Glycoglycerolipids

Lipid Classes, Fatty Acid Composition, and Glycerolipid Molecular Species of the Red Alga Gracilaria vermiculophylla, a Prostaglandin-Producing Seaweed

The red alga Gracilaria vermiculophylla is a well-known producer of prostaglandins, such as PGE2 and PGF2α. In this study, the characteristics of glycerolipids as substrates of prostaglandin production were clarified, and the lipid classes, fatty acid composition, and glycerolipid molecular species were investigated in detail. The major lipid classes were monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), and sulfoquinovosyldiacylglycerol (SQDG), as well as phosphatidylcholine (PC), which accounted for 43.0% of the total lipid profile. Arachidonic acid (20:4n-6), a prostaglandin precursor, and palmitic acid (16:0) were the predominant fatty acids in the total lipid profile. The 20:4n-6 content was significantly high in MGDG and PC (more than 60%), and the 16:0 content was significantly high in DGDG and SQDG (more than 50%). Chiral-phase high-performance liquid chromatography determined that fatty acids were esterified at the sn-1 and sn-2 positions of those lipids. The main glycerolipid molecular species were 20:4n-6/20:4n-6 (sn-1/sn-2) for MGDG (56.5%) and PC (40.0%), and 20:4n-6/16:0 for DGDG (75.4%) and SQDG (58.4%). Thus, it was considered that the glycerolipid molecular species containing one or two 20:4n-6 were the major substrates for prostaglandin production in G. vermiculophylla.

Molecular and lipid biomarker analysis of a gypsum-hosted endoevaporitic microbial community

Modern evaporitic microbial ecosystems are important analogs for understanding the record of earliest life on Earth. Although mineral-depositing shallow-marine environments were prevalent during the Precambrian, few such environments are now available today for study. We investigated the molecular and lipid biomarker composition of an endoevaporitic gypsarenite microbial mat community in Guerrero Negro, Mexico. The 16S ribosomal RNA gene-based phylogenetic analyses of this mat corroborate prior observations indicating that characteristic layered microbial communities colonize gypsum deposits world-wide despite considerable textural and morphological variability. Membrane fatty acid analysis of the surface tan/orange and lower green mat crust layers indicated cell densities of 1.6 × 10(9) and 4.2 × 10(9)  cells cm(-3) , respectively. Several biomarker fatty acids, ∆7,10-hexadecadienoic, iso-heptadecenoic, 10-methylhexadecanoic, and a ∆12-methyloctadecenoic, correlated well with distributions of Euhalothece, Stenotrophomonas, Desulfohalobium, and Rhodobacterales, respectively, revealed by the phylogenetic analyses. Chlorophyll (Chl) a and cyanobacterial phylotypes were present at all depths in the mat. Bacteriochlorophyl (Bchl) a and Bchl c were first detected in the oxic-anoxic transition zone and increased with depth. A series of monomethylalkanes (MMA), 8-methylhexadecane, 8-methylheptadecane, and 9-methyloctadecane were present in the surface crust but increased in abundance in the lower anoxic layers. The MMA structures are similar to those identified previously in cultures of the marine Chloroflexus-like organism 'Candidatus Chlorothrix halophila' gen. nov., sp. nov., and may represent the Bchl c community. Novel 3-methylhopanoids were identified in cultures of marine purple non-sulfur bacteria and serve as a probable biomarker for this group in the lower anoxic purple and olive-black layers. Together microbial culture and environmental analyses support novel sources for lipid biomarkers in gypsum crust mats.

Synthesis and thermotropic phase behavior of four glycoglycerolipids

Four glycoglycerolipids with different head groups have been synthesized and their physicochemical properties studied. The lengths of the head groups from a mono-saccharide to a trisaccharide, in addition to the anomeric stereochemistry for the smaller glycoglycerolipids, have been modified. The synthesis has been optimized to avoid glycerol epimerization and to allow up-scaling. The physicochemical properties of the glycoglycerolipids were studied and a strong de-mixing of the gel-phase, depending on the head-group, was observed.

Self-assembly properties of alkyloxyethyl beta-glycosides with different types of carbohydrate headgroups

The effect of alkyl chain length on micelle formation in aqueous solutions of synthetic alkyloxyethyl glycosides containing an ethyl spacer with different conformations of the disaccharide headgroups was investigated. The molecular shape was systematically changed from a wedge-shaped to a rodlike geometry by changing the type of carbohydrate headgroup. The lipophilic part consists of dodecyl or tetradecyl chains. The adsorption at the liquid-air interface was investigated by surface tension measurements. The micellar phase region (L1) was studied using small-angle neutron scattering. We have observed a strong influence of the linkage between the sugar moieties in the disaccharide headgroup and the ethyl spacer on the micellar structure: the transformation from spherical to disklike aggregates was observed for compounds with a rodlike shape, but only spherical aggregates were formed by the wedge-shaped molecules.

Shotgun lipidomics: electrospray ionization mass spectrometric analysis and quantitation of cellular lipidomes directly from crude extracts of biological samples

Lipidomics, after genomics and proteomics, is a newly and rapidly expanding research field that studies cellular lipidomes and the organizational hierarchy of lipid and protein constituents mediating life processes. Lipidomics is greatly facilitated by recent advances in, and novel applications of, electrospray ionization mass spectrometry (ESI/MS). In this review, we will focus on the advances in ESI/MS, which have facilitated the development of shotgun lipidomics and the utility of intrasource separation as an enabling strategy for utilization of 2D mass spectrometry in shotgun lipidomics of biological samples. The principles and experimental details of the intrasource separation approach will be extensively discussed. Other ESI/MS approaches towards the quantitative analyses of global cellular lipidomes directly from crude lipid extracts of biological samples will also be reviewed and compared. Multiple examples of lipidomic analyses from crude lipid extracts employing these approaches will be given to show the power of ESI/MS techniques in lipidomics. Currently, modern society is plagued by the sequelae of lipid-related diseases. It is our hope that the integration of these advances in multiple disciplines will catalyze the development of lipidomics, and such development will lead to improvements in diagnostics and therapeutics, which will ultimately result in the extended longevity and an improved quality of life for humankind.

Sulfatide and Na+-K+-ATPase: A Salinity-sensitive Relationship in the Gill Basolateral Membrane of Rainbow Trout

We investigated the effect of salinity on the relationship between Na(+)-K(+)-ATPase and sulfogalactosyl ceramide (SGC) in the basolateral membrane of rainbow trout (Oncorhynchus mykiss) gill epithelium. SGC has been implicated as a cofactor in Na(+)-K(+)-ATPase activity, especially in Na(+)-K(+)-ATPase rich tissues. However, whole-tissue studies have questioned this role in the fish gill. We re-examined SGC cofactor function from a gill basolateral membrane perspective. Nine SGC fatty acid species were quantified by tandem mass spectrometry (MS/MS) and related to Na(+)-K(+)-ATPase activity in trout acclimated to freshwater or brackish water (20 ppt). While Na(+)-K(+)-ATPase activity increased, the total concentration and relative proportion of SGC isoforms remained constant between salinities. However, we noted a negative correlation between SGC concentration and Na(+)-K(+)-ATPase activity in fish exposed to brackish water, whereas no correlation existed in fish acclimated to freshwater. Differential Na(+)-K(+)-ATPase/SGC sensitivity is discussed in relation to enzyme isoform switching, the SGC cofactor site model and saltwater adaptation.

Synthesis and mesogenic properties of a Y-shaped glyco-glycero-lipid

We synthesised a new glyco-glycero-lipid [1,3-di-O-(beta-D-glucopyranosyl)-2-deoxy-2-amino-N-palmitoyl-sn-glycerol] with a Y-shaped structure bearing two sugar head groups and only one fatty acid chain. Instead of an ester linkage between the glycerol and the fatty acid an amido function was introduced. The mesogenic properties were investigated using polarising microscopy and are discussed with respect to similar compounds. The lyotropism was measured using the contact preparation method and small-angle neutron-scattering.

Determination of stereochemical configuration of the glycerol moieties in glycoglycerolipids by chiral phase high-performance liquid chromatography

This study reports a simple and sensitive method for determining the absolute configuration of the glycerol moieties in glycoglycerolipids. The method is based on chiral phase high-performance liquid chromatography (HPLC) separations of enantiomeric di- and monoacylglycerols released from glycosyldi- and monoacylglycerols, respectively, by periodate oxidation followed by hydrazinolysis. The released di- and monoacylglycerols were chromatographed as their 3,5-dinitrophenylurethane (3,5-DNPU) and bis(3,5-DNPU) derivatives, respectively. The derivatives were separated on two chiral phases of opposite configuration, (R)- and (S)-1-(1-naphthyl)ethylamine polymers for diacylglycerols and N-(R)- -(1-naphthyl)ethylaminocarbonyl-(S)-valine and N-(S)-1 -(1-naphthyl)ethylamino-carbonyl-(R)-valine for monoacylglycerols. Clear enantiomer separations, which permit the assignment of the glycerol configuration, were achieved for sn-1,2(2,3)-diacyl- and sn-1(3)-monoacylglycerols generated from linseed oil triacylglycerols by partial Grignard degradation on all the chiral stationary phases employed. Using the method, we have determined the glycerol configuration in the glycosyldiacylglycerols (monogalactosyl-, digalactosyl-, and sulfquinovosyldiacylglycerols) and glycosylmonoacylglycerols (monogalactosyl-, digalactosyl-, and sulfoquinovosylmonoacylglycerols) isolated from spinach leaves and the coralline red alga Corallina pilulifera. The results clearly showed that the glycerol moieties in all the glycoglycerolipids examined have S-configuration (sn-1,2-diacyl- and sn-1-monoacylglycerols). The new method demonstrates that chiral phase HPLC provides unambiguous information on the configuration of the glycerol backbone in natural glycosyldi- and monoacylglycerols, and that the two-step liberation of the free acylglycerols does not compromise glycerol chirality.

Conformational studies on a unique bis-sulfated glycolipid using NMR spectroscopy and molecular dynamics simulations

The time-averaged solution conformation of a unique bis-sulfated glycolipid (HSO3)2-2,6Manalpha-2Glcalpha-1-sn-2,3-O-alkylglycerol , was studied in terms of the torsional angles of two glycosidic linkages, phi (H1-C1-O-Cx) and psi (C1-O-Cx-Hx), derived from heteronuclear three-bond coupling constants (3JC,H), and inter-residual proton-proton distances from J-HMBC 2D and ROESY experiments, respectively. The dihedral angles of Glcalpha1Gro in glycolipids were determined for the first time. The C1-C4 diagonal line of the alpha-glucose ring makes an angle of approximately 120 degrees with the glycerol backbone, suggesting that the alpha-glucose ring is almost parallel to the membrane surface in contrast with the perpendicular orientation of the beta-isomer. Furthermore, minimum-energy states around the conformation were estimated by Monte Carlo/stochastic dynamics (MCSD) mixed-mode simulations and the energy minimization with assisted model building and energy refinement (AMBER) force field. The Glcalpha1Gro linkage has a single minimum-energy structure. On the other hand, three conformers were observed for the Manalpha2Glc linkage. The flexibility of Manalpha2Glc was further confirmed by the absence of inter-residual hydrogen bonds which were judged from the temperature coefficients of the chemical shifts, ddelta/dT (-10-3 p.p.m. degrees C-1), of hydroxy protons. The conformational flexibility may facilitate interaction of extracellular substances with both sulfate groups.

Unique poly(glycerophosphate) lipoteichoic acid and the glycolipids of a Streptococcus sp. closely related to Streptococcus pneumoniae

The Streptococcus sp. studied here is closely related to Streptococcus pneumoniae with 98.6% 16S rRNA similarity and 65% DNA/DNA homology. We isolated the lipoteichoic acid and the membrane glycolipids whose structures were established using conventional procedures and NMR spectroscopy. The lipoteichoic acid contains a linear 1,3-linked poly(glycerophosphate) chain which is partly substituted with D-alanine ester and is phosphodiester-linked to O6 of beta-D-Galf(1-->3)acyl2Gro. This lipoteichoic acid is the first example in which a monohexosylglycerol serves as the glycolipid anchor; and with an average chain length of 10 glycerophosphate residues it is the shortest known to date. MS analysis, applied for the first time to a native acylated lipoteichoic acid, revealed a continuous increase in chain length from seven to 17 glycerophosphate residues with a maximum at 10, and allowed identification of the fatty acid combinations. Membrane glycolipids consisted of beta-D-Galf(1-->3)acyl2Gro (9%), alpha-D-Glcp(1-->3)acyl2Gro (22%), alpha-D-Galp(1-->2)-alpha-D-Glcp(1-->3)acyl2Gro (64%) and alpha-D-Galp(1-->2)-(6-O-acyl)-alpha-D-Glcp(1-->3)acyl2Gro (5%). It is noteworthy that in lipoteichoic acid biosynthesis, Galfacyl2Gro, a less abundant membrane glycolipid, is selected as the lipid anchor. Despite the genetic relatedness to Streptococcus pneumoniae, the lipoteichoic acid structure is quite different to the complex structure of pneumococcal lipoteichoic acid [T. Behr et al. (1992) Eur. J. Biochem. 207, 1063-1075], thus providing an example that minor differences in DNA sequence exert major changes in macromolecular structure.

Requirement of seminolipid in spermatogenesis revealed by UDP-galactose: Ceramide galactosyltransferase-deficient mice

Although seminolipid has long been suspected to play an essential role in spermatogenesis because of its uniquely abundant and temporally regulated expression in the spermatocytes, direct experimental evidence has been lacking. We have tested the hypothesis by examining the testis of the UDP-galactose:ceramide galactosyltransferase-deficient mouse, which is incapable of synthesizing seminolipid. Spermatogenesis in homozygous affected males is arrested at the late pachytene stage and the spermatogenic cells degenerate through the apoptotic process. This stage closely follows the phase of rapid seminolipid synthesis in the wild-type mouse. These observations not only provide the first experimental evidence that seminolipid is indeed essential for normal spermatogenesis but also support the broader concept that cell surface glycolipids are important in cellular differentiation and cell-to-cell interaction.

Glyceroglycolipids preventing tert-butylhydroperoxide-induced cell death from Microbacterium sp. and Corynebacterium aquaticum strains

Galactosyl diacylglycerols M874B and S365B obtained from the recently isolated bacteria identified as Microbacterium sp. M874 and Corynebacterium aquaticum S365 were found to prevent oxidative cell death induced by tert-butylhydroperoxide. Their structures were determined to be 1,2-di-O-(12-methyltetradecanoyl)-3-O-beta-D-galactopyranosyl-sn-glycerol and 1-O-(14-methylhexadecanoyl)-2-O-(12-methyltetradecanoyl)-3-O-beta-D-galactopyranosyl-sn-glycerol, respectively.

Structure and phase behavior of a charged glycolipid (1,2-O-dialkyl-3-O-beta-D-glucuronosyl-sn-glycerol)

In order to investigate the effects of a net surface charge on the properties of glycolipid membranes, we have synthesized a glyceroglycolipid, 1,2-O-dialkyl-3-O-beta-D-glucuronosyl- sn-glycerol (GlcUA lipid), with saturated alkyl chains of varying length (14, 16, and 18 carbon atoms; 14-, 16-, and 18-GlcUA, respectively) and glucuronic acid with an ionizable 6-carboxyl group as polar residue. Aqueous dispersions of GlcUA lipids have been characterized by differential scanning calorimetry, densitometry, and X-ray diffraction methods as a function of pH. The carboxyl group deprotonation of apparent pK about 5.5 leads to a decrease of the melting temperatures by about 7 degrees C for all three compounds and to a chain-length-dependent reduction of the transition enthalpies by 0, 7, and 14% for 14-, 16-, and 18-GlcUA, respectively. The decrease of the transition temperature is consistent with current electrostatic concepts and models of charged membrane interfaces, but the chain-length-specific dependence of the enthalpy decrease with an increase of pH shows that the pH effects in GlcUA lipids are not of purely electrostatic origin. However, these effects appear to be simpler in some instances than corresponding effects in phospholipids with multiply ionizable head groups. For this reason, the lipids with the glucuronic acid head group appear to represent an appropriate model system for studies of net electric charge effects on the membrane properties.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolation and structural characterization of a mono-sulfated isoglobotetraosylceramide, the first sulfoglycosphingolipid of the isoglobo-series, from rat kidney

A novel sulfoglycosphingolipid based on the isoglobo-series core structure was isolated from rat kidney and purified by column chromatographies with DEAE-Sephadex and silica beads. The structure was characterized by solvolysis, compositional analysis, proton NMR spectroscopy, Fourier-transform infrared spectroscopy, methylation analysis and liquid secondary ion mass spectrometry (LSIMS). The characteristic fragment ions for a sulfate and a sulfated N-acetylhexosamine were observed in LSIMS spectra. The two-dimensional chemical-shift-correlated spectroscopy (COSY) and nuclear Overhauser enhancement spectroscopy experiments evidenced the presence of a 3-O-sulfated N-acetylgalactosamine and a Gal alpha 1-3Gal structure in the molecule. The major ceramide consisted of 4-hydroxysphinganine linked to a C24 nonhydroxy fatty acid, deduced from both compositional analysis and LSIMS. From the above results, the following structure was established for this glycolipid: HSO3-3GalNAc beta 1-3Gal alpha 1-3Gal beta 1-4Glc beta 1-1Cer, isoglobotetraosylceramide (iGb4Cer) IV3-sulfate. Rat kidney also contained globotetraosylceramide (Gb4Cer) IV3-sulfate which has a carbohydrate core identical to that from human kidney. The yields of iGb4Cer IV3-sulfate and Gb4Cer IV3-sulfate were 0.27 and 0.07 nmol/g wet tissue, respectively.

Glycosphingolipids in cestodes. Chemical structures of ceramide monosaccharide, disaccharide, trisaccharide and tetrasaccharide from metacestodes of the fox tapeworm, Taenia crassiceps (Cestoda: Cyclophyllidea)

The presence of glycosphingolipids in the metacestodes of the fox tapeworm, Taenia crassiceps, has been established. The normal-phase TLC pattern of the neutral-fraction glycolipids revealed groups of bands corresponding to homologous components of increasing sugar chain length. The three simplest glycolipid components have been isolated and their chemical constitution determined as being of the neogala series: Gal beta 1Cer, Gal beta 6Gal beta 1Cer and Gal beta 6Gal beta 6Gal beta 1Cer. The ceramide tetrasaccharide fraction has been found to consist of a mixture of neogalatetraosylceramide, as an elongation of the neogala series, Gal beta 6Gal beta 6Gal beta 6Gal beta 1Cer and the component Gal alpha 4Gal beta 6Gal beta 6Gal beta 1Cer (both occurring in approximately equimolar proportions). The long-chain bases of the ceramide monogalactoside, digalactoside, trigalactoside and tetragalactosides contain, as well as small amounts of sphingosine, predominantly dihydrosphingosine/phytosphingosine in the approximate ratios 1.7:1, 1.4:1, 1:1 and 2.3:1, respectively. The major ceramide fatty acids have particularly long chains, with hexacosanoic and octacosanoic acids predominating. Upon reverse-phase TCL, the glycolipid components ceramide monogalactoside, digalactoside and trigalactoside were each separable into five component bands. Parent glycolipid components therefore show component band distributions comparable to one another in being governed by similar ceramide constitutions.

Role of a germ cell-specific sulfolipid-immobilizing protein (SLIP1) in mouse in vivo fertilization

Sulfolipid-immobilizing protein 1 (SLIP1) is a germ cell plasma membrane protein that binds specifically to sulfogalactosylglycerolipid, a sulfoglycolipid found preferentially in mammalian male germ cells (Lingwood, Can. J. Biochem. Cell. Biol. 63:1077-1085, 1985b). SLIP1 in mouse and rat sperm exists on the periacrosomal membrane, where sperm initially bind to eggs. Using the in vitro mouse sperm-egg binding assay with in vitro-capacitated sperm, we obtained results previously suggesting that sperm SLIP1 is involved in mouse sperm-zona pellucida interaction. In this study, using the in vitro sperm-egg binding assay, we showed that SLIP1 in uterine sperm was similarly engaged in this process. Involvement of mouse sperm SLIP1 was also shown to be important in the in vivo fertilization process. Superovulated females inseminated with caudal epidididymal and vas deferens sperm preexposed to anti-SLIP1 IgG yielded only 20% fertilized zygotes, while 80% fertilization was observed in females inseminated with sperm preincubated with preimmune serum IgG. The lower fertilization rate was not due to changes in the sperm capacitation rate as assessed by chlortetracycline staining.