Cell-free synthesis of mycolic acids in Mycobacterium aurum: radioactivity distribution in newly synthesized acids and presence of cell wall in the system
| Autor: | Charlotte Lacave, Gilbert Lanéelle, Annaïk Quémard |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
Radioisotope Dilution Technique
Chromatography Gas Stereochemistry Biophysics Acetates Cleavage (embryo) Biochemistry Mycobacterium aurum Mycobacterium Cell-free system Cell wall Hydroxylation chemistry.chemical_compound Endocrinology Biosynthesis Cell Wall Carbon Radioisotopes Cell-Free System biology Hydrolysis biology.organism_classification Mycolic Acids chemistry Peptidoglycan Oxidation-Reduction Derivative (chemistry) |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism. 1045:58-68 |
| ISSN: | 0005-2760 |
| DOI: | 10.1016/0005-2760(90)90203-a |
| Popis: | Distribution of radiolabelling in different parts of the newly synthesized mycolic acids, by a cell-free system from Mycobacterium aurum previously described, is examined, [1-14C]acetate being the precursor. By oxidation cleavage of mycolic acids and examination of the fragments, it was shown that acetate was not uniformly incorporated into the molecule: the methyl terminal part was not labelled, while the central fragments — between unsaturations or between oxygenated functions (oxo or ester) and unsaturations — presented the major part of radioactivity, suggesting the elongation of a preformed compound that the cell-free extract was unable to synthesize. Moreover, the side-chain R2-CH2-COOH was only weakly labelled compared to the central fragments. Since non-hydroxylated fatty acids were not synthesized by the system, it is suggested that de novo C18 fatty acids may be elongated with C2 units by the cell-free extract into C22 fatty derivative, only a low level of labelling being recorded (two C2 units for all the molecule). A scheme is proposed to summarize the main results. Identification of meso-DAP which is a characteristic amino-acid of the peptidoglycan in Actinomycetes and analysis of the profiles of total fatty esters, demonstrated that the cell-free extract is partly constituted by fragments of the cell wall as has already been noticed by examination of micrographs of the extract. |
| Databáze: | OpenAIRE |
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