Etude d'un glycolipide polyinsature synthetise par Mycobacterium phlei
| Autor: | Cécile P. Asselineau, Henri Montrozier, Arlette Savagnac, Michèle Welby, Jean-Claude Promé |
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| Rok vydání: | 1972 |
| Předmět: | |
| Zdroj: | European Journal of Biochemistry. 28:102-109 |
| ISSN: | 1432-1033 0014-2956 |
| DOI: | 10.1111/j.1432-1033.1972.tb01889.x |
| Popis: | Mycobacterium phlei synthesizes an homologous series of polyunsaturated fatty acids, the main member of which is hexatriaconta-4,8,12,16,20-pentaenoic acid. These acids will be refered to as “phleic acids”. Natural derivatives of these acids and their subcellular localization are studied in this paper. A series of esters of trehalose and phleic acids, called “lipids P”, have been isolated from Mycobacterium phlei. They differ by their number of esterified hydroxyl groups. Because of their low stability, it is difficult to make a distinction between natural product and artefact. The main member of this series, lipid P1, has been isolated in an homogeneous form by chromatographic procedures. Saponification of lipid P1 gives only phleic acids and trehalose. Quantitative estimation by gas chromatography, as methyl phleate and trehalose trimethylsilyl ether, and examination of infrared and nuclear magnetic resonance spectra of the whole lipid P1 suggest the structure of octaphleate of trehalose for this lipid. Then lipid P1 is a glycolipid having a strong lipidic character, that differs from most other natural lipid compounds by its high molecular weight (4400) and its high unsaturation (40 double bonds). Lipids P appear to be the main form of phleic acid derivatives. They are located in the outer part of the cell, and can be extracted by a simple washing of the bacteria with hexane; bacterial cells are still living after this treatment. Phleic acids are not obligatory components of mycobacteria, as they have been found in two saprophytic strains (Mycobacterium phlei and Mycobacterium smegmatis), but not in two strains of Mycobacterium tuberculosis and one strain of Mycobacterium bovis (BOG). On the basis of chemical structure, subcellular localization and species distribution, lipids P exhibit analogies with other kinds of esters of trehalose found in some strains of mycobacteria devoid of phleic acids. Although the content of phleic acids in a culture of Mycobacterium phlei reaches a constant value long before the end of the logarithmic phase of growth, phleic acids do not appear to be simple excretion products. They are not storage compounds: unlike common fatty acids, they are neither used when no carbon source is supplied to the medium, nor accumulated when the main nitrogen source of the medium (asparagin) is omitted. An important decrease of the content of phleic acids is observed when the medium is supplemented with a surfactant, which prevents bacterial aggregation. |
| Databáze: | OpenAIRE |
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