Lipid composition of some species of Arthrobacter

Latarcins: versatile spider venom peptides

Arthropod venoms feature the presence of cytolytic peptides believed to act synergetically with neurotoxins to paralyze prey or deter aggressors. Many of them are linear, i.e., lack disulfide bonds. When isolated from the venom, or obtained by other means, these peptides exhibit common properties. They are cationic; being mostly disordered in aqueous solution, assume amphiphilic α-helical structure in contact with lipid membranes; and exhibit general cytotoxicity, including antifungal, antimicrobial, hemolytic, and anticancer activities. To suit the pharmacological needs, the activity spectrum of these peptides should be modified by rational engineering. As an example, we provide a detailed review on latarcins (Ltc), linear cytolytic peptides from Lachesana tarabaevi spider venom. Diverse experimental and computational techniques were used to investigate the spatial structure of Ltc in membrane-mimicking environments and their effects on model lipid bilayers. The antibacterial activity of Ltc was studied against a panel of Gram-negative and Gram-positive bacteria. In addition, the action of Ltc on erythrocytes and cancer cells was investigated in detail with confocal laser scanning microscopy. In the present review, we give a critical account of the progress in the research of Ltc. We explore the relationship between Ltc structure and their biological activity and derive molecular characteristics, which can be used for optimization of other linear peptides. Current applications of Ltc and prospective use of similar membrane-active peptides are outlined.

Review of the taxonomy of the genus Arthrobacter, emendation of the genus Arthrobacter sensu lato, proposal to reclassify selected species of the genus Arthrobacter in the novel genera Glutamicibacter gen. nov., Paeniglutamicibacter gen. nov., Pseudoglutamicibacter gen. nov., Paenarthrobacter gen. nov. and Pseudarthrobacter gen. nov., and emended description of Arthrobacter roseus

In this paper, the taxonomy of the genus Arthrobacter is discussed, from its first description in 1947 to the present state. Emphasis is given to intrageneric phylogeny and chemotaxonomic characteristics, concentrating on quinone systems, peptidoglycan compositions and polar lipid profiles. Internal groups within the genus Arthrobacter indicated from homogeneous chemotaxonomic traits and corresponding to phylogenetic grouping and/or high 16S rRNA gene sequence similarities are highlighted. Furthermore, polar lipid profiles and quinone systems of selected species are shown, filling some gaps concerning these chemotaxonomic traits. Based on phylogenetic groupings, 16S rRNA gene sequence similarities and homogeneity in peptidoglycan types, quinone systems and polar lipid profiles, a description of the genus Arthrobacter sensu lato and an emended description of Arthrobacter roseus are provided. Furthermore, reclassifications of selected species of the genus Arthrobacter into novel genera are proposed, namely Glutamicibacter gen. nov. (nine species), Paeniglutamicibacter gen. nov. (six species), Pseudoglutamicibacter gen. nov. (two species), Paenarthrobacter gen. nov. (six species) and Pseudarthrobacter gen. nov. (ten species).

Description of Tersicoccus phoenicis gen. nov., sp. nov. isolated from spacecraft assembly clean room environments

Two strains of aerobic, non-motile, Gram-reaction-positive cocci were independently isolated from geographically distinct spacecraft assembly clean room facilities (Kennedy Space Center, Florida, USA and Centre Spatial Guyanais, Kourou, French Guiana). A polyphasic study was carried out to delineate the taxonomic identity of these two isolates (1P05MAT and KO_PS43). The 16S rRNA gene sequences exhibited a high similarity when compared to each other (100 %) and lower than 96.7 % relatedness with Arthrobacter crystallopoietes ATCC 15481T, Arthrobacter luteolus ATCC BAA-272T, Arthrobacter tumbae DSM 16406T and Arthrobacter subterraneus DSM 17585T. In contrast with previously described Arthrobacter species, the novel isolates maintained their coccidal morphology throughout their growth and did not exhibit the rod–coccus life cycle typically observed in nearly all Arthrobacter species, except A. agilis . The distinct taxonomic identity of the novel isolates was confirmed based on their unique cell-wall peptidoglycan type (A.11.20; Lys-Ser-Ala2) and polar lipid profile (presence of phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, an unknown phospholipid and two unknown glycolipids). The G+C content of the genomic DNA was 70.6 mol%. The novel strains revealed MK-9(H2) and MK-8(H2) as dominant menaquinones and exhibited fatty acid profiles consisting of major amounts of anteiso-C15 : 0 and anteiso-C17 : 0 and moderate amounts of iso-C15 : 0 discriminating them again from closely related Arthrobacter species. Based on these observations, the authors propose that strains 1P05MAT and KO_PS43 be assigned into a separate genus Tersicoccus gen. nov. For this new taxon, comprising strains 1P05MAT and KO_PS43, we propose the name Tersicoccus phoenicis gen. nov., sp. nov. (the type species of Tersicoccus), represented by the type strain Tersicoccus phoenicis 1P05MAT ( = NRRL B-59547T = DSM 30849T).

Structure and function of glycoglycerolipids in plants and bacteria

Phosphoglycerolipids are abundant membrane constituents in prokaryotic and eukaryotic cells. However, glycoglycerolipids are the predominant lipids in chloroplasts of plants and eukaryotic algae and in cyanobacteria. Membrane composition in chloroplasts and cyanobacteria is highly conserved, with monogalactosyldiacylglycerol (MGD) and digalactosyldiacylglycerol (DGD) representing the most abundant lipids. The genes encoding enzymes of galactolipid biosynthesis have been isolated from Arabidopsis. Galactolipids are crucial for growth under normal and phosphate limiting conditions. Furthermore, they are indispensable for maximal efficiency of photosynthesis. A wide variety of glycoglycerolipids is found in different bacteria. These lipids contain glucose or galactose, in some cases also mannose or other sugars with different glycosidic linkages in their head group. Some bacterial species produce unusual glycoglycerolipids, such as glycophospholipids or glycoglycerolipids carrying sugar head groups esterified with acyl residues. A number of genes coding for bacterial glycoglycerolipid synthases have been cloned and the enzymes characterized. In contrast to the breadth of information available on their structural diversity, much less is known about functional aspects of bacterial glycoglycerolipids. In some bacteria, glycoglycerolipids are required for membrane bilayer stability, they serve as precursors for the formation of complex membrane components, or they are crucial to support anoxygenic photosynthesis or growth during phosphate deficiency.

Production and structure elucidation of glycoglycerolipids from a marine sponge-associated microbacterium species

The bacterium Microbacterium sp., isolated from the sponge Halichondria panicea, produced four unusual cell-associated glycoglycerolipids and one diphosphatidylglycerol when grown on marine broth and on artificial seawater media. The lipids were isolated by chromatography on silica columns and their structures elucidated using a combination of multidimensional NMR and MS techniques. The main compound was 1-O-acyl-3-[alpha-glucopyranosyl-(1-3)-(6-O-acyl-alpha-mannopyranosyl )]glycerol (GGL.2) with 14-methyl-hexadecanoic acid and 12-methyl-tetradecanoic acid positioned at C-6 of the mannose unit and at the glycerol moiety. Glycolipid production was correlated with growth and reached a maximum value of 200 mg/L when grown on artificial seawater medium with 20 g/L glucose. The main compound decreased the surface tension of water down to 33 mN/m and the interfacial tension of the water/n-hexadecane system down to 5 mN/m. In addition to this good surface-active behavior, the main glycoglycerolipid showed antitumor activities.

Use of gel electrophoresis for the study of enzymatic activities of cold-adapted bacteria

Glutamate dehydrogenase (GDH) and lactate dehydrogenase (LDH) activity of 13 cold-adapted strains, isolated from cold soils and showing GDH and/or LDH activity in spectrophotometric assays, were revealed by the use of electrophoresis on a nondenaturing acrylamide gel (zymogram). Psychrophilic strains were grown at 4 degrees C and 10 degrees C and the psychrotolerant strains at 4 degrees, 20 degrees and 28 degrees C. Incubation with the specific substrate and staining were done at 4, 28 or 37 degrees C. In the most cold-adapted strains, LDH and GDH production was high at 4 degrees C. In psychrotrophic strains, enzyme production and activity were greater at 20 or 28 degrees C than at lower temperatures. LDH remained active up to 37 degrees C while GDH activity was more thermolabile. GDH activity was NAD-dependent in some psychrophilic strains. In other strains, it was dependent on NAD(P) only or on both NAD and NAD(P). Two bands were seen for GDH or LDH activity in some strains. This method, which does not require a dialysis step, can be used to study the influence of temperature on enzyme production and activity, and the co-factor dependence. It detects phenotypic differences between isozymes, providing data for systematics.

Intraspecific variation of unusual phospholipids from Corynebacterium spp. containing a novel fatty acid

The novel fatty acid trans-9-methyl-10-octadecenoic acid was isolated from the coryneform bacterial strain LMG 3820 (previously misidentified as Arthrobacter globiformis) and identified by spectroscopic methods and chemical derivatization. This fatty acid is attached to the unusual lipid acyl phosphatidylglycerol. Five different species of this lipid type were identified; their structures were elucidated by tandem mass spectrometry and are reported here for the first time. Additionally, we identified three different cardiolipins, two bearing the novel fatty acid. The characteristic 10-methyl-octadecanoic acid was present only in phosphatidylinositol. Because of the unusual fatty acid pattern of strain LMG 3820, the 16S rDNA sequence was determined and showed regions of identity to sequences of Corynebacterium variabilis DSM 20132(T) and DSM 20536. All three strains possessed the novel fatty acid, identifying trans-9-methyl-10-octadecenoic acid as a potential biomarker characteristic for this taxon. Surprisingly, the fatty acid and relative abundances of phospholipids of Corynebacterium sp. strain LMG 3820 were similar to those of the type strain but different from those of Corynebacterium variabilis DSM 20536, although all three strains possessed identical 16S rDNA sequences and strains DSM 20132(T) and DSM 20536 have 90.5% DNA-DNA homology. This is one of the rare cases wherein different organisms with identical 16S rDNA sequences have been observed to present recognizably different fatty acid and lipid compositions. Since methylation of a fatty acid considerably lowers the transition temperature of the corresponding lipid resulting in a more flexible cell membrane, the intraspecific variation in the lipid composition, coinciding with the morphological and Gram stain reaction variability of this species, probably offers an advantage for this species to inhabit different environmental niches.

Uptake and utilization of n-octacosane and n-nonacosane by Arthrobacter nicotianae KCC B35

Arthrobacter nicotianae KCC B35 isolated from blue-green mats densely covering oil sediments along the Arabian Gulf coast grew well on C10 to C40 n-alkanes as sole sources of carbon and energy. Growth on C20 to C40 alkanes was even better than on C10 to C18 alkanes. Biomass samples incubated for 6 h with n-octacosane (C28) or n-nonacosane (C29) accumulated these compounds as the predominant constituent alkanes of the cell hydrocarbon fractions. The even chain hexadecane C16 and the odd chain pentadecane C15 were the second dominant constituent alkanes in C28 and C29 incubated cells, respectively. n-Hexadecane-incubated cells accumulated in their lipids higher proportions of C16-fatty acids than control cells not incubated with hydrocarbons. On the other hand, C28 and C29-incubated cells did not contain any fatty acids with the equivalent chain lengths, but the fatty acid patterns of the cell lipids suggest that there should have been mid-chain oxidation of these very long chain alkanes. This activity qualifies A. nicotianae KCC B35 to be used in cocktails for bioremediating environments polluted with heavy oil sediments.

Phases and phase transitions of the glycoglycerolipids

LIPIDAT is a computerized database providing access to the wealth of information scattered throughout the literature concerning synthetic and biologically derived polar lipid polymorphic and mesomorphic phase behavior. The database is considered comprehensive for glycerophospholipids, glycoglycerolipids, sphingolipids and natural membrane extracts. Here, a review of the LIPIDAT data subset referring to glycoglycerolipids is presented together with an analysis of these data. The glycoglycerolipids subset represents 4% of all LIPIDAT records. It includes data collected over a 20-year period and consists of 419 records obtained from 37 articles in 13 journals. An analysis of the data in the subset has allowed us to identify trends in hydrated glycoglycerolipids phase behavior reflecting differences in hydrocarbon chain length, chain branching, chain-glycerol linkage type (ether vs. ester), sugar headgroup-glycerol linkage type (alpha vs. beta) and sugar headgroup identity. Included is a summary of the data concerning the effect of pH and of stereochemical purity on glycoglycerolipid phase behavior. Information on the mesomorphism of biologically derived and dry glycoglycerolipids is also presented. This review includes 92 references.

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)

Glycolipids from some extreme thermophilic bacteria belonging to the genus Thermus

The lipids of Thermus aquaticus YT1, Thermus thermophilus HB8, Thermus sp. strains H and J (from Icelandic hot springs), and Thermus sp. strain NH (from domestic hot water) have been investigated. Each strain contained two major components, a glycolipid and a glycophospholipid, which have been isolated and analyzed. All of the strains contained as the principal component (41 to 57% of total lipid) a diacyldiglycosyl-(N-acyl)glycosaminylglucosylglycerol, but the five glycolipids differed in carbohydrate composition. The glycophospholipid appeared to be identical in each strain and contained an N-acylglucosamine residue. The principal fatty acids were C15 and C17 branched-chain compounds. This unique polar lipid composition should be of value in the classification of other thermophiles in the genus Thermus. The exceptionally high carbohydrate content of the lipids of these extreme thermophiles may be of significance in relation to the molecular basis of thermophily.

Synthesis of glycolipids

The chemical syntheses of naturally occurring glycolipids derived from sphingosine bases and glycerol derivatives, and the syntheses of polyisoprenoid lipid intermediates and other miscellaneous glycolipids recorded up to the end of 1977 are reviewed.

The polar lipids of group B Streptococci. II. Composition and positional distribution of fatty acids

1. The polar lipids from group B Streptococci have been isolated. Unless overlapping fractions are worked up on each step molecular species can be lost resulting in a fatty acid composition different from the original one. 2. The lipids were shown to be 1(3),2-diacyl-3(1)-O-alpha-D-glucopyranosyl-sn-glycerol, 1(3),2-diacyl-3(1)-O-[alpha--D-glucopyranosyl-(1,2)-O-alpha-D-glucopyranosyl]-sn-glycerol, 1,2-diacyl-sn-glycero-3-phospho-1'-sn-glycerol, lysylphosphatidylglycerol and 1'-3'-bis(1,2-diacyl-sn-glycero-3-phospho-glycerol. The sterochemical configuration of the phospholipids was achieved by combinations of chemical degradations. 3. The fatty acid composition of group B Streptococci lipids is qualitatively the same as in other Streptococci, but differs by a high content of stearic acid and by a low degree of unsaturation and cyclopropanization. 4. The forementioned polar lipids as well as the glucosyldiphsphatidylglycerol,, which is also found in this organism, showed a very similar composition and the same non-radom positional distribution of fatty acids. Apart from short chain fatty acids the positioning differentiates between saturated and unsaturated fatty acids: short chain and unsaturated fatty acids are accumulated at Position 2, saturated acids are preferentially linked to Position 1. 5. The uniform fatty acid make-up in all polar lipids favours the hypothesis that their diacylglycerol portions are derived from a common phosphatidic acid precursor with negligible postsynthetic rearrangements of the constituent fatty acids.

Extractable lipids of gram-negative marine bacteria: phospholipid composition

Phospholipid compositions of 20 strains of marine and estuarine bacteria were determined. Results showed that phospholipids of marine bacteria differed very little from those of nonmarine organisms with phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol being the predominant phospholipids in all strains examined. Lyso-phosphatidylethanolamine occurred in significant quantities among a number of the marine bacteria, and two of the isolates contained significant quantities of poly-beta-hydroxybutyrate. Effects of age and growth temperature on the phospholipid composition were also investigated. It is suggested that phylogenetic relationships among bacteria may be correlated with phospholipid composition.

Lipid composition of growing and starving cells of Arthrobacter crystallopoietes

The lipid composition of growing and starving cells of Arthrobacter crystallopoietes was compared. Although the lipid composition of the two cell types was similar, the amount of total lipids recovered from the starving cells was 30.4% less than that recovered from the growing cells. The loss of lipids, as compared to the loss of total cell mass during starvation, was (i) proportional to the loss of the cell mass (phosphatidylinositol, phosphatidylglycerol-2, and cardiolipin), (ii) greater than the loss in cell mass (neutral lipids, "glycophospholipids," and phosphatidic acid), or (iii) less than the loss in cell mass (coenzyme Q, glycolipids, and phosphatidylglycerol-1).