A structure-function correlation for fatty acids inSaccharomyces cerevisiae
01 Mar 1984-Experimental Mycology (Academic Press)-Vol. 8, Iss: 1, pp 55-62
TL;DR: A relationship which distinguishes those fatty acids that support the growth of oxygen-deprived Saccharomyces cerevisiae from those that do not was found and a hydroxyl group or trans -double bond appeared to act as an interrupting group.
Abstract: A relationship which distinguishes those fatty acids that support the growth of oxygen-deprived Saccharomyces cerevisiae from those that do not was found. To function properly, a long chain of saturated carbon atoms appears to require interruption by an appropriate chemical group such that only a maximum number of contiguous saturated carbon atoms is present anywhere in the chain. A double bond was found to serve as an interrupting group, and for 19 cis -unsaturates studied, ranging from C 14:1 -Δ 9 to C 22:6 -Δ 4,7,10,13,16,19 , the number of saturated C atoms was 9. The chain length and the position and number of double bonds had no influence in determining whether the acids were active or inactive except as these structural features related to the interruption rule. Although less extensively examined, a hydroxyl group or trans -double bond also appeared to act as an interrupting group with allowed numbers of 9 and 7, respectively, for saturated C atoms. Oxygen deprivation did not result in a shift to shorter chain length of the saturates formed, and the presence of unsaturates did not prevent biosynthesis of saturates.
TL;DR: In this article, thermal and pulsed electric field (PEF) treatments have been evaluated to assess their effect on fatty acids and free amino acids contents of Parellada grape juice.
Abstract: Common thermal and pulsed electric field (PEF) treatments have been evaluated to assess their effect on fatty acids and free amino acids contents of Parellada grape juice. These compounds have great importance in winemaking as nutritive compounds for yeasts growth. The effect of thermal and PEF treatments has also been determined on several physicochemical properties and a population of inoculated Saccharomyces cerevisiae. Both technologies reduced the population of the spoilage microorganism inoculated in grape juice. No viable cells were observed after thermal processing of grape juice whereas PEF treatment achieved four logarithmic reductions of the microbial viability. No significant changes were noticed on physicochemical properties measured such as reducing sugar content, total acidity and pH. Neither thermal nor PEF treatments modified the total content of fatty acids and free amino acids of Parellada grape juice. However, the concentration of lauric acid diminished after PEF processing and the concentration of some amino acids varied after both treatments.
TL;DR: It is apparent that yeast lipids regulate many membrane functions and also have decisive involvement in its structure, and a multidisciplinary approach is required where both its physical and physiological parameters should be simultaneously studied.
Abstract: Publisher Summary This chapter describes several aspects of lipids with regard to their involvement in the structure and function of yeast membrane. The neutral lipid composition of the majority of yeasts consists of mainly triacylglycerols, free sterols, sterol esters, and free fatty acids. The predominant component among neutral lipids is triacylglycerol, whereas the levels of sterol esters, free sterols, and free fatty acids vary between trace amounts to 7–8%. The lipid composition of yeast exhibits great variation depending upon its growth conditions. Yeast is an ideal model for ascertaining the involvement of lipids in its structure and function. However, yeast has not been fully exploited to predict a detailed relationship between its structure and function. It is apparent that yeast lipids regulate many membrane functions and also have decisive involvement in its structure. To have greater insight into the relationship of lipid and yeast membrane, a multidisciplinary approach is required where both its physical and physiological parameters should be simultaneously studied.
••01 Jan 1995
TL;DR: Lipid production from fungi becomes economically viable, however, when it either yields special metabolites not available more cheaply from other sources, such as polyunsaturated fatty acids (PUFAs), or offers easy conversion to products of biochemical and pharmaceutical importance.
Abstract: Since most fungi are capable of degrading a wide diversity of readily available substrates, there has been much interest in their exploitation for the production of lipids. Even on inexpensive carbon sources, the conversion efficiency of substrate to fungal lipid is currently unable to compete in price with the plant oils widely used as human food. For example, approximately 5 t of substrate is needed to produce 1 t of fungal oil (Ratledge 1988). Lipid production from fungi becomes economically viable, however, when it either yields special metabolites not available more cheaply from other sources, such as polyunsaturated fatty acids (PUFA), or offers easy conversion to products of biochemical and pharmaceutical importance. This is especially true when utilizing waste products from other processes, particularly if direct disposal of such materials is environmentally hazardous.
TL;DR: Liposomes constructed from phospholipid and sterol extracted from RD5-R grown on different sterols indicated that exogenously supplied sterol modulated cellularospholipids such that lipid-phase transitions were avoided.
Abstract: Plasma membranes isolated from a yeast sterol auxotroph (RD5-R) grown on 1, 5, and 15 μg ml −1 exogenous concentrations of sterol showed no discontinuity in plots of steady-state fluorescence anisotropy. Liposomes constructed from phospholipid and sterol extracted from RD5-R grown on different sterols indicated that exogenously supplied sterol modulated cellular phospholipids such that lipid-phase transitions were avoided. Liposomes derived from sterol and phospholipid extracted from the same culture exhibited no lipid-phase transitions. However, when phospholipid extracted from a culture grown on a specific sterol was mixed with sterol extracted from a heterologous culture grown on a different sterol to form liposomes, discontinuities were detected in the anisotropy measurements of the liposomes produced. Quantitative analyses revealed that the exogenously supplied sterol coordinately regulated specific phospholipid species, fatty acid composition, and sterol to phospholipid ratios in yeast auxotrophs.
TL;DR: The data strongly suggest that the normal biosynthetic processes removal of methyl groups from the nucleus and introduction of one in the side chain are of functional significance and that the natural sterol probably acts functionally in the form of its preferred conformer in which C-22 is to the right ("right-handed") in the usual view.
Abstract: As an approach to the study of the relationship between the structure of sterols and their capacity to function in the lipid leaflet of membranes, various sterols were examined for their ability to support the growth of anaerobic Saccharomyces cerevisiae. A marked dependence on precise structural features was observed in growth-response and morphology. Of the chemical groups which distinguish ergosterol, the main sterol of S. cerevisiae, the hydroxyl group at C-3 was obligatory, and the other groups were found to be of the following relative importance: 24beta-methyl-delta22-grouping greater than 24beta-methyl group greater than delta5,7-diene system = delta5-bond approximately or equal to no double bond. Methyl groups at C-4 and C-14 were inconsistent with activity. Consequently, the data strongly suggest that the normal biosynthetic processes removal of methyl groups from the nucleus and introduction of one in the side chain are of functional significance. A double bond between C-17 and C-20 joining the steroidal side chain to the nucleus had no deleterious effect on the growth process but only if C-22 was trans-oriented to C-13. In the cis-case no growth at all proceeded. This means the natural sterol probably acts functionally in the form of its preferred conformer in which C-22 is to the right ("right-handed") in the usual view. Since the placing of a substituent (OH or CH3) in the molecule at C-20 in such a way that it appears on the front side in the right-handed conformer completely destroyed activity, the sterol apparently presents its front face to protein or phospholipid when complexing occurs.
TL;DR: The growth conditions known to influence the occurrence of mitochondrial profiles and other cell membrane systems in anaerobic cells of S. cerevisiae have been examined, and the effect of the several growth media on the lipid composition of the organism has been determined.
Abstract: The growth conditions known to influence the occurrence of mitochondrial profiles and other cell membrane systems in anaerobic cells of S. cerevisiae have been examined, and the effect of the several growth media on the lipid composition of the organism has been determined. The anaerobic cell type containing neither detectable mitochondrial profiles nor the large cell vacuole may be obtained by the culture of the organism on growth-limiting levels of the lipids, ergosterol, and unsaturated fatty acids. Under these conditions, the organism has a high content of short-chain saturated fatty acids (10:0, 12:0), phosphatidyl choline, and squalene, compared with aerobically grown cells, and it is especially low in phosphatidyl ethanolamine and the glycerol phosphatides (phosphatidyl glycerol + cardiolipin). The high levels of unsaturated fatty acids normally found in the phospholipids of the aerobic cells are largely replaced by the short-chain saturated acids, even though the phospholipid fraction contains virtually all of the small amounts of unsaturated fatty acid present in the anaerobic cells. Such anaerobic cells may contain as little as 0.12 mg of ergosterol per g dry weight of cells while the aerobic cells contain about 6 mg of ergosterol per g dry weight. Anaerobic cell types containing mitochondrial profiles can be obtained by the culture of the organism in the presence of excess quantities of ergosterol and unsaturated fatty acids. Such cells have increased levels of total phospholipid, ergosterol, and unsaturated fatty acids, although these compounds do not reach the levels found in aerobic cells. The level of ergosterol in anaerobic cells is markedly influenced by the nature of the carbohydrate in the medium; those cells grown on galactose media supplemented with ergosterol and unsaturated fatty acids have well defined mitochondrial profiles and an ergosterol content (2 mg per g dry weight of cells) three times that of equivalent glucose-grown cells which have poorly defined organelle profiles. Anaerobic cells which are low in ergosterol synthesize increased amounts of squalene.
TL;DR: These studies provide a basis for exploring the properties of the fatty acids and phospholipids required for the formation, structure, and function of membranes.
Abstract: Unsaturated fatty acids having structural features which are different from those of the monoenoic acids normally synthesized by Escherichia coli can serve as growth factors for an auxotroph requiring unsaturated fatty acids. These analogues were incorporated into the phospholipids, as shown by gas-liquid and thin-layer chromatographic analysis of the phospholipid fatty acid composition. Some of these fatty acids were cisΔ5- and cis-Δ9-tetradecenoic, cis-Δ11-eicosenoic, cis,cis-Δ11,14-eicosadienoic, cis,cis,cis-Δ11,14,17-eicosatrienoic, trans-Δ9- and trans-Δ11-octadecenoic acids. Although partial degradation of some of these analogues to shorter even-chain homologues occurred, chain elongation of the exogenous fatty acids was not detected. Trans-olefinic acids were utilized without stereochemical or positional isomerization. These studies provide a basis for exploring the properties of the fatty acids and phospholipids required for the formation, structure, and function of membranes.
TL;DR: Cholesterol-enriched cells contained about 2% more lipid than cells enriched in any of the other sterols, which was largely accounted for by increased contents of triacylglycerols and, to a lesser extent, esterified sterols.
Abstract: Saccharomyces cerevisiae NCYC 366, grown under strictly anaerobic conditions to induce requirements for an unsaturated fatty acid (supplied by Tween 80) and a sterol, contained free sterol fractions enriched to the extent of 67 to 93% with the exogenously supplied sterol (campesterol, cholesterol, 7-dehydrocholesterol, 22, 23-dihydrobrassicasterol, beta-sitosterol, or stigmasterol). Cells enriched in any one of the sterols did not differ in volume, growth rate, contents of free sterol, esters and phospholipids, or phospholipid composition. Cholesterol-enriched cells contained about 2% more lipid than cells enriched in any of the other sterols, which was largely accounted for by increased contents of triacylglycerols and, to a lesser extent, esterified sterols. Phospholipids were enriched to the extent of about 52 to 63% with C18:1 residues. Cells enriched in ergosterol or stigmasterol were slightly less susceptible to the action of a wall-digesting basidiomycete glucanase than cells enriched with any one of the other sterols. The capacity of the plasma membrane to resist stretching, as indicated by the stability and volume of spheroplasts suspended in hypotonic solutions of buffered sorbitol (particularly in the range 0.9 to 0.7 M), was greater with spheroplasts enriched in sterols with an unsaturated side chain at C17 (ergosterol or stigmasterol) than with any of the other sterols. Plasma membranes were obtained from spheroplasts enriched in cholesterol or stigmasterol and had free sterol fractions containing 70 and 71%, respectively, of the sterol supplied exogenously to the cells. The sterol-phospholipid molar ratios in these membranes were, respectively, 1:7 and 1:8.