Inhibition of lipid synthesis in Escherichia coli cells by the antibiotic cerulenin

Cerulenin-induced changes in the lipopolysaccharide content and phospholipid composition of Proteus mirabilis

Inhibition of Proteus mirabilis growth by cerulenin, a specific inhibitor of fatty acid biosynthesis, was reversed by exogenously supplied fatty acid mixtures containing oleic acid and palmitic or pentadecanoic acids. The growth rate of the cells treated with cerulenin in the presence of the fatty acid mixtures was slower, however, than that of untreated cells, and their lipopolysaccharide content was decreased by 30-50%, resulting in an increased sensitivity of the organisms to rifamycin and vancomycin. Polyacrylamide gel electrophoresis of the lipopolysaccharide fraction from cerulenin-treated cells revealed that of the two P. mirabilis lipopolysaccharide types, the relative amount of the higher molecular weight lipopolysaccharide was reduced from 50% to 30% of the total lipopolysaccharide. Fatty acid analysis of the phospholipid and lipopolysaccharide fractions from cells grown with cerulenin, pentadecanoate, and oleate revealed that over 60% of the native even-numbered fatty acids of the phospholipid fraction was substituted by the odd-numbered fatty acid, while no incorporation of either the pentadecanoate or oleate could be demonstrated in the lipid A moiety of the lipopolysaccharide. The only change in the lipid A observed was an increase in the content of 3-hydroxymyristic acid accompanied by a decrease in the nonhydroxylated fatty acids, supporting the highly conserved nature of this molecule.

Consequence of cerulenin-released beta-lactamase in clinical coliforms

Periplasmic beta-lactamase of certain clinical coliforms was released, without affecting cell viability, by perturbation of the outer membrane utilizing the fatty acid-mimicking antibiotic cerulenin. Release of such compartmentalized beta-lactamase, at high population density, seems to provide an extra margin of resistance to the organisms against cephaloridine.

Inhibition of the Development of Induced Respiration and Cyanide-insensitive Respiration in Potato Tuber Slices by Cerulenin and Dimethylaminoethanol

The interdependence of the development of wound-induced respiration and membrane-related phospholipid biosynthesis in potato tuber (Solanum tuberosum var. Russet) slices was established by the use of agents which selectively affect lipid and phospholipid synthesis. Cerulenin, a specific inhibitor of de novo fatty acid synthesis, inhibited the ultimate development of wound-induced respiration and of cyanide resistance only when given in the critical first 10 to 12 hours of slice aging. Similarly, when slices were exposed to the choline analogue dimethylaminoethanol within the first 10 hours, the phospholipid composition of the membrane lipids was drastically altered, the wound-induced respiration in a 24-hr period was substantially curtailed, and the development of cyanide insensitivity was sharply inhibited. These observations indicate that time-restricted membrane-related phospholipid synthesis is prerequisite to the development of wound-induced respiration and concurrent cyanide insensitivity.

Stability of Lactic Acid Bacteria to Freezing as Related to Their Fatty Acid Composition

The viability of Streptococcus lactis and Lactobacillus sp. A-12 after freezing at -17°C for 48 h was better preserved when the cells were grown in medium supplemented with oleic acid or Tween 80 (polyoxyethylene sorbitan monooleate). A pronounced change in the cellular fatty acid composition was noted when the bacteria were grown in the presence of Tween 80. In S. lactis the ratio of unsaturated to saturated fatty acids increased from 1.18 to 2.55 and in Lactobacillus sp. A-12 it increased from 0.85 to 1.67 when Tween 80 was added to the growth medium. The antibiotic cerulenin markedly inhibited the growth of lactic acid bacteria in tomato juice (TJ) medium but had almost no effect on the growth of the bacteria in TJ medium containing Tween 80 (or oleic acid). The antibiotic inhibited markedly the incorporation of [1- 14 C]acetate but had no inhibitory effect on the incorporation of exogenous [1- 14 C]oleate (or [1- 14 C]palmitate) into the lipid fractions of lactic acid bacteria. Thus, the fatty acid composition of lactic acid bacteria, inhibited by the antibiotic cerulenin, can be modulated by exogenously added oleic acid (or Tween 80) without the concurrent endogenous fatty acid synthesis from acetate. The data obtained suggest that cerulenin inhibits neither cyclopropane fatty acid synthesis nor elongation of fatty acid acyl intermediates. The radioactivity of cells grown in the presence of [1- 14 C]oleate and cerulenin was associated mainly with cyclopropane Δ19:0, 20:0 + 20:1, and 21:0 acids. As a consequence, cerulenin caused a decrease in the ratio of unsaturated to saturated fatty acids in lactic acid bacteria as compared with cells grown in TJ medium plus Tween 80 but without cerulenin. Cerulenin caused a decrease in the viability of S. lactis and Lactobacillus sp. A-12 after freezing at -17°C for 48 h only when Tween 80 was present in the growth medium. We conclude that the sensitivity of lactic acid bacteria to damage from freezing can be correlated with specific alterations in the cellular fatty acids.

Cerulenin-inhibited cells of Staphylococcus aureus resume growth when supplemented with either a saturated or an unsaturated fatty acid

In the presence of an inhibitory concentration of cerulenin, cells of Staphylococcus aureus can resume growth when supplemented with either a saturated or an unsaturated fatty acid. A requirement for both types of acids for growth could not be demonstrated.

Effect of cerulenin on the growth and differentiation of Dictyostelium discoideum

The growth of Dictyostelium discoideum Ax-2 was inhibited completely by cerulenin at a concentration of 5 mug/ml. This inhibition of growth was found to be due to the inhibition of fatty acid synthesis. Acetate incorporation into a long-chain fatty acid was inhibited completely by cerulenin, and the growth inhibition could be reversed by inclusion of certain saturated fatty acids in the medium. Unsaturated fatty acids and sterols failed to reverse the inhibitory effect. The fatty acid and sterol compositions of cerulenin-treated cells were determined to establish whether the drug could be used to manipulate the organism's lipid composition. Only relatively small manipulations were obtained under the conditions employed in this study. Cerulenin inhibited differentiation but only at high concentrations (150 mug/ml). This inhibition could be reversed by palmitic acid, suggesting that the prime cause of the inhibition was an inhibition of fatty acid synthesis. Thus, it appears that continued fatty acid synthesis is required for the cellular process of differentiation in D. discoideum.

Isolation and characterization of a glycerol auxotroph of Rhodopseudomonas capsulata: effect of lipid synthesis on the synthesis of photosynthetic pigments

A glycerol auxotroph was isolated from Rhodopseudomonas capsulata for use as a system for studying membrane synthesis and function. When the mutant was deprived of glycerol, net phospholipid synthesis ceased immediately and a small amount of free fatty acids accumulated. A turnover of lipid occurred in both deprived and supplemented cultures. Deoxyribonucleic acid and protein synthesis continued for one doubling of cell massand then slowed down in deprived cells. Net ribonucleic acid synthesis slowed down more dramatically. Oxidative phosphorylation activity of membrane preparations from aerobically and semi-anaerobically grown cells appeared unaffected by glycerol deprivation, indicating that simultaneous lipid synthesis is not a requirement for new oxidative phosphorylating activity. In the absence of net phospholipid synthesis, bacteriochlorophyll and carotenoid syntheses were reduced to 30% of the activity of supplemented cultures. Delta-Aminolevulinic acid synthase, the first enzyme on the bacteriochlorophyll pathway that is subject to regulatory control, increased in activity in deprived cultures. Lascelles and Szilagyi (1965) showed an association between phospholipid synthesis and pigment production. They found an increased lipid content associated with pigmented cells. The present results indicate that not only is there an association between lipid and pigment synthesis, but also there is actually a dependence of bacteriochlorophyll synthesis on phospholipid synthesis.

The antibiotic cerulenin, a novel tool for biochemistry as an inhibitor of fatty acid synthesis

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Effect of cerulenin on growth and lipid metabolism of mycoplasmas

Cerulenin markedly inhibited the growth of Acholeplasma laidlawii. A. axanthum and A. granularum were less susceptible, whereas the sterol-requiring Mycoplasma species examined showed very little susceptibility. The inhibition was not reversed by the addition of long-chain fatty acids to the medium. At a concentration of 20 mug/ml, cerulenin inhibited the incorporation of [(14)C]acetate into A. laidlawii membrane lipids, but it had no effect on either protein or nucleic acid biosynthesis. Cerulenin inhibited both the de novo synthesis of long-chain fatty acids and the elongation of medium-chain fatty acids. As a result, carotenoid biosynthesis was stimulated, and increased amounts of oleic and elaidic acids were incorporated into membrane polar lipids. Our studies support the concept that cerulenin can serve as a useful tool for obtaining better control of fatty acid composition of A. laidlawii membranes.

Pharmacokinetic interpretation of penicillin levels in serum and urine after intravenous administration

Sporulation of Saccharomyces cerevisiae G2-2 was inhibited by the antibiotic cerulenin which is known to be a specific inhibitor of fatty acid and sterol synthesis. This inhibition was reversed by various fatty acids, especially by oleic acid (C_18:1) and pentadecanoic acid (C_15:0). Ergosterol showed only slight reversibility of this inhibition. When cerulenin was added to the sporulation medium later than 12 h after the start of incubation, the marked inhibition disappeared. When the fatty acid fraction extracted from the sporulated yeasts was added to the cells pretreated with cerulenin for more than 6 h, sporulation became evident 6 h after the fatty acid fraction addition. Therefore, sufficient synthesis of fatty acids required for sporulation was assumed to occur during the first 6 h in phase I of yeast sporulation.

Substitution of cellular fatty acids in yeast cells by the antibiotic cerulenin and exogenous fatty acids

Cell growth of Saccharomyces cerevisiae ATCC 12341 inhibited by the antibiotic cerulenin, a specific inhibitor of fatty acid and sterol syntheses, was reversed by various exogenous fatty acids. Myristic acid (14 : 0), pentadecanoic acid (15 : 0), palmitic acid (16 : 0), and oleic acid (18 : 1) reversed effectively the growth inhibition by cerulenin. When these cells were reversed by adding pentadecanoic acid, over 90% of native even-numbered fatty acids was substituted by odd-numbered fatty acids. Those in the cells reversed by adding oleic acid were almost all unsaturated fatty acids. Cerulenin did not inhibit either elongation or desaturation systems in S. cerevisiae.

Inhibition of de novo fatty acid synthesis by the antibiotic cerulenin in Bacillus subtilis: effects on citrate-Mg2+ transport and synthesis of macromolecules

Inhibition of de novo fatty acid biosynthesis by the antibiotic cerulenin in Bacillus subtilis stopped de novo synthesis of neutral lipids and phospholipids. The bacteria ceased growing but remained completely viable. Addition of 12-methyltetradecanoic acid and palmitic acid to the culture medium of cerulenin-treated cells restored growth of the bacteria, albeit at a reduced rate. Although the de novo synthesis of all lipid components of the membrane was blocked, citrate-Mg(2+) transport activity remained inducible, and induced cells did not lose this transport activity when treated with cerulenin. Shortly after the addition of cerulenin, the rate of ribonucleic acid synthesis dropped rapidly and was followed by a slower decrease in the rate of protein synthesis. The rate of deoxyribonucleic acid synthesis remained almost unaffected. The rapid decrease of ribonucleic acid synthesis in cerulenin-treated cells might be due to the inhibition of de novo fatty acid biosynthesis or it might be due to a secondary effect of cerulenin in B. subtilis cells.

Insertion of a minor protein into the outer membrane of Escherichia coli during inhibition of lipid synthesis

The antibiotic cerulenin, a specific inhibitor of fatty acid synthetase systems, was used to demonstrate that a minor protein component of the outer membrane of Escherichia coli, which serves as the receptor for the phage lambda, can be synthesized and inserted into the outer membrane during inhibition of lipid synthesis.

Mechanism of action of CM-55, a synthetic analogue of the antilipogenic antibiotic cerulenin

CM-55 is a synthetic analogue of the antibiotic cerulenin with the chemical structure of 2, 3-dodecenyl-4-oxo-dimethyl amide. This compound inhibited the growth of Saccharomyces cerevisiae ATCC 12341 and inhibited protein and lipid synthesis by 91 and 95%, respectively, at a concentration of 50 mug/ml (2.1 x 10(-4) M). The inhibition of protein synthesis was associated with the partial reduction of ribonucleic acid synthesis and leucine transport. The mechanism of inhibition of lipid synthesis was further investigated in a cell-free extract of the yeast. CM-55 inhibited the incorporation of [(14)C]acetyl Coenzyme A (CoA) into both fatty acid (FAF) and non-saponifiable fractions (NSF). However, it did not inhibit [(14)C]malonyl CoA incorporation into FAF and only slightly inhibited [(14)C]mevalonate incorporation into NSF. The activity of 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) synthase was inhibited more strongly than the incorporation of [(14)C]3-hydroxy-3-methylglutaryl CoA into NSF; this could account for the CM-55 inhibition of [(14)C]acetyl CoA incorporation into NSF.