isolated trimethylornithine lipid confirmed the structural identification. Similar fatty acid distributions between mono-, di-, and trimethylornithine lipids suggest that the three lipid classes are biosynthetically linked, as in the sequential methylation of the terminal nitrogen in phosphatidylethanolamine to produce phosphatidylcholine. The mono-, di-, and trimethylornithine lipids described here represent the first report of methylation of the ornithine head groups in biological membranes. Various bacteria are known to produce OLs under phosphorus limitation or fatty-acid-hydroxylated OLs under thermal or acid stress. The sequential methylation of OLs, leading to a charged choline-like moiety in the trimethylornithine lipid head group, may be an adaptation to provide membrane stability under acidic conditions without the use of scarce phosphate in nutrient-poor ombrotrophic wetlands.

Ornithine lipids and their structural modifications: from A to E and beyond

Ornithine lipids (OLs) are phosphorus-free membrane lipids that are widespread in eubacteria, but absent from archaea and eukaryotes. They contain a 3-hydroxy fatty acyl group attached in amide linkage to the α-amino group of the amino acid ornithine. A second fatty acyl group is ester-linked to the 3-hydroxy position of the first fatty acid. About 25% of the bacterial species whose genomes have been sequenced are predicted to have the capacity to form OLs. Distinct OL hydroxylations have been described in the ester-linked fatty acid, the amide-linked fatty acid, and the ornithine moiety. These modifications often seem to form part of a bacterial stress response to changing environmental conditions, allowing the bacteria to adjust membrane properties by simply modifying already existing membrane lipids without the need to synthesize new lipids.

Ekhidna lutea gen. nov., sp. nov., a member of the phylum Bacteroidetes isolated from the South East Pacific Ocean

A novel aerobic, heterotrophic bacterium, designated BiosLi39(T), was isolated from the South East Pacific Ocean. Cells were Gram-negative gliding rods forming yellow colonies on marine agar. The isolate was oxidase-, catalase- and alkaline phosphatase-positive and β-galactosidase-negative. Strain BiosLi39(T) grew at 20-37°C (optimum 30°C), at pH7.0-9.0 (optimum pH8.0) and with 20-60 g NaCl l(-1) (optimum 30-50 g NaCl l(-1)). The fatty acids (>1 %) comprised iso-C(14 : 0), iso-C(15 : 1) G, iso-C(15 : 0), anteiso-C(15 : 0), C(15 : 1) G, C(15 : 0), iso-C(15 : 0) 2-OH, iso-C(16 : 1) G, iso-C(16 : 0), iso-C(16 : 0) 3-OH, iso-C(16 : 0) 2-OH, iso-C(17 : 0) 3-OH, C(17 : 0) 2-OH and three unidentified components with equivalent chain lengths of 17.87, 18.10 and 18.71. A significant proportion of the hydroxylated fatty acids are amide-linked. The lipid pattern indicated the presence of phosphatidylethanolamine, two unidentified aminolipids and three unidentified polar lipids. The strain contained menaquinone 7 as the sole respiratory lipoquinone and did not produce flexirubin-type pigments. The G+C content of the genomic DNA was 37.2 mol%. Comparative 16S rRNA gene sequence analysis indicated that strain BiosLi39(T) was distantly related to all of the representatives of the phylum Bacteroidetes. Its closest relative was Marinoscillum furvescens IFO 15994(T), with which it shared 92.5 % 16S rRNA gene sequence similarity. On the basis of genotypic, phenotypic and chemotaxonomic characteristics, we propose a novel genus and species, Ekhidna gen. nov., sp. nov., with type strain BiosLi39(T) (=DSM 19307(T) =CIP 109600(T) =OOB 398(T)).

The elmiric acids: biologically active anandamide analogs

As chemical entities, lipoamino acids have been known for some time. However, more recently their occurrence and importance in mammalian species has been discovered. They appear to have close relationships with the endocannabinoids not only structurally but also in terms of biological actions. The latter include analgesia, anti-inflammatory effects, inhibition of cell proliferation and calcium ion mobilization. To date about 40 naturally occurring members of this family have been identified and, additionally, several synthetic analogs have been prepared and studied. To facilitate their identity, a nomenclature system has been suggested based on the name elmiric acid (EMA). The prototypic example, N-arachidonoyl glycine, does not bind to CB1, however it does inhibit the glycine transporter GLYT2a and also appears to be a ligand for the orphan G-protein-coupled receptor GPR18. It may also have a role in regulating tissue levels of anandamide by virtue of its inhibitory effect on FAAH the enzyme that mediates inactivation of anandamide. Its concentration in rat brain is several-fold higher than anandamide supporting its possible role as a physiological mediator. Future studies should be aimed at elucidating the actions of all of the members of this interesting family of molecules.

Potential anti-inflammatory actions of the elmiric (lipoamino) acids

A library of amino acid-fatty acid conjugates (elmiric acids) was synthesized and evaluated for activity as potential anti-inflammatory agents. The compounds were tested in vitro for their effects on cell proliferation and prostaglandin production, and compared with their effects on in vivo models of inflammation. LPS stimulated RAW 267.4 mouse macrophage cells were the in vitro model and phorbol ester-induced mouse ear edema served as the principal in vivo model. The prostaglandin responses were found to be strongly dependent on the nature of the fatty acid part of the molecule. Polyunsaturated acid conjugates produced a marked increase in media levels of i15-deoxy-PGJ(2) with minimal effects on PGE production. It is reported in the literature that prostaglandin ratios in which the J series predominates over the E series promote the resolution of inflammatory conditions. Several of the elmiric acids tested here produced such favorable ratios suggesting that their potential anti-inflammatory activity occurs via a novel mechanism of action. The ear edema assay results were generally in agreement with the prostaglandin assay findings indicating a connection between them.

[Arachidonoyl amino acids and arachidonoyl peptides: synthesis and properties]

N-Arachidonoyl (AA) derivatives of amino acids (glycine, phenylalanine, proline, valine, gamma-amino butyric acid (GABA), dihydroxyphenylalanine, tyrosine, tryptophan, and alanine) and peptides (Semax, MEHFPGP, and PGP) were synthesized in order to study the biological properties of acylamino acids. The mass spectra of all the compounds at atmospheric pressure electrospray ionization display the most intense peaks of protonated molecular ions; the detection limits for these compounds are 10 fmol per sample. AA-Gly showed the highest inhibitory activity toward fatty acid amide hydrolase from rat brain (IC50 6.5 microM) among all the acylamino acids studied. AA-Phe, AA-Tyr, and AA-GABA exhibited a weak but detectable inhibitory effect (IC50 55, 60, and 50 microM, respectively). The acylated amino acids themselves, except for AA-Gly, were stable to the hydrolysis by this enzyme. All the arachidonoylamino acids inhibited cabbage phospholipase D to various degrees; AA-GABA and AA-Phe proved to be the most active (IC50 20 and 27 microM, respectively). Attempts to detect the biosynthesis of AA-Tyr in homogenates of rat liver and nerve tissue showed no formation in vitro of either this acylamino acid or AA-dopamine and AA-Phe, the products of its metabolism. The highest contents of these metabolites were detected in liver homogenate and in the brain homogenate, respectively. Acylamino acids exert no cytotoxic effect toward the glioma C6 cells. It was shown that N-acylation of Semax with arachidonic acid results in enhancement of its hydrolytic stability and increases its affinity for the sites of specific binding in rat cerebellum membranes. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2006, vol. 32, no. 3; see also http://www.maik.ru.

Petrimonas sulfuriphila gen. nov., sp. nov., a mesophilic fermentative bacterium isolated from a biodegraded oil reservoir

A mesophilic, anaerobic, fermentative bacterium, strain BN3(T), was isolated from a producing well of a biodegraded oil reservoir in Canada. Cells were Gram-negative, non-motile rods that did not form spores. The temperature range for growth was 15-40 degrees C, with optimum growth at 37-40 degrees C. The strain grew with up 4 % NaCl, with optimum growth in the absence of NaCl. Tryptone was required for growth. Yeast extract and elemental sulfur stimulated growth. Growth was also enhanced during fermentation of glucose, arabinose, galactose, maltose, mannose, rhamnose, lactose, ribose, fructose, sucrose, cellobiose, lactate, mannitol and glycerol. Acetate, hydrogen and CO(2) were produced during glucose fermentation. Elemental sulfur and nitrate were used as electron acceptors and were reduced to sulfide and ammonium, respectively. The G + C content of the genomic DNA was 40.8 mol%. Phylogenetic analyses of the 16S rRNA gene sequence indicated that the strain was a member of the phylum 'Bacteroidetes', distantly related to the genera Bacteroides and Tannerella (similarity values of less than 90 %). The chemotaxonomic data (fatty acids, polar lipids and quinones composition) also indicated that strain BN3(T) could be clearly distinguished from its closest cultivated relatives. This novel organism possesses phenotypic, chemotaxonomic and phylogenetic traits that do not allow its classification as a member of any previously described genus; therefore, it is proposed that this isolate should be described as a member of a novel species of a new genus, Petrimonas gen. nov., of which Petrimonas sulfuriphila sp. nov. is the type species. The type strain is BN3(T) (= DSM 16547(T) = JCM 12565(T)).

Identification of N-arachidonylglycine, U18666A, and 4-androstene-3,17-dione as novel insulin Secretagogues

The glucose-induced insulin secretion is fine-tuned by numerous factors. To systematically identify insulinotropic factors, we optimized a primary beta-cell-based functional assay to monitor intracellular Ca2+ flux ([Ca2+]i). By this assay system, we successfully identified several insulinotropic peptides including cholecystokinin, gastrin releasing peptide, vasopressin, and oxytocin from tissue extracts. Screening of an assortment of chemical compounds, we determined three novel insulin secretagogues: N-arachidonylglycine (NAGly), 3beta-(2-diethylamino-ethoxy) androstenone hydrochloride (U18666A), and 4-androstene-3,17-dione. The NAGly increased [Ca2+]i through stimulation of the voltage-dependent Ca2+ channels and it was dependent on extracellular glucose level. On the other hand, U18666A and 4-androstene-3,17-dione increased [Ca2+]i in the presence of K ATP channel opener diazoxide while it was inhibited by the presence of Ca2+ channel blocker nitrendipine, suggesting that their effects are independent of K ATP channel. These unique features will be useful for further development of insulinotropic factors and drugs for treating type 2 diabetes.

Toll-like receptor 4-MD-2 complex mediates the signal transduction induced by flavolipin, an amino acid-containing lipid unique to Flavobacterium meningosepticum

Flavolipin, an amino acid-containing lipid isolated from Flavobacterium meningosepticum, induces many immune responses. It has been shown that flavolipin does not induce an immune response of macrophages derived from C3H/HeJ mice, which possess a point mutation in Toll-like receptor 4 (TLR4). To determine whether TLR4 or the molecular complex of TLR4 and TLR4 association molecule MD-2 mediates the flavolipin signal, flavolipin responsiveness was examined by measuring NF-kappaB activation in Ba/F3 cells and Ba/F3 transfectants expressing TLR4 or both TLR4 and MD-2. Flavolipin-induced NF-kappaB activation was detected in the cells expressing both TLR4 and MD-2, but not in the other cells. Expression of CD14 in the transfectant expressing both TLR4 and MD-2 increased the sensitivity to flavolipin. Furthermore, flavolipin stereoisomers were chemically synthesized, and their abilities to induce NF-kappaB activation were examined. (R)-Flavolipin, in which the configuration of the lipid moiety is R, induced NF-kappaB activation via the TLR4-MD-2 complex, but (S)-flavolipin did not. In this study, we demonstrated the involvement of TLR4-MD-2 and CD14 in flavolipin signaling and the importance of the (R)-configuration of the flavolipin lipid moiety for the induction of an immune response via TLR4-MD-2.

Identification of a new class of molecules, the arachidonyl amino acids, and characterization of one member that inhibits pain

In mammals, specific lipids and amino acids serve as crucial signaling molecules. In bacteria, conjugates of lipids and amino acids (referred to as lipoamino acids) have been identified and found to possess biological activity. Here, we report that mammals also produce lipoamino acids, specifically the arachidonyl amino acids. We show that the conjugate of arachidonic acid and glycine (N-arachidonylglycine (NAGly)) is present in bovine and rat brain as well as other tissues and that it suppresses tonic inflammatory pain. The biosynthesis of NAGly and its degradation by the enzyme fatty acid amide hydrolase can be observed in rat brain tissue. In addition to NAGly, bovine brain produces at least two other arachidonyl amino acids: N-arachidonyl gamma-aminobutyric acid (NAGABA) and N-arachidonylalanine. Like NAGly, NAGABA inhibits pain. These findings open the door to the identification of other members of this new class of biomolecules, which may be integral to pain regulation and a variety of functions in mammals.

The polar-lipid composition of the sphingolipid-producing bacterium Flectobacillus major

Polar lipids comprise about 90% of the total chloroform-methanol extractable lipids of the Gram-negative, fresh-water, ring-forming bacterium Flectobacillus major FM and consist of at least 10 constituents. These are aminophosphosphingolipids, 2-N-(2'-D-hydroxy-13'-methyltetradecanoyl)-15-methyl-4(E)-hexad ecasph ingenyl-1-phosphoethanolamine (36.8% of the total polar lipids) and its 2'-deoxy derivative (3.7%); sulfonic-acid analogues of ceramide, 2-D-(2'-D-hydroxy-13'-methyltetradecanoyl)amino-3-D-hydroxy-15-met hyl hexadecane-1-sulfonic acid (18.1%) and its 2'-deoxy derivative (3. 5%); a lipoamino acid, N-[3-D-(15'-methylhexadecanoyloxy)-15-methylhexadecanoyl]-gl ycine (3. 7%); a lipodipeptide, N-¿N'-[3"-D-(15"'-methylhexadecanoyloxy)-15"-methylhexadecanoyl ]glycy l¿-L-serine (7.8%); 1,2-diacyl-sn-glycero-3-phosphoethanolamine (7. 7%), 1,2-diacyl-3-alpha-D-galactopyranosyl-sn-glycerol (2.9%); ceramide phospho-myo-inositol (4.9%), and a previously described unusual glycosphingolipid, 7-deoxy-7-amino-D-manno-heptulosonopyranosyl (1-hydroxycarbonyl-6-deoxy-6-amino-alpha-D-mannopyranosyl) ceramide (10.9%); the last two lipids contain only 15-methyl-4(E)-hexadecasphingenine as a long-chain base. The sole structural type of amide-bound fatty acids in the sphingolipids, including the sulfonic-acid analogues, is iso-15:0, either non-hydroxylated or hydroxylated at 2-C, whereas 15-methylhexadecanoic acid is the major ester-bound fatty acid in the remaining lipids.

Phospholipid analogue distribution in Capnocytophaga

Polar lipids of nineteen previously characterised culture collection strains of Capnocytophaga were analysed using fast atom bombardment mass spectrometry (FAB MS) in negative mode. All strains examined had a major peak at m/z 241, consistent with the expected presence of the pentadecanoate anion. The most intense higher mass anions, consistent with expected presence of phospholipid molecular species, were as follows: m/z 574, 588, 618 and 662 which are consistent with presence of PE(24:2), PE(25:2), PE(27:1) and PE(30:0) respectively. Other anions putatively identified as phospholipid anions were: m/z 572, 578, 592, 602, 604, 616 and 720 consistent with presence of PE(24:3), PE(24:0), PE(25:0), PE(26:2), PE(26:1), PE(27:2) and OH-PE(33:0). Capnocytophaga isolates share a distinctive phospholipid fingerprint which appears to lack the somewhat higher mass phospholipid analogues observed in related oral bacteria. Within the genus, the profiles obtained showed only quantitative differences which did not correlate with previous studies.

Novel glycine containing glucolipids from the alkane using bacterium Alcanivorax borkumensis

The polar lipids from the hydrocarbon using and biosurfactant-producing bacterium Alcanivorax borkumensis were isolated and identified by mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy. The biosurfactant produced by this species is an anionic glucose lipid with a tetrameric oxyacyl side chain. The glycolipids extracted from the cell wall consist of this biosurfactant N-terminally esterified with glycine. Ten different derivatives of this lipid type were identified and their structures elucidated by MSMS. They vary by the chain length of one or two of the four beta-hydroxy fatty acids (C6, C8 and C10) and by the location of these different fatty acids within the molecule. All compounds are reported here for the first time. In addition to these glycolipids, three different phosphatidylglycerols were identified. While these lipids were found in all strains of A. borkumensis, the relative abundances of the different lipids vary between the strains.

A novel sulfonic-acid analogue of ceramide is the major extractable lipid of the gram-negative marine bacterium Cyclobacterium marinus WH

The extractable lipids of the gram-negative, sea-water bacterium Cyclobacterium marinus strain WH contain about 94% of polar components which consist of two phospholipids, phosphatidylethanolamine (29% of the total lipids) and phosphatidylcholine (7%), and two phosphorus-free lipids. One of the latter has been shown to be a novel sulfonic-acid analogue of ceramide, 2-D-(2'-D-hydroxy-13'-methyltetradecanoyl) amino-3-D-hydroxy-15-methylhexadec-4 (E)-en-1-sulfonic acid (48%), and other is a lipodipeptide, N-[3-d-(13'-methyltetradecanoyloxy)-15-methylhexadecanoyl] glycyl-L-serine (11%), which has so far been found only in a Flavobacterium sp. strain. The dominant fatty acid residues of the phospholipids are iso-15:0, n-16:0, 16:1 and 18:1, the acyl residues linked to the sn-1 carbon of the glycerol moiety being somewhat more saturated as compared with those located at the sn-2 position. A new procedure for determination of the absolute configuration of 2- and 3-hydroxy fatty acids is briefly described.

N-acyl amino acid biosynthesis in marine bacterium, Deleya marina

We reported previously that the marine bacterium, Deleya marina (ATCC 25374), produced N-acyl leucine and isoleucine, in which nonhydroxy fatty acid was linked to alpha-amino group of amino acid. Further analysis of bacterium lipids revealed the additional production of N-acyl ornithine. The N-acyl ornithine had a 3-hydroxy fatty acid linked by an amide bond to a-amino group of ornithine and a nonhydroxy fatty acid esterified to the hydroxy group of the 3-hydroxy fatty acid. N-acyl ornithine was located in the cell membrane and N-acyl leucine and isoleucine in cytoplasm. N-acyl ornithine is thought to be a functional analogue of phosphatidylethanolamine (PE) because of their similar structure. PE replacement into N-acyl ornithine in the cell membrane under phosphate-limited conditions was observed with other bacteria, so we anticipated the nonbiosynthesis of N-acyl ornithine under phosphate-sufficient conditions. We did not anticipate that N-acyl leucine and isoleucine in cytoplasm, whose structure is dissimilar to that of PE, would be replaced into PE in the cell membrane. Neither N-acyl leucine, N-acyl isoleucine, nor N-acyl ornithine was biosynthesized under phosphate-sufficient condition. Thus, we report here for the first time that N-acyl amino acids in cytoplasm were not biosynthesized under phosphate-sufficient conditions.

Hypothermic response of mice to ornithine-containing lipids and to endotoxin

The hypothermic response of mice to ornithine-containing lipids (Orn-Ls) of the form alpha-N-(3-acyloxyacyl)-ornithine and to endotoxin (Escherichia coli 0111:B4 lipopolysaccharide [LPS]) was studied. After the administration of Orn-L or LPS to C3H/HeSlc mice, body temperature decreases were determined at 30-min intervals by inserting a thermistor into the rectum of each mouse. When Orn-L (750 microg) or LPS (70 microg) was injected into the mice, body temperature decreases of 0.8 and 2.0 degrees C, respectively, occurred 1.8 to 2.0 h later. These body temperature decreases were completely suppressed by the preadministration of indomethacin. When anti-tumor necrosis factor alpha (TNF-alpha) antibody was administered before the administration of Orn-L or LPS, only the body temperature decrease by LPS was suppressed. The body temperature decrease by Orn-L was suppressed by anti-interleukin-1beta (IL-1beta) antibody preadministration. Next, in order to study IL-1beta and TNF-alpha mRNA expression in macrophages, peritoneal macrophages were collected 40 min after the administration of Orn-L or LPS to mice. The expression of IL-1beta mRNA by stimulation with Orn-L was as strong as that by stimulation with LPS, but the expression of TNF-alpha mRNA by stimulation with Orn-L was very weak. Our previous studies of in vitro macrophage activation by Orn-L proved that strong induction of IL-1 and prostaglandin E2 generation by Orn-L occurred (Y. Kawai and K. Akagawa, Infect. Immun. 57:2086-2091, 1989). From these experiments, the weak body temperature decrease in mice caused by Orn-L was found to be mediated by cytokines different from those which mediate the strong body temperature decrease caused by LPS. Namely, it was caused by prostaglandin E2 being mediated by IL-1 but not by TNF-alpha.