Phospholipids and glycolipids of sterol-requiring Mycoplasma

The phospholipids of Mycoplasma hominis type 2 strain 07 are composed almost entirely of phosphatidyl glycerol. Traces of other glycerophospholipids may exist. No glycolipids are found. The phospholipids of Mycoplasma sp. avian strain J are composed of diphosphatidyl glycerol, which predominates in older cultures, a monoacyl glycerophosphoryl glycerophosphate, which may serve as a precursor of diphosphatidyl glycerol, and phosphatidyl glycerophosphate. This organism also contains cholesteryl glucoside and an unidentified glycolipid which appears to be similar to a monoglucosyl diglyceride. No turnover or radioisotope labeling of the phospholipids occurs during metabolism. This lack of turnover during growth is indicative of a structural role for these glycerophospholipids. A concomitant decrease of monoacyl glycerophosphoryl glycerophosphate and increase of diphosphatidyl glycerol occurs during growth.     

Changes in phospholipid composition of Thiobacillus neapolitanus during growth

Summary During the stationary growth phase, the phospholipids of Thiobacillus neapolitanus consisted of phosphatidyl glycerol (PG), diphosphatidyl glycerol (DPG), phosphatidyl-N-monomethylethanolamine (PME) and phosphatidyl ethanolamine (PE) in increasing amounts. In general, the phospholipids increased to a maximum concentration during the stationary phase and then decreased in concentration. Individually, PG and PE increased to a maximum in late lag or early exponential phase and then decreased in concentration. DPG and PME increased during the transition between the exponential and the stationary phase and reached a maximum concentration in the stationary phase. In older cultures, a quantitative interconversion between PG and DPG and PE and PME was observed. A lyso-phospholipid compound also appeared in the late stationary phase.The phospholipid composition of the culture supernatant fluid was essentially similar to that of the cells at all stages of growth. No excessive secretion of these products into the medium was observed at any growth stage of the culture.Abbreviations used PG Phosphatidyl glycerol - DPG Diphosphatidyl glycerol - PME Phosphatidyl-N-monomethylethanolamine - PE Phosphatidyl ethanolamine - GPGPG Glycerophosphoryl glycerophosphoryl glycerol - GPG Glycerophosphoryl glycerol - GPE Glycerophosphoryl ethanolamine - GPME Glycerophosphoryl-N-monomethylethanolamine     

Phospholipids from Bacillus stearothermophilus

The lipids of Bacillus stearothermophilus strain 2184 were extracted with chloroform-methanol and separated into neutral lipid and three phospholipid fractions by chromatography on silicic acid columns. The phospholipids were identified by specific staining reactions on silicic acid-impregnated paper, by chromatography of alkaline and acid hydrolysis products, and by determination of acyl ester:glycerol:nitrogen:phosphorus molar ratios. The total extractable lipid was 8% of the dry weight of whole cells and consisted of 30 to 40% neutral lipid and 60 to 70% phospholipid. The phospholipid consisted of diphosphatidyl glycerol (23 to 42%), phosphatidyl glycerol (22 to 39%), and phosphatidyl ethanolamine (21 to 32%). The concentrations of diphosphatidyl glycerol and phosphatidyl glycerol were lower in 2-hr cells than in 4- and 8-hr cells. Whole cells were fractionated by sonic treatment and differential centrifugation. The total lipid content, expressed in per cent of dry weight of each fraction was: whole protoplasts, 10%; membrane fraction, 18%; 30,000 x g particulate fraction, 22%; and 105,000 x g particulate fraction, 26%. The relative phospholipid concentrations in each fraction were about the same. As had been previously reported, none of the phospholipid was stable to alkaline hydrolysis.     

Phospholipid Alterations During Growth of Escherichia coli

As cultures of Escherichia coli progressed from the exponential growth phase to the stationary growth phase, the phospholipid composition of the cell was altered. Unsaturated fatty acids were converted to cyclopropane fatty acids, and phosphatidyl glycerol appears to have been converted to cardiolipin. With dual isotope label experiments, the kinetics of synthesis of cyclopropane fatty acid for each of the phospholipids was examined in vivo. The amount of cyclopropane fatty acid per phospholipid molecule began to increase in phosphatidyl ethanolamine at a cell density below the density at which this increase was observed in phosphatidyl glycerol or cardiolipin. The rate of this increase in phosphatidyl glycerol or in cardiolipin was faster than the rate of increase in phosphatidyl ethanolamine. After a few hours of stationary-phase growth, all the phospholipids were equally rich in cyclopropane fatty acids. It is suggested that the phospholipid alterations observed are a mechanism to protect against phospholipid degradation during stationary phase growth. Cyclopropane fatty acid synthetase activity was assayed in cultures at various stages of growth. Cultures from all growth stages examined had the same specific activity in crude extracts.     

Lipid Composition of Bacillus cereus During Growth and Sporulation

The lipid composition of Bacillus cereus during growth and sporulation was examined. The total lipid extract accounted for 2 to 3% of the dry weight of the cells and consisted of neutral lipids (30 to 40%) and phospholipids (60 to 70%). Phospholipids were separated by thin-layer chromatography into eight components; phosphatidyl ethanolamine, phosphatidyl glycerol, and diphosphatidyl glycerol were the major phospholipids and accounted for over 90% of the total. Also identified was a diglycosyl diglyceride and an alanine ester of phosphatidyl glycerol. Diphosphatidyl glycerol was more difficult to extract than the other components in vegetative and stationary-phase cells, but became increasingly easy to extract during spore maturation, and during sporulation cellular levels increased. Phosphatidyl glycerol had a high turnover rate; it accounted for about 70% of the phospholipid synthesis throughout sporulation but only represented between 30 and 40% of the total phospholipid at any time. Phosphatidyl ethanolamine, on the other hand, accounted for about 20% of the synthesis but was the major phospholipid (50 to 60% of the total).     

Phospholipids of Thiobacillus thiooxidans

Cells and spent growth media from sulfur- and thiosulfate-grown cultures of Thiobacillus thiooxidans were analyzed. The phosphatides were examined by thinlayer chromatography, and the products of their hydrolysis by hydrochloric acid and methanolic potassium hydroxide were separated by paper chromatography. The phospholipids in both cells and spent growth media were identified as phosphatidyl ethanolamine, phosphatidyl-N-monomethylethanolamine, phosphatidyl glycerol, and diphosphatidyl glycerol. These comprised about 97% of the total lipid phosphorus. Lyso-phosphatidyl-N-monomethylethanolamine and lysophosphatidyl glycerol accounted for the remaining 3%. The percentage of the total lipid phosphorus accounted for by each phospholipid depended on the age of the culture.     

Phospholipid turnover in hamster and chick embryo fibroblasts

The stability of the glycerol backbone of phosphatidyl choline, phosphatidyl ethanolamine and phosphatidyl serine was measured in growing and non-growing hamster and chick embryo fibroblasts. Major differences were found for the rates of degradation of the individual glycerophospholipids in both hamster and chick embryo fibroblasts: considerable degradation of phosphatidyl choline was detected over a 24 h period while at the same time no degradation of the glycerol backbone of phosphatidyl ethanolamine and phosphatidyl serine was observed. The patterns of stability of these glycerophospholipids were similar in growing and non-growing cells.     

Phospholipid Metabolism During Penicillinase Production in Bacillus licheniformis

During membrane-bound penicillinase production, Bacillus licheniformis forms vesicles and tubules that do not appear in the absence of penicillinase production. The major lipids of B. licheniformis were shown to be phospholipids. The proportions, metabolism, and the total phospholipid per cell were shown to be essentially the same in the uninduced control, induced and constitutive penicillinase forming cells during both the exponential and stationary growth phases. Membrane phospholipids were not secreted into the medium during penicillinase formation. In the shift from the exponential to the stationary growth phase, there was an accumulation of phosphatidyl glycerol and a marked decrease in cardiolipin. These two lipids had the most active turnover of their phospholipid phosphate of all the lipids studied.     

Lipid composition of Mycoplasma neurolyticum

The total lipid content of Mycoplasma neurolyticum comprises about 14% of the dry weight of the organisms and is about equally distributed between the phospholipid and the neutral-glycolipid fractions. The neutral lipids were identified as triglycerides, diglycerides, and cholesterol. The glycolipid fraction contained 1-O-beta-glucopyranosyl-d-2,3-diglyceride and 1-[O-beta-d-glycopyranosyl-(1-->6)-O-beta-d-glucopyranosyl]-d-2,3-diglyceride. The latter lipid is structurally identical to the diglucosyl diglyceride which occurs in Staphylococcus aureus. The phospholipids of the organism consist of a fully acylated glycerophosphoryl-glycerophosphoryl glycerol, phosphatidic acid, diphosphatidyl glycerol, phosphatidyl glycerol, and amino acyl esters of phosphatidyl glycerol. Phosphatidic acid and phosphatidyl glycerol account for greater than 90% of the phospholipids of organisms in the exponential phase of growth. The predominant fatty acids found in all of the acyl lipids were palmitic, stearic, and oleic acids.     

Removal of the sphingolipid impurity from preparations of yeast phosphatidyl inositol

A complex sphingolipid containing inositol and mannose, present in lipid extracted from toluene-autolyzed baker's yeast, was eluted from silicic acid columns immediately after phosphatidyl inositol, and was the main nitrogenous impurity in crude preparations of this phospholipid. Nitrogenfree phosphatidyl inositol was obtained by rechromatography on alumina. Modifications to the chromatographic procedure also gave diphosphatidyl glycerol containing the theoretical 4.29% P.     

Transformed cells have lost control of ribosome number through their growth cycle.

Previous studies on the synthesis and function of the protein synthetic machinery through the growth cycle of normal cultured hamster embryo fibroblasts (HA) were extended here to a series of four different clonal lines of polyoma virus-transformed HA cells. Under our culture conditions, these transformed cells could enter a stationary phase characterized by no mitotic cells, very low rates of DNA synthesis, and arrest in a post-mitotic pre-DNA synthetic state. Cellular viability was initially high in stationary phase but, unlike normal cells, transformed cells slowly lost viability. The rate of protein synthesis in the stationary phase of the transformed cells fell to 25-30% of the exponential rate. Though this reduction was similar to that seen in normal cells, it was accomplished by different means. The specific reduction in the ribosome complement per cell to values below that of any cycling cell seen in normal cells, was not seen in any of the transformed lines. This observation, which implies a loss of normal control of ribisome synthesis through the growth cycle after transformation, was confirmed in normal Chinese hamster embryo fibroblasts and transformed CHO cell lines. Normal control of ribosome synthesis was restored in L-73 and LR-73, growth control revertants of one of the transformed CHO lines. The transformed lines reduced their protein synthetic rates in stationary phase either by a greater reduction in the proportion of functioning ribosomes than that seen in normal cells or by a decrease in the elongation rate of functioning ribosomes; the latter effect was not seen in the normal cells. A model for growth control of normal cells and its derangement in transformed cells is presented.     

Elevation of a threonine phospholipid in polyoma virus transformed hamster embryo fibroblasts.

Analysis of the lipids of normal hamster embryo fibroblasts and polyoma virus transformed fibroblasts shows a decrease in phosphatidylcholine and phosphatidylethanolamine and a marked increase in a threonine phospholipid after transformation. Transformed cells also react differently with fluorodinitrobenzene and trinitrobenzenesulfonate. phosphatidylethanolamine of transformed cells reacts to a greater extent with both probes. Phosphatidylserine and the threonine phospholipid of both cells do not react with trinitrobenzenesulfonate. The threonine phospholipid is provisionally identified as phosphatidylthreonine.     

Synthesis of glycolipids and phospholipids in hamster cells: dependence on cell density and the cell cycle.

Sakiyama et al. ('72) reported the isolation of a line of hamster cells (NIL 1c1) which contains only three glycolipids, hematoside, ceramide monohexoside and ceramide dihexoside. The incorporation of radiolabeled palmitate into hematoside during 24 hours was three fold higher in normal confluent, non growing cells than sparse, growing ones. Polyoma transformed cells did not exhibit this effect. We have continued studies with the untransformed cell line and have found that the higher incorporation of radiolabeled palmitate into hematoside by normal confluent cells is not due to a higher rate of turnover of hematoside at confluence but represents a true chemical increase. We have also found that this increase is not a gradual process during cell growth but instead occurs only when the cells become confluent and stop growing. The increase of hematoside at confluence is not due to a higher rate of synthesis of hematoside during G1, relative to the other phases of the cell cycle. We found the rate of synthesis of hematoside to be constant throughout the cell cycle. The rate of synthesis of phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl serine, phosphatidyl inositol and sphingomyelin was also studied as a function of the cell cycle. We found no large differences in the synthetic rate of any given phospholipid species throughout the cell cycle although the rate of synthesis of the glycerophospholipids was somewhat higher during late G1 and S. We did, however, find major differences in the rates of synthesis of the different phospholipid species.     

Composition of membranes and mycelia ofStreptomyces levoris at different stages of growth

The composition of cell membranes and mycelia ofStreptomyces levoris, producer of the polyene antibiotic levorin, was studied. The membrane protein/lipid ratio was shown to be constant during growth of the microorganism. The membrane protein was found to be heterogeneous and to have a low molecular weight. The lipid component of the membranes consisted mainly of polar lipids—phosphatidyl ethanolamine, diphosphatidyl glycerol, and phosphatidyl inositol mannoside being predominant. During growth, the phospholipid content of the polar lipid fraction decreased, apparently due to replacement of phospholipids by phosphorus-free analogs.     

Turnover of Phospholipids in Normal and Phosphorus-deficient Spirodela

When ³²P₁ was supplied as a 15-minute pulse to normal Spirodela oligorrhiza plants, the first phospholipid to become fully labeled was phosphatidic acid. Phosphatidyl glycerol reached maximum labeling before the other major phospholipids. In phosphorus-deficient plants, however, phosphatidyl glycerol became labeled much more slowly than either phosphatidyl choline or phosphatidyl ethanolamine, and also the proportion of phosphatidyl glycerol present was smaller. Thus, phosphatidyl glycerol synthesis is sensitive to phosphorus deficiency. Since most of the phosphatidyl glycerol present in Spirodela was localized in the chloroplast, this effect appeared to be specifically one on chloroplast composition. The phosphorus-deficient chloroplast had a 60% lower phospholipid content and a normal phospholipid pattern, but the phospholipid which was present was apparently cycling much less rapidly. Zeatin, which ameliorates the visual symptoms of phosphorus deficiency, also reduces the effect of phosphorus deficiency on phospholipid synthesis.     

Early effects of serum on phospholipid metabolism in untransformed and oncogenic virus-transformed cultured fibroblasts.

The addition of serum to previously serum-deprived 3T3 fibroblasts in culture caused a pronounced, rapid and selective stimulation of the incorporation of [³²P]phosphate into phosphatidyl inositol. Comparison of the content of radioactivity in phosphatidyl inositol after a short pulse with that obtained following a prolonged labeling period showed that serum accelerated the rate of the turnover (and not the net accumulation) of this substance. In cells transformed by SV-40 virus, the rate of labeling of phosphatidyl inositol was relatively high, and was not influenced significantly by the deprivation of serum or its resupplementation. It is suggested that the rate of phosphatidyl inositol turnover may be related to the state of the mobility of membrane constituents, and that this process escapes the control of serum factors in malignantly transformed cells.     

Alterations in the phospholipid composition of Escherichia coli B during growth at different temperatures

The major phospholipid classes of Escherichia coli B, phosphatidyl ethanolamine, cardiolipin, and phosphatidyl glycerol, were quantitated at different stages of the growth cycle. The organisms were incubated at both 27 and 37 C. Significant differences were observed both in the amounts of total lipid phosphorus per gram (dry weight) of cells and in the relative percentages of the individual phospholipids. At 37 C the total amount of lipid phosphorus decreased significantly throughout the growth cycle. However, at 27 C total lipid phosphorus accumulated. The patterns of the three major phospholipid classes of Escherichia coli exhibited complex quantitative changes. In addition, some evidence based on glycerol to phosphate molar ratios indicated that phosphatidyl glycerolphosphate replaced phosphatidyl glycerol during the late growth stages of E. coli B when grown at 27 C. A comparative analysis of phospholipid and fatty acid patterns led to a hypothesis attempting to explain some reported variations in the lipid composition of E. coli under different conditions of growth.     

Composition of Phospholipids and Fatty Acids cf Mitochondria of Chilling-Sensitive and Chilling-Tolerant Corns

The phospholipids of the mitochondria of chiUing-sensitive (Zhang Dang No. 9) and chilling-tolerant (HD103×Ferumac) corn shoots are composed of phosphatidyl choline, phosphatidyl ethaaolamine, phosphatidic acid, phosphatidyl inositol, diphosphatidyl glycerol, lysophosphatidyl choline and so on. The weight per cent composition of various phospholipid components in there two varieties of corn are not apparently different. The fatty acid composition of the mitochondria of both corn shoots arc similar except the palmitic acid and linoleic acid.     

Chemotaxonomy of aerobic Actinomycetes: Phospholipid composition

A survey of the phospholipid composition of 97 strains representing 20 genera of the Actinomycetales showed that five groups could be distinguished on the basis of the presence or absence of certain nitrogenous phospholipids. Phospholipid type PI (no nitrogenous phospholipids) is characteristic of the genera Actinomadura (madurae, pelletieri).Corynebacterium, Microtetraspora and Nocardioides. Actinomycetes of Type PII contain only one nitrogenous phospholipid, phosphatidyl ethanolamine. These include members of the genera Actinoplanes, Chainia, Dactylosporangium, Microellobosporia, Micromonospora, Micropolyspora (brevicatena), Mycobacterium, Nocardia (all species examined but autotrophica), Streptomyces and Streptoverticillium. Phospholipid pattern type PIII (characteristic phospholipid, phosphatidyl choline) was found in Actinomadura (dassonvillei). Micropolyspora (faeni), Nocardia (autotrophica), and Pseudonocardia. Actinomycetes having a type P IV pattern contain an unknown, previously undescribed phospholipid containing glucosamine (GluNU) which was found to be characteristic of members of the genera Intrasporangium, Microbispora and Streptosporangium. Actinomycetes of type PV contain phosphatidyl glycerol in addition to GluNU and include members of the genera Promicromonospora and Oerskovia. Other phospholipids found variably in all groups included phosphatidyl inositol, phosphatidyl inositol mannosides, phosphatidyl methylethanolamine, acyl phosphatidyl glycerol (APG) and diphosphatidyl glycerol (DPG). The fatty acids present in DPG (or APG when DPG was absent) may be species-specific. The chemical heterogeneity of the genera Actinomadura, Corynebacterium, Micropolyspora and Nocardia is discussed.     

Fatty acid composition of glycerolipids from potato leaves

A method for rapid isolation of glyco- and phospholipids from potato leaves by a two-fold separation in a thin layer of silica gel is described. Using gas-liquid chromatography, the fatty acid compositions of monogalactosyldiglyceride, digalactosyldiglyceride, sulfolipid, phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl glycerol, phosphatidyl inositol, diphosphatidyl glycerol, phosphatidic acid and non-identified lipid from potato leaves were determined. The monogalactosyl diglyceride was found to contain up to 25% of 7,10,13-hexadecatrienic acid. Trans-3-hexadecenic acid as well as phosphatidyl glycerol is a constituent component of phosphatidic acid, diphosphatidyl glycerol and the non-identified lipid.